Enfora Enabler III-G
Modem Integration Guide
6.6.17. Using VBAK
VBAK
is a backup voltage that can maintain the RTC clock and alarm functions. If
VBAK
is not present
in the system (intentionally or not) the RTC clock may still be powered if leakage voltage exists on VCC.
Otherwise, the RTC clock will lose power and be reset when VCC is restored.
VBAK
had been tested in the above scenarios and does not contribute to leakage. It will properly provide
backup power to the RTC clock.
6.6.18. 32 kHz output (Pin 56)
A 32.768 kHz signal is available as an output from the module. This signal should only be used as an
input to a high impedance device. Additional loads or capacitance on the line may cause performance
issues with the module. If the line is not used, leave floating.
32kHz Clock-Out
Parameter/Conditions
Min
Typ
Max
Units
V
IH
Vdc
V
IL
Vdc
Maximum capacitor load
tbd
pF
Maximum resistive load
Ω
Frequency
±
30 ppm
32.768 kHz
6.6.19. 13 MHz output (Pin 52)
A 13 MHz signal is available as an output from the module. This signal should only be used as an input
to a high impedance device. Additional loads or capacitance on the line may cause performance issues
with the module. If the line is not used, leave floating.
13 MHz Clock-Out
Parameter/Conditions
Min
Typ
Max
Units
V
IH
TBD
Vdc
V
IL
0.3
Vdc
Maximum capacitor load
TBD
pF
Maximum resistive load
TBD
Ω
Frequency
±
0.1 ppm when registered on
GSM network;
±
12 ppm typical when not
registered;
13.000 MHz
PARAMETER
PARAMETER / CONDITIONS
MIN
TYP
MAX
UNIT
Backup Voltage (Real-Time-Clock)
V
BACKUP
Backup Voltage for Real-Time-Clock
2.7
3.0
4.5
Vdc
I
BACKUP
Input Current (V
BACKUP
= 3.2 V, V
BAT
= 0 V,
No Load on GPIO or Serial Port)
3.0
6.0
μ
Adc
GSM0308PB001
49
Version DRAFT – 2/9/2007