M20 Hardware Design
3 Application interface
The module is equipped with a 50-pin 0.5mm pitch B2B connector that connects to the cellular
application platform. Sub-interfaces included on this B2B connector are described in details in the
following chapters:
z Power supply (refer to Chapter 3.3
)
z Serial interface (refer to Chapter 3.9
)
z Analog audio interface (refer to Chapter 3.10
)
z SIM interface (refer to Chapter 3.11
)
Electrical and mechanical characteristics of the B2B connector are specified in Chapter 5 & Chapter
7.
3.1 Pin description
Table 5: Pin description
Power Supply
PIN NAME I/O DESCRIPTION DC CHARACTERISTICS COMMENT
VBAT I VBAT pins of the B2B are
dedicated to connect the
supply voltage. The power
supply of module has to be a
single voltage source of
VBAT= 3.4V...4.5V. It must
be able to provide sufficient
current in a transmitting
burst which typically rises to
2A. Mostly, these 5 pins are
voltage inputs.
Vmax= 4.5V
Vmin=3.4V
Vnorm=4.0V
VCHG I
Voltage input for the
charging circuit
Vmax=6.5V
Vmin=1.1 * VBAT
Vnorm=5.0V
If unused,
keep this pin
open.
VRTC I/O Power supply for RTC when
VBAT is not supplied for the
system.
Charging backup battery or
golden capacitor when the
VBAT is supplied.
VImax=VBAT
VImin=2.6V
VInorm=2.75V
VOmax=2.85V
VOmin=2.6V
VOnorm=2.75V
Iout(max)= 730uA
Iin=2.6~5 uA
Recommend
to connect to
a backup
battery or a
golden
capacitor.
M20_HD_V1.01 - 18 -
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