A scan chain collects scan chain data from testing of a functional circuit and outputs a scan chain signal containing the scan chain data. A voltage monitor circuit operates to compare a supply voltage against a threshold and assert a reset signal when the supply voltage crosses the threshold. The reset signal resets a flip flop circuit whose output signal controls operation of a logic circuit that blocks passage of the scan chain signal to an integrated circuit probe pad and instead applies a constant logic signal to the probe pad indicating a voltage monitoring error.

A circuit is for coupling test access port (TAP) signals to a Joint Test Action Group (JTAG) interface in an integrated circuit package. An nTRST pin receives a test reset signal, a TMS pin receives a test mode select signal, a testing test access port (TAP) has a test reset signal input and a test mode select signal input, and a debugging test access port (TAP) has a test reset signal input coupled to the nTRST pin and a test mode select signal input coupled to the TMS pin. An inverter has an input coupled to the nTRST pin and an output coupled to the test reset signal input of the testing TAP, and an AND gate has a first input coupled to the output of the inverter, a second input coupled to the TMS pin, and an output coupled to the test mode select input of the testing TAP.

In one embodiment, a device comprises: a first die having disposed thereon a first plurality of latches wherein ones of the first plurality of latches are operatively connected to an adjacent one of the first plurality of latches; and a second die having disposed thereon a second plurality of latches wherein ones of the second plurality of latches are operatively connected to an adjacent one of the second plurality of latches. Each latch of the first plurality of latches on said first die corresponds to a latch in the second plurality of latches on said second die. Each set of corresponding latches are operatively connected. A scan path comprises a closed loop comprising each of said first and second plurality of latches. One of the second plurality of latches is operatively connected to another one of the second plurality of latches via an inverter.

A JTAG interface in an IC includes a test mode select (TMS) pin receiving a TMS signal, a testing test access port (TAP) having a TMS signal input, a debugging test access port (TAP) having a TMS signal and glue logic coupled to receive a first output from the testing TAP and a second output from the debugging TAP. A flip-flop receives input from the testing TAP and the debugging TAP through the glue logic. A first AND gate has output coupled to the TMS signal input of the debugging TAP, and receives input from an output of the flip-flop and the TMS signal. An inverter has an input coupled to receive input from the flip-flop. A second AND gate has output coupled to the TMS signal input of the testing TAP, and receives input from the TMS signal and output of the inverter.

A device comprising includes an output terminal and a first current path from the output terminal to a first reference voltage. The first current path includes a series connection of current electrodes of a first transistor and a second transistor. The first transistor receives at a control electrode a signal to set a desired level of current to be conducted by the first current path. The second transistor generates at a control electrode a feedback signal indicative of an actual current conducted by the first transistor.

A JTAG interface in an IC includes a test mode select (TMS) pin receiving a TMS signal, a testing test access port (TAP) having a TMS signal input, a debugging test access port (TAP) having a TMS signal and glue logic coupled to receive a first output from the testing TAP and a second output from the debugging TAP. A flip-flop receives input from the testing TAP and the debugging TAP through the glue logic. A first AND gate has output coupled to the TMS signal input of the debugging TAP, and receives input from an output of the flip-flop and the TMS signal. An inverter has an input coupled to receive input from the flip-flop. A second AND gate has output coupled to the TMS signal input of the testing TAP, and receives input from the TMS signal and output of the inverter.

The exemplary embodiments of the present invention provides a scan cluster reordering method and apparatus which perform a scan correlation aware scan cluster reordering to reduce a power generated during the scan test and place scan cells having a high correlation to be adjacent to each other by analyzing the correlation between scan cells, and reduce a test power generated during the scan test.

The disclosure describes a novel method and apparatus for improving silicon interposers to include test circuitry for testing stacked die mounted on the interposer. The improvement allows for the stacked die to be selectively tested by an external tester or by the test circuitry included in the interposer.

A device comprising includes an output terminal and a first current path from the output terminal to a first reference voltage. The first current path includes a series connection of current electrodes of a first transistor and a second transistor. The first transistor receives at a control electrode a signal to set a desired level of current to be conducted by the first current path. The second transistor generates at a control electrode a feedback signal indicative of an actual current conducted by the first transistor.

A scan chain collects scan chain data from testing of a functional circuit and outputs a scan chain signal containing the scan chain data. A voltage monitor circuit operates to compare a supply voltage against a threshold and assert a reset signal when the supply voltage crosses the threshold. The reset signal resets a flip flop circuit whose output signal controls operation of a logic circuit that blocks passage of the scan chain signal to an integrated circuit probe pad and instead applies a constant logic signal to the probe pad indicating a voltage monitoring error.