Weak knee voltage in new packages (by Gerard Larooy)

Component: TL431

Category: Analog IC's

There are new TL431's in SMD packages that are manufactured with old semi conductor dyes that leak like they did in the 1980's. In other words the divider resistors need to be much lower than you think and the anode current has to be higher than you think for there to be any predictability in the simple equations for output voltage and divider resistor values. Lack of predictability can mean that you are no better off than using a Zener diode. With SMD PCB's, component value changes are not welcome.

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By Gerard Larooy on 17 Sep 2014