X9C103 changing to MAX5451 or MAX5389

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aless2056

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Guys, I'm going to exchange a digital potentiometer X9C103 that is used connected to the RT of an SG3525.

The goal is to have more resolution, more steps since X9C103 is 100 steps and MAX5451 or MAX5389 is 256 steps.

Controlling the X9C103 today is done by a PICF628A.

The questions are as follows:

1) The Max5451 or Max5389 look the same to me, I just see that the Max5389 is a newer item, I didn't see any difference between them in relation to the X9C103, the more experienced ones tell me.

2) The uc is connected to X9C103 using this board below, in which I have 4 capacitors, I believe it is one for each IC input X9C103 in relation to ground and one on vdd, am I correct?

The pins and outputs of the direct uc can I connect directly to the control pins of the IC Max5451 or Max5389, without putting a resistor or capacitor?
 

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As an example, remembering that I am a beginner in electronics. I'm going to use MAX5389 or MAX5451 in place of the RT resistor on an SG3525. As I know, as an example, which current leaves the SG3525 and passes through the RT, and where I find in the datasheet the maximum current of the resistance of the MAX5389.
 

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Hi,

Please show your schematic. Hand drawn is O.K.

Klaus
--- Updated ---

Hi,

The X9c... is a
* single pot
* non volatile

The newer ones are
* dual pot
* volatile
* different package and pin count

Capacitors on the X9c breakout board: Breakout boards are useful for prototyping and breadboard tests. But if there are 4 capacitors with unknown connection without documentation ... I'd not use it.
The only place where I'd install a single capacitor is across VCC and GND. On every other place it may cause malfunction...with uC interface as well as with SG3xxx operation.

My recommendation: A good device/circuit comes with a good description. Without detailed description it is useless for me.

Klaus
 
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Using an alternative digital potentiometer is easy as long as you send it the correct bytes to control it. Why do you need such precision to control the RT pin on the SG3525 though?

Brian.
 

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The idea is to use the SG3525 with fixed Duty Cycle and change the frequency from 10KHz to 20KHz using a RT with adjustable resistance and a fixed CT.

Today this circuit is made with an X9C103, I want to have more values at 10KHz and 20KHz with an adjustable resistance with more steps (8 bits)
 

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