Electrical Engineering Stack Exchange
Electrical Engineering Stack Exchange

Questions tagged [lm317]

3-terminal adjustable linear regulator

266 questions
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LM317 Sealed lead acid charger

I have a couple of Yuasa NPW36-12 12V 7.2Ah batteries from a phased out UPS unit. The batteries are barely one year old and have less than 100 charge cycles on them. I don't have a lead acid battery charger and thought I could whip something quick…
jm11011
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LM317s in parallel connection

Is it possible to connect 3 LM317s in parallel to get upto 4A of current output ? I need 4A but I'm not able to figure out any other possibility. Is there any other possibility to achieve this ?
Thameem Abbas
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Why a diode to GND in 0-30V LM317 circuit?

I'm looking at reference design 9.3.1 from http://www.ti.com/lit/ds/symlink/lm317.pdf where a LM317 is used between 35V and -10V to obtain a 0-30V regulation. What is the purpose of the diode? would the circuit work without it without connection of…
FarO
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How to protect LM317 from output short?

In the below circuit, the diodes protect the LM317 against both of the caps discharging into the IC when input or output is shorted. LM317 is itself capable of having it's output shorted without damage. But the input-output voltage difference must…
downthewire
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Adding overload indicator to LM317

I am working at a LM317 power supply (tracking pre regulator) and I found on the internet a schematic for overload indicator, which I added into my simulation and into my test circuit. After simulating, I found that the Base current of Q9 has spikes…
beard999
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Typical LM317 resistor values

Is there a place that I can get a hold of a table with common voltages by using standard resistors? (Sorry that this is poorly worded but I cant figure out how to say it better, so I will give an example) For example, a website that has a table that…
Reid
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LM317 Dropout Voltage

The LM317 Data Sheet doesn't appear to specify a dropout voltage in the table of electrical characteristics. 1.2V - 1.3V sounds about right for the dropout voltage; is "reference voltage" an alternate name for it?
user94748
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LM317, supply connected to output

I am designing a prototype 5VDC fan speed control unit. I am using an LM317 as a voltage regulator. This will step the voltage from a LiPo battery or arbitrary wall adapter down to 5V. Pulse width modulation is used for actually controlling the fan…
Void Star
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Solar charger in commercial application based on an LM317 IC

I have been working on a project of a commercial LoRaWan node. I want it to be powered by 3.7 battery and I consider to add a solar charger. For now, I have implemented a circuit based on an LTC3652 IC and it works quite good. I found such solution…
user188731
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LM317 - Caps necessary on 9v Battery?

I am designing a circuit which uses the LM317 variable voltage regulator to power a device from 1.25v-3.7v. The device powered by the LM317 will accept +-0.2V from the output of the LM317 and takes about 100mA. The device that will be powered is a …
skyler
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LM317 Voltage Regulator With Inversely Selected Output

I am dealing with an old circuit that used a curious form of voltage regulator control. It relied on seven resistors that it would control individually, and the parallel combination of this resistance set the output of a voltage regulator. This was…
Smith
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LM317 low output current

I need to make a 1.5 V voltage source for a motor with maximum current drain 1 A. I made this circuit: The output voltage without load is 1.46 V, which is fine. When I connect a load resistor which is smaller than 35 ohm, then the output voltage…
Jakub Šmíd
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Changing speed on DC motor with LM317?

I'm working on an old portable cassette recorder I had lying around and was wondering if it's possible to slow down the motor with an LM317 and a potentiometer. I've read about PWM, but I'm not sure how to do that or if it'll fit inside the…
Ryan Knutson
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LM317 Get Stable Output voltage at 1,25 V

I am currently trying to use the LM317 with a stable output voltage of 1,25 V. The general formula is $$ Vo = Vref\cdot\left(1+\frac{R2}{R1}\right) + Iadj\cdot R2 $$ I used this circuit to create the 1,25 V output voltage: simulate this circuit…
Merki
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LM317 equivalent backfeeding

I have a simple circuit using an LM317-type voltage regulator (ZLDO1117GTA) as a constant-current source. The input is connected to a 15v source, and the output is charging a lead-acid battery. In one mode, the output will be connected to the…
0xDBFB7
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