Stack Exchange Network

Stack Exchange network consists of 175 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers.

Visit Stack Exchange

Questions tagged [linear-regulator]

A linear voltage or current regulator provides a continuous non-pulsed supply of current or voltage. It may be fixed or adjustable, and can be put under control by a CPU/MPU. In spite of sometimes low efficiency they are popular because they provide clean noise-free DC current or voltage, as opposed to switching supplies that can be very efficient with power regulation but induce much RF noise into the outputs which need extra parts to filter out.

4
votes
4answers
175 views

Aluminum electrolytic or ceramic capacitors for linear regulator input and output?

I am using this linear voltage regulator. The datasheet indicates the input and output values for the capacitance to use, 1uF and 10uF respectively. Should these capacitors be or a particular type, ...
0
votes
1answer
28 views

wiring ac input to linear DC power supply

I have a vintage linear DC power supply. Terminals 1 and 2 are labeled just "AC input". Wanted to double check if there is a convention for which pin is hot, or if the polarity is irrelevant in this ...
7
votes
1answer
590 views

Series pass transistor, LM7812

I am making a 12 volt regulator for a solar panel to power an audio amplifier. I already have a switching regulator for most application but it is very noisy for amplifier even with a lot of filtering....
0
votes
0answers
64 views

Powering and regulating supply DC voltage for a digital MEMS microphone

I want to use Infineon IM69D120 microphones [1][2] in an array (about eight of them), and I am confused as to how exactly (with which components) should the MEMS microphones be supplied. I chose USB ...
14
votes
3answers
1k views

Will linear voltage regulator step up current?

I have a regulated 9 volt 300mA power supply I want to step it down to 5 volt using Linear Voltage Regulator LM7805 , I want to know how much current can I can draw at 5 volts, will it be 300mA or ...
1
vote
2answers
75 views

How can I estimate TL431 output voltage swings based on datasheet alone?

I am trying to design a series-pass regulator that brings 12V down to 3.3V. If I see a 20 mA step change in current, I would like to stay within a certain output voltage range (±2%). What parameters ...
0
votes
2answers
81 views

Voltage regulator and loss of ground

I have a design that has a +24VDC supply, a 7805 voltage regulator converting it to 5 volts and then a microcontroller and some peripherals behind the regulator. The design and the 24V supply ...
1
vote
0answers
33 views

Thermal Faliure of thermal overload protected ICs

I have encountered a number of instances now where ICs that supposedly include "thermal overload protection" will still heat up until they fry. Examples: LM338,LM2576. These devices datasheets ...
1
vote
0answers
57 views

Linear Regulator Operation

I have a linear regulator with three pins. It's identifier is LM7805. I've taken a look at it's datasheet and it looks unlike linear regulators I've encountered. Is the the op amp circuit included in ...
0
votes
2answers
54 views

AMS vs LD vs ZLDO vs NCP in 1117 Linear Regulators

I was in the process of choosing a 3.3V Linear Regulator for my ESP based Project when I stumbled upon the different types of these voltage regulators. The 1117 regulator had different prefixes, AMS, ...
-1
votes
4answers
118 views

Too low efficiency with “0-30V 2mA-3A DC Regulated Power Supply unit with Continuously Adjustable Current Limiting Protection” PSU kit [closed]

I ordered and assembled the kit (link and image added below). Everything works fine. But as everybody knows, it requires a great heat sink for the regulator. The ordered unit costs less than $5, but ...
0
votes
2answers
54 views

Is this a suitable Voltage Regulator to replace an old circuit on my board and is my logic correct?

I have 4 of these 2n3904 transistor setups on my board: A1 -- requires 5v on these 2 connected pins to be enabled. I control this by driving r2 high at 3.3v which should allow 5v to flow through the ...
0
votes
1answer
47 views

PI controlled linear voltage regulator with overcurrent protection

I designed a simple linear voltage regulator for high voltage application around 500V which is controlled by a PI controller. Schematic 1 shows the raw design using a bipolar transistor to control ...
1
vote
1answer
61 views

Can I use same LDO for two outputs?

Can I use same LDO for two or three outputs? Given that the LDO provides enough needed current for three devices.
1
vote
1answer
53 views

How to connect two LDOs in parallel?

I have two LDOs that convert different input voltages into the same voltage. I'm not sure how to safely connect the outputs together so they become the same signal and can be both be used to power the ...
0
votes
2answers
226 views

LM317 Soft-start circuit

assuming the below circuit is functional. Can you tell me how soft-start part is working? Would the same setup be valid for Vin=~3V and Vo =~1.3V, or would I need to change the C1 and R3. Also how can ...
2
votes
2answers
81 views

Any downside to feeding a buck regulator into a linear one?

I need to convert 12 V down to 5 V and 3.3 V. I am using linear regulators right now but they get pretty warm and eventually I would like to supply more current for it (around 500-700&...
0
votes
1answer
29 views

LM2940, 7808 and Multichannel PWM chip

I'm putting together a circuit board to power and dim 5 LED channels. The average voltages on the channels are 12.3V, 11V, 11.4V, 7.8V, 6.6V, and max current is 1A. So my current plan is: 12V ...
1
vote
1answer
248 views

High voltage linear regulator (with pre-regulator)

I need to build a linear voltage regulator like this: The problem with the usual linear regulators (LM317, LM337, ..) is the limited voltages they can withstand. I have taken inspiration from a ...
0
votes
1answer
120 views

PWM duty cycle RPM regulation via sensing DC motor current

I have a DC motor that needs to be RPM regulated, that is, it needs to turn at constant RPM regardless of the load. I've read this can be done by monitoring current thru the motor windings and ...
0
votes
1answer
131 views

Bad 100Hz ripple in linear regulator circuit

Background I'm a beginner trying to make a linear regulator and made some decent progress on a breadboard powering from a 20V laptop charger. After battling off the typical opamp instability issues I ...
1
vote
2answers
246 views

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
vote
2answers
62 views

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 ...
0
votes
2answers
124 views

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 ...
0
votes
3answers
98 views

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
votes
1answer
60 views

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
vote
3answers
293 views

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
votes
6answers
3k views

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 ...
0
votes
1answer
52 views

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.
0
votes
1answer
316 views

Explain adjustable 4A regulator

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 ...
0
votes
0answers
61 views

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
votes
1answer
130 views

Linear current driver with several BJTs in parallel

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 ...
0
votes
3answers
205 views

Lm317 input connected to output?

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
vote
0answers
54 views

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 ...
0
votes
1answer
149 views

The L7805 got hot when connected to ATMega8?

I tried to make the blinking LED example, I took the power from L7805 directly to ATMega8 and the output of MCU is through pin 28 to 3mm LED and 390 Ohm resistor. But when I ran the project, the L7805 ...
2
votes
3answers
191 views

Driving a 12v LED, substituting a PWM chip for a 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
votes
3answers
4k views

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
votes
2answers
176 views

LM350 not reducing the ripple [closed]

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 ...
0
votes
0answers
169 views

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
vote
1answer
196 views

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

I would like to understand the meaning / function of the transistor on LM317 ADJ pin on the following circuit. Image source
1
vote
1answer
577 views

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. ...
1
vote
1answer
155 views

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 ...
0
votes
3answers
1k views

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 ...
0
votes
2answers
1k views

Would this circuit work on AMS1117?

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
vote
1answer
150 views

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 ...
0
votes
0answers
121 views

Is this regulator circuit safe to use?

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,...
0
votes
0answers
47 views

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 ...
0
votes
0answers
147 views

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 ...
2
votes
1answer
188 views

LT3080 Set pin voltage

LT3080 documentation states under absolute maximum ratings: SET Pin Voltage (Relative to OUT) ±0.3V (http://cds.linear.com/docs/en/datasheet/3080fc.pdf page 2) In the documentation there's also ...
1
vote
1answer
419 views

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

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 ...