LM2917 Zener Accuracy

Clare,

The Min/Max data is not available since this value can vary depending on your conditions. The most important consideration in choosing a dropping resistor from the unregulated supply to the device is that the tachometer and op amp circuitry alone require about 3 mA at the voltage level provided by the zener. At low supply voltages there must be some current flowing in the resistor above the 3 mA circuit current to operate the regulator. As an example, if the raw supply varies from 9V to 16V, a resistance of 470Ω will minimize the zener voltage variation to 160 mV. If the resistance goes under 400Ω or over 600Ω the zener variation quickly rises above 200 mV for the same input variation. So the Zener voltage variation depends on the dropping resistor value.

-Michael

Michael,

I was hoping you could confirm the 160mV includes initial variation, as well as any change over temperature.

- Clare

Clare,

The 160mV does include initial variation and the temperature stability is +1 mv/C so this means at the maximum operating temperature, the variation could be slightly higher.

-Michael