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I am a newbie in electronics. Please correct me if I am wrong. I am replacing a pot with a digital pot (DS3502) in a circuit. The Vcc of the circuit is 12V. But the digital pot can have a maximum of 5.5V as Vcc. I am controlling the digital pot with an Arduino UNO. Can I use 5V from the Arduino as the Vcc of the digital pot and 12V as the Vcc of the circuit? I kept the ground common for both.

The connection is as below:

DS3502 Arduino Uno

VCC --- 5V

GND --- GND

SDA --- A4

SCL --- A5

DS3502 Circuit

RL --- GND

RW --- Circuit

enter image description here

This is a constant current circuit of 21mA, to drive a laser. But I want to slightly tune the intensity of laser using the digital pot. So I am replacing it with digital pot. But I am getting an open connection in the place of resistor. I have only use RL and RW to circuit. RH is kept opened. Do I need to connect RH and V bias to 12V(Vcc of my constant current circuit)? I don't have much knowledge in circuits. Please spare me if I am wrong

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    it depends on the circuit that the digital pot is part of ... a question about incorporating a digital pot into an existing circuit is not related to the Arduino ... it belongs at electronics.stackexchange.com/questions
    – jsotola
    Commented Jul 26, 2023 at 5:37
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    In addition to jsotola's comment, the data sheet of the digital pot will give you the answer, once you know what the operating conditions are, which depend on the specific circuit. Commented Jul 26, 2023 at 6:09
  • I don't know why you guys closed this question. It's about connecting a digital pot to an Arduino. Would you prefer questions about connecting nothing to an Arduino?
    – Nick Gammon
    Commented Jul 26, 2023 at 6:41
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    @NickGammon Since this question is supposed to be asked on SE/EE, I refrained to write an answer and gave a constructive hint how to proceed, even to avoid to post a question at all. The question is clearly off-topic. I would be glad if such questions would not receive positive feedback by an answer. Commented Jul 26, 2023 at 8:20
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    @NickGammon Oh, dear. Reading skills are apparently being lost. Help vampires are sucking my blood. Commented Jul 26, 2023 at 10:56

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If you look at the datasheet it mentions that Vcc can be from 2.5V to 5.5V, and clearly the I2C connection is referenced to Gnd. Therefore you would connect the Uno to the DS3502 in the usual way (Gnd, Vcc, SDA and SCL).

The "digital pot" side has a separate input (V+) which can be from 4.5V to 15.5V.

Can I use 5V from the Arduino as the Vcc of the digital pot and 12V as the Vcc of the circuit?

Your terminology is a bit loose here. You can use 5V from the Arduino to the Vcc pin of the pot (pin 3) and 12V to V+ and RH (pins 6 and 9). The output will be on RW (the wiper, pin 7).

It also looks like you would connect Gnd and RL (pins 2 and 8) to Gnd on the Arduino.

Although, conceivably I think, you could connect Gnd (pin 2) to Gnd on the Arduino, and RL (pin 8) to the Gnd of the "other circuit" - the one you are controlling. It looks like they are separate.

I think you might keep RL and Gnd not connected, to reduce digital noise.

The A0 and A1 pins are for modifying the I2C address.

DS3502 typical wiring

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  • Thank you for your answer. I have updated my circuit diagram. I am getting an open connection in place of pot. I have not connected RH and V bias now. Is it because of that? I don't have much knowledge in circuits. Please spare me if I am wrong
    – Teena
    Commented Jul 26, 2023 at 7:28
  • Also A0 and A1 needs to be connected to Arduino to which pins of Arduino as I already connect the SDA and SCL of pot to A4 and A5 (I2C) of Arduino
    – Teena
    Commented Jul 26, 2023 at 7:33
  • Just connect A0 and A1 to Gnd. They modify the I2C address, if zero (Gnd) it is the published address. The slave address is 1010xx where xx are A1 and A0. So if they are grounded the address will be 101000 in binary (40 in decimal).
    – Nick Gammon
    Commented Jul 26, 2023 at 7:41
  • What is V bias, that you refer to?
    – Nick Gammon
    Commented Jul 26, 2023 at 7:43
  • V+ of the digital pot is what I meant. Thanks a lot for your support. I am a beginner and I wasn't sure about the connections even. Thanks again for all the explanations.
    – Teena
    Commented Jul 26, 2023 at 7:55

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