I am using DS90UB926QSQNOPB in my design.This is a 24-Bit Color FPD-Link III Deserializer

With Bidirectional Control Channel.I have a question regarding Power-down Mode Input Pin.

Below is the description of PDB pin.

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TI recommendations for PDB pin is given below.

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My circuit is given below.

enter image description here

My question is can I connect the PDN circuit to Microcontroller GPIO as shown below.

I need to control power up/down using a microcontroller.

Below is my circuit. Will it make any issues

enter image description here

In the above circuit PD is coming from Microcontroller GPIO

May I know is this circuit is fine or not. Can I control as shown above.


1 Answer 1


Having a 22uF capacitor directly on a MCU output is not OK, the current will be too large when toggling the pin.

If you intend to control the IC anyway with a MCU, you can enable it after power supplies are stable.

So if you do control the pin with MCU, you can leave out the RC delay circuit that would automatically pull the pin high.

  • \$\begingroup\$ Thank you . You mean,If I want to control PDB ,I need to remove the RC circuit and directly connect the Microcontroller GPIO to PDB pin.Please correct me if I am wrong. \$\endgroup\$
    – Hari
    Feb 19 at 6:46
  • \$\begingroup\$ @Hari That is what I said. If you want, you can also drive the RC circuit from MCU instead of from 3.3V directly, so there will be a hardware delay and current limit for the IO pin. There are many solutions, many that are good and many that are not good, and having a 22uF capacitor on an IO pin directly is definitely not good. \$\endgroup\$
    – Justme
    Feb 19 at 6:51
  • \$\begingroup\$ My VDDIO and VDD33_X are same .I will put an RC circuit which can add a delay of 1.5ms.May I know your thoughts \$\endgroup\$
    – Hari
    Feb 19 at 7:49
  • 1
    \$\begingroup\$ @Hari I don't know what to think as I can't know what kind of circuit you will do. But anyway, your original question is answered. \$\endgroup\$
    – Justme
    Feb 19 at 10:45

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