wm8400 Wolfson Microelectronics plc, wm8400 Datasheet - Page 93

• Manufacturer Part Number: wm8400
• Description: Wolfson Audioplustm Hi-fi Audio Codec And Power Management Unit For Mobile Multimedia
• Manufacturer: Wolfson Microelectronics plc

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Pre-Production
Table 59 Speaker Boost Control
In Class D mode, the Class D switching clock must be configured as described earlier (see “Clocking
and Sample Rates). See Table 12 for definitions of the associated register fields.
HEADPHONE OUTPUT CONFIGURATIONS
The headphone outputs LOUT, ROUT, OUT3 and OUT4 are each driven by different output mixers
as described below.
The LOUT and ROUT pins output the LOMIX and ROMIX outputs respectively.
The output mixer OUT3MIX produces an output OUT3 that is a combination of:
The output mixer OUT4MIX produces an output OUT4 that is a combination of:
Full volume control is available on LOUT and ROUT. 0dB and -6dB attenuation is available on OUT3
and OUT4, with full volume control available using LOPGA and ROPGA for the LOMIX and ROMIX
signals.
The outputs LOUT, ROUT, OUT3 and OUT4 are capable of driving 40mW into 16Ω loads such as
stereo headsets, headphones, and/or a handset ear speaker. AC-coupled, capless mode and fully
differential headphone drive modes are available.
AC-coupled output is possible on each of LOUT, ROUT, OUT3 and OUT4 simultaneously.
Capless headphone output is possible on LOUT and ROUT by using either OUT3 or OUT4 as the
common return path. (This is achieved by muting OUT3 or OUT4 as required.)
If RXP and RXN are a mono differential input (e.g. a connection to an external voice CODEC), then
OUT3 and OUT4 may be used as a differential output capable of driving a handset ear speaker. The
signal paths from RXP to OUT4 and from RXN to OUT3 are direct, and do not pass through any
additional amplifiers. This reduces standby and active power consumption and improves signal
quality.
R35 (23h)
R37 (25h)
REGISTER
ADDRESS
•
•
•
•
LIN4/RXN
LOMIX output via volume control LOPGA
RIN4/RXP
ROMIX output via volume control ROPGA
8
5:3
2:0
BIT
CDMODE
DCGAIN
[2:0]
ACGAIN
[2:0]
LABEL
0b
000b
(1.0x)
000b
(1.0x)
DEFAULT
Speaker Class D Mode Enable
0 = Class D mode
1 = Class AB mode
DC Speaker Boost
000 = 1.00x boost (+0dB)
001 = 1.27x boost (+2.1dB)
010 = 1.40x boost (+2.9dB)
011 = 1.52x boost (+3.6dB)
100 = 1.67x boost (+4.5dB)
101 = 1.80x boost (+5.1dB)
110 to 111 = Reserved
AC Speaker Boost
000 = 1.00x boost (+0dB)
001 = 1.27x boost (+2.1dB)
010 = 1.40x boost (+2.9dB)
011 = 1.52x boost (+3.6dB)
100 = 1.67x boost (+4.5dB)
101 = 1.80x boost (+5.1dB)
110 to 111 = Reserved
DESCRIPTION
PP, April 2009, Rev 3.0
WM8400
93