TPS720-Q1: VBIAS always has to be greater than Vout by 1.4V even if a novel feature is not required where the output of the LDO regulates under light loads when the IN pin is left floating?

Kazuhiko Hirano

Genius 11613 points

Part Number: TPS720-Q1

Hello,

At TPS72029, my customer does not want VBIAS to source the light-load drive current when IN pin is left floating.

They would like TPS72029 drive the load only when Vin is available.

In this case, VBIAS still has to be greater than Vout by 1.4V?

My customer would like Vin=VBIAS=3.3V and Vout=2.9V if possible, though.

Best regards,

K.Hirano

over 4 years ago

0 Jason Song over 4 years ago

TI__Mastermind 23361 points

Hi Hirano-san,

The required 1.4V Vbias voltage over Vout is needed to turn on the NMOS pass-fet swtich and even at light loads, this voltage headroom needs to be maintained. With this being said, having a Vin = Vbias = 3.3V for a 2.9V output will not work. The Vbias needs to be 1.4V higher than the output voltage.

Regards,

Jason Song

Power management

Power management forum

TPS720-Q1: VBIAS always has to be greater than Vout by 1.4V even if a novel feature is not required where the output of the LDO regulates under light loads when the IN pin is left floating?