TL431 Shunt Regulator Resitor Values

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Baterka274

Joined Oct 2, 2015
6
Hello,
I have got a circuit which works as high current shunt regulator and indicator of battery status (for stethoscope). Input voltage from battery is 9V and output voltage 5V. I have finished my indicator yet, but I am not sure about regulator and his values. Can you help me with values of resistors in this regulator (R16, R20, R22)? I use diode TL431 in this circuit.
Thank you very much
Tom
 

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GopherT

Joined Nov 23, 2012
8,012
Hello,
I have got a circuit which works as high current shunt regulator and indicator of battery status (for stethoscope). Input voltage from battery is 9V and output voltage 5V. I have finished my indicator yet, but I am not sure about regulator and his values. Can you help me with values of resistors in this regulator (R16, R20, R22)? I use diode TL431 in this circuit.
Thank you very much
Tom
How about changing the title to something more descriptive. Like, "TL431 shunt regulator question"
 

DickCappels

Joined Aug 21, 2008
6,100
R16 and R22 need to be the same value for a 5 volt output. Each can be 10k ohms.

As for R 20, how many milliamps is the load on your +5 volt output?
 

ronv

Joined Nov 12, 2008
3,770
You really don't need VR2 to regulate the voltage for the led.
You can just set the LED current with a resistor.
 

MikeML

Joined Oct 2, 2009
5,444
You really don't need VR2 to regulate the voltage for the led.
You can just set the LED current with a resistor.
@ronv : He is using the left TL431 as a low voltage detector that lights on low battery voltage; not using it to regulate the current through the LED.

@Baterka274 Dobry Den.
Answer Dick's question about the load current...
 
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