We would need your technical support on a TI product: The gate driver: DRV8705S-Q1.
We encountered a problem of failure of the DRV8705S following a diagnostics validation test ("Test: Short Circuit of SH1 to GND").
*The driver is used to manage two external N-Mosfets (High Side: HS & Low Side: LS): (RDSON=3.3 mΩ) in split HS and LS configuration (with a shunt current resistor of 3mΩ) to control a load of 2Ω resistance.
Ie: In our case, we don’t implement the freewheeling diode in parallel with Load (R=2Ω , L=10uH).
*Diagnosis is performed in “ON STATE” and in “OFF STATE”.
In “ON STATE”: We set VDS_LVL=0.06V
*In “OFF STATE”, we do three consecutive cycles of diagnostics. Each one lasts 4 ms, as follows:
1- Pull-Down_SH1=1 Pull-up_SH1=0
2- Pull-Down_SH1=0 Pull-up_SH1=1
3- Pull-Down_SH1=0 Pull-up_SH1=1
* We launch a cycle with a PWM=100% (Frequency=4Hz) and we apply a short circuit to ground on the signal relied to Pin 21: SH1 of the gate driver.
The gate driver DRV8705S is no more operational following the application of the short circuit.
Investigation of the failure:
*After checking the 2 N-MOSFETS high side and low side and the gate driver, we found a very low impedance between the following pins:
->Interpretation: The internal circuit linked to the measurement of the VDS voltage of the LOW SIDE MOSFET of the 2nd half-bridge is faulty.
1/-Would you have an explanation for the test result?
2/-Why is it the circuit linked to the Low Side Mosfet that was destroyed and not the one linked to the HIGH-SIDE Mosfet (It's "strange")?
Thank you for answering our questions as soon as possible.