Specifications

Cinterion
®
ELS81-US Hardware Interface Description
3.4 Power Supply
77

els81-us_hid_v01.004 2017-09-27
Confidential / Preliminary
Page 72 of 107
3.4.2 Measuring the Supply Voltage (V
BATT+
)
To measure the supply voltage V
BATT+
it is possible to define two reference points GND and
BATT+. GND should be the module’s shielding, while BATT+ should be a test pad on the ex-
ternal application the module is mounted on. The external BATT+ reference point has to be
connected to and positioned close to the SMT application interface’s BATT+ pads 53
(BATT+
RF
) or 204 (BATT+
BB
) as shown in Figure 39.
Figure 39: Position of reference points BATT+ and GND
3.4.3 Monitoring Power Supply by AT Command
To monitor the supply voltage you can also use the AT^SBV command which returns the value
related to the reference points BATT+ and GND.
The module continuously measures the voltage at intervals depending on the operating mode
of the RF interface. The duration of measuring ranges from 0.5 seconds in TALK/DATA mode
to 50 seconds when ELS81-US is in IDLE mode or Limited Service (deregistered). The dis-
played voltage (in mV) is averaged over the last measuring period before the AT^SBV com-
mand was executed.
If the measured voltage drops below or rises above the voltage shutdown thresholds, the mod-
ule will send an "^SBC" URC and shut down (for details see Section 3.2.5).
Reference point GND:
Module shielding
Reference point BATT+:
External test pad connected to
and positioned closely to BATT+
pad 53 or 204.
External application