Monitoring Power Supply By At Command; Measuring The Supply Voltage V; Batt; Figure 3: Power Supply Limits During Transmit Burst - Siemens TC65 Hardware Interface Description

TC65 Hardware Interface Description
Strictly confidential / Draft
Example: If the length of the flex cable reaches the maximum length of 100mm, this
connection may cause, for example, a resistance of 30mΩ in the BATT+ line and
30mΩ in the GND line. As a result, a 2A transmit burst would add up to a total
voltage drop of 120mV. Plus, if a battery pack is involved, further losses may
occur due to the resistance across the battery lines and the internal resistance of
the battery including its protection circuit.

BATT+

min. 3.2V
3.2.2

Measuring the Supply Voltage V

The reference points for measuring the supply voltage V
GND, both accessible at a capacitor located close to the board-to-board connector of the
module.
Reference
point
BATT+

Figure 4: Position of the reference points BATT+ and GND

3.2.3

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 0.5s in TALK/DATA mode
to 50s when TC65 is in IDLE mode or Limited Service (deregistered). The displayed voltage
(in mV) is averaged over the last measuring period before the AT^SBV command was
executed.
TC65_HD_V00.521
Transmit
burst 2A

Figure 3: Power supply limits during transmit burst

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Transmit
burst 2A
BATT+
on the module are BATT+ and
BATT+
Reference
point GND
s
Ripple
Drop
24.05.2005