TPA0112 Datasheet, PDF (30/34 Pages) Texas Instruments – 2-W STEREO AUDIO POWER AMPLIFIER WITH FOUR SELECTABLE GAIN SETTINGS

TPA0112
2-W STEREO AUDIO POWER AMPLIFIER
WITH FOUR SELECTABLE GAIN SETTINGS
SLOS204B – MAY 1999 – REVISED MARCH 2000
APPLICATION INFORMATION
SE/BTL operation
The ability of the TPA0112 to easily switch between BTL and SE modes is one of its most important cost saving
features. This feature eliminates the requirement for an additional headphone amplifier in applications where
internal stereo speakers are driven in BTL mode but external headphone or speakers must be accommodated.
Internal to the TPA0112, two separate amplifiers drive OUT+ and OUT–. The SE/BTL input (terminal 15) controls
the operation of the follower amplifier that drives LOUT– and ROUT– (terminals 9 and 16). When SE/BTL is held
low, the amplifier is on and the TPA0112 is in the BTL mode. When SE/BTL is held high, the OUT– amplifiers
are in a high output impedance state, which configures the TPA0112 as an SE driver from LOUT+ and ROUT+
(terminals 4 and 21). I_DD is reduced by approximately one-half in SE mode. Control of the SE/BTL input can
be from a logic-level CMOS source or, more typically, from a resistor divider network as shown in
Figure 47.
20 RHPIN
23 RLINEIN
R
MUX
8 RIN
–
ROUT+ 21
+
VDD
COUTR
330 µF
–
ROUT– 16
+
100 kΩ
1 kΩ
SE/BTL 15 ^{100 kΩ}
Figure 47. TPA0112 Resistor Divider Network Circuit
Using a readily available 1/8-in. (3.5 mm) stereo headphone jack, the control switch is closed when no plug is
inserted. When closed the 100-kΩ/1-kΩ divider pulls the SE/BTL input low. When a plug is inserted, the 1-kΩ
resistor is disconnected and the SE/BTL input is pulled high. When the input goes high, the OUT– amplifier is
shutdown causing the speaker to mute (virtually open-circuits the speaker). The OUT+ amplifier then drives
through the output capacitor (C_O) into the headphone jack.
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