Recently, I tested the voltage reference ADR420. The datasheet states the input range is 5V ~ 15V, but when I give it a 5V input, the output is 1.25V, when give a 15V input, the output went to 4V or so. I tested 3 chips, all behave this. But when I solder an ADR421 to the same place, all are OK. The output is always 2.5V, no matter the input is 5V or 15V. So I guess the problem is caused by ADR420 itself.
Anyone can confirm me that the ADR420 can be used with 15V input? And why my all 3 chips behave bad, what can cause this?
The problem is solved, the workers made a mistake with the pin 1, so they soldered the chip in a wrong direction!!!!