TPS7A84A: Paralleling Multiple TPS7A84A Devices with adjustable operation(R divider)

Justin Zou

Part Number: TPS7A84A
Other Parts Discussed in Thread: TPS7A57, TPS7A52

Hi,

Could you provide the schematic reference design for paralleling multiple TPS7A84A devices with the adjustable operation(R divider)?

Many thanks,

Justin

over 2 years ago

Stephen Ziel over 2 years ago

TI__Mastermind 37145 points

Hi Justin,

Please ask if you have any questions on this topic at all. If you would like me to help design your parallel LDOs, I can do that if you provide me with your system requirements:

Shown below is a representative schematic to parallel the TPS7A84A LDOs. The feedforward capacitors (C3 and C8) are not required but will provide better performance, per the datasheet (see section 8.1.1.8 in the TPS7A84A datasheet). For your reference, the TPS7A52/3/4 series LDOs are the next generation component to the TPS7A84A, and the TPS7A57 LDO is the next generation component to the TPS7A52/3/4. If you need 5A or less, the TPS7A57 will do that for you without any paralleling. The TPS7A57 also has an orderable reference design if you need even more current:

A Scaleable, High-Current, Low-Noise Parallel LDO Reference Design

All of the values in this notional schematic are placeholders. You will want to use the PARALLEL-LDO-CALC tool to help you select the number of parallel LDOs needed and the ballast resistance. Additional helpful white papers are located here:

Comprehensive Analysis and Universal Equations for Parallel LDO's Using Ballast Resistors
Parallel LDO Architecture Design Using Ballast Resistors

Thanks,

Stephen

Justin Zou over 2 years ago in reply to Stephen Ziel

Prodigy 30 points

Hello Stephen,

Thanks for your reply.

I want to confirm that the SNS pin leaves floating or connects to the output.

Because I don't use the "ANY-OUT". I use the adjustable operation like page 100 in the datasheet.

Thanks for your support.

BR,

Justin

Stephen Ziel over 2 years ago in reply to Justin Zou

TI__Mastermind 37145 points

Hi Justin,

You are correct. Do not connect the SNS pin. Leave the SNS pin floating.

FYI - we have customers using the TPS7A84A in a parallel configuration, so it should work and let me know if you need anything else.

Thanks,

Stephen

Justin Zou over 2 years ago in reply to Stephen Ziel

Prodigy 30 points

Hello Stephen,

Because I need dynamically adjust the voltage by variable resistors. I think that TPS7A57 maybe suit me.

Is TPS7A57 available now?

I can't understand the TPS7A57 Bias pin. if I only connect the cap to the ground and the CP_IN pin connects to VIN.
Is it correct?

Vin=2V, Vout= 0.99-1.21V.

Many thanks,

Justin

Stephen Ziel over 2 years ago in reply to Justin Zou

TI__Mastermind 37145 points

Hey Justin,

Yes, the TPS7A57 is available right now. I'll look at your other questions and reply back by COB tomorrow.

Thanks,

Stephen

Stephen Ziel over 2 years ago in reply to Stephen Ziel

TI__Mastermind 37145 points

Hey Justin,

Hopefully this section in the datasheet helps to clear up the BIAS and CP_IN pin.

In your case you can leave the BIAS pin open and tie CP_IN to VIN. If you need 5A or less, a single LDO should work for you. If you need more than 5A you will want to parallel the TPS7A57 LDOs. See the reference design linked below for details and please let me know if you need anything else.

A Scaleable, High-Current, Low-Noise Parallel LDO Reference Design

Thanks,

Stephen

Power management

Power management forum

TPS7A84A: Paralleling Multiple TPS7A84A Devices with adjustable operation(R divider)