Datasheet

HPR

HPL

RLS-

RLS+

LSS-

LSS+

HPS

ENABLE

LM49450

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SNAS440D –FEBRUARY 2008–REVISED MAY 2013

The LM49450 3D function is controlled through the I

C interface. The headphone and speakers have

independent 3D controls, allowing each signal path to have its own individual 3D configuration. The LM49450 3D

features two effect modes, a narrow effect that decreases the channel separation, making the speakers sound

closer together, and a wide effect that makes the speakers sound farther apart. Because the narrow effect mode

adds a portion of the left and right signals together, a selectable 6dB attenuation mode is provided to maintain a

constant output amplitude when the narrow effect mode is active without changing the volume level. The high

pass 3dB roll off frequency, 3D gain (amount channel mixing), and narrow/wide effect selection is done through

registers 0x05h (headphone) and 0x06h (speaker. See the Headphone 3D Configuration Register and

Headphone 3D Configuration Register sections for more information.

Headphone Sense

The LM49450 features a headphone sense input (HPS) that monitors the headphone jack and configures the

device depending on the presence of a headphone. When the HPS pin is low, indicating that a headphone is not

present, the LM49450 speaker amplifiers are active and the headphone amplifiers are disabled. When the HPS

pin is high, indicating that a headphone is present, the headphone amplifiers are active while the speaker

amplifiers are disabled.

Figure 71. HPS Connection

Volume Control

The LM49450 features two separate 32-step volume controls, one for the speaker channels and one for the

headphone channels. This allows for the gain of the headphone and speakers to be set independently of each

other.

External Reference

The LM49450 can be used with an external reference. Disable the internal reference by setting bit B7 of the

Mode Control Register (0x00h) to 1. This allows an external reference voltage to be applied to REF. For proper

operation, do not allow the V

REF

to exceed V

Product Folder Links: LM49450