RFM22B/23B
3.2. Operating Mode Control
There are four primary states in the RFM22B/23B radio state machine:SHUTDOWN, IDLE, TX, and RX (see
Figure 7). The SHUTDOWN state completely shuts down the radio to minimize current consumption. There are five
different configurations/options for the IDLE state which can be selected to optimize the chip to the applications
needs. "Register 07h. Operating Mode and Function Control 1" controls which operating mode/state is selected
with the exception of SHUTDOWN which is controlled by SDN pin 20. The TX and RX state may be reached
automatically from any of the IDLE states by setting the txon/rxon bits in "Register 07h. Operating Mode and
Function Control 1". Table 11 shows each of the operating modes with the time required to reach either RX or TX
mode as well as the current consumption of each mode.
pply (LPLDO) which is internally connected in parallel
The RFM22B/23B includes a low-power digital regulated su
to the output of the main digital regulator (and is available externally at the VR_DIG pin). This common digital
supply voltage is connected to all digital circuit blocks including the digital modem, crystal oscillator, SPI, and
register space. The LPLDO has extremely low quiescent current consumption but limited current supply capability;
it is used only in the IDLE-STANDBY and IDLE-SLEEP modes. The main digital regulator is automatically enabled
in all other modes.
SHUTDOWN
SHUT DWN
LEID*
TX
RX
*Five Different Options for IDLE
Figure 7. State Machine Diagram
Table 11. Operating Modes Response Time
State/Mode
Response Time to
Current in State /Mode
[µA]
TX
RX
Shut Down State
16.8 ms
16.8 ms
15 nA
Idle States:
Standby Mode
Sleep Mode
Sensor Mode
Ready Mode
Tune Mode
800 µs
800 µs
800 µs
200 µs
200 µs
800 µs
800 µs
800 µs
200 µs
200 µs
450 nA
1 µA
1 µA
800 µA
8.5 mA
TX State
RX State
NA
200 µs
NA
30 mA @ +13 dBm
18.5 mA
200 µs
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