Data Sheet

LC840PA
Datasheet
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The LC840PA power supply system enters one of two supply voltage modes, normal or high voltage mode, depending on how
the external supply voltage is connected to these pins.
LC840PA power supply options:
▪ 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 range 3.0V to 3.6V range to LC840PA
VDD and VDD_HV pins.
OR
▪ Option 2 – High voltage mode power supply mode (using LC840PA 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 range 3.0V to 5.5V range to LC840PA VDD_HV pin. LC840PA VDD pin left unconnected.
For either option, if you use USB interface then the LC840PA VBUS pin must be connected to external supply within the range
4.35V to 5.5V. When using the LC840PA VBUS pin, you MUST externally fit a 4.7uF to ground.
Table 14 summarizes these power supply options.
Table 14: LC840PA powering options
Power Supply Pins
and Operating
Voltage Range
OPTION 1
Normal voltage mode
operation connect?
OPTION 2
High voltage mode
operation connect?
OPTION 1 with USB
peripheral,
operation, and normal
voltage connect?
OPTION 2 with USB
peripheral,
operation, and high
voltage connect?
VDD (pin31)
3.0V to 3.6V
Yes
(Note 1)
No
(Note 2)
Yes
No
(Note 2)
VDD_HV (pin25)
3.0V to 5.5V
No
Yes
No
Yes
(Note 5)
VBUS (pin24)
4.35V to 5.5V
No
(Note 3)
Yes
(Note 4)
Yes
(Note 4)
Power Supply Option Notes:
Note 1
Option 1 – External supply voltage is connected to BOTH the VDD and VDD_HV pins (so that VDD equals
VDD_HV). Connect external supply within range 3.0V to 3.6V range to BOTH LC840PA VDD and VDD_HV pins.