FAN7382 design with PWM

[Elec-engineer]

Hi,

Attached is a part of the schematics of the board. DO_TEC_HS and DO_TEC_LS are coming from microcontroller at level 3.3V. My question is when the microcontroller gives a 3.3V,8KHz signal to DO_TEC_HS pins, can the bootstrap circuit handle the speed it? The Vin to this circuit can be from 16v to 60V.

If the DO_TEC-HS is 3.3V (continuously on), the outputs Q8 and Q11 will be on, but my main concern is if the input is 3.3V, 8KHz, I have seen my board works fine in one direction but the other direction output is not right.

Thank you in advance!

 

[amitjagtap]

Check the input deriving volage levels for FAN7382.....DO_TEC_HS and DO_TEC_LS lines should swing between GND and VCC......
Try to give these inputs (with approx 15V ) from function generator..just for testing purpose..n check the output...

 

[Elec-engineer]

I tested the board, when the LO is high, it seems the board was drawing high current so I added a gate resistor of about 50Kohms at Q9.

Also when I checked the DC voltage across the capcitor C29 when Q9 is ON, the DC voltage across the capacitor C29 was almost 12.5 V.
When Ho and Lo are off , the DC voltage across C29 was almost 0V. I thought when the FETs are off, the capacitor should maintain the voltage and it should have read approx 12.5V.
I replaced the capacitor also just to make sure it was not damaged.

Is this value right?
If wrong, what part would have been wrong and causing the capacitor not to maintain the value?

Thank you in advance!