Hi,
I'm trying to understand how Zener diodes exactly behave but I'm failing so far... I'm making a battery charger for a tool which uses a voltage comparator to stop the charging once the battery is full. I'm using a Zener diode to generate a reference voltage, connected in series to a resistor.
My problem is that the voltage across the Zener diode is NOT stable but seems to greatly depend on the value of the resistor (i.e. the current). I've found that all Zeners seem to produce the specified voltage when the current is 5mA (as in the specs sheet) but any variation to the current (within their dissipation specs of course) will also change the voltage, sometimes pretty significantly.
I.e. I'm not getting a stable voltage irrespective of current which I though was the function of a Zener...
What am I doing wrong???
Thanks,
George
I'm trying to understand how Zener diodes exactly behave but I'm failing so far... I'm making a battery charger for a tool which uses a voltage comparator to stop the charging once the battery is full. I'm using a Zener diode to generate a reference voltage, connected in series to a resistor.
My problem is that the voltage across the Zener diode is NOT stable but seems to greatly depend on the value of the resistor (i.e. the current). I've found that all Zeners seem to produce the specified voltage when the current is 5mA (as in the specs sheet) but any variation to the current (within their dissipation specs of course) will also change the voltage, sometimes pretty significantly.
I.e. I'm not getting a stable voltage irrespective of current which I though was the function of a Zener...
What am I doing wrong???
Thanks,
George