TPS7A4501-SP: power up over voltage

assaf matia

Part Number: TPS7A4501-SP

hi,

feedback resistors are calculated to 3.3V, but when power up the device there is overshoot to 3.6V and then dropping to 3.3V. the time from overshoot until stable is about 20uS

1. is this normal behaviour?

2. can i do anything to fix this?

the resistors I am using are 5.32K, 3.01K and compensation capacitor of 220pF.

I tried to increase the compensation capacitor to 820pF but no change.

please advise.

Thanks

over 5 years ago

0 Kyle Rakos over 5 years ago

TI__Mastermind 20045 points

Hello Assaf,

Is this with the EVM or your own design? Also what is load at startup?

Thanks,
Kyle

0 assaf matia over 5 years ago in reply to Kyle Rakos

Prodigy 220 points

sorry for late respond, i was on vacation.

its not an evm.

load is about 300mA

0 Daniel Hartung over 5 years ago in reply to assaf matia

TI__Mastermind 22065 points

Hey Assaf,

Are you able to measure the frequency response of the design?

Overshoot can happen is the Phase margin is too low or the frequency response is too slow.
Changing the compensation capacitor can help, but without a baseline its hard to know.

One other thing I would ask you to try is increasing the load at start up so see if that helps.

Thanks,
Daniel

0 Daniel Hartung over 5 years ago in reply to Daniel Hartung

TI__Mastermind 22065 points

Hey Assaf,

Were you able to take measurements on the board?
Did the issue resolve itself?

Thanks,
Daniel

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TPS7A4501-SP: power up over voltage