Datasheet

TLV320AIC3120

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SLAS653A –FEBRUARY 2010–REVISED MAY 2012

5.6.3 Volume-Control Pin

The range of voltages used by the 7-bit SAR ADC is shown in the Electrical Characteristics table.

The volume-control pin is not enabled by default, but it can be enabled by writing 1 to page 0 / register

116, bit D7. The default DAC volume control uses software control of the volume, which occurs if page 0 /

D1–D0.

When the volume-pin function is used, a 7-bit Vol ADC reads the voltage on the VOL/MICDET pin and

updates the digital volume control. (It overwrites the current value of the volume control.) The new volume

setting which has been applied due to a change of voltage on the volume control pin can be read on

page 0 / register 117, bits D6–D0. The 7-bit Vol ADC clock source can be selected on page 0 / register

116, bit D6. The update rate can be programmed on page 0 / register 116, bits D2–D0 for this 7-bit SAR

ADC.

The VOL/MICDET pin gain mapping is shown in Table 5-27.

Table 5-27. VOL/MICDET Pin Gain Mapping

VOL/MICDET PIN SAR OUTPUT DIGITAL GAIN APPLIED

0 18 dB

1 17.5 dB

2 17 dB

: :

35 0.5 dB

36 0.0 dB

37 –0.5 dB

: :

89 –26.5 dB

90 –27 dB

91 –28 dB

: :

125 –62 dB

126 –63 dB

127 Mute

The VOL/MICDET pin connection and functionality are shown in Figure 1-1.

As shown in Table 5-27, the VOL/MICDET pin has a range of volume control from 18 dB down to –63 dB,

and mute. However, if less maximum gain is required, then a smaller range of voltage should be applied

to the VOL/MICDET pin. This can be done by increasing the value of R2 relative to the value of (P1 + R1),

so that more voltage is available at the bottom of P1. The circuit should also be designed such that for the

values of R1, R2, and P1 chosen, the maximum voltage (top of the potentiometer) does not exceed

AVDD/2 (see Figure 5-31). The recommended values for R1, R2, and P1 for several maximum gains are

shown in Table 5-28. Note that in typical applications, R1 should not be 0 Ω, as the VOL/MICDET pin

should not exceed AVDD/2 for proper ADC operation.

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