Charge pumps are a form of DC-DC converter that use a capacitor as the storage element. They often have a higher efficiency and lower cost than inductor based designs when current requirements are low.
Questions tagged [charge-pump]
175 questions
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What are some ways to improve a voltage multiplier?
I am working on a Nixie power supply, but I would like to improve it.
I have 4x9V batteries in series for a total of 36V to be switched across a multiplier.
A (TTL) 555 timer is running astable from only the first 9V battery to generate a 8.5-ish…
Yankee
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14
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Why are charge pumps only used for low current applications?
Typically the most expensive (and hard to get) elements in a SMPS are the inductors. Thus I was wondering if it's possible to use inductor-less switching mode power supplies (i.e. charge pumps) for generic use cases, for example a bench-top power…
Ali Alavi
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What is physically happening when there is a square wave input on the left plate of a capacitor and open circuit on right plate of a capacitor?
Mathematically I understand that through KVL that the output in the first image will match the input square wave. I am trying to understand physically what is happening. How is the voltage transferring across from the left plate to the right…
maldingRookie
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What is that component from the ADP5091 Schematic?
I am looking for an explanation what that component does inside of that circuit.
It can be found on page 3 of the Datasheet of ADP5091:
https://www.analog.com/media/en/technical-documentation/data-sheets/ADP5091-5092.pdf
It would help me out a…
Maurice Pannard
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Charging a circuit to around 10kV from 3V (two AA batteries) for discharge over 20msec
How can I design a circuit that can be charged to around 10kV (somewhere between 5 and 20kV is fine) from two AA batteries (~3V)?
I am going to draw about 20mA over a high resistance load for a short amount of time, around 20 to 50msec. It is okay…
bjarkef
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Voltage doubler
I'm a little lost as to what is going on in this circuit. The book I am reading mentions that the load would see double the voltage of the input voltage. How does this work?
ergodicsum
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dual of voltage doubler
Voltage doublers, like those close to be one stage of Cockroft-walton multipliers, are well known. They allow to double the voltage of an AC input and can be useful at the output of a transformer for instance. Of course, the price is that the output…
MikeTeX
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Any downside to using a charge pump for an op-amp negative supply
Background: I'm often building audio op-amp circuits for various purposes, and for small projects usually prefer single "wall adapter" supply. So for a ground reference I'll either use a simple resistor pair with a capacitor, or better, a spare OP…
Randy
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How come a charge pump works without a reservoir capacitor?
I was trying to understand the charge pump which generates a negative voltage. As far as I understood, the basic operation is as follows:
SquareWaveInput is a 0 to 5V, 10kHz square wave. When the input is high, Q1 is ON and Q2 is OFF. Q1 charges C1…
abdullah kahraman
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Is it safe to "top up" bootstrap capacitors using a charge pump?
This document from TI describes a method to allow use of bootstrapped N-Channel MOSFETS at high duty-cycles, by keeping the bootstrap capacitor "topped up" with an external charge pump, separate from the gate driver IC.
My question is: wouldn't this…
user371366
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EMI in charge pump switching regulator
I want to use a charge pump to convert 5V to regulated 3.3V output. The charge pump I want to use has the switching frequency of 1200 kHz max. Do I need to be concerned about this switching frequency to avoid EMC issues? How is the EMI from charge…
zud
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Having trouble understanding textbook explanation of "hot chassis" in full-wave voltage doubler vs half-wave
The textbook explanation is not doing it for me.
The half-wave voltage doubler shown in Fig. 4-27(a) offers some improvement in safety over the full-wave voltage doubler. Compare Figs. 4-24(a) and 4-27(a). The chassis is always hot in the…
Al T
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TC962 Voltage Doubler - Why the slightly lower output?
I am prototyping this voltage doubler circuit based off the datasheet of the TC962. Capacitors are GRM21BZ71E106KE15L. When applying 9V at the input, the output is 17.96V at no load. When drawing around 67mA using a 215Ohm resistor across the…
Luke Galea
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Charge pump has an unexpected voltage drop with a 1K load
I have been reading this tutorial about how to design a charge pump with BJTs.
I have built my own one, that aims to produce ~-6V instead of the above's -5V. I'm able to reach -6V when no load is connected. However, when I connect a 1K resistor to…
Martel
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Why is a switched-capacitor voltage replicator useful?
The figure below is a switched-capacitor voltage replicator. It is from Reconfigurable Switched-Capacitor Power Converters by Dongsheng Ma and Rajdeep Bondade. You can read it here.
As you can see the output voltage Vout is finally charged to Vin.…
emnha
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