TPS61021A: Startup problem with a load is connected

S. Gaudreau

Part Number: TPS61021A

Hello,

I am testing a design with the TPS61021A.

Input voltage is 0.9V to 1.8V

Output voltage is 2.2V

Output current is 100 mA

I have a design pretty similar to the webench attached. I have more capacitor on the input.

Inductor is the datasheet recommended from Coilcraft.

When I apply the power between 0.9V to 1.8V, with my small load connected (Resistor for 100mA current), the output voltage stays at around 0.7 V.

If I remove the load, the output goes at 2.2V.

What could be the problem ? What needs to be checked first ?

Could it be the enable attached directly to Vin ?

Thanks !

over 6 years ago

0 Helen chen over 6 years ago

TI__Mastermind 40080 points

Dear Sir,

For the TPS61021A, it is recommended to startup at the no load condition. It can't start up with 100mA load current. So please startup at no load, then add the load!

0 S. Gaudreau over 6 years ago in reply to Helen chen

Intellectual 455 points

Hello,

The Webench gives a warning about a minimum voltage but I don't see any warning about a load.

Is it possible to tweak some components to make it work ?

Is there any indication in the datasheet about this ?

In another answer, you are talking about a possibility of 200mA load at startup. I am only at 100mA.

0 Helen chen over 6 years ago in reply to S. Gaudreau

TI__Mastermind 40080 points

Dear Sir,

It is fixed inside the IC, so the startup current can't be changed. you can found the related description on datasheet section 7.3.7: But this 100mA current has big tolerance, it may only less than 50mA when Vin=0.9V. That's why we suggest customer startup at no load.

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TPS61021A: Startup problem with a load is connected