TPA6017A2 Datasheet, PDF (17/26 Pages) Texas Instruments – 2 W STEREO AUDIO POWER AMPLIFIER WITH FOUR SELECTABLE GAIN SETTINGS

TPA6017A2
APPLICATION INFORMATION
SLOS386 – NOVEMBER 2001
shutdown modes
The TPA6017A2 employs a shutdown mode of operation designed to reduce supply current, I_DD, to the absolute
minimum level during periods of nonuse for battery-power conservation. The SHUTDOWN input terminal
should be held high during normal operation when the amplifier is in use. Pulling SHUTDOWN low causes the
outputs to mute and the amplifier to enter a low-current state, I_DD = 150 µA. SHUTDOWN should never be left
unconnected because amplifier operation would be unpredictable.
gain setting via GAIN0 and GAIN1 inputs
The gain of the TPA6017A2 is set by two input terminals, GAIN0 and GAIN1.
Table 1. Gain Settings
GAIN0
0
0
1
1
GAIN1
0
1
0
1
AV(inv)
6 dB
10 dB
15.6 dB
21.6 dB
INPUT
IMPEDANCE
90 kΩ
70 kΩ
45 kΩ
25 kΩ
The gains listed in Table 1 are realized by changing the taps on the input resistors inside the amplifier. This
causes the input impedance, Z_I, to be dependent on the gain setting. The actual gain settings are controlled
by ratios of resistors, so the actual gain distribution from part-to-part is quite good. However, the input
impedance will shift by 30% due to shifts in the actual resistance of the input impedance.
For design purposes, the input network (discussed in the next section) should be designed assuming an input
impedance of 10 kΩ, which is the absolute minimum input impedance of the TPA6017A2. At the higher gain
settings, the input impedance could increase to as high as 115 kΩ. The typical input impedance at each gain
setting is given in Table 1.
input capacitor, C_I
In the typical application an input capacitor, C_I, is required to allow the amplifier to bias the input signal to the
proper dc level for optimum operation. In this case, C_I and the input impedance of the amplifier, Z_I, form a
high-pass filter with the corner frequency determined in equation 1.
–3 dB
f_c(highpass)
+
1
2pZ_IC_I
(1)
fc
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