Datasheet
ADAU1381
Rev. B | Page 25 of 84
STARTUP, INITIALIZATION, AND POWER
This section details the procedure for setting up the ADAU1381
properly. Figure 27 provides an overview of how to initialize the IC.
START
CONFIGURE CLOCK GENERATION
REGISTER 16384 (0x4000)
AND REGISTER 16386 (0x4002)
SUPPLY POWER TO AVDD1/AVDD2
PINS SIMULTANEOUSLY
SET UP SOUND ENGINE REGISTERS
FOR CUSTOMIZED SIGNAL PATH
(INCLUDING VOLUME, SAMPLE RATES,
FILTER COEFFICIENTS)
INITIALIZATION
COMPLETE
WAIT 14ms FOR POWER-ON RESET
AND INITIALIZATION ROM BOOT
SUPPLY POWER TO IOVDD
ENABLE DIGITAL POWER TO
FUNCTIONAL SUBSYSTEMS
REGISTER 16512 (0x4080)
AND REGISTER 16513 (0x4081)
WAIT FOR PLL LOCK
(2.4ms TO 3.5ms)
ARE AVDD1 AND AVDD2
SUPPLIED SEPARATELY?
CAN AVDD1 AND AVDD2
BE SIMULTANEOUSLY
SUPPLIED?
SUPPLY POWER
TO AVDD2
SUPPLY POWER
TO AVDD1
NOYES
YES
08313-025
NO
Figure 27. Initialization Sequence
POWER-UP SEQUENCE
If AVDD1 and AVDD2 are from the same supply, they can
power up simultaneously. If AVDD1 and AVDD2 are from
separate supplies, then AVDD1 should be powered up first.
IOVDD should be applied simultaneously with AVDD1, if
possible.
The ADAU1381 uses a power-on reset (POR) circuit to reset the
registers upon power-up. The POR monitors the DVDDOUT
pin and generates a reset signal whenever power is applied to
the chip. During the reset, the ADAU1381 is set to the default
values documented in the register map (see the Control Register
Map section).
The POR is also used to prevent clicks and pops on the speaker
driver output. The power-up sequencing and timing involved is
described in Figure 28 in this section, and in Figure 36 and
Figure 37 of the Speaker Output section.
A self-boot ROM initializes the memories after the POR has
completed. When the self-boot sequence is complete, the control
registers are accessible via the I
2
C/SPI control port and should
then be configured as required for the application. Typically,
with a 10 F capacitor on AVDD1, the power supply ramp-up,
POR, and self-boot combined take approximately 14 ms.
AVDD1
AVDD2
DVDDOUT
POWER-UP
(INTERNAL
SIGNAL)
INTERNAL MCLK
(NOT TO SCALE)
IOVDD
INPUT/OUTPUT
PINS
ACTIVE
1.35V
1.5V
0.95V
MAIN SUPPLY ENABLED
POR
ACTIVE
1.5V
MAIN SUPPLY DISABLED
14ms
HIGH-ZHIGH-Z
POR COMPLETE/SELF-BOOT INITIATES
SELF-BOOT COMPLETE/MEMORY
IS ACCESSIBLE
POR ACTIVATES
08313-026
Figure 28. Power-Up and Power-Down Sequence Timing Diagram