adau1361 Analog Devices, Inc., adau1361 Datasheet - Page 34

• Manufacturer Part Number: adau1361
• Description: Stereo, Low Power, 96 Khz, 24-bit Audio Codec With Integrated Pll
• Manufacturer: Analog Devices, Inc.

ADAU1361
Capless Headphone Configuration
The headphone outputs
configuration with the MONOOUT pin used as a dc virtual
ground reference. Figure 43 depicts a typical playback path in
a capless headphone configuration. Table 19 lists the register
settings for this configuration. As shown in this table, the
MONO
is used as t
Table 19. Capless Headphone Register Settings
Register
R36
R22
R24
R28
R33
R29
R30
Headphone Output Power-Up/Power-Down Sequencing
To prevent pops when turning on the headphone outputs, the
user must wait at least 4 ms to unmute these outputs after
enabling the headphone output with the HPMODE bit. This i
because of an internal capacitor that m
outputs can be used. Figure 44 and Figure 45 illustrate
headphone power-up/power-down sequencing.
Fo capless headphones, configure the MONOOUT pin before
un uting the headphone outputs.
r
m
OUT pin outputs common mode (AVDD/2), wh
Figure 43. Capless Headphone Configuration Diagram
RIGHT
he virtual headphone reference.
LEFT
DAC
DAC
Bit Name
DACEN[1:0]
MX3EN
MX3LM
MX4EN
MX4RM
MX7EN
MX7[1:0]
MONOM
MOMODE
LHPVOL[5:0]
LHPM
HPMODE
RHPVOL[5:0]
RHPM
MX3LM
MX4RM
MX7[1:0]
can be co
MIXER 3
MIXER 7
MIXER 4
MX3EN
MX7EN
MX4EN
Setting
11 = both DACs on
1 = enable Mixer 3
1 = unmute left DAC input
1 = enable Mixer 4
1 = unmute right DAC input
1 = enable Mixer 7
00 = common-mode output
1 = unmute mono output
1 = headphone output
Desired volume for LHP output
1 = unmute left headphone output
1 = headphone output
Desired volume for RHP output
1 = unmute right headphone output
LHPVOL[5:0]
RHPVOL[5:0]
nfigur
MOMODE
MONOM
ust charge before these
ed in a capless output
LHP
MONOOUT
RHP
the
ich
Rev. 0 | Page 34 of 80
s
Ground-Centered Headphone Configuration
The headphone outputs can also be configured as ground-
centered outputs by placing coupling capacitors on the LHP
and RHP pins. Ground-centered headphones should use the
AGND pin as the ground reference.
When the headphone outputs are configured in this manner,
the capacitors create a high-pass filter on the outputs. The corner
frequency of this filter, at which point its attenuation is 3 dB, is
calculated by the following formula:
where :
C is the capacitor value.
R is the impedance of the headphones.
For a typical headphone impedance of 16 Ω and a 47 μF
capacitor, the corner frequency is 211 Hz.
Jack Detection
When the JACKDET/MICIN pin is set to the jack detect func-
tion, a flag on this pin can be used t
when headphones are plugged
configured in Register R2 (dig
control register, Address 0x4008). The JDFUNC[1:0] bits set t
functionality of the JACKDET/MICIN pin.
The JDMUTE bit enables a line output muting function, which
mutes all of the line outputs when a headphone jack is detected.
When headphones are unplugged from the jack, the headph
driver and outputs are muted.
Additional settings for jack detection include debounce time
(JDDB[1:0] bits) and detection polarity (JDPOL bit). Because
the jack detection and digital microphone share a pin, both
functions cannot be used simultaneously.
RHPM AND LHPM
RHPM AND LHPM
0 = LINE OUTPUT
f
1 = HEADPHONE
3dB
PRECHARGE
= 1/(2π × R × C)
1 = UNMUTE
INTERNAL
HPMODE
0 = MUTE
Figure 45. Headphone Output Power-Down Timing
HPMODE
Figure 44. Headphone Output Power-Up Timing
ital microphone/jack detection
into their jacks. This pin can be
USER DEFINED
o mute the line outputs
4ms
DEFINED
USER
one
he