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3.6.2. Reference Design for Power Supply
Power design for a module is critical to its performance. It is recommended to use a low quiescent current
LDO with output current capacity of 0.8 A when supplying power for BC65. A Li-MnO2/2S alkaline battery
can also be used as the power supply. The supply voltage of the module ranges from 3.2 to 4.2 V. When
the module is working, make sure its input voltage will never drop below 3.2 V; otherwise, the module will
be abnormal.
For better power performance, it is recommended to place a 100 μF tantalum capacitor with low ESR
(ESR = 0.7 Ω) and three ceramic capacitors (100 nF, 100 pF and 22 pF) near the VBAT pins. Also, it is
recommended to add a TVS diode on the VBAT trace (near VBAT pins) to improve surge withstand
capability. In principle, the longer the VBAT trace is, the wider the TVS diode should be. A reference
circuit for power supply is illustrated in the following figure.
3.7. Turn On/Off and Reset
3.7.1. Turn On
BC65 will be turned on after driving PWRKEY
Table 10: PWRKEY Pin
Pin Name
Pin No.
PWRKEY
7
BC65_Hardware_Design
VBAT
+
C1
C2
D1
TVS
100 μF
100 nF 100 pF 22 pF
GND
Figure 5: Reference Circuit for Power Supply
1)
Description
Turn on the module
Module
VBAT
VBAT
C3
C4
GND
to a low-level voltage for at least 1000 ms.
NB-IoT Module Series
BC65 Hardware Design
PWRKEY Pull-down Time
≥ 1000 ms
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