WEBENCH® Tools/TPS61178: TPS611781 Vout issue

John chuang

Part Number: TPS61178
Other Parts Discussed in Thread: TPS61022

Tool/software: WEBENCH® Design Tools

Hello Sir,

I use the TPS611781 for a 5V output without load disconnect function design, and the EN pin is PD/100K to GND to disable.

But use the 4.2V for Vin and got a 3.7V in the Vout when the EN pin is low, if add PU/3.3V on the EN pin and got the output is correct 5V.

Could you give me a advice for the PD EN pin and got the 3.7V in the Vout?

Sincerely,

John

over 6 years ago

0 Jasper Li over 6 years ago

TI__Mastermind 46905 points

Hi John,

it is normal behavior for a boost converter without disconnect function.

EN=L, the device is disable, the VOUT will be VIN-Vd. the Vd is body diode of the high side MOSFET, about 0.4V

EN=H, The device is enable, the VOUT is the setting voltage.

0 John chuang over 6 years ago in reply to Jasper Li

Prodigy 20 points

Hi Jasper,

Thanks for the reply, I need check again if added the disconnect function and measure the P-FET D-side Vout and it will be 0V on the setting EN=L,right?

Sincerely,

John

0 Jasper Li over 6 years ago in reply to John chuang

TI__Mastermind 46905 points

Hi John,

yes.

if the output is only 5V, you can select TPS61022 which integrated the disconnect function.

Power management

Power management forum

WEBENCH® Tools/TPS61178: TPS611781 Vout issue