Huawei MU509 Series Hardware Manual page 29

HUAWEI MU509 Series HSDPA LGA Module
Hardware Guide
Table 3-3 Keep-alive capacitor values vs. SMPL timer settings
SMPL timer setting
0.5s
1.0s
1.5s
2.0s
If the SMPL counter expires without VBAT returning to its valid range, the MU509
must undergo the normal power-on sequence whenever the VBAT is detected.
Real-time clock
If RTC is used, a manganese-lithium rechargeable battery is recommended, for
example, the SII Micro Parts HB-414 and the Panasonic ML-series. Two sets of coin
cell specifications are compared in Table 3-4 . When the MU509 is off, RTC and its
oscillator source are still active, provided by a coin cell battery which is installed. This
allows continued monitoring of RTC alarms programmed via software.
Table 3-4 Coin cell characteristics
Parameter
Nominal voltage
Nominal capacity
Continuous standard
load
Operating temperature
Diameter
Height
Weight
An interrupt is generated if the coin cell voltage drops too low (and the main battery is
not present). If this interrupt occurs, the RTC might be corrupted. A different interrupt
is generated if the crystal oscillator stops; this signifies that handset timing is no longer
accurate. Again, the RTC is corrupted.
When the VBAT power supply of the MU509 is normal, the coin cell is charged from
VBAT. The MU509 reads the coin cell voltage and monitors the charging. During
normal operation, the VCOIN pin voltage will stay above 2.2 V, even when the coin
cell charger is turned off. Figure 3-3 shows the reference RTC circuit.
Issue 09 (2014-03-06)
Capacitor value
1.5 μF
3.3 μF
4.7 μF
6.8 μF
Specifications
HB-414
3 V
0.3 mAh
5 mA
–20°C to +60°C
4.8 mm
1.4 mm
0.07 g
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Copyright © Huawei Technologies Co., Ltd.
Description of the Application Interfaces
Capacitor package (X5R)
0805
0805
0805
1206
ML-series
3 V
3.4 mAh
10 mA
–20°C to +60°C
6.8 mm
1.45 mm
0.17 g
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