TPS65150: VGH output abnormal

Hello user5185699,

Please send a scope plot of the normal and abnormal VGH. Normally if VGH is too low, the device should shut down totally after some time. When you are taking these plots, please plot as well the input voltage close to the input and PGND pins.

"turn off the ignation" means that you are turning off and on the car, is this correct?

Best regards,
Brigitte

Hi Brigitte,

Thank you for your replay.

The answer is Yes for you questioned at the end of your reply.

I have got some plots to show.

The purple line is VGH, the yellow one is VIN, and the iceblue one is VGL.  Other plots are the same. The first plot is normal situation.

The second、third 、fourth plots is abnormal situation,  The differences is the switch time from ignation off to on.

Do you think is the speed of VGL discharge cause the problem？I'll try later.

This is the PCB layout of the design. Please confirm whether it's ok or not.

I'll tell you the discharge test result a moment later.

Thank you for your consideration and I will be looking forward to your reply.

Best regards,
Yang

Hello Yang,

Thank you very much for the scope plots. Could you please check as well CPI and CTRL? As you have a capacitor connected to FDLY, the part has to shut down after roughly 2.5ms to 6.5ms, which seems not to be the case according to VGL. I wonder if there is an issue with the CTRL signal which turns on the VGH output.

Best regards,
Brigitte

Hi Brigitte,

I got the CPI plot when turn off the ignation. But I can't get the CTRL signal plot. The VGH can't output when connected oscillograph probe  no matter how much time between ignation off and on.

The yellow line is CPI, the purple one is VGH and the iceblue line is VGL. 

I connected the CTRL port to I/O of MCU directly. I still cann't understand the function of the CTRL port. Just as a reserved function connect to MCU. Is that ok? 

Best regards,

Yang

Hello Yang,

Only if CTLR is high, VGH will be connected to CPI. Could you plese trigger on a rising edge on CPI and make the same plot as you did above? CTRL is a high impedance input.

Best regards,
Brigitte

Hi Brigitte，

The plot below is the rising edge on CPI. Should I pull up the CTRL signal after VIN turns on and set a pull down resistor to ensure low level after power off.

Hello Yang,

The CTRL signal needs to be high, when the CPI signal needs to be applied to VGH. If the microcontroller connected to CTRL does not deliver a high signal, VGH will stay low. What is the shaping_ctrl signal doing?
If you do not need the gate voltage shaping function, I recommend to connect CTRL to VIN.

Best regards,
Brigitte