User's Manual
PCS3_HD_v01.000-03
Confidential / Preliminary
Page 33 of 101
2013-10-21
PCS3 Hardware Interface Description
3.4 Power Saving
3.4
Power Saving
PCS3 is able to reduce its functionality to a minimum (during the so-called SLEEP mode) in
order to minimize its current consumption. The following sections explain the module’s CTS0
behavior and also mention how to wake up from or disable the so-called SLEEP mode.
The implementation of the USB host interface also influences the module’s power saving
behavior and therefore its current consumption. For more information see Section 3.6.
Note. The module’s SLEEP mode current consumption can be reduced significantly (0.8mA)
by enabling the VEXT power save mode. Hence, it is recommended to enable power saving on
VEXT if at all possible. For more information see Table 22: VEXT.
Another feature influencing the current consumption is the configuration of the GNSS antenna
interface. For details see Section 6.9.
3.4.1
Power Saving while Attached to CDMA Networks
The so-called slotted paging in CDMA is similar to the WCDMA paging timing cycles for power
saving.
During normal CDMA operation, i.e., the module is connected to a CDMA network, the duration
of a power saving period varies. It may be calculated using the following formula:
T=2
i
* 1.28s (16 slots of 80ms)
The slot cycle index i is determined by the CDMA network and can be an integer between -4
to 7 inclusive. The typical value is 2. Therefore, the typical power saving period would be
(2
2
)*1.28s = 5.12s.
3.4.2
Timing of the CTS0 Signal, CDMA
As long as PCS3 is operated via the ASC0 interface and not in power saving mode, the CTS0
line is always active. This means that while attached to a network the CTS0 signal will be tem
poraly active during each paging.
After a concluding activity on the serial interface ASC0 - and depending on the module’s other
activities - it takes by default 5 seconds before CTS0 goes inactive (again) and power saving
starts. The 5 second delay period can be configured using the AT^SCFG parameter "MEop-
Mode/PwrSave", <PwrSaveDelay> (see [1]).
With regard to programming or using timeouts, the UART must take the varying CTS0 inactivity
periods into account.
Note: Hardware handshaking is mandatory if employing PCS3’s ASC0 interface with enabled
power saving. Thus AT commands are only recognized by the module while CTS0 is active.