# linear-regulator's questions - English 1answer

145 linear-regulator questions.

### 1 What is a simple voltage limiting circuit?

I am searching for a neat solution for an input voltage limiting circuit. Situation: I have a circuit with an input voltage range from 6 V to 20 V at 3 A peak (the load), however my source can be ...

### 1 Use regulator when input voltage is above threshold other wise use direct input voltage

I don't have much practical knowledge of electronics. I am trying to operate esp12e with single Li-ion battery with charging circuit. I am planning to use a good LDO regulator because Li-ion battery ...

### Best power supply for a BLDC motor; linear or SMPS?

I am coming into a design that uses a custom designed, 24V brush-less DC motor controller. I am wondering, is it better to power this type of system with a linear power supply, a switch mode power ...

I cannot understand how this circuit works. https://imgur.com/a/OAQSF4Y I have found a basic explanation online but is not enought to make calculations. "Using three LM317-N devices in parallel ...

### Will battery last longer with larger capacity but lower efficiency (high V through LDO) or vice versa?

Given a simple circuit of a draw around 28mA (when supplied 3.3v). I'm trying to maximize run time on a battery, but working with what I've got on hand... I have the following batteries: 5000mAh 3S ...

### 2 Using a higher C than necessary in a voltage regulator circuit

I've two questions: If I've a voltage regulator that says in the datasheet to use electrolytic capacitors is it possible to use 'normal' capacitors with the same capacitance? I've the circuit drawn ...

### 1 Negative input, negative output switching regulator?

I've got a component within a larger device that requires both +15 and -15V, drawing about 100mA per rail. In addition, the main power supply of the larger device is providing +/- 28V, with a common ...

### 10 Best way to power a microcontroller, SMPS vs Linear Regulator

I'm using a 12V adapter and a 2S 7.4V Li-ion battery to power my electronics, and I would also like to power my MCU with it. To switch between the adapter and battery I'm using a BQ24133 from TI. I ...

### Any 12 or 14 v 100amp voltage regulator it? [closed]

I have searched the Internet but didn't find one, can anybody please suggest me any regulator ic that is 12 or 14 volts and can bear upto 100 amps.

### 1 Linear regulator loop dynamics

Given a step change in the input voltage of a standard op-amp based linear regulator, a finite amount of time is needed for the op-amp to sense the voltage difference at its input and do whatever it ...

### MCU controlled adjusting LED current with current sensing regulators?

I'm really sorry for the noobly formulated question, if I knew how to formulate it I'd probably find what I need by searching, this has to have been asked and dealt with many times. I've been using ...

### 2 Linear current driver with several BJTs in parallel

1 answers, 99 views led bjt led-driver linear-regulator
With the circuit setup shown below, if I have available a type of Q2 transistor with a certain maximum dissipated power and need that D1 withstands a large current that would lead Q2 in trouble, it is ...

### Lm317 input connected to output?

3 answers, 112 views power lm317 linear-regulator
I am figuring out the schematic of an existing e-bike controller. Specifically I am trying to replace an lm317t with a custom made switch regulator that outputs the same voltage. But first I want to ...

### 1 Stable 12V 1.5A

I'm in need of a stable 12V 1.5A power which I could carry with myself. One way of doing it would be to strap, say, 12x 1.2V rechargeable batteries and use LM317. But then I read about buck ...

### 2 Driving a 12v LED, substituting a PWM chip for a linear regulator?

3 answers, 104 views led pwm led-driver linear-regulator
I'm trying to reverse engineer a broken control box for some dual intensity motorcycle LED spotlights, and I note on the circuit board there is an AX 3007-50 12V ...

### 2 Connecting Voltage Regulators 7812 in Parallel for High Current [duplicate]

Could I use two L7812 voltage regulator ICs in parallel to get 12 volt and more current that with just one?

### -2 LM350 not reducing the ripple [closed]

2 answers, 121 views power-supply linear-regulator ripple
I share the picture of the schematic of my circuit. I want to use the LM350 variable voltage regulator to reduce the 40mV p-p ripple i have in my bridge rectified DC. Though it has no effect at ...

### Linear mosfet driver floating supply

I've been trying to find ways to drive an N-Channel MOSFET gate higher than the power rail in order to make use of the full supply available. The MOSFET needs to operate in the linear region using an ...

### 1 Why there is transistor on LM317 ADJ pin? [closed]

1 answers, 130 views lm317 linear-regulator
I would like to understand the meaning / function of the transistor on LM317 ADJ pin on the following circuit. Image source

### Designing a linear regulated dual-rail power supply

I'm building a dual-rail power supply and need to drop about 5-10 V from the rectification output. It's for powering an amp so I need low noise and about 2A therefore I opted for linear regulators. ...

### What causes a faulty Linear Voltage regulator to output wrong voltage [closed]

I made a circuit where I needed DC 8v supply. I was using a KA7808 to regulate the voltage. While testing the voltage regulator unit, I identified that the Regulator IC might be faulty because I was ...

### 1 How many MOSFETs can a linear controller handle?

I designed a circuit for a high current linear regulator (20A peak, 16.4V (max) input regulated to 13.8V) using a Micrel MIC5158 together with a BUK9575-55A. The 20 A peaks are short, since the use is ...

### Would this circuit work on AMS1117?

2 answers, 564 views voltage-regulator linear-regulator
Just a quick question. is this a correct circuit? would it drive 500mA device? given using AMS1117 as the regulator? Do we need to add heatsink? any alternative to step down the 12V to 3.3V without ...

### 1 Connection between PID, Pole placement and LQR

I am trying to control a wheeled inverted pendulum with a PID controller. I already designed a linear quadratic regulator (LQR) and a pole placement regulator (PPR). I would like to design a PID ...

### 20 Can I use two 7805 ICs in parallel to get double current capacity?

7 answers, 10.466 views linear-regulator 7805
I use a 7805 for a project where the circuit needs a higher current (~2.8 A) at 5 V. So I assume that if I use both ICs in parallel I can increase the maximum current capacity. Would it work?...

### Is this regulator circuit safe to use?

0 answers, 121 views op-amp mosfet linear-regulator
A friend asked me to make a simple regulator for a high current load: a 13.8+-15% V, 20 A (a radio). The input is a 13.5-16.8 V LiPo 4S pack. Obviously, the pack cannot be discharged completely. Still,...

### employing a series resistor to mitigate an absolute maximum voltage rating

I am trying to run an IC with an absolute maximum voltage spec of 3.6 V. The linear voltage regulator that feeds the whole board specifies a maximum output voltage of 3.63 V. For a given input current ...

### analog voltage minimum for preregulator

I try to design a lab power supply with a DC/DC preregulator(for now LTC3646), and linear regulator(LT3080). I found a really clever hack that sets voltage produced on the preregulator to voltage set ...

### Converting voltages using LM337

I have 2 questions: Is it possible to generate -35V from LM337 regulator with -12V in input?? The voltage output from LM337 is supposed to follow this equation, -Vout=-1.25(1+R2/R1)+Iadj.R2 but in ...

### 2 LT3080 Set pin voltage

1 answers, 102 views power-supply linear-regulator
LT3080 documentation states under absolute maximum ratings: SET Pin Voltage (Relative to OUT) Â±0.3V (http://cds.linear.com/docs/en/datasheet/3080fc.pdf page 2) In the documentation there's also ...

### 1 100 mA current sink with LM317 does not work above 25V

1 answers, 253 views lm317 linear-regulator
I needed a current sink for something and I arranged one with LM317T: simulate this circuit – Schematic created using CircuitLab It has a switch to select whether I want to sink 100mA or 500mA ...

### Linear behavior from 0-10V and steady at 3.3V from 10-24V

1 answers, 98 views circuit-design linear-regulator
Apologies as I have very basic electronics background, and after searching for a whole afternoon I couldn't find out how to implement a circuitry that has this behavior as shown in the graph. If ...

### 2 Solar voltage waivering

Folks, Hopefully this is the right place to ask this. I'm a software engineer with VERY limited EE experience and am trying to learn. At the moment, I've got a project that I'm trying to power using a ...

### 2 Switching pre regulator and linear regulators

I need to have a 5v supply with around an amp of current draw max, and a 6v supply with around a 4amps current draw max. I was thinking: instead of having two switching regulator circuits, just having ...

### Linear regulator using emitter follower and operational amplifier

I have understood that you can create a linear regulator using a high-current BJT power transistor in the emitter follower configuration and one operational amplifier (and a voltage reference, which ...

### 1 5 volt regulator not getting desired output

I have been trying to assemble a simple 5V regulator circuit using the L7805CV and have had no luck at all getting the output to 5V. I have tried many circuits and multiple L7805CV regulators, ...

### 78xx switching regulator question

I would like to know how a 78xx series linear regulator can be used in a switching application. I have found a circuit that shows such a use, but I have trouble understanding how the circuit ...

### Voltage regulation for Atmega328p

I am designing a circuit containing two Atmega328p. First chip will drive TFT screen with 3.3 V linear voltage reg. Second one will drive BT module, couple of relays, two sensors, SD card module, and ...

### Why Vin should be above Vout by a Vbe in LDO using NPN?

This is a description of LDO in Switch-Mode Power Supplies Spice Simulations and Practical Designs by Christophe Basso. I am wondering if there is any mistake here. The author said that for linear ...

### Is it acceptable to use 1uF decoupler on a 7805?

I am feeding an arduino, presently through its Vin pin, with a 0.9V drop on its onboard regulatorZ I'd of course like to feed it via its 5V pin, which has a strict upper limit of 5.5V. I don't have ...

### Linear regulator GND pin MUST be connected to common ground?

I'm trying to make a constant current source of 2.1A which will operate around 1.7V. I did some web searching, and I decided to use linear voltage regulators; simply put a adjusting resistor between ...

### 4 Linear Regulator: MOSFET vs BJT

Currently I am doing a project on a voltage regulator. Can you tell me some advantages of MOSFETs over BJT? Apart from a higher power loss, I can not find much. In control engineering it is much more ...

### Smoothing unregulated DC input voltage to a voltage regulator

I am building a USB mobile charger powered by manually rotating a 12V DC motor shaft. This voltage goes as an input to a LM7805 voltage regulator and the output of the voltage regulator is used to ...

### 1 High Power Series Pass Regulator Design

3 answers, 169 views power-supply linear-regulator
For my internship, I am tasked to design a power supply whose main purpose will be to power a 90 Vdc motor. The motor is used for a short amount of time (roughly 30 seconds), pulling about 1 A during ...

### LM350 variable voltage regulator SNAFU

2 answers, 179 views power-supply lm317 linear-regulator
My LM350 regulator with smoothing caps (C1:0.33uF, C2:1uF polarized, R1:150 R2:10ohms+trimpot) does not work. It works without capacitors. I am an idiot. What have I done wrong? I tested all the ...

### Where am I going wrong with LM317 power supply circuit?

I am still learning analog electronics and possibly making a mistake here. I am trying to build this power supply circuit but I am getting 0V as output instead of 4V. This is the schematic Both of ...

### 1 Purpose of capacitor in op amp feedback loop of power supply comparator

I've been analyzing the schematic for an old commercial linear power supply, the Farnell LT30/2 (schematic). The schematic contains a couple of examples of an op amp arrangement that seems very ...

### 3 Linear Power Supply Design Tap Switch

Computer science & math major here. I'm designing a linear power supply to introduce myself to electronics. To keep things cool and cheap, I am trying to limit the amount of power dissipated in ...

### 2 Making LM317 output voltage adjustable down to 0 V

3 answers, 6.509 views power-supply lm317 linear-regulator
I want to design a variable voltage regulator that will get from it`s maximum output (lets say 10V) down to 0V (or very close) considering the input as regulated 12V (from a PC power supply). All the ...

### 1 Need alternative way to deal with LDOs minimum current requirement

I am designing a circuit that uses an LDO to produce 3.3v from a 10 to 18v input. I sometimes will need 1.2 amps from this regulator and at other times I only need microamps. When I need even less I ...