VOLTAGE DOUBLER SWITCHED CAPACITOR CIRCUIT CAPABLE OF DETECTING SHORT CIRCUIT OF FLYING CAPACITOR AND DETECTION METHOD THEREOF

Abstract

The invention provides a voltage doubler switched capacitor circuit capable of detecting short circuit of flying capacitor and a detection method thereof. The voltage doubler switched capacitor circuit provides a way to connect the flying capacitor in parallel to the charging path, and calculate whether it is charged to a predetermined voltage in the designed charging time interval, and then it can effectively detect whether the flying capacitor is short-circuited.

Claims

1. A voltage doubler switched capacitor circuit capable of detecting short circuit of a flying capacitor, comprising: a main voltage source comprising a positive terminal, and a negative terminal electrically connected to a ground side; a voltage output terminal comprising a first output terminal, and a second output terminal electrically connected to said ground side; a first switch having two ends thereof connected in series between said positive terminal of said main voltage source and said first output terminal of said voltage output terminal; two second switches, two third switches and a flying capacitor, one said second switch and one said third switch being connected in series between said positive terminal of said main voltage source and said first output terminal of said voltage output terminal, the other said third switch and said flying capacitor being connected in series and then connected in parallel at the two ends of said second switch, one end of the other said second switch being electrically connected between the other said third switch and said flying capacitor, and the other end of the other said second switch being electrically connected to said ground side; a stabilizing capacitor having two ends thereof respectively connected across said first output terminal and said second output terminal; a first logic gate that controls the on and off of one of said second switches and a second logic gate that controls the on and off of one of said third switches; and a detection circuit having two ends thereof respectively connected across said first output terminal and said second output terminal, said detection circuit comprising a controller, said controller having an input side thereof electrically connected with two comparators, the said input side of said controller being for a charging pulse as a signal input, said controller having an output side thereof outputting plural control signals including a first switch control signal, a second switch control signal and a third switch control signal for controlling said first switch, said second switches and said third switches.

2. The voltage doubler switched capacitor circuit capable of detecting short circuit of a flying capacitor as claimed in claim 1, wherein said first logic gate and said second logic gate each are composed of an OR Gate, said first logic gate having two input terminals thereof respectively connected to said first switch control signal and said second switch control signal output by said output side of said controller, said second logic gate having two input terminals thereof respectively connected to said first switch control signal and said third switch control signal output by said output side of said controller.

3. The voltage doubler switched capacitor circuit capable of detecting short circuit of a flying capacitor as claimed in claim 1, wherein each said comparator comprises a voltage input terminal, and the voltage input terminal of each said comparator comprises a positive phase input terminal and a negative phase input terminal, said positive phase input terminals of said two comparators being respectively provided with a voltage divider across said first output terminal and said second output terminal, so that a divided voltage of a voltage output terminal between the two said voltage dividers input into the two said positive phase input terminals, the two said negative phase input terminals of said two comparators being each provided with a first reference voltage and a second reference voltage as an input.

4. The voltage doubler switched capacitor circuit capable of detecting short circuit of a flying capacitor as claimed in claim 1, wherein the input side of said controller is electrically connected to a timer, said timer is used to determine whether the charging time of said main voltage source to said stabilizing capacitor is less than a preset time.

5. The voltage doubler switched capacitor circuit capable of detecting short circuit of a flying capacitor as claimed in claim 1, wherein the capacitance value of said stabilizing capacitor is greater than that of said flying capacitor, and the capacitance value range of said flying capacitor is 0.5 to 0.05 times that of said stabilizing capacitor.

6. A detection method of a voltage doubler switched capacitor circuit capable of detecting the short circuit of a flying capacitor, comprising the steps of: A: using a first switch with a larger impedance of the voltage doubler switched capacitor circuit for a soft start; B: turning on the first switch to disconnect a second switch and a third switch, so that a main voltage source charges a stabilizing capacitor; C: using a timer of a detection circuit to determine whether the charging time of said main voltage source for said stabilizing capacitor is less than a preset time, if yes, going to step D; if not, going to step H; D: determining whether the divided voltage of a voltage output terminal is greater than a second reference voltage of a second comparator; E: turning on said second switch and turning off said third switch, so that said main voltage source charges a flying capacitor, and said flying capacitor stores the voltage difference as the voltage of said main voltage source; F: turning on said second switch and said third switch to let the voltage of said main voltage source of said flying capacitor be discharged to a stabilizing capacitor connected between the voltage output terminals, so that the voltage output terminal is doubled the voltage of said main voltage source; G: determining whether the divided voltage of one voltage output terminal is greater than a first reference voltage of a first comparator, if yes, going to step I; if not, going to step E. H: turning off the charging pulse and issuing a short-circuit warning. I: turning off the charging pulse.

7. The detection method of a voltage doubler switched capacitor circuit capable of detecting the short circuit of a flying capacitor as claimed in claim 6, wherein the voltage doubler switched capacitor circuit in step A comprises: a main voltage source comprising a positive terminal, and a negative terminal electrically connected to a ground side; a voltage output terminal comprising a first output terminal, and a second output terminal electrically connected to said ground side; a first switch having two ends thereof connected in series between said positive terminal of said main voltage source and said first output terminal of said voltage output terminal; two second switches, two third switches and a flying capacitor, one said second switch and one said third switch being connected in series between said positive terminal of said main voltage source and said first output terminal of said voltage output terminal, the other said third switch and said flying capacitor being connected in series and then connected in parallel at the two ends of said second switch, one end of the other said second switch being electrically connected between the other said third switch and said flying capacitor, and the other end of the other said second switch being electrically connected to said ground side; a stabilizing capacitor having two ends thereof respectively connected across said first output terminal and said second output terminal; a first logic gate that controls the on and off of one of said second switches and a second logic gate that controls the on and off of one of said third switches; and a detection circuit having two ends thereof respectively connected across said first output terminal and said second output terminal, said detection circuit comprising a controller, said controller having an input side thereof electrically connected with two comparators, the said input side of said controller being for a charging pulse as a signal input, said controller having an output side thereof outputting plural control signals including a first switch control signal, a second switch control signal and a third switch control signal for controlling said first switch, said second switches and said third switches.

8. The detection method of a voltage doubler switched capacitor circuit capable of detecting the short circuit of a flying capacitor as claimed in claim 7, wherein each said comparator comprises a voltage input terminal, and the voltage input terminal of each said comparator comprises a positive phase input terminal and a negative phase input terminal, the positive phase input terminals of said two comparators being provided with a voltage divider across said first output terminal and said second output terminal, so that the divided voltage of a voltage output terminal between the two said voltage dividers input into the two said positive phase input terminals, the two said negative phase input terminals of said two comparators being each provided with a first reference voltage and a second reference voltage as an input.

9. The detection method of a voltage doubler switched capacitor circuit capable of detecting the short circuit of a flying capacitor as claimed in claim 6, wherein said detection circuit in Step C further comprises a controller, said controller having an input side thereof electrically connected with two comparators, the said input side of said controller being for a charging pulse as a signal input, said controller having an output side thereof outputting plural control signals including a first switch control signal, a second switch control signal and a third switch control signal for controlling said first switch, said second switches and said third switches.

10. The detection method of a voltage doubler switched capacitor circuit capable of detecting the short circuit of a flying capacitor as claimed in claim 6, wherein the capacitance value of said stabilizing capacitor is greater than that of said flying capacitor, and the capacitance value range of said flying capacitor is 0.5 to 0.05 times that of said stabilizing capacitor.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0018] FIG. 1 is a circuit diagram of the voltage doubler switched capacitor circuit of the present invention.

[0019] FIG. 2 is a diagram of the first conduction state of the voltage doubler switched capacitor circuit of the present invention.

[0020] FIG. 3 is a diagram of the second conduction state of the voltage doubler switched capacitor circuit of the present invention.

[0021] FIG. 4 is a flow chart of the detection method of the voltage doubler switched capacitor circuit in detecting the short circuit of the flying capacitor according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0022] In order to achieve the above-mentioned purpose and effect, the technical means and structure adopted by the present invention, the characteristics and functions of the preferred embodiment of the present invention are described in detail as follows, for the benefit of a complete understanding.

[0023] Please refer to FIGS. 1-3, where FIG. 1 is a circuit diagram of the voltage doubler switched capacitor circuit of the present invention; FIG. 2 is a diagram of the first conduction state of the voltage doubler switched capacitor circuit of the present invention; and FIG. 3 is a diagram of the second conduction state of the voltage doubler switched capacitor circuit of the present invention.

[0024] The circuit of the present invention mainly comprises: a voltage doubler switched capacitor circuit 1 and a detection circuit 2. The detailed structure and connection relationship are as follows:

[0025] The present invention mainly discloses a voltage doubler switched capacitor circuit with a soft start function, and the switched-capacitor charge pump in the circuit is additionally provided with the function of detecting whether the flying capacitor is short-circuited.

[0026] The voltage doubler switched capacitor circuit 1 comprises a main voltage source VDD, a voltage output terminal OUT, a first switch CKC, two second switches CK, two third switches CKB, a flying capacitor C.sub.FLY, a stabilizing capacitor C.sub.OUT, and two logic gates.

[0027] The main voltage source VDD comprises a positive terminal 11, and a negative terminal 12 electrically connected to a ground side 13.

[0028] The voltage output terminal OUT comprises a first output terminal 14, and a second output terminal 15 electrically connected to the ground side 13.

[0029] The first switch CKC has the two ends thereof connected in series between the positive terminal 11 of the main voltage source VDD and the first output terminal 14 of the voltage output terminal OUT.

[0030] One second switch CK and one third switch CKB are connected in series between the positive terminal 11 of the main voltage source VDD and the first output terminal 14 of the voltage output terminal OUT. The other third switch CKB and the flying capacitor C.sub.FLY are connected in series and then connected in parallel at the two ends of the second switch CK. One end of the other second switch CK is electrically connected between the other third switch CKB and the flying capacitor C.sub.FLY, and the other end of the other second switch CK is electrically connected to the ground side 13.

[0031] The two ends of the stabilizing capacitor C.sub.OUT are respectively connected across the first output terminal 14 and the second output terminal 15.

[0032] The two logic gates include a first logic gate 16 that controls the on and off of one of the second switches CK and a second logic gate 17 that controls the on and off of one of the third switches CKB.

[0033] The two ends of the detection circuit 2 are respectively connected across the first output terminal 14 and the second output terminal 15. The detection circuit 2 comprises a controller 21. One input side 211 of the controller 21 is electrically connected with two comparators (first comparator 22, second comparator 23) with two voltage input terminals. The input side 211 of the controller 21 is for a charging pulse CLOCK as a signal input. One output side 212 of the controller 21 outputs plural control signals (first switch control signal 2121, second switch control signal 2122, third switch control signal 2123) that can control the first switch CKC, the second switches CK, and the third switches CKB.

[0034] The above two logic gates each are composed of an OR Gate. Two input terminals 161 of the first logic gate 16 are respectively connected to the first switch control signal 2121 and the second switch control signal 2122 output by the output side 212 of the controller 21. Two input terminals 171 of the second logic gate 17 are respectively connected to the first switch control signal 2121 and the third switch control signal 2123 output by the output side 212 of the controller 21. The input and output comparison table of the first logic gate 16 and the second logic gate 17 is as follows:

[0035] First Logic Gate 16:

TABLE-US-00001 first switch control second switch control signal signal (first input value) (second input value) output value 0 0 0 0 1 1 1 0 1 1 1 1

[0036] Second Logic Gate 17:

TABLE-US-00002 first switch control third switch control signal signal (first input value) (second input value) output value 0 0 0 0 1 1 1 0 1 1 1 1

[0037] It can be seen from the above two comparison tables, the first switch control signal 2121 is combined with the second switch control signal 2122 or the third switch control signal 2123 to form a first input value and a second input value, as long as either input value is not 0, its output value is 1; only when both input values are 0, its output value will be 0.

[0038] The two voltage input terminals of the above-mentioned two comparators (first comparator 22 and second comparator 23) each comprise a positive phase input terminal 221, 231 and a negative phase input terminal 222, 232. The positive phase input terminals 221, 231 of the two comparators (first comparator 22, second comparator 23) are provided with a voltage divider 24 across the first output terminal 14 and the second output terminal 15, so that a divided voltage VDIV of a voltage output terminal between the two voltage dividers 24 input into the two positive phase input terminals 221, 231. The two negative phase input terminals 222, 232 of the two comparators (first comparator 22, second comparator 23) are each provided with a first reference voltage VREFA and a second reference voltage VREFB as an input.

[0039] The input side 211 of the controller 21 is electrically connected to a timer 25. The timer 25 is used to determine whether the charging time of the main voltage source VDD to the stabilizing capacitor C.sub.OUT is less than a preset time.

[0040] The capacitance value of the stabilizing capacitor C.sub.OUT is greater than that of the flying capacitor C.sub.FLY, and the capacitance value range of the flying capacitor C.sub.FLY is 0.5 to 0.05 times that of the stabilizing capacitor C.sub.OUT.

[0041] Please refer to FIG. 4, which is a flow chart of the detection method of the voltage doubler switched capacitor circuit in detecting the short circuit of the flying capacitor according to the present invention. The detection method comprises the following steps:

[0042] Step 31: Use a first switch with the larger impedance of the voltage doubler switched capacitor circuit (as shown in FIGS. 1 to 3) for a soft start.

[0043] Step 32: The first switch is turned on, and a second switch and a third switch are disconnected, so that a main voltage source charges a stabilizing capacitor.

[0044] Step 33: Use a timer of a detection circuit to determine whether the charging time of the main voltage source for the stabilizing capacitor is less than a preset time, if yes, go to step 34; if not, go to step 38.

[0045] Step 34: Determine whether a divided voltage of a voltage output terminal is greater than a second reference voltage of a second comparator.

[0046] Step 35: The second switch is turned on and the third switch is turned off, the main voltage source charges a flying capacitor, and the flying capacitor stores the voltage difference as the voltage of the main voltage source.

[0047] Step 36: The second switch and the third switch are turned on, and the voltage of the main voltage source of the flying capacitor is discharged to a stabilizing capacitor connected between the voltage output terminals, so that the voltage output terminal is doubled the voltage of the main voltage source.

[0048] Step 37: Determine whether the divided voltage of one voltage output terminal is greater than a first reference voltage of a first comparator, if yes, go to step 39; if not, go to step 35.

[0049] Step 38: Turn off the charging pulse and issue a short-circuit warning.

[0050] Step 39: Turn off the charging pulse.

[0051] The voltage doubler switched capacitor circuit in step 31 above comprises:

[0052] a main voltage source VDD comprising a positive terminal 11 and a negative terminal 12 electrically connected to a ground side 13;

[0053] a voltage output terminal OUT comprising a first output terminal 14, and a second output terminal 15 electrically connected to the ground side 13;

[0054] a first switch CKC that has the two ends thereof connected in series between the positive terminal 11 of the main voltage source VDD and the first output terminal 14 of the voltage output terminal OUT;

[0055] two second switches CK, two third switches CKB and a flying capacitor C.sub.FLY, wherein one second switch CK and one third switch CKB are connected in series between the positive terminal 11 of the main voltage source VDD and the first output terminal 14 of the voltage output terminal OUT; the other third switch CKB and the flying capacitor C.sub.FLY are connected in series and then connected in parallel at the two ends of the second switch CK; one end of the other second switch CK is electrically connected between the other third switch CKB and the flying capacitor C.sub.FLY, and the other end of the other second switch CK is electrically connected to the ground side 13;

[0056] a stabilizing capacitor C.sub.OUT with two ends thereof respectively connected across the first output terminal 14 and the second output terminal 15;

[0057] two logic gates including a first logic gate 16 that controls the on and off of one of the second switches CK and a second logic gate 17 that controls the on and off of one of the third switches CKB; and

[0058] a detection circuit 2 with two ends thereof respectively connected across the first output terminal 14 and the second output terminal 15, wherein the detection circuit 2 comprises a controller 21; one input side 211 of the controller 21 is electrically connected with two comparators (first comparator 22, second comparator 23) with two voltage input terminals; the input side 211 of the controller 21 is for a charging pulse CLOCK as a signal input; one output side 212 of the controller 21 outputs plural control signals (first switch control signal 2121, second switch control signal 2122, third switch control signal 2123) that can control the first switch CKC, the second switches CK, and the third switches CKB.

[0059] The two voltage input terminals of the above-mentioned two comparators (first comparator 22 and second comparator 23) each comprise a positive phase input terminal 221, 231 and a negative phase input terminal 222, 232. The positive phase input terminals 221, 231 of the two comparators (first comparator 22, second comparator 23) are provided with a voltage divider 24 across the first output terminal 14 and the second output terminal 15, so that the divided voltage VDIV of a voltage output terminal between the two voltage dividers 24 input into the two positive phase input terminals 221, 231. The two negative phase input terminals 222, 232 of the two comparators (first comparator 22, second comparator 23) are each provided with a first reference voltage VREFA and a second reference voltage VREFB as an input.

[0060] The detection circuit 2 in the step 33 above further comprises a controller 21. One input side 211 of the controller 21 is electrically connected with two comparators (first comparator 22, second comparator 23) with two voltage input terminals. The input side 211 of the controller 21 is for a charging pulse CLOCK as a signal input. One output side 212 of the controller 21 outputs plural control signals (first switch control signal 2121, second switch control signal 2122, third switch control signal 2123) that can control the first switch CKC, the second switches CK, and the third switches CKB.

[0061] The capacitance value of the stabilizing capacitor C.sub.OUT is greater than that of the flying capacitor C.sub.FLY, and the capacitance value range of the flying capacitor C.sub.FLY is 0.5 to 0.05 times that of the stabilizing capacitor C.sub.OUT.

[0062] The problem to be solved by the present invention is that the voltage doubler switched capacitor circuit 1 provides a first switch CKC with a relatively large conduction impedance, which can prevent the inrush current from damaging the load circuit, thereby forming a soft start mechanism, and connects the flying capacitor C.sub.FLY in parallel to the charging path in the soft-start phase, and calculates whether it is charged to the predetermined voltage in the designed charging time interval, and then it can effectively detect whether the flying capacitor C.sub.FLY is short-circuited. If the flying capacitor C.sub.FLY is short-circuited, the current used to charge the stabilizing capacitor C.sub.OUT during the soft-start phase will be shunted to the ground side of the flying capacitor C.sub.FLY short-circuited, causing the voltage output terminal OUT to fail to charge to the rated voltage. If the stabilizing capacitor C.sub.OUT is short-circuited, the voltage output terminal OUT cannot be charged to the rated voltage. The voltage doubler switched capacitor circuit 1 provides a timer 25 as an electronic component for calculating the charging time. In the soft-start charging phase of flying capacitor C.sub.FLY and stabilizing capacitor C.sub.OUT, if the charging time exceeds the preset time, the charging pulse will be stopped to avoid the continuous short current from burning the controller 21. The preset circuit board (not shown) on which the voltage doubler switched capacitor circuit 1 is set is also provided with a preset warning circuit (not shown) that can issue a short alert to warn the flying capacitor C.sub.FLY of the preset circuit board is in a short-circuit state.

[0063] The above are only the preferred embodiments of the present invention, and the scope of the patent of the present invention is not limited thereby. All simple modifications and equivalent structural changes made by using the description and schematic content of the present invention shall be included in the patent scope of the present invention in the same way.

[0064] In summary, the voltage doubler switched capacitor circuit capable of detecting short circuit of flying capacitor and detection method thereof of the present invention can indeed achieve its effect and purpose when used. Therefore, the present invention is truly an invention with excellent practicability. In order to meet the requirements of the invention patent application, the application is filed in accordance with the law. The applicant hopes that the review committee will grant this application as soon as possible to protect the inventor's hard-working invention. If the review committee has any doubts, please feel free to write instructions.