NB-IoT Module Series
BC65 Hardware Design
BC65_Hardware_Design 22 / 55
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.
VBAT
C2
C1
+
C3
C4
GND
100
μ
F
100 nF
100 pF 22 pF
VBAT
Module
GND
D1
VBAT
TVS
Figure 5: Reference Circuit for Power Supply
3.7. Turn On/Off and Reset
3.7.1. Turn On
BC65 will be turned on after driving PWRKEY
1)
to a low-level voltage for at least 1000 ms.
Table 10: PWRKEY Pin
Pin Name Pin No.
Description
PWRKEY Pull-down Time
PWRKEY
7
Turn on the module
≥ 1000 ms
