how can I choose a zener?

[zhengchao201105]

GDZ16B zener voltage is 16v,so if I add a 26V voltage to VBD for 1 hour , is the zener will damaged?or can recovery after add a 12v to VBD?

 

[picgak]

Hi zhengchao,
If you apply 26v without the required current limit resistor in series to the cathode your zener will be damaged.
regards ani

 

[zhengchao201105]

but if I add a current limit resistor in series to the zener,the zener will lose effect of stablizing the voltage.am I right?
such as if I add a 26v to VBD,the output will become 26V because of the resistor in series to the zener
if without the zener,the output is stablized in 16v

 

[picgak]

No if it is a 16v zener, 16v will be available accross the zener and balance will be accross the resistor

 

[zhengchao201105]

such as if I add a 26v to VBD,the output will become 26V because of the resistor in series to the zener
if without the resistor,the output is stablized in 16v

 

[picgak]

resistor connected to cathode, input dc + 26 at the resistor free end and -ve at the anode.
you take output accross the zener the voltage will be 16v

 

[zhengchao201105]

Thank you picgak,I understand what you said,so if the VBD is 26v and in series with a 1k resistor which connect to the GDZ16B(16v zener),the current is (26-16)/1k=10mA,is this current value OK?
which parameter should I focus on for GDZ16B,I find the GDZ16B reverse current is 0.1uA,does 10mA will damage the zener?

 

[picgak]

your calculation is right for 10mA but as per datasheet Iz is 5mA so you can use 2.2k or above (if you are using zener just for reference voltage) (if some load is connected you can reduce the resistance)