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Questions tagged [charge-pump]

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.

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Charge Injection Confusion

I'm having some trouble understanding the effect that charge injection has on capacitors - more specifically, when there is unequal charge on a capacitor. Consider the following circuit: My ...
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43 views

Supply current for dual supply

I have a circuit with 3 op amps who require dual +- 5 volt supplies. The datasheets mention their supply currents at 19 mA ,19 mA and ~5 mA. I intend to provide the -5 volts from a charge pump IC . ...
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Provide opAmp supply voltage using charge pump

I have low power (USB 5V, up to 500mA) available on a microcontroller board I am developing. Because the voltages I am going to measure (1.2-2.3V) using the MCU are not filling the ADC's range (0-3.3V)...
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Medium Power Charge Pumps

I'm working on an MRI research project where I need to power my device with a single BNC cable. Internally my device needs 15V, -8.5V, 5V, 3.3V and 1.2V supplies. The 15V, -8.5V and 1.2V only need ...
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53 views

LM2776 is it normal to have the oscillations in “bursts”

Is it normal LM2776 to oscillate in "bursts": The frequency of the oscillation is OK, but they come in the 8 oscillation bursts every ~9us. Is it normal? The board design and the schematic is ...
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68 views

How can we use the same charge-pumps circuit for varying input voltage?

As I understood it, a charge-pump increases the input voltage by stages Vout=Vin(N+1). In my example, the two stages of charge-pumps, I have Vout=3Vin. So in case of Vin=5.5V this leads to Vout=5.5*(3)...
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67 views

Why doesn't my charge pump work with 1.5v supply?

I have been trying to get the following circuit to work with 1.5V AA battery but it does not work, even though it works fine with a 3.3v supply. I built the multivibrator circuit by discrete ...
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101 views

power efficiency's definition

Power Efficiency is defined as output power/input power, right? And there are a little bit different definition of power efficiency ...output power/(output power+power loss). Is these mean same ...
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187 views

max232 charge pump problem

I have a problem with my MAX232 chip and can't find the solution. The schematic of the chip is in the attachment. The chip is soldered on to a PCB. I've checked all the connections, the supply ...
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78 views

Charge Pump - pre-existing ICs? [closed]

I would like to generate a biasing voltage of around ~300-500V. The load is small, less than 1mA (i.e., ~1W power transfer). Input is 30V DC, so I need a 10x voltage amplification. Normally, given I ...
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120 views

how does a charge pump boost works? [closed]

I have looked how charge pump works and I can understand for example the doubler voltage as it based on charge/discharge of the capacitor. as I have asked one of my student colleagues how it works, ...
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Input of boost converter or charge pump in the energy harvest [closed]

I read some paper about the energy harvest, and lots of paper said the induced voltage from, for example, the thermo-electric harvesting could be as low as tens of millivolts in a realistic case, so ...
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315 views

L6203 H-bridge output current rings in response to step input

I have an L6203 H-bridge connected to a brushed DC motor, and today I was testing the worst-case voltage drops across my 1Ω current sensing resistor with the motor stalled. My setup is as basic as it ...
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150 views

Why is the peak efficiency of most charge pump less than boost converter,but still can be published in IEEE [closed]

I read some paper about boost converter recently ,and find some author will compare the peak efficiency of their boost converter with charge pump,and the highest peak efficiency i saw is 33%,the ...
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124 views

Transfer function of a digital phase frequency detector

I'm confused about the transfer function of a digital phase frequency detector. Why can we say that the pfd output is proportional to the phase error? The pfd (with charge pump) generates current ...
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58 views

Pump Automatic Pressure Control Electronic Switch

What is the name of this small part?
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77 views

Use MAX680 charge pump positive side only?

I'm thinking of using a MAX680 charge pump IC to generate 10V from a 5V source, but I don't need the -10V output. The example here... ...shows four capacitors, presumably two for the +10V and two for ...
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179 views

LM2664 can I use the ceramic capacitors instead of the electrolytic ones?

I need the negative voltage for my OPAMP and I use the LM2664 inverter. I have a very limited space available on my PCB. Is it OK to replace the electrolytic capacitors with the ceramic ones?
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Charge pump to a specific potential somewhere else in the circuit

Just for context: The original problem I was originally trying to solve was measuring current through a shunt whose voltage potential may be outside the range of my control circuit's supply voltage. ...
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102 views

switched capacitor voltage doubler for strobe circuit

I am interested in making an LED blink fast with a low duty cycle. To make the LED bright again (despite the low duty cycle), I thought I'd try to use some sort of charge pump to overdrive the LED. I'...
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303 views

Noise of a charge pump in analog design

I am designing a DAC and have a Vin of 5V. For the analog stage I have a couple of options : Use an Op amp that has +5V in (low audio quality) Use an Opamp that has +-5V in (better audio quality) ...
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219 views

MOSFET Driving On The Cheap And Cheerful

I need (unless I'm XYing) to high side switch a FET pair from a (PIC16) microcontroller in the simplest way possible. They are switching an audio line with significant current (presently the output of ...
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272 views

Negative charge pump problem

I have an 18V 1.5A mains transformer (outputs around 30V peak with no load at 50Hz) followed by a full-bridge rectifier and a filter capacitor: (there would be a schematic here if SE allowed me more ...
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330 views

Charge pump design for pll

I am designing this charge pump for a pll. But the control voltage always stays between 1.7 and 1.8V. Because of this the VCO after this always oscillates at its higher end of frequency. What ...
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273 views

Op amp design for charge pump

This is the charge pump design from Razavi. I want to design the opamp for the circuit, a design for which is as given below. Is the op-amp architecture correct for this circuit, since it requires ...
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1answer
409 views

How to choose reference current in a charge pump circuit?

The figure shows a charge pump circuit using servo loop. The circuit is from Razavi RF Microelectronics text book. How to fix the Iref in the first branch?
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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 ...
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1answer
131 views

Voltage conversion +1V to -3V inside a new IC design

I am looking for a good integrated CMOS solution for creating -3V out of a 1V supply. The -3V are just used for biasing and hence do not load the supply. This means that the solution should be switch ...
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2answers
93 views

SIM card power supply design, from 3V/50mA into 2.7V/10..100mA

I am designing a SIM card with RF radio included. The radio with its CPU needs minimum 2.7V to run. The current consumption is my problem: - for a period of 50msec (during transmission), it requires ...
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171 views

Charge pump for stepping up 9V to 45V

I need to step up a 9V power supply (from a battery) to (at least) 45V, very small output current (less than 1mA, but it may be much less). My purpose is to drive a Russian rod vacuum tube, which ...
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1answer
231 views

DC-DC converter to regulated +/-30V supply

I'm having trouble with a circuit that converts a low DC voltage (e.g. from a wall adapter) to a +/- 30V regulated supply. The circuit has a boost regulator (LT8330) followed by a dual supply ...
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92 views

Can you run a capacitor voltage doubler backwards to center an output between two voltages?

If a charge pump is run backwards, will it transmit power to the load at a voltage roughly centered between the high and low inputs? Will it self-balance? The intent of this circuit is to reduce the ...
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426 views

Charge Pump 9v to 15v?

I need to power a device (it's an analog bucket brigade delay) from a 9v power supply or battery. The device takes 15v. Is there anyway? I have a few 7660s IC chips, if that helps. I've made charge ...
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252 views

Charge Pump Inverter Noise

I'm using an Charge Pump Inverter,MAX899R in free run mode with switching frequency of 500kHz like in the circuit attached. The problem is that I'm seeing a lot of switching noise in the output, much ...
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101 views

Initial input current of voltage inverter

The figure below is a voltage inverter from the book Reconfigurable Switched-Capacitor Power Converters by Dongsheng Ma and Rajdeep Bondade. Link: Reconfigurable Switched-Capacitor Power Converters -...
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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 ...
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Why is this charge-pump regulator less efficient when operating with a lower supply voltage?

I'm currently doing some power analysis for an electronics project and am attempting to make my design more efficient. My design uses a 3V coin cell as it's primary power source. Out of good practice (...
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311 views

Circuit to harvest power

I am working with a homemade material. I can harvest a power from this system. Thus a load, plugged to short cut my material, is crossed by a current. I would like to really harvest this power, it ...
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187 views

Large voltage spikes on charge pump output

I'm prototyping a small charge pump out of a NE555 timer. However, I'm getting some spikes on the output along the rising and falling edges of the timer. Channel 1 is the output signal with AC-...
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92 views

Auxiliary swicht-mode-power-supply topology

The application notes of several boost-converters, e.g. from TI (TPS61070, p.18) or LT (LT3464, p.14), show similar unregulated auxiliary output circuits for doubling or inverting the (regular) ...
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203 views

Low impedance rail to rail 24V output from NE555

I'm designing charge pump based 24V to 144V converter for powering up my experimental tube amplifier. So I need a low impedance driver circuit with rail to rail output. Can you suggest me the best way ...
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1answer
153 views

charge pump doubler

I am not fully sure as to how this circuit works. I know that during the positive half cycle D1 is on and C1 charges to V volts, and that during the negative half cycle D1 will become off and D2 ...
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2answers
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Charging capacitor in parallel and discharging in series

I wanted to use multiple capacitors to step up the voltage in a circuit. A little bit of google searching told me that it is called a Charge Pump. I figured out the charging each capacitor ...
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296 views

How does this PIC board achieve RS-232 communication without a line driver?

All the develooment boards I have seen yet with serial communication support usually have MAX232 line trasceiver. However, I have come across this Olimex PIC-LCD development board that does not have ...
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2answers
433 views

Charge pump circuit with one MOSFET

This is an example of charge pump from MOSFET Models for SPICE Simulation: Including BSIM3v3 and BSIM4 by William Liu. Could anyone explain why \$ v_D = \frac{(v_{IN} - V_T)}{2} \$ here? Why \$ V_T \...
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2k views

Are charge pumps better than boost converters since charge pumps do not use inductors?

Charge pumps use capacitors and not inductors. https://en.wikipedia.org/wiki/Charge_pump Boost converters require inductors. https://en.wikipedia.org/wiki/Boost_converter Both charge pumps and boost ...
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Why do charge pumps use capacitors?

https://en.wikipedia.org/wiki/Charge_pump A charge pump is a kind of DC to DC converter that uses capacitors as energy-storage elements to create either a higher- or lower-voltage power source. ...
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555 high amperage charge pump inductorless voltage doubler

There's a few resources out there for indcutorless boost circuits, or charge-pump voltage doublers and triplers. http://www.electroschematics.com/648/555-voltage-doubler/ But this circuit is only ...
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LM2776 Inverter is not producing -3.3v with 3.3v input

Background I am using a TI LM2776 Switched Capacitor Inverter (datasheet here) to obtain a -3.3v bias voltage for an LCD (Newhaven Display, NHD-12864MZ-FSW-GBW-L, datasheet here). The LM2776 is ...
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4answers
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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 ...