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Author Topic: Changing Charge Pump frequency  (Read 2229 times)

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Changing Charge Pump frequency
« on: October 13, 2016, 08:49:38 PM »
HI

Planning to use a 57CNCdb25 USB to parallel port unit on my existing parallel port connected CNC  machine.

Have just realised I’m possibly going to have a problem with incompatible charge pump frequencies.
 The 57CNCdb25  generates a 5KHz signal but the breakout board that it will interface to rquires a 12.5KHz input signal.......................

 Does anyone know if it’s possible (and how it can be done) to change the 57CNCdb25 charge pump to generate a 12.5KHz output?. I’m hoping it would likely be a simple software change.

Can anyone help please?

Thanks
Richard 

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Re: Changing Charge Pump frequency
« Reply #1 on: October 23, 2016, 01:24:48 AM »
Unfortunately, not. It is generated in a complex routine that runs at 10 kHz. Most charge-pump controllers will be 'satisfied' with 5 kHz, some very delicate will have problems.
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Re: Changing Charge Pump frequency
« Reply #2 on: October 24, 2016, 11:24:28 PM »
Thanks for the reply - the 5KHz charge pump is not too much of a problem. I built a switched 12.5KHz oscillator using a LM555 IC to replace the 5KHz charge pump and I can see that will work fine for the setup I have here.

Thanks
Richard