TLV431B-Q1: Current source using a shunt regulator

Hi Vamsi,

Thanks for the clarification!

The capacitor between the cathode and reference pins of the TLV431 is for stability as described in the description. This is the same for the two 100 Ohm resistors shown in the circuit schematic. 

For a more up to date app note regarding current sources using voltage references, please see the app note below:

https://www.ti.com/lit/an/snoaa46/snoaa46.pdf

In addition, if you are interested in a current source, I recommend the LMx34 family of devices:

https://www.ti.com/product/LM334

I hope this helps!

Best Regards,

Andrew Li

Hello Vamsi,

From the conditions shown in Figure 2, the voltage across the 100nF capacitor is approximately 14.3V.

This can be found by using the IQ, RLIM, and VCC values to calculate the voltage drop across RLIM, which will help you determine the voltage drop across the 100nF capacitor. 

However, if TLV431 is in the off state, the worst case voltage on the cathode would be VCC, meaning the worst case voltage across the capacitor could be as high as VCC. Please choose components accordingly.

Thanks,

Jackson