TPSM82866A: TPSM82866AA0SRDJR design review and suggestions.

Hi Chris,

Thanks for review and support

Hi Chris,

I am unable to find the part TPSM82866AH. Can you please share full part number or link?

TPSM82866AA0HRDMR is the full part number.  It's in the same D/S as the other TPSM82864/6 modules.

Chris

Hi Chris,

Can you please explain working of VSET/MODE pin. In datasheet we have observed that after power ON, this pin works as digital input. Applying high level selects PWM mode and LOW selects power saving mode. Please see below snapshot from datasheet.

As per WeBench power designer circuit, it will operate in power saving mode. Do we need to connect it with GPIO or just connect it to GND through a resistor as done by WeBench. Please let us know. It will be very helpful if you can explain it in detail.

Thank you so much.

Hi,

Do you want power save mode or forced PWM mode?

Section 8.4.4 in the D/S goes into this in detail, as well as this app note: https://www.ti.com/lit/an/slvaf64a/slvaf64a.pdf 

Chris

I am confused between both. Which should I use? Which one is better? What are the advantages and disadvantages of both? I am unable to understand through datasheet.

With a high level on the VSET/MODE pin, the device enters forced PWM (FPWM) mode and operates with a constant switching frequency over the entire load range, even at very light loads. This reduces the output voltage ripple and allows simple filtering of the switching frequency for noise-sensitive applications but lowers efficiency at light loads.

Is efficiency at light loads (mA) a concern for you?  If so, use power save mode.  If not, use FPWM mode.

Chris

Okay. For my knowledge, can you please explain what are disadvantages of power save mode over FPWM mode at heavy loads?

They work the same at heavy loads.  The only difference is at light loads.

Chris

So isnt it better to use power save mode?

Understood. Thank you so much for prompt response and support

Hi Chris,

1 more query.

As per WebBench power designer circuit, we have connected VSET/MODE pin to GND through 205K resistor. So, will it operate in power save mode? 

How can we achieve PWM mode in this case? Do we need to use GPIO to make pin HIGH or hard pull-up? It would be very helpful if you could share connection diagram.

Hi,

Got it... Thanks!!