lm49370rl National Semiconductor Corporation, lm49370rl Datasheet - Page 48

• Manufacturer Part Number: lm49370rl
• Description: Audio Sub-system With An Ultra Low Emi, Spread Spectrum, Class D Loudspeaker Amplifier, A Dual-mode Stereo Headphone Amplifier, And A Dedicated Pcm Interface For Bluetooth Transceivers
• Manufacturer: National Semiconductor Corporation

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Bits
3:2
5:4
0
1
6
7
12.31 3D CONFIGURATION REGISTER
This register is used to control the configuration of the 3D circuit.
CUST_COMP
ATTENUATE
3D_TYPE
3D_ENB
LEVEL
FREQ
Field
Setting this bit enables the 3D effect. When cleared to zero, the 3D effect is disabled and the 3D module
then passes the I
unaffected by the 3D module.
This bit selects between type 1 and type 2 3D sound effect. Clearing this bit to zero selects type 1 effect
and setting it to one selects type 2.
Type1: Rout = Ri-G*Lout3d, Lout = Li-G*Rout3d
Type2: Rout = -Ri-G*Lout3d, Lout = Li+G*Rout3d
where,
Ri = Right I
Li = Left I
G = 3D gain level (Mix ratio)
Rout3d = Ri filtered through a high-pass filter with a corner frequency controlled by FREQ
Lout3d = Li filtered through a high-pass filter with a corner frequency controlled by FREQ
This programs the level of 3D effect that is applied.
This programs the HPF rolloff (-3dB) frequency of the 3D effect.
Clearing this bit to zero maintains the level of the left and right input channels at the output. Setting this
bit to one attenuates the output level by 50%.
This may be appropriate for high level audio inputs when type 2 3D effect is used. Type 2 effect involves
adding the same polarity of left and right inputs to give the final outputs. Type 2 effect has the potential
for creating a clipping condition, however this bit offers an alternative to clipping.
If set, the DAC compensation filter may be programmed by the user through registers (0x20h) to( 0x25h).
Otherwise, the defaults are used.
00
01
10
11
00
01
10
11
2
S channel input
2
2
2
2
2
2
2
2
2
S channel input
2
S left and right channel inputs to the DAC unchanged. The stereo AUX inputs are
TABLE 32. 3D (0x19h)
48
Description
LEVEL
300Hz
600Hz
900Hz
37.5%
FREQ
25%
50%
75%
0Hz