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tps63020 Vout deviation in power save mode

Kocela Chang

Intellectual 280 points

Hi:

Sorry need you guys help.

1. Could you provide Vout’s deviation in power save mode?

2. Do you have formula about estimating Vout range in power save mode?

3. Why Vout in save mode is a little higher than PWM mode's?

please see sheet2

2061.tps63020 issue.xls

thanks

over 14 years ago

0 Daniel Acevedo over 14 years ago

TI__Genius 17240 points

The TPS6302x is expected to have a higher output voltage in power save (PFM) mode.

This prevents the output voltage from dipping below the set output when a load is applied.

In PFM mode, the feedback is between two points near .500V and .525V which is why the average output is measured at .512.

I have measured this on an evaluation module with no load to demonstrate. The results are visible in the following scope shot:

0 Daniel Acevedo over 14 years ago in reply to Daniel Acevedo

TI__Genius 17240 points

Though we don't have a formula for estimating Vout range in power save mode (PFM), I recommend designing for significant margin using 25mV as the range on Vfb for PFM.

0 Daniel Acevedo over 14 years ago in reply to Daniel Acevedo

TI__Genius 17240 points

The other possibility is to operate in PWM mode where Vfb is specified in the datasheet to be 495-505mV. This will however decrease your efficiency at loads less than approx. 100mA.

0 Kocela Chang over 14 years ago in reply to Daniel Acevedo

Intellectual 280 points

Daniel:

thanks for your detail explanation

do you have the presentation about this PFM principle?

Power management

Power management forum

tps63020 Vout deviation in power save mode