TPS51623: TPS51623 Vout insufficient issue

Hi Hugo,

Can you help check the voltage of B-RAMP? B-RAMP voltage will be the VBOOT voltage.

Thanks

Chasel

Hi Sir,

Thanks for your support.

We are check the B-RAMP found out the R381 is 63.5k, This is not the right design of schematic, We modify it.

But Vout Lower results only 0.916V, We have measured some data for your reference.

 
Pin15(SLEWA)=1.2018V
P27(VREF)=1.698V
Pin24(VFB)=0.9161V
CPU monitor point =0.916V
PWM=800kHz
VOUT=0.916V
Pin11(B-RAMP)=0.9926V

Hugo

Hi Hugo,

Rramp is 150k which means 40mV ramp amplitude now, can you try to change to 100k to see if higher ramp helps to get stable Vout?

You will need to get R381 resistance because changing R386.

Thanks.

Chasel

Hi Sir,

We are change the R381 to 105k Vout is Lower the before, then R381=R386=105k.

Pin15(SLEWA)=1.2011V
P27(VREF)=1.6973V
Pin24(VFB)=0.8247V
CPU monitor point =0.8247V
PWM=800kHz
VOUT=0.8247V
Pin11(B-RAMP)=0.8429V

Hugo

Hi Hugo,

Can you please check SW to see if any double pulse or unstable behavior?

Is there any resistor divider on VSENSE ?

Thanks

Chasel

Hi Sir,

This is 3A Load SW pin,

the VSENSE is VFB Pin? if yes, they are have R351-100R in schematic.

Hi Sir,

Thank you very much,

Please share your mail address for me.

Hugo