User's Manual

HiLo3G-850 User Manual
04 March 2011 - Page 23 / 36
4.2 Module Power up
There are two ways to start HiLo3G-850, one is using PWON and the other is using USB.
4.2.1 PWON Power up
To start the module, first power up VBAT, which must be in the range 3.2V ~ 4.4V, and able to provide 1.75A during the
TX bursts.
PWON is a low level active signal internally pulled up to a dedicated power domain to 2.9V.
As PWON is internally pulled up, a simple open collector or open drain transistor can be used for ignition.
To start the module, a low level pulse must be applied on PWON during 500ms.
After a few seconds, the CTS goes to the active state when the module is ready to receive AT commands.
VGPIO is a supply output from the module that can be used to check if the module is alive.
• When VGPIO = 0V the module is OFF
• When VGPIO = 2.9V the module is ON
Figure 24: Power on sequence
AT+CPOF
CTS
Module Off