Datasheet

TPA2001D1
1-W FILTERLESS MONO CLASS-D AUDIO POWER AMPLIFIER
SLOS338D – SEPTEMBER 2000 – REVISED DECEMBER 2002
8
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
APPLICATION INFORMATION
Table 1. Gain Settings
GAIN1 GAIN0
AMPLIFIER GAIN
(dB)
INPUT IMPEDANCE
(kΩ)
GAIN1
GAIN0
TYP TYP
0 0 6 104
0 1 12 74
1 0 18 44
1 1 23.5 24
input resistance
Each gain setting is achieved by varying the input resistance of the amplifier, which can range from its smallest
value to over six times that value. As a result, if a single capacitor is used in the input high-pass filter, the –3dB
or cutoff frequency also changes by over six times.
C
i
IN
Z
I
Z
F
Input
Signal
The –3 dB frequency can be calculated using equation 4.
(4)
f
c
+
1
2p Z
I
C
i
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 5.
f
c
+
1
2p Z
I
C
i
–3 dB
f
c
(5)