TPS23861: Is TPS23861 possible to use for +/- 24V Power input

Shinichi Inoue

Guru 21686 points

Part Number: TPS23861
Other Parts Discussed in Thread: TPS23841

Dear Specialists,

My customer is considering TPS23861 and has a question.

I would be grateful if you could advise.

---

I'm considering TPS23861 for the original power deliverly system.

Is it possible to use for +/-24V input instead of 48V.

If possible, could you please see the diagram listed below.

(1) VPWR is connected to 24V.

(2) GND marked with blue is connected to -24V.

(3) In this case, AGND(22pin) where should be connected regarding GND pin.

(4) Are there any other points to change?

---

I appreciate your great help in advance.

Best regards,

Shinichi

over 7 years ago

0 Penny Xu over 7 years ago

TI__Genius 15685 points

Hi Shinichi,

Unfortunately, TPS23861 doesn't support 24V input as the port can be turned on when the voltage is >30V. If customer requires 24V input, TPS23841 is the only option for them. How much current is flowing through the cable? Will auto mode be sufficient for your customer? As TPS23841 is an old part and we don't support on the software side, auto mode is recommended. Thanks.

Best regards,

Penny

0 Shinichi Inoue over 7 years ago in reply to Penny Xu

Guru 21686 points

Hi Penny,

Thank you for your reply.

In customer's case, RJ45(+) is +24V(VPWR) and RJ45(-) is -24V.

So there is differentially 48V between RJ45(+) and RJ45(-).

Even in this case, the device is not able to use.

Also, I'll confirm if customers can use TPS23841.

I appreciate your great help.

Best regards,

Shinichi

0 Penny Xu over 7 years ago in reply to Shinichi Inoue

TI__Genius 15685 points

Hi Shinichi,

Sorry I misinterpret your original post. Basically the voltage across the port is still 48V. This should be doable for TPS23861, but this would require both AGND and DGND to be -24V and in turn the 3.3V VDD pin would need to be relative to the -24V GND and not a separate GND. Thanks!

Best regards,

Penny

0 Shinichi Inoue over 7 years ago in reply to Penny Xu

Guru 21686 points

Hi Penny,

Thank you for your reply.

I understand where to connect regarding AGND and DGND.

You mentioned the 3.3V VDD pin would need to be relative to the -24V GND and not a separate GND.

This means VDD pin voltage should be -20.7V, is it correct ?

I appreciate your great help.

Best regards,

Shinichi

0 Shinichi Inoue over 7 years ago in reply to Shinichi Inoue

Guru 21686 points

HI Penny,

Regarding additional question,
I will be waiting for your response.

I appreciate your great help.

Best regards,
Shinichi

0 Penny Xu over 7 years ago in reply to Shinichi Inoue

TI__Genius 15685 points

Hi Shinichi，

Sorry for the delay. Yes, that's correct. Thanks!

Best regards,

Penny

0 Shinichi Inoue over 7 years ago in reply to Penny Xu

Guru 21686 points

Hi Penny,

Thank you for your reply.

I understand.

I'll share with the customer.

I appreciate your great help.

Best regards,
Shinichi

Power management

Power management forum

TPS23861: Is TPS23861 possible to use for +/- 24V Power input