TPS61025: TPS61025 output only ~ 1V

Egis P

Part Number: TPS61025

Hi, Iam doing low power board design and just get ~1V output from TPS61025 VOUT pin. C3 is used low ESR Tantalum Capacitor - KEMET T520B107M006ATE040. Where can be issue ?

Schematic_ESP8266 low power board Sensor_2020-05-11_08-20-55.pdf

over 5 years ago

0 Egis P over 5 years ago

Prodigy 50 points

PCB layout

0 Minqiu Xie over 5 years ago in reply to Egis P

TI__Mastermind 21565 points

Hi Egis:

May you catch a waveform of Vin, Vout, SW for me?

And what's the Vin range and the load condition during startup?

0 Egis P over 5 years ago in reply to Minqiu Xie

Prodigy 50 points

don't own any oscilloscope for waveform.... Vin is around 3V as it comes from 2xAA elements. Load shouldn't be more then 250mA as its ESP8266 module.

Can such part layout make things not to work ?

0 Jasper Li over 5 years ago in reply to Egis P

TI__Mastermind 46905 points

Hi Egis,

the layout is too bad, i would suggest to improve the layout according http://www.ti.com/lit/an/slva773/slva773.pdf?&ts=1589245399494

is the IC damaged? you could measure the input current and pins to GND impedance to check that

0 Egis P over 5 years ago in reply to Jasper Li

Prodigy 50 points

such one is better ?

0 Jasper Li over 5 years ago in reply to Egis P

TI__Mastermind 46905 points

Hi Egis,

from the schematic, the FB should be floating for fixed output voltage

in the layout, the output capacitor should be connected to VOUT short and strong. but i didn't see that in the updated layout..

0 Egis P over 5 years ago in reply to Jasper Li

Prodigy 50 points

FB was connected to VOUT via 0R resistor. So it should be left without any resistor to be floating ?

Updated according your suggestions, I believe all should be fine now.

0 Minqiu Xie over 5 years ago in reply to Egis P

TI__Mastermind 21565 points

Hi Egis:

Yes, the FB should be float for fixed version.

And the layout is much better now.

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TPS61025: TPS61025 output only ~ 1V