We want to implement standby mode for board with LC79D.
According to the datasheet, power off should looks like this:
- Host processor detect, that main power is switched off
- External active antenna power switched off by hardware, LC79D continue to work on backup battery/capacitor
- Host processor issue $PQSTOPGNSS command to LC79D
(GNSS module write to NVM and continue to draw full current, 40+ mA)
- Host processor need to wait until the command above will be executed
(what is timing here ? 100us, 1ms, 10ms, 100ms ? )
- Host processor driving NSTANDBY low with open collector
circuit, GNSS module switched off (what is timing here ?
100us, 1ms, 10ms ?) and draw 15 uA standby current from backup battery.
Power on procedure looks simple:
Do not drive NSTANDBY
So, we have few questions.
- What is minimal timing between end of the $PQSTOPGNSS command and
driving NSTANDBY low ? What happens, if host processor put NSTANDBY low
immediately after end of $PQSTOPGNSS command ?
- What is timing between driving NSTANDBY low and GNSS module
switching off to the standby mode ?