Questions about the use of TL431

ena

Questions about the use of TL431 [Copy link]

As shown in the figure below: ZJ8V voltage is 8V, VSTAND voltage should be 5V, but the actual voltage is 2.96V. When R113 is removed and R112 is short-circuited, the voltage is 2.5V, which is normal.

maychang

"ZJ8V voltage is 8V, VSTAND voltage should be 5V, but the actual voltage is 2.96V"

Why not measure the voltage between pin 2 of TL431 and ground at the same time?

In addition, the two resistors should also be measured to see if their resistance values are correct.

maychang

By the way: No matter which package, the Ref pin of TL431 is not pin 2. The three-leg TO92 package, the pins are downward, from left to right are Ref, Anode, Cathode. I'm afraid you connected the pins wrongly.

ena

maychang posted on 2021-10-16 16:32 By the way: No matter which package, the Ref pin of TL431 is not 2 pins. The three-leg TO92 package, with the pins facing downward, from left to right are Ref, An ...

Yes, the pinout is wrong.