Can I use STUSB4710 without using ST1S14? I am already using another DC-DC converter to provide voltage, but there is no feedback pin for the same. So, is it compulsory that I should use ST1S14?

EAbra.3 · ‎2022-12-20

Peter BENSCH · ‎2022-12-21

Of course, a DDCD device other than the ST1S14 can be used. The data sheet for the STUSB4710 also shows how the programmed voltage is set via a voltage divider.

However, if your DCDC has no feedback pin, it can only be a fixed voltage regulator that cannot be set to other voltages. In this case you should choose an adjustable one.

BTW: a similar question has already been asked here, maybe it will help you?

Does it answer your question?

Regards

/Peter

In order to give better visibility on the answered topics, please click on Accept as Solution on the reply which solved your issue or answered your question.

EAbra.3 · ‎2022-12-21

Hi Peter,

Thank you very much for your reply.

However, if your DCDC has no feedback pin, it can only be a fixed voltage regulator that cannot be set to other voltages. In this case you should choose an adjustable one.

Can you please explain your answer in detail. I didn't get the point if there is no feedback pin for DCDC converter and also how should I connect the SEL_PDO if I don't have feedback pin in my DCDC converter.

Thanking you in advance

Peter BENSCH · ‎2022-12-22

Well, I don't know what kind of DCDC you have, so I can't go into details about it.

A DCDC converter normally always has a feedback pin that the converter uses to monitor and readjust the output voltage. This feedback pin is either connected directly to the output voltage in the case of fixed voltage regulators, or via a voltage divider in the case of adjustable ones.

The STUSB4710 now has several open drain outputs that are activated at certain target output voltages and with which the resistors of such a voltage divider can be bridged in order to adjust the divider ratio and thus the output voltage.

Regards

/Peter

In order to give better visibility on the answered topics, please click on Accept as Solution on the reply which solved your issue or answered your question.

EAbra.3 · ‎2022-12-28

Hi Peter,

Thank you very much for the reply.

In my design, I am using EPC2152 as buck converter which converts 48V input to 20V.This buck converter doesn't have feedback pin. So, in order to use STUSB4710 as USB PD, should I use ST1S14 after EPC2152? Or is there any other USB PD that doesn't require FB pin? Please clarify my doubts.

Please find EPC2152 datasheet from attachment.

Thanking you in advance

Peter BENSCH · ‎2023-01-02

EPC2152 is not a complete buck converter, but only a power stage and therefore has no feedback input. If you control the EPC2152 at the HIN and LIN inputs accordingly, you could build a buck converter with a feedback pin and then use it as a DCDC block.

Regards

/Peter

In order to give better visibility on the answered topics, please click on Accept as Solution on the reply which solved your issue or answered your question.

EAbra.3 · ‎2023-01-02

Hi Peter,

Thank you very much for your reply. Now, my question is that, in order to use STUSB4710, should I use another buck converter (like ST1S14) at the output of EPC2152(will it make sense)? Please suggest a solution for this as I cannot avoid EPC2152 in my design.

Thanking you in advance

Peter BENSCH · ‎2023-01-04

Well, a power stage like the EPC2152 needs to be controlled by a suitable PWM controller with dead-time control at HIN and LIN, which can be realised with microcontrollers like the STM32. In addition, the switching frequency is extremely high, which makes the design (passive components, layout, etc.) extremely demanding.

Converters like the ST1S14, on the other hand, only need a few additional components (some passive and maybe a free-wheeling diode) to realise a complete DCDC, but also delivers considerably less output power. However, it does not help you in any way in connection with the EPC2152.

Your wish amounts to a complete development of a DCDC, which the community can hardly help with. It is therefore advisable to contact a local distributor who can support you.

If the problem is solved, please mark this thread as answered by selecting Select as best, as also explained here. This will help other users find that answer faster.

Good luck!

/Peter

In order to give better visibility on the answered topics, please click on Accept as Solution on the reply which solved your issue or answered your question.

Peter BENSCH · ‎2023-01-04

I just saw that this topic has already been partially addressed in another thread.

In order to give better visibility on the answered topics, please click on Accept as Solution on the reply which solved your issue or answered your question.