TLV320AIC29 Datasheet, PDF (28/85 Pages) Texas Instruments – STWREO AUDIO CODEC WITH INTERGRATED HEADPHONE AND SPEAKER AMPLIFIERS

TLV320AIC29
SLAS494A − DECEMBER 2005 − REVISED JANUARY 2006
www.ti.com
DAC Powerdown
The DAC powerdown flag (D4D3 of control register 05H/page 2) along with D10 of control register 05H/page
2 denotes the powerdown status of the DAC according to Table 2.
Table 2. DAC Powerdown Status
D10, D4, D3
0,0,0
0,0,1
0,1,0
0,1,1
1,0,0
1,0,1
1,1,0
1,1,1
POWERUP/POWERDOWN STATE OF DAC
DAC left and right are in stable powerup state.
DAC left is in stable powerup state.
DAC right is in the process of powering up. The length of this state is determined by PLL and output driver powerup delays
controlled by register programming.
DAC left is in the process of powering up. The length of this state is determined by PLL and output driver powerup delays
controlled by register programming.
DAC right is in stable powerup state.
DAC left and right are in the process of powering up. The length of this state is determined by PLL and output driver
powerup delays controlled by register programming.
DAC left and right are in the process of powering down. The length of this state is determined by soft−stepping of volume
control block.
DAC left is in the process of powering down. The length of this state is determined by soft−stepping of volume control block.
DAC right is in stable powerdown state.
DAC left is in stable powerdown state.
DAC right is in the process of powering down. The length of this state is determined by soft−stepping of volume control
block.
DAC left and right are in stable powerdown state.
Analog Outputs
The AIC29 has the capability to route the DAC output to any of the selected analog outputs. The AIC29 provides
various analog routing capabilities. All analog outputs other than the selected ones are powered down for
optimal power consumption.
D Headphone Drivers
The AIC29 features stereo headphone drivers (SPK1 and SPK2) that can deliver 44 mW per channel at 3.3-V
supply, into 16-Ω loads. The AIC29 provides flexibility to connect either of the DAC channels to either of the
headphone driver outputs. It also allows mixing of signals from different DAC channels. The headphones can
be connected in a single ended configuration using ac-coupling capacitors, or the capacitors can be removed
and virtual ground (VGND) powered for a cap-less output connection. Note that the VGND amplifier must be
powered up if the cap-less configuration is used.
In the case of an ac-coupled output, the value of the capacitors is typically chosen based on the amount of
low−frequency cut that can be tolerated. The capacitor in series with the load impedance forms a high-pass
filter with –3 dB cutoff frequency of 1/(2πRC) in Hz, where R is the impedance of the headphones. Use of an
overly small capacitor reduces low-frequency components in the signal output and lead to low-quality audio.
When driving 16-Ω headphones, capacitors of 220-µF (a commonly used value) result in a high-pass filter cutoff
frequency of 45 Hz, although reducing these capacitors to 50 µF results in a cutoff frequency of 199 Hz, which
is generally considered noticeable when playing music. The cutoff frequency is reduced to half of the above
values if 32-Ω headphones are used instead of 16-Ω.
The AIC29 programmable digital effects block can be used to help reduce the size of capacitors needed by
implementing a low frequency boost function to help compensate for the high-pass filter introduced by the
ac-coupling capacitors. For example, by using 50-µF capacitors and setting the AIC29 programmable filter
coefficients as shown below, the frequency response can be improved as shown in Figure 21.
Filter coefficients (use the same for both channels):
N0 = 32767, N1 = −32346, N2 = 31925, N3 = 32767, N4 = 0, N5 = 0
D0 = 32738, D1 = −32708, D4 = 0, D5 =0
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