RFM31
2.1. Operating Modes
The RFM31 provides several modes of operation which can be used to optimize the power consumption of the
device application. Depending upon the system communication protocol, the optimal trade-off between the radio
wake time and power consumption can be achieved.
Table 8 summarizes the modes of operation of the RFM31. In general, any given mode of operation may be
classified as an Active mode or a Power Saving mode. The table indicates which block(s) are enabled (active) in
each corresponding mode. With the exception the Shutdown mode, all can be dynamically selected by sending the
appropriate commands over the SPI in order to optimize the average current consumption. An ―X‖ in any cell
means that, in the given mode of operation, that block can be independently programmed to be either ON or OFF,
without noticeably affecting the current consumption. The SPI circuit block includes the SPI interface and the register
space. The 32 kHz OSC circuit block includes the 32.768 kHz RC oscillator or 32.768 kHz crystal oscillator, and
wake-up timer. AUX (Auxiliary Blocks) includes the temperature sensor, general purpose ADC, and low-battery
detector.
Table 8. Operating Modes
Mode
Name
Circuit Blocks
Digital LDO
SPI
SPI
32 kHz
OSC AUX
OFF
30 MHz PLL
XTAL
RX
IVDD
Shutdown
OFF
(Register contents lost)
ON
OFF
OFF
OFF
OFF
OFF
10 nA
Standby
Sleep
ON
ON
ON
ON
ON
ON
OFF
ON
X
OFF
X
OFF
OFF
OFF
ON
OFF
OFF
OFF
OFF
ON
OFF
OFF
OFF
OFF
OFF
ON
400 nA
800 nA
1 μA
(Register contents retained)
Sensor
Ready
Tuning
Receive
ON
X
X
600 μA
9.5 mA
18.5 mA
X
X
ON
X
X
ON
ON
11
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