Data Sheet

LC840PA
Datasheet
https://www.lairdconnect.com
27
© Copyright 2021 Laird Connectivity
All Rights Reserved
Americas: [phone]
Europe: [phone]
Hong Kong: [phone]
Power Supply Option Notes:
Note 2
Option 2 – External supply within range 3.0V to 5.5V range to the LC840PA VDD_HV pin ONLY. LC840PA VDD
pin left unconnected.
In High voltage mode, the VDD pin becomes an output voltage pin. It can be used to supply external circuitry
from the VDD pin. Before any current can be taken from the LC840PA VDD pin, this feature must be enabled in
the LC840PA. Additionally, the VDD output voltage is configurable from 1.8V to 3.3V with possible settings of
1.8V, 2.1V, 2.4V, 2.7V, 3.0V, and 3.3V. The default voltage is 1.8V.
The supported LC840PA VDD pin output voltage range depends on the supply voltage provided on the LC840PA
VDD_HV pin. The minimum difference between voltage supplied on the VDD_HV pin and the voltage output on
the VDD pin is 0.3 V. The maximum output voltage of the VDD pin is VDDH – 0.3V. Table4 shows the current
that can be drawn by external circuitry from VDD pin in high voltage mode (supply on VDD_HV).
Table 15: Current that can be drawn by external circuitry from VDD pin in High voltage mode (supply on VDD_HV)
Parameter
Min
Typ
Max
Unit
External current draw (from VDD pin) allowed in High Voltage mode
(supply on VDD_HV) during System OFF (LC840PA Deep Sleep)
1
mA
External current draw (from VDD pin) allowed in High Voltage mode
(supply on VDD_HV) when radio Tx RF power higher than 4dBm.
5
mA
External current draw (from VDD pin) allowed in High Voltage mode
(supply on VDD_HV) when radio Tx RF power lower than 4dBm.
25
mA
Minimum difference between voltage supplied on VDD_HV pin and
voltage on VDD pin
0.3
V
Note 3
External current draw is the sum of all GPIO currents and current being drawn from VDD.
Depends on whether USB operation is required
Note 4
When using the LC840PA VBUS pin, you must externally fit a 4.7uF capacitor to ground.
Note 5
To use the LC840PA USB peripheral:
1. Connect the LC840PA VBUS pin to the external supply within the range 4.35V to 5.5V. When using the
LC840PA VBUS pin, you MUST externally fit a 4.7 uF to ground.
2. Connect the external supply to either the VDD (Option 1) or VDD_HV (Option 2) pin to operate the rest of
LC840PA module.
When using the LC840PA USB peripheral, the VBUS pin can be supplied from same source as VDD_HV
(within the operating voltage range of the VBUS pin and VDD_HV pin).