JAJSGB9B January 2010 – October 2018 TLV320DAC3101
PRODUCTION DATA.
The volume-control pin is not enabled by default but is 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 / register 116, bit D7 = 0. Soft-stepping the volume level is set up by writing to page 0 / register 63, bits 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 by overwriting the current value of the volume control. The new volume setting which has been applied because of a change of voltage on the volume control pin is read on page 0 / register 117, bits D6–D0. The 7-bit Vol ADC clock source is selected on page 0 / register 116, bit D6. The update rate is programmed on page 0 / register 116, bits D2–D0 for this 7-bit SAR ADC.
Table 6-18 lists The 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 |
Figure 6-16 shows the VOL/MICDET pin connection and functionality.
As shown in Table 6-18, 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 must be applied to the VOL/MICDET pin. Applying a smaller range of voltage occurs 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 must 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 6-16). The recommended values for R1, R2, and P1 for several maximum gains are shown in Table 6-19.
R1
(kΩ) |
P1
(kΩ) |
R2
(kΩ) |
ADC VOLTAGE
for AVDD = 3.3 V (V) |
DIGITAL GAIN RANGE
(dB) |
---|---|---|---|---|
25 | 25 | 0 | 0 to 1.65 | 18 to –63 |
33 | 25 | 7.68 | 0.386 to 1.642 | 3 to –63 |
34.8 | 25 | 9.76 | 0.463 to 1.649 | 0 to –63 |