User Manual

Advanc
e
Information
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2015 Microchip Technology Inc.
page
9
BM78SPPS5MC2 , RN4678
1.1 Power Tree
Figures 2-1 : Power Tree
1.2 UART Interface
Figures 2-2 : Power and MCU interface examples.
Figure 2‐2 shows an example power scheme using a 3.3 volt to MCU VDD. Battery power is
applied to BAT_IN pin. From the LDO33_O pin, voltage can be routed the VDD_IO pin and external
circuitry including the MCU. This power scheme ensures that BM78 and MCU I/O voltages are
compatible.
CAUTION: The internal 3.3volt LDO current source: 50mA maximum!!