AN332
176
Confidential Rev. 0.2
7. Powerup
There are two procedures for booting the device to move it from powerdown mode to the powerup mode. The first
and most common is a boot from internal device memory. The second is a boot from a firmware patch that is
written from the system controller to the device.
To power up the device:
1. Supply VDD and VIO while keeping the RST = 0.
The minimum VDD and VIO rise time is 25 µs, and VDD and VIO must be stable 250 µs before setting
RST = 1.
Power supplies may be sequenced in any order.
RST is in the VIO supply domain and therefore RST = 0 must be maintained before VIO is supplied.
2. Set GPO1 and GPO2 for the desired bus mode.
The minimum setup time for GPO1 and GPO2 before RST = 1 is 30 ns when actively driven by the system
controller and 100 µs if the internal 1 M
Ω
resistor is allowed to set the default GPO1 (high) and GPO2 (low).
3. Set RST = 1.
4. Write POWER_UP to the command register.
The POWER_UP command instructs the device to boot from internal memory, see Section “7.1. Powerup from
Device Memory”, or from a firmware patch sent from the system controller, see Section “7.2. Powerup from a
Component Patch”. After CTS = 1, the device is ready to commence normal operation and accept additional
commands. The POWER_UP command configures the state of DIN (pin 13), DFS (pin 14), and RIN (pin 15)
and LIN (pin 16) for analog or digital audio modes and GPO2/INT for interrupt operation. Prior to this command
these pins are set to high impedance. The GPIO_CTL and GPIO_SET commands configure the state of
GPO2/INT and GPO3. Prior to this command these pins are set to high impedance.
5. Provide RCLK.
Note that the RCLK buffer is in the VIO supply domain and may therefore be supplied at any time after VIO is
supplied. The RCLK must be valid 10 ns before any command that enables the TX carrier, such as the
TX_TUNE_FREQ command, and for 10 ns after any command that disables the carrier, such as the
TX_TUNE_POWER command with a value of 0x00. 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.
Figure 11. Device Power Up Timing
VDD
VIO
RSTB
Control
Bus
POWER_UP
Command
RCLK
TX_TUNE
FREQ
Command
>250 us
>25 us
>10 ns
>10 ns