TPS40090: Powerdown on EN Timing

Antonio Fadhel

Part Number: TPS40090
Other Parts Discussed in Thread: TPS40091

Hi Team,

Can you please share what is the expected TPS40090 powerdown timing when EN is pulled low? Should the converter stop switching immediately, or is it dependent on the BP5 discharging below UVLO (similar to the startup on EN timing based on the Cbp5 cap)?

Thanks,

Antonio

over 4 years ago

0 Qian Chen over 4 years ago

TI__Mastermind 24075 points

Hi Antonio,

When EN is pulled low, the part will stop switching immediately.

Thanks

Qian

0 Antonio Fadhel over 4 years ago in reply to Qian Chen

TI__Genius 9410 points

Hi Qian,

Just to confirm, my customer sees on the PWM a 2.3us delay followed by what seems like high impedance (they are testing the controller by itself). If they add a load, it goes to 0V after the 2.3us delay. Is this the expected behavior from the TPS40090 (not TPS40091)? Or should PWM be driven low by the device?

Here is the scope capture:

Ch#4 is the ENABLE/SYNC
Ch#2 is the PWM output
Ch#3 is the 0.7V Ref

Thanks,

Antonio

0 Qian Chen over 4 years ago in reply to Antonio Fadhel

TI__Mastermind 24075 points

Hi Antonio,

Sorry, I can not verify this behavior on EVM as I'm working from home now.

Can you ask customer to check all four PWM pins after EN pin is low?

Thanks

Qian

Power management

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TPS40090: Powerdown on EN Timing