Datasheet
Summing Two Single-Ended Input Signals
Gain 1 +
V
O
V
I1
+
2 x 150 kW
R
I1
ǒ
V
V
Ǔ
(11)
Gain 2 +
V
O
V
I2
+
2 x 150 kW
R
I2
ǒ
V
V
Ǔ
(12)
C
I1
+
1
ǒ
2p R
I1
f
c1
Ǔ
(13)
C
I2
+
1
ǒ
2p R
I2
f
c2
Ǔ
(14)
C
P
+ C
I1
) C
I2
(15)
R
P
+
R
I1
R
I2
ǒ
R
I1
) R
I2
Ǔ
(16)
_
+
IN-
IN+
PWM H-
Bridge
V
O+
V
O-
Internal
Oscillator
C
S
To Battery
V
DD
GND
Bias
Circuitry
R
I2
R
P
Filter-Free Class D
SHUTDOWN
R
I1
Single-Ended
Input 2
C
I2
C
P
Single-Ended
Input 1
C
I1
Component Location
TPA2006D1
SLOS498A – SEPTEMBER 2006 – REVISED JULY 2008 .................................................................................................................................................
www.ti.com
Four resistors and three capacitors are needed for summing single-ended input signals. The gain and corner
frequencies (f
c1
and f
c2
) for each input source can be set independently (see Equation 11 through Equation 14 ,
and Figure 32 ). Resistor, R
P
, and capacitor, C
P
, are needed on the IN+ terminal to match the impedance on the
IN- terminal. The single-ended inputs must be driven by low impedance sources even if one of the inputs is not
outputting an ac signal.
Figure 32. Application Schematic With TPA2006D1 Summing Two Single-Ended Inputs
Place all the external components close to the TPA2006D1. The input resistors need to be close to the
TPA2006D1 input pins so noise does not couple on the high impedance nodes between the input resistors and
the input amplifier of the TPA2006D1. Placing the decoupling capacitor, C
S
, close to the TPA2006D1 is important
for the efficiency of the class-D amplifier. Any resistance or inductance in the trace between the device and the
capacitor can cause a loss in efficiency.
14 Submit Documentation Feedback Copyright © 2006 – 2008, Texas Instruments Incorporated
Product Folder Link(s): TPA2006D1