AN332
182
Confidential Rev. 0.2
8. Powerdown
The procedure for moving the device from powerup to powerdown modes requires writing the POWER_DOWN
command.
To Power Down the device and remove VDD and VIO (optional):
1. Write TX_TUNE_POWER to the command register to disable the carrier.
2. Set RCLK = 0 (optional).
Note that the RCLK buffer is in the VIO supply domain and may therefore be supplied at any time that VIO is
supplied. The RCLK must be valid 10 ns before and 10 ns after sending the TX_TUNE_MEASURE,
TX_TUNE_FREQ, and TX_TUNE_POWER commands. In addition, the RCLK must be valid at all times when
the carrier is enabled for proper AGC operation. The RCLK may be removed or reconfigured at other times.
The RCLK is required for proper AGC operation when the carrier is enabled. The RCLK may be removed or
reconfigured when the carrier is disabled.
3. Write POWER_DOWN to the command register.
Note that all register contents will be lost.
4. Set RST = 0.
Note that RST must be held high for 10 ns after the completion of the POWER_DOWN command.
5. Remove VDD (optional).
6. Remove VIO (optional).
Note that VIO must not be removed without removing VDD.
Unexpected device operation may result.
Figure 12. Device Power Down Timing
Table 39. Using the POWER_DOWN command
Action
Data
Description
CMD
STATUS
0x11
→
0x80
POWER_DOWN
Reply Status. Clear-to-send high.
VDD
VIO
RSTB
Control
Bus
RCLK
POWER_DOWN
Command
TX_TUNE
POWER
Command
>10 ns
>10 ns