Charge Pump and switched capacitor circuit

HW-nut

Joined May 12, 2016
94
I have used switched capacitor charge pumps in many designs for a low current negative supply. Converting +5v to -5v for example.

Only one ic is required.

In operation, an oscillator drives some analog switches that toggle between the input and output of the supply. The capacitor is first connected to the input (+5v) an then switched to the output of the supply except with the positive side of the switched capacitor connected to ground. The negative side of the capacitor is switched to the negative side of the supplies output. This results in a negative output voltage. An output capacitor is used to hold the charge up during the switch cycles.

Switched capacitor designs are also used for filters, this is much more involved.
 

Thread Starter

mishra87

Joined Jan 17, 2016
851
I have used switched capacitor charge pumps in many designs for a low current negative supply. Converting +5v to -5v for example.

Only one ic is required.

In operation, an oscillator drives some analog switches that toggle between the input and output of the supply. The capacitor is first connected to the input (+5v) an then switched to the output of the supply except with the positive side of the switched capacitor connected to ground. The negative side of the capacitor is switched to the negative side of the supplies output. This results in a negative output voltage. An output capacitor is used to hold the charge up during the switch cycles.

Switched capacitor designs are also used for filters, this is much more involved.
Thanks for your reply !!!
I also want to know that is there any difference between switched capacitor and charge pump circuit.
 

bertus

Joined Apr 5, 2008
20,650

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Thread Starter

mishra87

Joined Jan 17, 2016
851
Hello,

Charge pump circuits are mainly used as DC-DC converters:
https://en.wikipedia.org/wiki/Charge_pump
https://www.maximintegrated.com/en/app-notes/index.mvp/id/725
Switched capacitor circuits can be used as filters:
https://en.wikipedia.org/wiki/Switched_capacitor
http://www.swarthmore.edu/NatSci/echeeve1/Ref/FilterBkgrnd/SwitchedCap.html

For the switched capacitor filter circuits, you can also have a look at the attached LMF100 datasheet.

Bertus
Thank you so much !!!
 
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