Degradations detection for MOS-transistors and gate-drivers
In accordance with an embodiment, a method includes: generating a gate voltage for a field-effect transistor in response to an input signal; generating a pulse signal with a pulse length that corresponds to the time that it takes until the gate voltage attains a specific level transition in response to a corresponding level transition in the input signal; and monitoring the pulse signal to detect whether the pulse length is outside a specific range.
1 . A circuit comprising:
a control circuit configured to generate a gate voltage for a field-effect transistor in response to an input signal;
a pulse generator configured to generate a pulse signal, wherein the pulse signal has a pulse length that corresponds to a length of time from a level transition of the input signal to a specific level transition of the gate voltage in response to the level transition of the input signal; and
a monitoring circuit configured to receive the pulse signal and to detect whether the pulse length is outside a specific range.
2 . The circuit of claim 1 , wherein the monitoring circuit is configured to detect whether the pulse length is above a first threshold or below a second threshold.
3 . The circuit of claim 2 , wherein the monitoring circuit is configured to signal an error when the pulse length is above the first threshold or below the second threshold.
4 . The circuit of claim 2 , wherein:
the control circuit comprises a gate driver and the pulse generator; or
the first threshold and the second threshold are parameters stored in a memory.
5 . The circuit of claim 1 , wherein the pulse length represents the time that it takes until the gate voltage reaches a predefined reference voltage subsequent to the level transition in the input signal.
6 . The circuit of claim 5 , wherein the predefined reference voltage is either equal to a target level of the gate voltage or a predefined fraction of the gate voltage.
7 . The circuit of claim 1 , wherein the monitoring circuit is further configured to measure the pulse length, store the measured pulse length in a memory, and signal an error when a currently measured pulse length is outside the specific range.
8 . The circuit of claim 7 , wherein the specific range depends on the measured pulse lengths stored in the memory.
9 . The circuit of claim 1 , further comprising the field-effect transistor.
10 . A method comprising:
generating a gate voltage for a field-effect transistor in response to an input signal;
generating a pulse signal with a pulse length that corresponds to a length of time from a level transition of the input signal to a specific level transition of the gate voltage in response to the level transition of the input signal; and
monitoring the pulse signal to detect whether the pulse length is outside a specific range.
11 . The method of claim 10 , wherein the specific range is between a second threshold and a first threshold.
12 . The method of claim 11 , further comprising signaling an error when the pulse length is above the first threshold or below the second threshold.
13 . The method of claim 11 , wherein:
the first threshold and the second threshold are parameters stored in a memory of a microcontroller; or
the monitoring of the pulse signal is performed by the microcontroller.
14 . The method of claim 10 , wherein generating the pulse signal comprises detecting a time, from the level transition in the input signal, that it takes until the gate voltage reaches a predefined reference voltage.
15 . The method of claim 14 , wherein the reference voltage is either equal to a target level of the gate voltage or a predefined fraction of the gate voltage.
16 . The method of claim 10 , further comprising:
measuring the pulse length;
storing the measured pulse length in a memory; and
signaling an error when a currently measured pulse length is outside the specific range.
17 . The method of claim 16 , wherein the specific range depends on the measured pulse lengths stored in the memory.
18 . A circuit comprising:
a pulse generator comprising a trigger input node and a pulse signal output node;
a gate driver circuit having an input coupled to the pulse signal output node of the pulse generator and an output configured to be coupled to a control node of a switching transistor;
a feedback circuit coupled between the output of the gate driver circuit and a pulse width adjustment input of the pulse generator, wherein the feedback circuit is configured to cause the pulse generator to generate a signal at the pulse signal output node having a pulse width corresponding to a length of time from a level transition of an input signal at the trigger input node to a specific level transition of a gate voltage at the output of the gate driver circuit in response to the level transition of the input signal; and
a pulse width comparator having an input node coupled to the pulse signal output node of the pulse generator, and an output configured to indicate that the pulse width of the signal at the pulse signal output node of the pulse generator is outside of a first range of values.
19 . The circuit of claim 18 , wherein the pulse width comparator comprises:
a processor;
a memory coupled to the processor with instructions stored thereon, wherein the instructions, when executed by the processor enable the processor to:
measure the pulse width of the signal at the pulse signal output node of the pulse generator;
compare the measured pulse width to a first threshold and a second threshold stored in the memory; and
assert an error signal in response to the measured pulse width being less than the first threshold or greater than the second threshold.
20 . The circuit of claim 18 , wherein the feedback circuit comprises:
a sample and hold circuit having an input coupled to the output of the gate driver circuit; and
an amplifier having a first input coupled to an output of the sample and hold circuit, a second input coupled to a node configured to provide a signal representative of a gate driver output target voltage, and an output coupled to the pulse width adjustment input of the pulse generator.