Sierra Wireless MC5720, Hardware Integration Manual, Page: 12 / 30

MC5720/8755/8765 Hardware Integration Guide
Note: The module unit defaults
to the Normal state when
VCC3.3 is first applied in the
absence of W_Disable# control
.
Note: The difference between
the Disconnected and Off states
is that in the Off state, the
module is still connected to the
power source and draws minimal
current.
Note: ESD protection is highly recommended for the SIM connector
at the point where the contacts are exposed, and any other signals
from the host interface that would be subjected to ESD by the user of
the end product.
Module power states
At any time, the module will be in one of four power states:
•
Disconnected
No power to the module.
•
Off
Power to the module, but the module is powered off.
•
Normal
The module is active. Several modes are possible (Receive,
Transmit, Sleep, Shutdown).
•
Low power (“airplane mode”)
The module is active, but RF is disabled.
State machines are implemented in the module to monitor the
power supply and operating temperature.
Disconnected state
This state occurs when there is no power to the module — the
host power source is disconnected from the module and all
voltages associated with the module are at 0 V.
Whether the host device is also powered off depends on the
power rail design. If the connection between the power rail
and the module is controlled by the host, the host can stay
powered on and cut the power to put the modem into the
disconnected state. If the power rail is shared between the host
device and the module, the host is powered off when the
module is powered off.
Off state
In this state, the host is powered up and the module is
powered down (but still connected to the power source).
The host keeps the module powered off by asserting (driving
low) the
W_Disable#
signal. In this state, the module draws
minimal current.
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