Datasheet

11.10. Analogue Audio Output Path
The codec supports five Analogue Audio Output paths:
 HPOUTL/R, HPOUTFB
 SPOLP/N
 SPORP/N
11.10.1. Headphone Output
HPOUTL/R provides two-channel single-ended output to headphone driver. The HPOUTL/R PA input
source can be selected from output mixer or directly from DAC by register HPOUT_CTRL Bit15 & Bit14
set. It also can be muted by register HPOUT_CTRL Bit13 & Bit12 set. The headphone PA power up or
down by register HPOUT_CTRL Bit11 set.
HPOUTL/R can drive a 16R or 32R headphone load without DC capacitors by using Charge Pump to
generate the negative rails. HPOUTFB is the ground loop noise rejection feedback. HBIAS provides
reference voltage for electret condenser type(ECM) microphones. Audio jack insert/ button press detection
function is also provided through measuring the HBIAS current.
Figure 27 Suggested Headphone Output Application
HPOUTL/R volumes can be independently adjusted under software control using the HP_VOL[5:0] of the
headphone output control registers. The adjustment is logarithmic with an 64dB rang in 1dB step from 0dB
to -62dB. The headphone outputs can be muted by writing codes 0x0 to HP_VOL[5:0] bits.
There are a DC offset cancellation circuit to remove the headphone output DC offset for preventing POP
noise in AC101. The function can be enabled or disabled by the register HP_DCRM_EN. This bit must be
set 0xf before headphone PA enabled, and this bit must be set 0x0 before headphone PA disabled.
A zero cross detect circuit is provided at the input to the headphones under the control of the ZCROSS_EN
bit . Using these controls the volume control values are only updated when the input signal to the gain stage
is close to the analogue ground level. This minimizes and audible clicks and zipper noise as the gain values
are changed or the device muted.
11.10.2. Speaker Output
SPOLP/N, SPORP/N provides two differential output without internal speaker amplifier. Using external
amplifier, a stereo speakers can be implemented. The SPOLP/N input source can be selected from left
output mixer or (left+right) output mixer. The SPORP/N input source can be selected from right output
mixer or (left+right) output mixer. So in mono speaker application, The best choice for SPOLP/N or