User's Manual

Table Of Contents
26 novatelwireless.com
If the modem's I/O lines have another source of power, the modem may not
completely shutdown/reset even with a mechanical power switch or with this
circuit implemented.
To alleviate this situation, make sure that the interface circuitry is set to tri-state
or as an input. If this is not possible, you may need additional hardware to shunt
high-impedance lines to ground during these situations.
The un-switched power source must be capable of supporting the inrush current
required by the bulk capacitance. The enable switch can be soft-started via
voltage ramp or modulation to reduce the peak current.
DO NOT USE a Modem Power Switch as a routine shutdown or reset. This
technique for shutting down the modem does not properly deregister the
modem from the network. The carrier may impose penalties if a fleet of
equipment does not follow a proper deregistration process.
Level Translation Reference Power (Pin 77)
Use pin 77 as a voltage reference source ONLY. Do not connect current loads to this pin. This
pin must be decoupled to ground with at least a 0.1 ?F capacitor at the output. Noise induced
on this pin will affect the performance of the baseband.
Low-Power Mode is entered when RTCWAKE is used to power down the modem with just
the RTC running.
VR I/O Parameter/Conditions Min Typ Max Units
Output voltage VOUT ON mode
LOW POWER mode 1.65
1.65 1.8
1.8 1.95
1.95 Vdc
Rated output current IOUT ON mode
LOW POWER mode 20
0.5 mA