14.2.1.2.2 SLEEP - Sleep State

In SLEEP state, the radio transceiver is disabled. The radio transceiver current consumption is reduced to leakage current plus the current of a low power voltage regulator (typ. 100nA). This regulator provides the supply voltage to the registers to preserve their contents. SLEEP state can only be entered from state TRX_OFF, by setting SLP_TR = H.

If CLKM is enabled with a clock rates higher than 250kHz, the SLEEP state is entered 35 CLKM cycles after the rising edge at pin 11 (SLP_TR). At that time CLKM is turned off. If the CLKM output is already turned off (register bits CLKM_CTRL = 0), the SLEEP state is entered immediately.

At clock rates of 250kHz and symbol clock rate (TRX_CTRL_0.CLKM_CTRL values six and seven), the main clock at pin 17 (CLKM) is turned off immediately.

Setting SLP_TR = L returns the radio transceiver back to the TRX_OFF state. During SLEEP state the radio transceiver register contents and the AES register contents remain valid while the contents of the Frame Buffer are lost.

/RST = L in SLEEP state returns the radio transceiver to TRX_OFF state and thereby sets all registers to their default values. Exceptions are the CLKM_CTRL bits in the TRX_CTRL_0 register (TRX_CTRL_0.CLKM_CTRL). These register bits require a specific treatment.