TPS61089EVM-742: VIN>VOUT operation

user4724780

Part Number: TPS61089EVM-742
Other Parts Discussed in Thread: TPS61089, TPS55288, TPS61022

Hello,

TPS61089EVM-742 output change to 5.25V.(R1=1M, R2=300k)
VIN=5.5V drive,
Q1. 1st output is 6.0V overshoot.(see attached PDF Fig.1)
        I want to start non overshoot.
Q2. VOUT conected E-load. Load is 0.0A to 3.0A ramp.
        VIN current measurement spike wave and VOUT big ripple.(Fig.2)
        3.0A load, SW pin operate mode DCM? PFM? strange behavior.(Fig.3)

Is there any way to improve on these issues?

wavedatea.pdf

over 3 years ago

0 Helen chen over 3 years ago

TI__Mastermind 40080 points

Dear Sir,

TPS61089 is a boost converter, it doesn't support Vin>Vo application. In your application, I think a buck-boost converter will helps. Like TPS55288.

0 user4724780 over 3 years ago in reply to Helen chen

Prodigy 20 points

Hi Helen,

Thank you. I am affraid...

You recomended TPS55288, but can not you use TPS61022?

TPS61022 have VIN>VOUT pass　through mode.

This choice, Is there any problem?

regards,

0 Helen chen over 3 years ago in reply to user4724780

TI__Mastermind 40080 points

Dear Sir,

TPS61022 is too marginal for the application. Its Max Vin is 5.5V. And the load current is really big, there may exists voltage stress issue on the SW pin in the maximum Vin and maximum load current condition.

TPS55288 will be a better choice.

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TPS61089EVM-742: VIN>VOUT operation