Laird BL654 User Manual page 10

All the external power sources listed above are buck-boost regulated to a fixed 5V on the development board.
The BL654 module has the following power supply pins:
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VDD pin (operating range of 1.7V to 3.6V) – Used for Normal Voltage mode
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VDD_HV pin (operating range of 2.5V to 5.5V) – Used for High Voltage mode
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VBUS pin (operating range of 4.35V to 5.5V) – Used for BL654 USB mode
It can be powered in the following ways:
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Normal Voltage mode operation
Option 1 – Normal voltage power supply mode entered when the external supply voltage is connected to both the
VDD and VDD_HV pins (so that VDD equals VDD_HV). Connect external supply within a 1.7V to 3.6V range to the
BL654 VDD and VDD_HV pins.
For Normal Voltage mode operation, the BL654 Development Board power supply section generates the following:
–
Regulated 3.3V
–
Regulated 1.8V
and then via selection switch SW5 (default is 3.3V position), you can select whether to use 3.3V or 1.8V.
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High Voltage mode operation
Option 2 – High voltage mode power supply mode (using BL654 VDD_HV pin) entered when the external supply
voltage in ONLY connected to the VDD_HV pin and the VDD pin is not connected to any external voltage supply.
Connect external supply within a 2.5V to 5.5V range to the BL654 VDD_HV pin. Leave the BL654 VDD pin unconnected.
For High Voltage mode operation, the BL654 Development Board power supply section generates the following:
–
Regulated 2.5V
–
3 x AAA generated 4.5V (or inject external voltage into J28pin1 up to 5.5V)
and then via selection switch SW8 (default is 2.5V position), you can select whether to use 2.5V or 4.5V.
Option 3 – High voltage mode with voltage via USB3
–
For either option, if you use the BL654 USB interface, the BL654 VBUS pin must be connected to an external
supply within the range of 4.35V to 5.5V.
The BL654 development board power supply section is designed to cater to the above. Follow the following steps:
1. Set SW7 – Select one of the following three positions:
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High Voltage mode operation and BL654 USB (connect USB cable to USB3 connector) – Top position. Source
from USB3.
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Normal Voltage mode operation – Middle position (default). Source from SW5.
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High Voltage mode operation – Bottom position. Source from SW8.
2. Depending on chosen SW7 position, select one of the following three positions:
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Plug in USB cable into USB3 – If SW7 is set to Top position.
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SW5 (either 3.3V or 1.8V) – Default SW5 on 3.3V position. If SW7 set to Middle position.
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SW8 (either 2.5V or 4.5V (3xAAA)) – Default SW8 on 2.5V position. If SW7 set to Bottom position.
Table 1 summarises the dev-board on-board power sources and switch positions.
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