Sierra Wireless AirPrime MC5727, Hardware Integration Manual

Page: 23 / 126

Power Interface
Rev 1.9.1 Feb.09 Proprietary and Confidential 23
In the event of a discrepancy in values between this guide and the Product Specification Document (PSD), the PSD takes precedence.
State change: Normal mode to Low Power mode
This state change causes the module to switch to low power
mode, suspending RF activity. It occurs when the module
temperature exceeds the limits described in Table 2 ‐ 2
(TEMP_HI_CRIT and TEMP_LO_CRIT).
When this state change occurs, the CnS notification
CNS_RADIO_POWER is issued, if enabled. For a detailed
description of this notification, see CDMA CnS Reference
(Document 2130754) or MC87XX Modem CnS Reference
(Document 2130602) . As well, the MC57xx issues the CnS notifi ‐
cation Modem Too Hot [0x4500] if it has to drop a call when
shifting to low power mode.
State change: Low Power mode to Normal mode
This state change causes the module to switch to normal mode,
resuming RF activity. It occurs when the module temperature
returns from critical to normal limits as described in Table 2 ‐ 2
(TEMP_HI_NORM and TEMP_LO_NORM).
When this state change occurs, the CnS notification
CNS_RADIO_POWER is issued, if enabled. For a detailed
description of this notification, see CDMA CnS Reference
(Document 2130754) or MC87XX Modem CnS Reference
(Document 2130602) .
State change: Power off / on
The module begins a shutdown sequence and powers off if it
has been in a powered ‐ on state for more than 10.5 seconds and
the host device drives the
W_Disable
# signal low for:
•
≥
50 ms (MC8775 / MC8775V)
•
≥
500 ms (MC5725 / MC5725V / MC5727 / MC5727V /
MC5728 / MC5728V / MC8780 / MC8781 / MC8785V /
MC8790 / MC8790V / MC8791V / MC8792V)
Note: The module ignores changes in the W_Disable# line for the first
10.5 seconds after it enters a powered-on state.
The module powers on when the host device leaves the
W_Disable
# signal floating (high impedance) as shown in
Figure 2 ‐ 1 on page 17 .
Figure 2 ‐ 3 shows the transition from ‘Low Temperature
Critical’ or ‘High Temperature Critical’ to ‘Power off’.
1. The module enters low power mode because it detects that
the operating temperature is critically low
(TEMP_LO_CRIT) or critically high (TEMP_HI_CRIT).