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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3answers
57 views

LM27762: 200 mV difference between positive and negative

I'm trying to figure out why there is 200 mV difference between positive and negative voltage on LM27762 (measured these values at op-amp pins). I used a schematic from their datasheet and everything ...
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1answer
66 views

How does a PLL PFD produce a high frequency?

I am going to work with a PLL and a VCO. I have read and understood the basic procedure in which the charge pump works. I understood that say, when the reference signal (or the divided signal) is up ...
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1answer
31 views

Charge pump with adjustable frequency: what frequency to pick and why?

I decided need a charge pump IC that I intend to use to get -3.3V from 3.3V to supply my op amps and diff amps to avoid running into output voltage swing limitations of those ICs (For true near zero ...
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58 views

Charge pump circuit- What is the need for caps near CLK pin?

Below is a charge pump circuit in NB680 IC Datasheet I was trying to understand the charge pump functionality by comparing it with the standard circuitry shown below: https://www.edn.com/capacitive-...
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3answers
268 views

How to design a boost converter? (1.5V to 4V)

I want to build a circuit that powers 2 standard red LEDs (forward voltage of 2V each) from 1 AA battery. I would like to learn how to design and build a boost converter that can take 1.5V in and ...
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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 ...
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128 views

Absolute cheapest/simplest voltage booster? (for High side Mosfet Switch) [closed]

what is the absolute cheapest solution to provide gate voltage for a high side switch? I will have to use NFETs due to 20A+ cont. with low losses. There is no switching happening (think of a load ...
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1answer
121 views

How can I simplify this charge pump?

In thinking about an answer to a different question, I came up with a likely-not-ideal solution to the following: Given a square-wave input of 125 Hz whose minimum is 0V and maximum is somewhere ...
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445 views

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 ...
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0answers
38 views

charge pump - failure analysis

I have a strange behavior on a custom powerstep01 board I designed. This is the Schematic of the CP / BOOT section: simulate this circuit – Schematic created using CircuitLab The values for ...
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3answers
93 views

Offsetting Op-Amp output offset in combination with charge pump

I want to have a +-12.0V square wave output from an opamp fed from a 3.3 and 5V power supply. The signal is 2.5kHz with a low duty cycle of 3-10% generated by an MCU. Peak voltage at both ends need to ...
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183 views

Charge Pump PWM to GND connection necessary?

Hey there, first post from an avid forum reader: This is the schematic for a simple Charge Pump circuit from circuitdigest.com* (great website). I am trying to build a charge pump with 12V VCC and 5V ...
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2answers
155 views

Using a AC capacitance voltage divider through diodes to charge a DC capacitor?

What I need help designing is a circuit that will be capacitor voltage divider that will be fed by a high Ac input voltage, but be able to discharge each capacitors through diodes at a set lower ...
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1answer
76 views

High voltage Dickson charge pump switching

I am working on a circuit based on the LT1930 (DC634A) to boost input voltage between 30 and 90V. I would like to take this boosted voltage and double it via a Dickson charge pump to the required ~...
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55 views

Do PWM Half-Bridge Gate-Drive ICs allow 100% DC?

I read in other questions that is not possible to use 100% DC as PWM input for drivers that use a bootstrap/charge pump to shift the gate levels. I'm talking about common brush DC motor gate drivers, ...
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64 views

charge pump with bootstrap gate driver

I was building a bootstrap based gate driver for BLDC motor control application.From this application note (https://www.infineon.com/dgdl/Infineon-HV_Floating_MOS_Gate_Drivers-ApplicationNotes-v01_00-...
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1answer
69 views

Can I use this circuit for a 15V voltage inverter using TC962 charge pump controller?

I need a +/-15V, 45mA source to power some current sensors. I think Microchip's TC962 (datasheet) would be suitable to provide a -15V rail. I had a look at the datasheet but they don't specifically ...
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1answer
137 views

Inverting Charge Pump with Push/Pull Stage

I am trying to build an inverting charge pump capable of supplying ~80-100mA at the second stage. Since the PWM signal must source the current, I decided on using a push-pull stage based on this ...
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1answer
123 views

What is the upper limit for a charge-pump voltage booster? [closed]

What is the highest voltage achieved with a voltage pump? Can it boost into the kV range, around 5-10kV?
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3answers
139 views

Why is the PNP transistor used in this circuit?

Why are there PNP transistors here? from: https://www.youtube.com/watch?v=5_uYE4EWSKY&t=884s&ab_channel=SparkFunElectronics This shows a charge pump circuit that will be controlled via the ...
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1answer
99 views

How to analyze this voltage doubler circuitry?

What does this circuitry used for? How should I analyze? (It is inserted in the capacitor voltage doubler circuitry between the two stages)
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1answer
62 views

Charge pumps operation

In a course of digital electronics, our Professor wanted to give us just an introduction to charge pumps. Here the basic topology: Then he says that the circuit behaves like a bucket brigade chain: a ...
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1answer
149 views

Power Circuit to Subtract a Voltage by a Known Amount

Using a charge-pump it's possible to add voltages together (i.e. source 10V + PWM 5V = 15V, ignoring diode drops) simulate this circuit – Schematic created using CircuitLab Surely there must ...
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1answer
52 views

Energy subtracted from a capacitor for a given voltage drop

I am trying to estimate, from a total energy of a capacitor (which is the output of a charge pump circuitry), how much energy do I have to power up an LED before the voltage goes below a certain ...
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1answer
199 views

Charge Injection in Charge Pumps

let's consider the following charge pump, which is used a lot in some PLL circuits (reference): Let's focus on the left part of the circuit (until the Loop Filter Network): its aim is simply that of ...
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1answer
250 views

Charge pump vs. boost converter for high current LED driver

I am designing a high current LED driver circuit to power a matrix of pulsed IR LEDs. The LEDs will operate at 5A; 4.6V; 0.1ms pulses (~10 pulses at this frequency, wait 300s, repeat.) The device is ...
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2answers
3k views

Charge Pump-Based Gate drive supply

I have heard many people talk about using a charge pump circuit instead of a bootstrap approach when supplying MOSFET gate drivers with a biasing level for the high side. I have yet to see anyone show ...
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1answer
430 views

Replace switching diode with MOSFET for lower voltage drop in charge pump?

I have seen reverse voltage protection circuits that use a pmos instead of a diode so that there is minimal power loss and voltage drop in that sector of the circuit. I want to make a charge pump for ...
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1answer
100 views

TI PCM51xx DAC Charge Pump Failure

I'm using a PCM5122 and previously a PCM5102 (this is the same part, but without the I2C/SPI interface) in my design and I've had a couple of prototypes end up with the 3.3v rail shorted to ground. A ...
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188 views

Two Different Charge Pump Circuit Variants. What Are Their Advantages?

While looking at the L6470 stepper driver datasheet I came across the following charge pump circuit suggestion (I will just name it Variant A). The charge pump is used to provide the "Bootstrap ...
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1answer
92 views

Bootstrapped charge pump design for phase frequency detector

I'm trying design a charge pump as it's showed in the following link: https://ibb.co/DDc6DsF (for some reason I couldn't upload it, I don't know why). what I don't understand is what is \$I_{ref}\$ (...
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233 views

Increasing output current of the inverting voltage doubler charge pump circuit, implemented with MAX1720

I have a +3.3V voltage rail available. And I want to generate a pair of negative and positive symmetrical supplies out of it. The magnitude of the output voltages must be less than 7V and should be ...
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1answer
229 views

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-...
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83 views

How to 3x or 4x a DC voltage while minimizing board space with no microcontroller?

I have a 3.7V DC voltage source that I'd like to boost to at least 10 Volts. I've been using Microchip's TC7660 component as a voltage doubler. But it only comes in SOIC (rather large for SMT). And ...
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1answer
141 views

Can I share charge pumps between multiple L6206 H-Bridge drivers?

I'm building a board to drive 8 separate motors, and I'm planning to use four L6206 dual full H-Bridge drivers. The device uses N-channel MOSFETS all round and, from the datasheet: Using N-channel ...
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80 views

Charge pump from discrete parts

I need to build a 2 stage inverting charge pump in order to convert a 12v rail into -24V which is then regulated to -12V using a 7912 LDO. it is used for a audio amplifier design and I need about ...
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1answer
155 views

LM2776 gets damaged after some time

It is almost the reference design from the DS. The only differences are those quite large inductances I had to add to remove the noise. The neg voltage is used to power RR OPamps feeding the ADC the ...
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2answers
402 views

Why won't this charge pump supply more than a couple of milliamps?

I am trying to generate 12V from a 5V source, capable of supplying around 15mA with less than 0.5V of ripple. The circuit must use all through-hole components, and cost is an issue. Having ...
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1answer
112 views

TC962 not inverting

I have a PCB which uses a TC962 to convert +3 V to -3 V so that I can use a split supply for an op-amp; however, I see ~Vdd at Vout when I have the TC962 on the PCB but it works fine when I desolder ...
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1answer
155 views

Voltage Doubler - Charge Pump

The basic understanding of this that I have is that: Assume clock low is 0V, clock high is 3V and Vin is at a fixed 3V. Ignore diode drops Initially Clock is low (0V) and Vin is at 3V (always). ...
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1answer
731 views

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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1answer
74 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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1answer
276 views

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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64 views

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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1answer
80 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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1answer
84 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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1answer
151 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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1answer
196 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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1answer
375 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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1answer
131 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 ...