Sierra Wireless AIRPRIME WISMO218 - Manual (Page 65)

WA_DEV_W218_PTS_002 Rev 006 April 29, 2010 65
Product Technical Specification &
Customer Design Guidelines Interfaces
Min Typ. Max Unit
T
ready
4 5 7 s
T
rampup
- - 120 ms
The ON/~OFF signal level is detected about 250ms after VBATT is available. Note that this timing
might be temperature dependant.
The voltage of this signal has to be pulled LOW for at least 685ms for powering ON. Within this
685ms, the WISMO_READY signal will initially reset to HIGH for about 135ms and then resume to
LOW.
During the power ON sequence, an internal reset is automatically performed for 38ms (typically).
During this phase, any external reset should be avoided.
Once the AirPrime WISMO218 is properly powered ON, the WISMO_READY pin will set to HIGH
level to acknowledge the successful powering ON of the AirPrime WISMO218 before it is ready to
operate. The ON/~OFF signal can be left at LOW level until power off.
Please note that temperature conditions may affect the timing for powering up.
The recommended way to release the ON/~OFF signal is to detect the WISMO_READY signal within
685ms of powering ON while the level pulse of the ON/~OFF signal is set to LOW, and wait until the
WISMO_READY signal goes HIGH again.