14.1.6.1 SLEEP State

The SLEEP state is used when radio transceiver functionality is not required, and thus the AT86RF212B can be powered down to reduce the overall power consumption.

A power-down scenario is shown in the figure below. When the radio transceiver is in TRX_OFF state, the microcontroller forces the AT86RF212B to SLEEP by setting SLP_TR = H. If pin 17 (CLKM) provides a clock to the microcontroller, this clock is switched off after 35 CLKM cycles. This enables a microcontroller in a synchronous system to complete its power-down routine and prevent deadlock situations. The AT86RF212B awakes when the microcontroller releases pin 11 (SLP_TR). This concept provides the lowest possible power consumption.

The CLKM clock frequency settings for CLKM_CTRL values six and seven are not intended to directly clock the microcontroller. When using these clock rates, CLKM is turned off immediately when entering SLEEP state.

Figure 14-15. Sleep and Wake-up Initiated by Asynchronous Microcontroller Timer

Note: Timing figures t_TR3 and t_TR1a refer to the State Transition Timing Summary.