TPS7A57: REF_PIN_Clarification

Dhanabal Kulandhaivel

Part Number: TPS7A57

Its noted that only one resistor available at the REF pin which is connected between GND and REF pin.

We planned to control the REF pin using DAC for adjusting the O/P voltage. Noted the it doesn't have have the R1 resistor which will be connected between Vout pin and ADJ.

Could you please confirm whether we can able to control the REF pin using External DAC?

over 2 years ago

0 Stephen Ziel over 2 years ago

TI__Mastermind 36485 points

Hi Dhanabal,

You can use a DAC to adjust the output voltage. Please see the following sections in the datasheet.

Section 8.1.16 Current Mode Margining
Section 8.1.17 Voltage Mode Margining

Thanks,

Stephen

0 Dhanabal Kulandhaivel over 2 years ago in reply to Stephen Ziel

Prodigy 110 points

Thanks for your reply.

Assume that margining can be done +/-10% .

0 Stephen Ziel over 2 years ago in reply to Dhanabal Kulandhaivel

TI__Mastermind 36485 points

The TPS7A57 will not limit your ability to margin +/- 10% as the DAC is directly controlling the reference node. So as long as your DAC and associated circuitry is capable of +/- 10%, this should be fine.

Thanks,

Stephen

0 Dhanabal Kulandhaivel over 2 years ago in reply to Dhanabal Kulandhaivel

Prodigy 110 points

Thanks for the response.

0 Dhanabal Kulandhaivel over 2 years ago in reply to Dhanabal Kulandhaivel

Prodigy 110 points

It Helps lot.

0 Dhanabal Kulandhaivel over 2 years ago in reply to Dhanabal Kulandhaivel

Prodigy 110 points

Could you please provide the webbench simulation model or TINA spice model for simulation?

0 Edgar Acosta1 over 2 years ago in reply to Dhanabal Kulandhaivel

TI__Genius 12535 points

Hi Dhanabal,

We have an unencrypted PSpice model readily available in our Product Folder.

TPS7A57_unencrypted_TINA.zip

I have taken the liberty to zip the .lib and .TSC file.

Best,

Edgar Acosta

0 Dhanabal Kulandhaivel over 2 years ago in reply to Edgar Acosta1

Prodigy 110 points

Could you please help to provide the tested circuit?

Getting error as below.

0 Edgar Acosta1 over 2 years ago in reply to Dhanabal Kulandhaivel

TI__Genius 12535 points

Hey Dhanabal,

I have tested the circuit again on my end and changed the REF resistor to 36K to expect a 1.8V output and I did not get any warnings or errors:

Although, you are getting a warning and not an error, have you tried measuring Vout and/or the voltage at the REF pin?

Also, I've seen that for some reason TINA sometimes does not properly connect wire, can you try deleting the wires for the input and reconnecting them?

Best,

Edgar Acosta

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TPS7A57: REF_PIN_Clarification