User Manual

Power Interface
Rev 1.2 Apr-05 Proprietary and confidential 25
Current consumption
Electrical requirements and current specifications are listed in Table 2.
Conditions related to the various modes of operation are described in subsections
following the table. These specifications identify the maximum current drain;
typical use should result in less drain, depending on the application.
For sleep modes, the figures are given for the actual sleep state. The modem
wakes at intervals to control timing and check for traffic. At those moments the
current consumption is higher.
Table 2: Current specifications
Condition Minimum Typical Maximum Units
CDMA Transmitting
1
250 300 950 mA
CDMA Receiving 90 100 120 mA
CDMA Sleep
2
(slot cycle 2) 1.4 1.7 1.75 mA
GSM Transmitting
3
- 140 2750 mA
GSM Receiving - 75 - mA
Deep Sleep average 0.5 0.7 1.5 mA
Shutdown 0.03 0.05 0.1 mA
Note 1— CDMA Transmitting
The transmit current is dependent on the radio band in use and the network’s
control of the modem output power. The “typical” value is based on 40% full
rate and 60% 1/8th rate over -35 – +23.5 dBm.
Note 2—CDMA Sleep
The EM supports slotted mode operation and Quick Paging Channel. Both of
these features enable reduced sleep current. The figures quoted are the lowest
power consumption (/DTR1 must be deasserted) during the sleep cycle.
The default Slot Cycle Index (SCI) for slotted mode operation is determined by
the PRI setting (usually set to 1). To achieve the lowest current consumption, the
DTR signal must be deasserted. Figures given are during the sleep state as
outlined in the mode details.
Note 1— GSM Transmitting
The transmit current is dependent on the radio band in use and the network’s
control of the modem output power. The “typical” value is based on 1Tx slot @
+5 dBm. The “maximum” value is the highest pulse current during a +33 dBm
Tx burst.
Modes
The EM operates in several different modes; the mode can have a significant
impact on current consumption.