Output pull-up at power on
kolyur
Posts: 43
I'm working on a design which has an AD7705 analog to digital converter connected to the Prop.
From the AD7705 datasheet:
Although the latch-up performance of the AD7705/AD7706 is good, it is important that power is applied to the AD7705/AD7706 before signals are applied at the REF IN, AIN, or logic input pins to avoid excessive currents.
The voltage regulator circuit I'm using to generate the REFIN and AIN signals (LP2951) has a shutdown pin, where logic high = shutdown. What I need to do is hold that pin high immediately at power-on (before Prop startup), then drive it low after a short time.
After reading some similar posts, I believe that I can drive the shutdown pin from a Prop pin, with a pull-up resistor to Vdd. Immediately at power-on, with DIRA=0, the shutdown pin will be high and the regulator will be disabled. By setting DIRA=1 and OUTA=0, the pin will then be forced low. Can someone verify my thinking on this?
Thanks.
From the AD7705 datasheet:
Although the latch-up performance of the AD7705/AD7706 is good, it is important that power is applied to the AD7705/AD7706 before signals are applied at the REF IN, AIN, or logic input pins to avoid excessive currents.
The voltage regulator circuit I'm using to generate the REFIN and AIN signals (LP2951) has a shutdown pin, where logic high = shutdown. What I need to do is hold that pin high immediately at power-on (before Prop startup), then drive it low after a short time.
After reading some similar posts, I believe that I can drive the shutdown pin from a Prop pin, with a pull-up resistor to Vdd. Immediately at power-on, with DIRA=0, the shutdown pin will be high and the regulator will be disabled. By setting DIRA=1 and OUTA=0, the pin will then be forced low. Can someone verify my thinking on this?
Thanks.
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