I found this diagram in the TI TLV431 datasheet. The diode symbol looks like a zener, but has an addition input on the side. What is this supposed to represent?
Electronic – What does this diode symbol mean
diodesschematicssymbol [~]voltage-regulator
Related Solutions
It's the symbol of a current source.
There are different symbols used to represent a current source:
The diagram on page 631 of the user guide has it labeled "Temp. Sensor".
This is the internal Block Diagram for the SD24_A ADC, but it's almost functionally the same for the other ADC Types
Best Answer
This symbol could represent any number of precision adjustable shunt regulators. Combined with a precision op-amp they are often a voltage reference for other circuits.
Typical internal reference is 1.24 volts, so by connecting Vref between 2 resistors, one to cathode and one to anode, it behaves like an op-amp feedback to multiple the Vref times the resistor ratio.
Connecting Vref to the cathode as the drawing shows gives it no gain, so its clamp (shunt) voltage would be 1.24 volts.
These type of adjustable zener diodes are often used with the opto-couplers LED input to set the output voltage of SMPS type power supplies, as part of a feedback loop. This allows for galvanic isolation between the high-voltage primary and a low voltage output(s).
See following image: