CO-PACKAGED CONTROLLED OVERCURRENT HANDLING
20240204768 ยท 2024-06-20
Inventors
- Daniele MIATTON (Carbonara al Ticino, IT)
- Alessandro PORTESAN (Trovo, IT)
- Massimo Grasso (Trivolzio, IT)
- Sergio Morini (Pavia, IT)
Cpc classification
International classification
Abstract
The application relates to co-packaged controlled overcurrent handling of a power switch assembly. The power switch assembly includes a power switch and an overcurrent handling logic. The overcurrent handling logic includes an overcurrent detection circuit configured to detect an overcurrent condition of a load current of the power switch and to provide an overcurrent detection signal indicative of an overcurrent condition of the load current of the power switch and a discharge current generation circuit coupled to the overcurrent detection circuit, and configured to generate a discharge current to at least partially discharge a control terminal of the power switch responsive to the overcurrent detection signal.
Claims
1. A power switch assembly having an assembly control terminal, a first assembly load terminal, and a second assembly load terminal, comprising: a power switch having a control terminal coupled to the assembly control terminal, a first load terminal coupled to the first assembly load terminal, and a second load terminal coupled to the second assembly load terminal; and overcurrent handling logic coupled between the assembly control terminal and the control terminal and between the second load terminal and the second assembly load terminal, the overcurrent handling logic including: an overcurrent detection circuit coupled between the second load terminal and the second assembly load terminal and configured to detect an overcurrent condition of a load current of the power switch and to provide an overcurrent detection signal indicative of the overcurrent condition of the load current of the power switch; and a discharge current generation circuit coupled to the overcurrent detection circuit, the control terminal, and the second load terminal, wherein the discharge current generation circuit is configured to generate a discharge current to at least partially discharge the control terminal responsive to the overcurrent detection signal.
2. The power switch assembly of claim 1, further comprising: a package configured to enclose the overcurrent handling logic and the power switch, wherein the package comprises the assembly control terminal, the first assembly load terminal, and the second assembly load terminal.
3. The power switch assembly of claim 1, wherein the discharge current is based on a fall time, wherein the fall time defines a timeframe from the detection of the overcurrent condition to a reduction of the load current to a safety load current value.
4. The power switch assembly of claim 1, wherein: the overcurrent handling logic further comprises a control path control circuit coupled between the assembly control terminal and the control terminal, and the control path control circuit is configured to switchably couple the assembly control terminal to the control terminal.
5. The power switch assembly of claim 4, wherein the control path control circuit is configured to decouple the assembly control terminal from the control terminal responsive to the overcurrent detection signal.
6. The power switch assembly of claim 5, wherein the control path control circuit is further configured to maintain the assembly control terminal decoupled from the control terminal until a voltage supplied by a gate driver coupled to the assembly control terminal and the second assembly load terminal falls below a threshold voltage of the power switch.
7. The power switch assembly of claim 1, wherein the discharge current generation circuit is configured to generate the discharge current such that the control terminal is discharged until the load current reaches or falls below a safety load current value.
8. The power switch assembly of claim 1, wherein the overcurrent detection circuit is configured to compensate a temperature coefficient of the overcurrent detection circuit to provide a temperature-compensated overcurrent detection signal.
9. The power switch assembly of claim 8, wherein the overcurrent detection circuit comprises: a current measurement resistor coupled between the second load terminal and the second assembly load terminal, wherein the current measurement resistor has a current measurement temperature coefficient; and a temperature compensation circuit coupled to the current measurement resistor, wherein the temperature compensation circuit has a compensation temperature coefficient, and wherein the compensation temperature coefficient is configured to compensate for the current measurement temperature coefficient.
10. The power switch assembly of claim 8, wherein the overcurrent detection circuit is configured to maintain at least a part of the overcurrent detection circuit in a linear operating region during operation of the power switch assembly.
11. The power switch assembly of claim 9, wherein the temperature compensation circuit comprises: a temperature coefficient compensation circuit having the compensation temperature coefficient; and a linear region maintenance and conversion circuit coupled to the temperature coefficient compensation circuit and configured to maintain at least a part of the temperature coefficient compensation circuit in a linear operating region.
12. The power switch assembly of claim 11, wherein: the temperature compensation circuit further comprises an overcurrent signal output stage coupled to the linear region maintenance and conversion circuit and configured to provide the temperature-compensated overcurrent detection signal based on a comparison of an output of the linear region maintenance and conversion circuit with an overcurrent threshold value.
13. The power switch assembly of claim 9, wherein: the temperature coefficient compensation circuit includes at least one compensation transistor having the compensation temperature coefficient, and the at least one compensation transistor is maintained in the linear operating region.
14. The power switch assembly of claim 11, wherein: the linear region maintenance and conversion circuit is further configured to increase a dynamic range of the temperature-compensated overcurrent detection signal.
15. A method for operating overcurrent handling logic of a power switch assembly, the overcurrent handling logic comprising an overcurrent detection logic and a discharge current generation circuit, the method comprising: detecting an overcurrent condition at a second load terminal of a load current of a power switch to provide an overcurrent detection signal indicative of the overcurrent condition of the load current of the power switch; and at least partially discharging a control terminal of the power switch with the discharge current responsive to the overcurrent detection signal.
16. The method of claim 15, further comprising: maintaining at least a part of the overcurrent detection logic in a linear operating region during operation of the power switch assembly.
17. The method of claim 15, further comprising: compensating a temperature coefficient of the overcurrent detection circuit to provide a temperature-compensated overcurrent detection signal.
18. A power switch assembly having an assembly control terminal, a first assembly load terminal, and a second assembly load terminal, the power switch assembly comprising: a power switch having a control terminal coupled to the assembly control terminal, a first load terminal coupled to the first assembly load terminal, and a second load terminal coupled to the second assembly load terminal; and overcurrent handling logic coupled between the assembly control terminal and the control terminal and between the second load terminal and the second assembly load terminal, the overcurrent handling logic including: an overcurrent detection circuit coupled between the second load terminal and the second assembly load terminal and configured to detect an overcurrent condition of a load current of the power switch, and compensate a temperature coefficient of the overcurrent detection circuit to provide a temperature-compensated overcurrent detection signal, wherein the compensation of the temperature coefficient does not delay the detection of the overcurrent condition; and a discharge current generation circuit coupled to the overcurrent detection circuit and the control terminal, wherein the discharge current generation circuit is configured to generate a discharge current to discharge the control terminal responsive to the temperature-compensated overcurrent detection signal.
19. A power switch assembly having an assembly control terminal, a first assembly load terminal, and a second assembly load terminal, the power switch assembly comprising: a power switch having a control terminal coupled to the assembly control terminal, a first load terminal coupled to the first assembly load terminal, and a second load terminal coupled to the second assembly load terminal; and overcurrent handling logic coupled between the assembly control terminal and the control terminal and between the second load terminal and the second assembly load terminal, the overcurrent handling logic including: an overcurrent detection circuit coupled between the second load terminal and the second assembly load terminal and configured to maintain at least a part of the overcurrent detection circuit in a linear operating region during operation of the power switch assembly, detect an overcurrent condition of a load current of the power switch, and compensate a temperature coefficient of the overcurrent detection circuit to provide a temperature-compensated overcurrent detection signal; and a control terminal control circuit coupled to the overcurrent detection circuit and the control terminal, wherein the control terminal control circuit is configured to control the control terminal responsive to the temperature-compensated overcurrent detection signal.
20. A power switch assembly having an assembly control terminal, a first assembly load terminal, and a second assembly load terminal, the power switch assembly comprising: a power switch having a control terminal coupled to the assembly control terminal, a first load terminal coupled to the first assembly load terminal, and a second load terminal coupled to the second assembly load terminal; and overcurrent handling logic coupled between the assembly control terminal and the control terminal and between the second load terminal and the second assembly load terminal, the overcurrent handling logic including: an overcurrent detection circuit coupled between the second load terminal and the second assembly load terminal and configured to maintain at least a part of the overcurrent detection circuit in a linear operating region during operation of the power switch assembly, detect an overcurrent condition of a load current of the power switch, and compensate a temperature coefficient of the overcurrent detection circuit to provide a temperature-compensated overcurrent detection signal; and a discharge current generation circuit coupled to the overcurrent detection circuit, the control terminal, and the second load terminal, wherein the discharge current generation circuit is configured to generate a discharge current to at least partially discharge the control terminal responsive to the temperature-compensated overcurrent detection signal.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] Implementations of the present implementation will be described with reference to the following appended drawings, in which like reference signs refer to like elements.
[0009]
[0010]
[0011]
[0012]
[0013]
[0014]
[0015]
[0016]
[0017]
[0018] It should be understood that the above-identified drawings are in no way meant to limit the disclosure of the present implementation. Rather, these drawings are provided to assist in understanding the implementation. The person skilled in the art will readily understand that aspects of the present implementation shown in one drawing may be combined with aspects in another drawing or may be omitted without departing from the scope of the present implementation.
DETAILED DESCRIPTION
[0019] The present disclosure generally provides a power switch assembly which includes a power switch and an overcurrent handling logic. The overcurrent handling logic is configured to detect an overcurrent through a load path of the power switch and to generate a discharge current. The discharge current at least partially discharges, in response to the overcurrent detection, a control terminal of the power switch. The discharge current is configured to quickly cause a reduction of the load current to a safe value while not discharging the control terminal too quickly to cause a voltage surge at parasitic inductances coupled in series with the power switch. Further, to avoid erroneous overcurrent detections, an overcurrent detection circuit of the overcurrent handling logic may be temperature-compensated, e.g., the overcurrent detection may be configured to compensate a temperature coefficient of at least a part of the overcurrent detection circuit. Since the temperature compensation is not to impact the detection speed, at least a part of the overcurrent detection may be maintained in a linear operating region. This enables fast detection of an overcurrent while at the same time enabling compensation of a temperature coefficient of at least a part of the overcurrent detection circuit.
[0020] This general concept will be explained with reference to the appended drawings with
[0021]
[0022] Power switch assemblies 10H and 10L are respectively coupled to gate drivers 20H and 20L. Gate drivers 20H and 20L may be any kind of gate driver configured to provide a control signal to a control terminal of a power switch. To this end, gate drivers 20H and 20L may for example be inverters coupled between a high logic supply voltage and a low logic supply voltage and configured to provide either one of the two logic supply voltages at an output of gate drivers 20H and 20L. The high logic supply voltage may be a voltage level higher than the threshold voltage of power switch 10. In a further example, gate drivers 20H and 20L may include individually controlled switches coupling either one of the two logic supply voltages to the output of gate drivers 20H and 20L. It will be understood that gate drivers 20H and 20L need not be identical in structure. Rather, given the different requirements for a high side gate driver and a low side gate driver, gate drivers 20H and 20L may be specially adapted to these different requirements and may thus differ in structure. Also, in some examples, gate drivers 20H and 20L may form a single half-bridge gate driver controlling both power switch assemblies 10H and 10L.
[0023] Finally, each one of the power switch assemblies 10H and 10L includes a power switch 100 and an overcurrent handling logic 200, which will be discussed in detail with regard to
[0024]
[0025] Power switch assembly 10 has an assembly control terminal T.sub.C, a first assembly load terminal T.sub.L1 and a second assembly load terminal T.sub.L2. Assembly control terminal T.sub.C, first assembly load terminal T.sub.L1 and second assembly load terminal T.sub.L2 may be comprised in a package 10P. Package 10P may thus enclose power switch 100 and overcurrent logic 200.
[0026] Power switch 100 has a control terminal 100.sub.C, a first load terminal 100.sub.L1 and a second load terminal 100.sub.L2. These terminals are respectively coupled to assembly control terminal T.sub.C, first assembly load terminal T.sub.L1 and second assembly load terminal T.sub.L2. As can be seen in
[0027] Power switch 100 may be any kind of power switch configured to have a high voltage blocking capability. For example, power switch 100 may be able to block voltages above at least 400V, such as 450V, 900V, 1200V or 1800V. To achieve such voltage blocking capabilities, power switch 10 may for example be a silicon or silicon carbide (SiC) metal oxide field effect transistor (MOSFET), a silicon or SiC insulated gate bipolar transistor (IGBT) or a Gallium nitride high electron mobility transistor (GaN-HEMT). It will be understood that both the voltage levels and the technology types discussed with regard to power switch 10 are merely provided as an example. The present disclosure may be practiced with other high voltage levels and other power switch technologies than those mentioned here.
[0028] Power switch 100 may, in some implementations of the present disclosure, include current sense capability. That is, power switch 100 may be configured to provide a signal indicative of a load current I.sub.L of power switch 100, e.g., the current flowing between first load terminal 100.sub.L1 and second load terminal 100.sub.L2, to overcurrent handling logic 200, for example. The current sense capability may for example be implemented by branching off a current flowing through some of the transistor cells forming power switch 100, such as 1 or 10 transistor cells. It will be understood that the current sense capability may also be provided in other ways and that in some examples of the present disclosure the current sense capability may not be present. For example, in some examples of the present disclosure, load current may be directly used to detect an overcurrent condition.
[0029] Overcurrent handling logic 200 is coupled between assembly control terminal T.sub.C and control terminal 100.sub.C as well as between second load terminal 100.sub.L2 and second assembly load terminal T.sub.L2. Within overcurrent handling logic 200, assembly control terminal T.sub.C may be coupled to an external control signal line CS.sub.ext, control terminal 100.sub.C may be coupled to an internal control signal line CS.sub.int, second load terminal 100.sub.L2 may be coupled to a load current signal line 100S and second assembly load terminal T.sub.L2 may be coupled to a ground signal line 200G.
[0030] Based on the arrangement between control terminal 100.sub.C and assembly control terminal T.sub.C as well as between second load terminal 100.sub.L2 and second assembly load terminal T.sub.L2, overcurrent detection circuit 200 is configured to detect an overcurrent condition of load current I.sub.L and to handle, e.g., to control, a voltage V.sub.CL2 between control terminal 100.sub.C and second load terminal 100.sub.L2. As will be discussed in the following, overcurrent handling logic 200 can further be configured to detect the overcurrent condition in a temperature-compensated manner and further controls voltage V.sub.CL2 and thereby load current IL in a way which avoids voltage surges at power switch 100 at parasitic inductances, such as parasitic inductance L.sub.par.
[0031] Overcurrent handling logic 200 includes an overcurrent detection circuit 240 and a discharge current generation circuit 230. Overcurrent handling logic 200 may further comprise a power supply generation circuit 210 and a control path control circuit 220. The various circuits of overcurrent handling logic 200 will be discussed in the following.
[0032] Power supply generation circuit 210 may be configured to generate a power supply for at least one of overcurrent detection circuit 240, discharge current generation circuit 230 and control path control circuit 220 based on a voltage supplied by a gate driver, such as gate drivers 20H and 20L of
[0033] Basing the generation of the power supply voltage of overcurrent handling logic 200 on the above-discussed voltage difference may ensure that power switch assembly 10 appears as a regular power switch when looking at the pin-out of power switch assembly 10, e.g., power switch assembly 10 has a pin-out like a power switch without any logic co-packaged with it. Further, such an arrangement may ensure that the internal control provided by overcurrent handling logic 200 cannot turn on power switch 100 if a gate driver controlling power switch assembly 10 provides a turn-off signal to power switch assembly 10.
[0034] One example implementation of power supply generation circuit 210 according to the present disclosure is shown in
[0035] It will be understood that in some example implementations of overcurrent handling logic 200, the functionality of power supply generation circuit 210 may be integrated into at least one of overcurrent detection circuit 240, discharge current generation circuit 230 and control path control circuit 220. That is, in such example implementations, overcurrent handling logic 200 may not include power supply generation circuit 210. Instead, overcurrent detection circuit 240, discharge current generation circuit 230 and control path control circuit 220 may in such example implementations implement their individual power supplies based on the voltage difference between control signal line CS.sub.ext and ground signal line 200G. Also, in some example implementations of overcurrent handling logic 200, overcurrent detection circuit 240, discharge current generation circuit 230 and control path control circuit 220 may not require a power supply and may be operated based on the detection of an overcurrent condition of load current I.sub.L. In other words, in such example implementations, an overcurrent detection signal 240S, which will be discussed later, may provide the power to operate overcurrent detection circuit 240, discharge current generation circuit 230 and control path control circuit 220. It will further be understood that both approaches, e.g., providing operating power to the components of overcurrent handling logic 200 based on the voltage difference between control signal line CS.sub.ext and ground signal line 200G and based on the load current I.sub.L may be mixed. That is, in some example implementations, some components of overcurrent handling logic 200 may be supplied by one of power supply generation circuit 210 or internal power supply and some components may be supplied by overcurrent detection signal 240S.
[0036] Control path control circuit 220 may be coupled between assembly control terminal T.sub.C and control terminal 100.sub.C and may be configured to switchably couple assembly control terminal T.sub.C to control terminal 100.sub.C. In the context of the present disclosure, switchably coupling may refer to the fact that control path control circuit 220 may be configured to switch between a variety of coupling states, which may for example include a decoupling state and a coupling state. In the decoupling state, control path control circuit 220 may provide a high impedance between assembly control terminal T.sub.C and control terminal 100.sub.C while at the same time enabling sinking of a current from control terminal 100.sub.C to assembly control terminal T.sub.C. In the coupling state, control path control circuit 220 may provide a low impedance between assembly control terminal T.sub.C and control terminal 100.sub.C, thereby enabling control of the control terminal 100.sub.C via external control signal line CS.sub.ext. In other words, control path control circuit 220 may switchably couple external control signal line CS.sub.ext to internal control signal line CS.sub.in. Control path control circuit 220 may thereby enable overcurrent handling logic 200 to switch between external control via an external gate driver and internal control via overcurrent handling logic 200 following the detection of an overcurrent condition. Therefore, control path control circuit 220 may in some implementations be configured to decouple assembly control terminal T.sub.C from control terminal 100.sub.C responsive to overcurrent detection signal 240S.
[0037] Control path control circuit 220 may further be configured to keep (maintain) assembly control terminal T.sub.C and thus external control signal line CS.sub.ext decoupled from control terminal 100.sub.C (and thus internal control signal line CS.sub.int) until a voltage supplied by an external gate driver coupled to assembly control terminal T.sub.C and second assembly load terminal T.sub.L2 falls below a threshold voltage of power switch 100 and/or until another predefined condition is met, such as when the detected overcurrent condition has passed. That is, control path control circuit 220 may keep (maintain) power switch assembly 10 in an internal control state until an external gate driver stops to supply a turn-on signal to power switch assembly 10.
[0038] One example implementation of control path control circuit 220 according to the present disclosure is shown in
[0039] Control path switch 221 may, based on one of a signal from gate driver 224, control path modulation signal 230S or overcurrent detection signal 240S, switchably couple external control signal line CS.sub.ext to internal control signal line CS.sub.int.
[0040] Gate driver 224 may be a gate driver similar to gate drivers 20H and 20L and may be configured to couple control path switch 221 to a voltage level causing control path switch 221 to be in a conductive state and to a voltage level causing control path switch 221 to be in a blocking state based on overcurrent detection signal 240S. These voltage level may for example correspond to power supply line 210S and to ground signal line 200G or may be derived by gate driver 224 from power supply line 210S and from ground signal line 200G (connection to ground signal line 200G not shown in
[0041] Alternatively, control path switch 221 may be directly coupled to overcurrent detection signal 240S in a manner ensuring that control path switch 221 decouples external control signal line CS.sub.ext from internal control signal line CS.sub.int if overcurrent detection signal 240S indicates an overcurrent condition. To this end, control path switch 221 may for example be a normally-on device or overcurrent detection signal 240S may be invertedly provided to control path switch 221. Further, control path switch 221 may receive control path modulation signal 230S determined by overcurrent detection circuit 240, which will be discussed below. Accordingly, in some implementations of the present disclosure, control path control circuit 220 may be controlled by overcurrent detection circuit 240.
[0042] Resistor 223 may, if control path switch 221 couples external control signal line CS.sub.ext to internal control signal line CS.sub.int, provide a current to control terminal 100.sub.C based on the voltage applied by an external gate driver at assembly control terminal T.sub.C.
[0043] Diode 222 is coupled in parallel with control path switch 221. The cathode of diode 222 is coupled to external control signal line CS.sub.ext and the anode of diode 222 is coupled to internal control signal line CS.sub.int. Accordingly, diode 222 is reverse biased while an external gate driver applies a voltage to assembly control terminal T.sub.C exceeding the voltage level of internal control signal line CS.sub.int. However, diode 222 may become forward biased and thus conductive if an external gate driver pulls a voltage applied at assembly control terminal T.sub.C below the voltage level of internal control signal line CS.sub.int. Based on this arrangement of diode 222, diode 222 may provide a path to sink current from control terminal 100.sub.C if an external gate driver indicates that power switch assembly should be turned into a blocking state. This may expedite switching power switch 100 to the blocking state. Diode 222 may be a body diode of control path switch 221 or may be a freewheeling diode provided with control path switch 221. It will be understood that diode 222 may be omitted in implementations of the present disclosure which do not require the current sinking functionality provided by diode 222.
[0044] Discharge current generation circuit 230 is coupled to overcurrent detection circuit 240, control terminal 100.sub.C and second load terminal 100.sub.L2 via ground signal line 200G. Based on this arrangement, discharge current generation circuit 230 is configured to generate a discharge current I.sub.dis to at least partially discharge control terminal 100.sub.C responsive to overcurrent detection signal 240S. In other words, discharge current generation circuit 230 at least partially discharges control terminal 100. For example, discharge current generation circuit 230 may at least partially discharge a capacitance of power switch 100 at control terminal 100, by providing the discharge current I.sub.dis, which flows from control terminal 100.sub.C to second load terminal 100.sub.L2.
[0045] The discharge current I.sub.dis may be based on a fall time t.sub.fall, wherein fall time t.sub.fall defines a timeframe from the detection of the overcurrent condition of load current I.sub.L to a reduction of the load current I.sub.L to a safety current value I.sub.safe. Safety current value I.sub.safe may for example correspond to a safety voltage level V.sub.safe of voltage V.sub.CL2. That is, timeframe t.sub.fall approximately determines a rate of change over time of load current I.sub.L. While this changing of load current I.sub.L may lead to a voltage surge due to parasitic inductance L.sub.par, timeframe t.sub.fall is determined such that such voltage surge is acceptable in light of a maximum blocking voltage of power switch 100. In other words, for a given application, fall time t.sub.fall is determined based on a difference between the load current I.sub.L and safety current value I.sub.safe and based on the parasitic inductance L.sub.par and maximum blocking voltage of the power switch 100, such that a voltage across the first load terminal 100.sub.L1 and second load terminal 100.sub.L2 of the power switch 100, including a voltage surge caused by a change of the load current I.sub.L, does not exceed the maximum blocking voltage of the power switch 100. This will be discussed in more detail in the following with regard to the upper signaling diagram of
[0046] The upper signaling diagram of
[0047] In equation (1),
represents the rate of change of the load current. As can be seen from equation (1), the rate of change of the load current leads to a voltage surge, which increases the voltage at first load terminal 100.sub.L1 from voltage level V.sub.DC+ to voltage level V.sub.over and thus increases voltage V.sub.L1L2. In
[0048] As can be seen in the upper signaling diagram of
[0049] The lower signaling diagram of
[0050] As can be seen from the above discussion of the upper signaling diagram of
[0051] This equation is derived from equation (1) relating to the voltage at parasitic inductance L.sub.par and the parameters discussed with regard to the upper signaling diagram of
[0052] ?I.sub.L may also be expressed by the load current density ?J.sub.L having the unit A/mm.sup.2, which is a technology parameter of power switch 100. Accordingly, equation (2) can also be expressed based on the area A.sub.a of power switch 100 as shown in equation (3):
[0053] The discharge current I.sub.dis of power switch 100 may generally be approximated as shown in equation (4):
[0054] In the above equation, g.sub.m denotes the transconductance of power switch 100, which may be determined according to equation (5):
[0055] In other words, transconductance g.sub.m may be determined by dividing the capacitance C.sub.100C of control terminal 100.sub.C by the fall time tai. Therefore, the discharge current I.sub.dis may be calculated according to equation (6), which is based on equations (4) and (5):
[0056] Since the capacitance C.sub.100C of control terminal 100.sub.C can be expressed as the product of a control terminal capacitance density c.sub.100C,u, e.g., a technology parameter of power switch 100, and the area A.sub.a of power switch 100, the discharge current I.sub.dis can be calculated by replacing capacitance C.sub.100C in equation (6) as shown in equation (7):
[0057] Finally, inserting equation (3) for fall time t.sub.fall in the above equation for the discharge current I.sub.dis leads to the equation (8):
[0058] As can be seen, area A.sub.a of power switch 100 cancels out. The discharge current I.sub.dis can thus be determined independent of the area of power switch 100. Thus, based on the fall time t.sub.fall, technology parameters of power switch 100 and parasitic inductance L.sub.par, a current value of the discharge current I.sub.dis can be determined, which quickly discharges control terminal 100.sub.C while avoiding voltage levels of overcurrent voltage V.sub.over which exceed the breakdown voltage of power switch 100. Note that the value I.sub.dis determined using equation (8) represents a maximum value for a given parasitic inductance L.sub.par value to achieve fastest discharge of control terminal 100.sub.C under the noted boundary conditions, and a lower value of I.sub.dis may be used to account for variations of the parameters entering into equation (8) to provide for a safety margin, for example. All parameters necessary to determine the discharge current I.sub.dis can be determined based on safety voltage level V.sub.safe, safety current value I.sub.safe, technology parameters of power switch 100 and an approximation of parasitic inductance L.sub.par, for example based on the traces on a printed circuit board on which power switch assembly 10 is placed. Discharge current I.sub.dis may for example be an essentially constant current having, as an upper limit, a value that is determined based on equation (8) above. Essentially constant is to be construed, in this case, as a current that does not drop more than up to a maximum predetermined fraction, for example up to 10%, up to 20%, up to 30%, up to 40%, or up to 50%, below a nominal value of discharge current I.sub.dis, excluding switching on or switching off transitions of the discharge current. In implementations, discharge current I.sub.dis can be an essentially constant current having a value that is lower than the maximum value, for example a current value below the maximum value according to safety margin, such as 5% or 10% or 20% or up to 50% lower than the maximum value.
[0059] Discharge current generation circuit 230 may be implemented in accordance with the above discussion as shown in
[0060] In the implementation of discharge current generation circuit 230 shown in
[0061] As previously discussed, to enable overcurrent handling logic 200 to control the power switch 100 when an overcurrent condition of the load current I.sub.L is detected, control terminal 100C needs to be decoupled from assembly control terminal T.sub.C. To this end, switch 221 may be in a conducting state while switch 231 is in a blocking state and vice versa, as indicated by voltages V.sub.221 and V.sub.231 in the middle signal diagram of
[0062] Discharge current generation circuit 230 of
[0063] Overcurrent detection circuit 240 is coupled between second load terminal 100.sub.L2 and second assembly load terminal T.sub.L2 and provides overcurrent detection signal 240S. As will be discussed in the following, overcurrent detection circuit 240 is configured to detect an overcurrent condition of load current I.sub.L and to compensate a temperature coefficient of overcurrent detection circuit 240 in order to prevent erroneous detections of overcurrent conditions. Overcurrent detection signal 240S may thus also be referred to as temperature-compensated overcurrent detection signal 240S.
[0064] Power switch 100 may for example be switched at switching frequencies up to the kHz range or even above. Accordingly, overcurrent detection circuit 240 needs to detect an overcurrent condition of load current I.sub.L in a short time frame, such as 100 ns. In order to comply with such a detection speed requirement, overcurrent detection circuit 240 is configured to maintain at least a part of overcurrent detection circuit 240 in a linear operating region during operation of power switch assembly 10. Power switch assembly 10 is in operation while an external gate driver applies a voltage across assembly control terminal T.sub.C and second assembly load terminal T.sub.L2. The linear operating region refers to an operating region of a semiconductor device, such as a MOSFET or a bipolar junction transistor (BJT), in which the semiconductor device behaves like a voltage-controlled current source. In other words, in the linear operating region a change of the gate voltage of the semiconductor device causes a proportional and essentially instant change of the current through the semiconductor device. Such a behavior enables fast response to a signal, such as a signal indicative of load current I.sub.L.
[0065] With overcurrent detection circuit 240 maintaining at least a part of overcurrent detection circuit 240 in the linear operating mode, overcurrent detection circuit 240 is further configured to detect an overcurrent condition of load current I.sub.L in a manner complying with the detection speed requirement discussed above. This enables overcurrent detection circuit 240 to compensate a temperature coefficient of the overcurrent detection circuit to provide temperature-compensated overcurrent detection signal 240S while complying with the detection speed requirement. In other words, maintaining at least a part of overcurrent detection circuit 240 in the linear operating mode, enables overcurrent detection circuit 240 to compensate the temperature coefficient without delaying the detection of the overcurrent condition.
[0066] For example, as shown in
[0067] As illustrated in
[0068] Temperature coefficient compensation circuit 241T may be coupled to current measurement resistor 242 and to linear region maintenance and conversion circuit 241L and may have the compensation temperature coefficient. Linear region maintenance and conversion circuit 241L may be coupled to temperature coefficient compensation circuit 241T and to overcurrent signal output stage 241O.
[0069] Linear region maintenance and conversion circuit 241L may be configured to maintain at least a part of temperature coefficient compensation circuit 241 T in the linear operating region. Further, linear region maintenance and conversion circuit 241L may also be configured to increase a dynamic range of temperature-compensated overcurrent detection signal 240S.
[0070] Overcurrent signal output stage 241O may be coupled to linear region maintenance and conversion circuit 241L and may be configured to provide temperature-compensated overcurrent detection signal 240S based on a comparison of an output of linear region maintenance and conversion circuit 241L with an overcurrent threshold value. The overcurrent threshold value may for example be inherently generated by temperature coefficient compensation circuit 241T. In such implementations of the present disclosure, overcurrent signal output stage 241O may also be coupled to temperature coefficient compensation circuit 241T.
[0071]
[0072] Accordingly, temperature coefficient compensation circuit 241T may include switches 245.sub.1 to 245.sub.5, bipolar transistors 246.sub.1 and 246.sub.2 and a biasing current source 243. Bipolar transistors 246.sub.1 and 246.sub.2 may also be referred to as compensation transistors. Bipolar transistors 246.sub.1 and 246.sub.2 may be arranged to cause a voltage drop exhibiting the compensation temperature coefficient at current measurement resistor 242 caused by temperature coefficients of bipolar transistors 246.sub.1 and 246.sub.2. This voltage drop may cancel out the current measurement temperature coefficient of resistor 242. Based on the voltage drop, the signal indicative of load current IL may thus be temperature-compensated, which may lead to overcurrent detection signal 240S being temperature-compensated.
[0073] Linear region maintenance and conversion circuit 241L may comprise switches 245.sub.6 and 245.sub.7. Switch 245.sub.6 is arranged with regard to bipolar transistor 256.sub.1 to maintain bipolar transistor 256.sub.1 in the linear operating region. In the implementation of temperature compensation circuit 241 of
[0074] Overcurrent signal output stage 241O may comprise switches 245.sub.8 to 245.sub.12 and a biasing voltage source 244. Switches 245.sub.11 and 245.sub.12 may form a current mirror mirroring the current signal indicative of load current I.sub.L. Transistors 245.sub.8 and 245.sub.9 may be coupled to temperature coefficient compensation circuit 241T to receive the overcurrent threshold value and accordingly couple the output of overcurrent signal output stage 241O to power supply line 210S if the current signal indicative of load current I.sub.L is indicative of an overcurrent condition of load current I.sub.L.
[0075]
[0076] In step 310, method 300 may maintain at least a part of overcurrent detection logic 200 in the linear operating region during operation of power switch assembly 10.
[0077] In step 320, method 300 detects an overcurrent condition at second load terminal 100.sub.L2 to provide overcurrent detection signal 240S.
[0078] In step 330, method 300 may compensate the temperature coefficient of overcurrent detection circuit 240 to provide temperature-compensated overcurrent detection signal 240S.
[0079] In step 340, method 300 generates the discharge current.
[0080] In step 350, method 300 at least partially discharges control terminal 100.sub.C responsive to temperature-compensated overcurrent detection signal 240S with the discharge current.
[0081] While the above discussion of
ASPECTS
[0082] The implementation may further be illustrated by the following aspects.
[0083] In an aspect, a power switch assembly having an assembly control terminal, a first assembly load terminal and a second assembly load terminal, may comprise a power switch having a control terminal coupled to the assembly control terminal, a first load terminal coupled to the first assembly load terminal and a second load terminal coupled to the second assembly load terminal, and an overcurrent handling logic coupled between the assembly control terminal and the control terminal and between the second load terminal and the second assembly load terminal, including an overcurrent detection circuit coupled between the second load terminal and the second assembly load terminal and configured to provide an overcurrent detection signal indicative of an overcurrent condition of a load current of the power switch, and a discharge current generation circuit coupled to the overcurrent detection circuit and the control terminal and configured to generate a discharge current to at least partially discharge the control terminal responsive to the overcurrent detection signal.
[0084] In an aspect, the power switch assembly may further comprise a package configured to enclose the overcurrent handling logic and the power switch, wherein the package comprises the assembly control terminal, the first assembly load terminal and the second assembly load terminal. In an implementation, the package exclusively comprises the assembly control terminal, the first assembly load terminal and the second assembly load terminal and no other or further terminals.
[0085] In an aspect, the discharge current may be based on a fall time, wherein the fall time defines a timeframe from the detection of the overcurrent to a reduction of the load current to a safety load current value.
[0086] In an aspect, the overcurrent handling logic may further comprise a control path control circuit coupled between the assembly control terminal and the control terminal, and the control path control circuit may further be configured to switchably couple the assembly control terminal to the control terminal.
[0087] In an aspect, the control path control circuit may be configured to decouple the assembly control terminal from the control terminal responsive to the overcurrent detection signal.
[0088] In an aspect, the control path control circuit may further be configured to keep or maintain the assembly control terminal decoupled from the control terminal until a voltage supplied by a gate driver coupled to the assembly control terminal and the second assembly load terminal falls below a threshold voltage of the power switch.
[0089] In an aspect, the discharge current generation circuit may be configured to generate the discharge current such that the control terminal is discharged until the load current reaches or falls below a safety load current value.
[0090] In an aspect, the overcurrent detection circuit may be configured to compensate a temperature coefficient of the overcurrent detection circuit to provide a temperature-compensated overcurrent detection signal.
[0091] In an aspect, the overcurrent detection circuit may comprise a current measurement resistor coupled between the second load terminal and the second assembly load terminal, wherein the current measurement resistor has a current measurement temperature coefficient, and a temperature compensation circuit coupled to the current measurement resistor, wherein the temperature compensation circuit has a compensation temperature coefficient, and wherein the compensation temperature coefficient may be configured to compensate the current measurement temperature coefficient.
[0092] In an aspect, the overcurrent detection circuit may be configured to maintain at least a part of the overcurrent detection circuit in a linear operating region during operation of the power switch assembly.
[0093] In an aspect, at least a part of the temperature compensation circuit may be maintained in the linear operating region during operation of the power switch assembly.
[0094] In an aspect, the temperature compensation circuit may comprise a temperature coefficient compensation circuit having the compensation temperature coefficient; and a linear region maintenance and conversion circuit coupled to the temperature coefficient compensation circuit and configured to maintain at least a part of the temperature coefficient compensation circuit in the linear operating region.
[0095] In an aspect, the temperature compensation circuit may further comprise an overcurrent signal output stage coupled to the linear region maintenance and conversion circuit and configured to provide the temperature-compensated overcurrent detection signal based on a comparison of an output of the linear region maintenance and conversion circuit with an overcurrent threshold value.
[0096] In an aspect, the temperature coefficient compensation circuit may include at least one compensation transistor having the compensation temperature coefficient, and the at least one compensation transistor may be maintained in the linear operating region.
[0097] In an aspect, the linear region maintenance and conversion circuit may further be configured to increase a dynamic range of the temperature-compensated overcurrent detection signal.
[0098] In an aspect, the overcurrent handling logic may further comprise a power supply generation circuit configured to generate a power supply for at least one of the overcurrent detection circuit, the discharge current generation circuit and the control path control circuit based on a voltage supplied by a gate driver coupled to the assembly control terminal and the second assembly load terminal.
[0099] In an aspect, a method for operating an overcurrent handling logic of a power switch assembly, the overcurrent handling logic comprising an overcurrent detection logic and a discharge current generation circuit, the method comprising detecting an overcurrent condition at a second load terminal of a load current of the power switch to provide an overcurrent detection signal indicative of the overcurrent condition of the load current of the power switch, and generating a discharge current, and at least partially discharging a control terminal of the power switch with the discharge current responsive to the overcurrent detection signal.
[0100] In an aspect, the method may further comprise maintaining at least a part of the overcurrent detection logic in a linear operating region during operation of the power switch assembly.
[0101] In an aspect, the method may further comprise compensating a temperature coefficient of the overcurrent detection circuit to provide a temperature-compensated overcurrent detection signal.
[0102] In an aspect, a power switch assembly having an assembly control terminal, a first assembly load terminal and a second assembly load terminal, may comprise a power switch having a control terminal coupled to the assembly control terminal, a first load terminal coupled to the first assembly load terminal and a second load terminal coupled to the second assembly load terminal, and an overcurrent handling logic coupled between the assembly control terminal and the control terminal and between the second load terminal and the second assembly load terminal, including an overcurrent detection circuit coupled between the second load terminal and the second assembly load terminal and configured to detect an overcurrent condition of a load current of the power switch, and compensate a temperature coefficient of the overcurrent detection circuit to provide a temperature-compensated overcurrent detection signal, wherein the compensation of the temperature coefficient does not delay the detection of the overcurrent condition, and a discharge current generation circuit coupled to the overcurrent detection circuit and the control terminal and configured to generate a discharge current to discharge the control terminal responsive to the temperature-compensated overcurrent detection signal.
[0103] In an aspect, a power switch assembly having an assembly control terminal, a first assembly load terminal and a second assembly load terminal, may comprise a power switch having a control terminal coupled to the assembly control terminal, a first load terminal coupled to the first assembly load terminal and a second load terminal coupled to the second assembly load terminal, and an overcurrent handling logic coupled between the assembly control terminal and the control terminal and between the second load terminal and the second assembly load terminal, including an overcurrent detection circuit coupled between the second load terminal and the second assembly load terminal and configured to maintain at least a part of the overcurrent detection circuit in a linear operating region during operation of the power switch assembly, detect an overcurrent condition of a load current of the power switch, and compensate a temperature coefficient of the overcurrent detection circuit to provide a temperature-compensated overcurrent detection signal, and a control terminal control circuit coupled to the overcurrent detection circuit and the control terminal and configured to control the control terminal responsive to the temperature-compensated overcurrent detection signal.
[0104] In an aspect, a power switch assembly having an assembly control terminal, a first assembly load terminal and a second assembly load terminal, comprises a power switch having a control terminal coupled to the assembly control terminal, a first load terminal coupled to the first assembly load terminal and a second load terminal coupled to the second assembly load terminal, and an overcurrent handling logic coupled between the assembly control terminal and the control terminal and between the second load terminal and the second assembly load terminal, including an overcurrent detection circuit coupled between the second load terminal and the second assembly load terminal and configured to maintain at least a part of the overcurrent detection circuit in a linear operating region during operation of the power switch assembly, detect an overcurrent condition of a load current of the power switch, and compensate a temperature coefficient of the overcurrent detection circuit to provide a temperature-compensated overcurrent detection signal, and a discharge current generation circuit coupled to the overcurrent detection circuit, the control terminal and the second load terminal and configured to generate a discharge current to at least partially discharge the control terminal responsive to the temperature-compensated overcurrent detection signal.
[0105] The preceding description has been provided to illustrate a power switch assembly including an overcurrent handling logic. It should be understood that the description is in no way meant to limit the scope of the implementation to the precise implementations discussed throughout the description. Rather, the person skilled in the art will be aware that these implementations may be combined, modified or condensed without departing from the scope of the implementation as defined by the following claims.