WEBENCH® Tools/TPS61089: Simulation error? Current increase causes Vout collapse

Andrew V

Part Number: TPS61089

Tool/software: WEBENCH® Design Tools

I am using TPS61089RNRR for Vin = 3.1-5.5V Vout = 10V, 0.7A. Testing of the actual circuit built according to the Webench shows that Vout collapses from 10V to ~4V if the current load reaches 200mA. I suspect that the L1 value given the simulation is wrong; L1= 1.5uH. I would post a schematic if I knew how

over 7 years ago

0 Helen chen over 7 years ago

TI__Mastermind 40080 points

Hi Andrew,

The maximum output capability of TPS61089 would be higher than 10V/1A at Vin=3.1V condition. Its so strange. Let's check your schematics. Or did you make some mistake during the board assembly?

0 Andrew V over 7 years ago

Intellectual 280 points

0 Andrew V over 7 years ago in reply to Andrew V

Intellectual 280 points

This circuit is identical to Webench, yet Vout collapses at I > 200mA

0 Helen chen over 7 years ago in reply to Andrew V

TI__Mastermind 40080 points

Hi Andrew,

The schematic is oK. So please check if the Rlim is well solderd on the board. if it is open, similar phenomenon will happened.

Then please send the inductor spec to me, I need to check whether it is OK in this application.

0 Andrew V over 7 years ago in reply to Helen chen

Intellectual 280 points

L1 is Coilcraft XAL4020-152MEB ( 1.5uH 20% 7.5A 23.6mOhms )

0 Helen chen over 7 years ago in reply to Andrew V

TI__Mastermind 40080 points

Hi Andrew,

The inductor is OK, then please check the solder on the board.

0 Andrew V over 7 years ago in reply to Helen chen

Intellectual 280 points

Rlim is fine. I should've mentioned that the max current clearly depends on the input voltage. @ Vin = 3.1V Imax < 200mA, however @ Vin = 5V, Imax < 500mA.

0 Helen chen over 7 years ago in reply to Andrew V

TI__Mastermind 40080 points

Hi Andrew,

Thanks for the update.

Do you check the onboard voltage? I mean the voltage at the input ceramic cap should be 3.1V.And what is your layout, is it layout according to the TPS61089 user guide?

0 Andrew V over 7 years ago in reply to Helen chen

Intellectual 280 points

Yes, that was a problem - too many interconnected wire leads. Thanks for your help

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WEBENCH® Tools/TPS61089: Simulation error? Current increase causes Vout collapse