Hi,
I have a LS20031 GPS and I am trying to interface it with a small embedded computer. The regulators I use to provide input voltage to the GPS have a relative slow ramp up, from 0V to 4V in approx 20ms. When I turn on the computer power the red LED on the GPS stays solid on and the TX line remains high. If instead I first turn on my computer (so the regulators power up) then connect the +4V power to the GPS unit then the LED flashed on for a second, then goes off and I see on my scope the TX line happily sending data. So I believe there is some limit to the ramp up time allowed on the GPS input voltage or else the GPS won’t properly initialize.
I have also tried a 3.3V supply just to confirm it wasn’t an issue with 4V. My oscilloscope shows low noise on the input power. And since I can power up the GPS after the regulators and have it start every time it seems to be related to the transient of the source voltage. I couldn’t find any specs regarding this in the datasheet.
Has anyone experienced this issue before? Is there any known requirements for input power transients?
Thanks for any help,
-Cam
