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TPA3002D2 View Datasheet(PDF) - Texas Instruments

Part NameDescriptionManufacturer
TPA3002D2 9-W STEREO CLASS-D AUDIO POWER AMPLFIER WITH DC VOLUME CONTROL TI
Texas Instruments TI
TPA3002D2 Datasheet PDF : 41 Pages
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TPA3002D2
SLOS402C − DECEMBER 2002 − REVISED JANUARY 2004
Some audio systems require that the gain be limited in the VAROUT mode to a level that is comfortable for
headphone listening. The VARMAX terminal controls the maximum gain for the VAROUT channels.
The functionality of the VARDIFF and VARMAX pin are combined to fix the VAROUT channel gain. A block
diagram of the combined functionality is shown in Figure 35. The value obtained from the block diagram for
VAROUT_VOLUME is a DC voltage that can be used in conjunction with Table 2 to determine the VAROUT
channel gain. Table 2 lists the gain in VAROUT mode as determined by the VAROUT_VOLUME voltage in
reference to the voltage on VREF.
The timing of the volume control circuitry is controlled by an internal 30 Hz clock. This clock determines the rate
at which the gain changes when adjusting the voltage on the external volume control pins. The gain updates
every 4 clock cycles (nominally 133 ms based on a 30Hz clock) to the next step until the final desired gain is
reached. For example, if the TPA3002D2 is currently in the +0.53 db class-D gain step and the VOLUME pin
is adjusted for maximum gain at +36 dB, the time required for the gain to reach 36dB is 14 steps x 133 ms/step
= 1.862 seconds. Referencing Table 1, there are 14 steps between the +0.53 dB gain step and the maximum
gain step of +36 dB.
VARDIFF (V)
VARMAX (V)
VOLUME (V)
+
VOLUME−VARDIFF
Is VARMAX>
YES
(VOLUME−VARDIFF)
VAROUT_VOLUME (V) = VOLUME (V) − VARDIFF (V)
?
NO
VAROUT_VOLUME (V) = VARMAX (V)
Figure 35. Block Diagram of VAROUT Volume Control
Decreasing Voltage on VOLUME Terminal
5.6
3.1
Increasing Voltage on VOLUME Terminal
0.5
2.00
(40.1%*VREF)
2.10 2.11
2.21
(44.1%*VREF)
(41.9%*VREF) (42.3%*VREF)
Voltage on VOLUME Pin − V
Figure 36. DC Volume Control Operation, VREF = 5 V
23
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