TDP158: The Level of OE Pin

Tony

A passive reset circuit using an external capacitor and the internal pullup resistor will set DP158 OE pin properly, but you will not see 3.3V on OE pin due to internal biasing. 

But why do they use 1uF pulldown capacitor? Do they have a very long power ramp up timing? 1uF will result in a very long reset duration.

Thanks

David

Hi David

So When I test the level of OE pin. What level should I test ? We test OE pin for power-on timing check.

If OE pin not 3.3V , what level should I used as High-voltage? How can I calculate TD2?

Tony

With 200k internal pullup, the TD2 timing will be 200k * external pulldown capacitor capacitance. 

With internal biasing, you should see ~2.3V on the OE pin. But OE should be pulled high by the internal pullup resistor.

Thanks

David