TPS568215: FB terminal control by external

T Kishi

Part Number: TPS568215
Other Parts Discussed in Thread: LM46001

My Customer has question.

Is it possible to set the output voltage from the outside using the FB terminal of TPS 568215?
For example, customer are assuming control from DAC, CPU and so on.
It is an attached image.

TPS568215.pdf

customer are worried about whether output will be affected even if FB changes abruptly.
I would appreciate it if you can comment.

Best Regar

T Kishi

over 7 years ago

0 Vental Mao over 7 years ago

TI__Expert 5745 points

Yes, it can be used like that to adjust Vout, and you had better add a low-pass filter as below.

And for the FB changes abruptly, it may trigger the Vout UVP and Vout will recoverry after hiccup. I'll double check it and give your more detail later.

0 Vental Mao over 7 years ago

TI__Expert 5745 points

Hi
I double check it, the Vout will be stable when FB changes abruptly. For the resistor connect the FB and LPF, its value should be a little big (xxK ohm is better) which can avoid huge current sink into FB abruptly.

0 T Kishi over 7 years ago in reply to Vental Mao

Genius 4425 points

Hi Vental
Thank you for reply.

I understand that it does not seem to be a problem even if there is no LPF in the answer you got.
If you added an LPF, how much time constant would you recommend?

Best Regad
T Kishi

0 Vental Mao over 7 years ago in reply to T Kishi

TI__Expert 5745 points

R=1K，C=100pF

0 Markus Barthold over 7 years ago in reply to Vental Mao

Prodigy 110 points

is this application only suited for the TPS? We want to use the LM46001. The CPU generates an output frequency of e.g. 500Hz. Or how can we controll the output voltage to supply a heater? e.g. switch on/off the stepdown-converter or an external low- or high-side fet.

0 Vental Mao over 7 years ago in reply to Markus Barthold

TI__Expert 5745 points

I don't know about LM46001. you can submit a new thread about this question

Power management

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TPS568215: FB terminal control by external