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SLOS417B – OCTOBER 2003 – REVISED JULY 2006
To Battery
C
I
Internal
Oscillator
R
I
IN-
_
C
I
R
I
+
IN+
GND
SHUTDOWN
Bias
Circuitry
TPA2010D1
Filter-Free Class D
PWM
H-
Bridge
V
DD
C
S
V
O+
V
O-
Differential
Input
Figure 28. TPA2010D1 Application Schematic With Differential Input and Input Capacitors
To Battery
C
I
Single-ended
Input
Internal
Oscillator
R
I
IN-
_
R
I
C
I
SHUTDOWN
Bias
Circuitry
+
IN+
GND
TPA2010D1
Filter-Free Class D
PWM
H-
Bridge
V
DD
C
S
V
O+
V
O-
Figure 29. TPA2010D1 Application Schematic With Single-Ended Input
SUMMING INPUT SIGNALS WITH THE TPA2010D1
Most wireless phones or PDAs need to sum signals at the audio power amplifier or just have two signal sources
that need separate gain. The TPA2010D1 makes it easy to sum signals or use separate signal sources with
different gains. Many phones now use the same speaker for the earpiece and ringer, where the wireless phone
would require a much lower gain for the phone earpiece than for the ringer. PDAs and phones that have stereo
headphones require summing of the right and left channels to output the stereo signal to the mono speaker.
Summing Two Differential Input Signals
Two extra resistors are needed for summing differential signals (a total of 5 components). The gain for each
input source can be set independently (see
and
and
V
V
Gain 1
+
O
+
2 x 150 kW
V
R
V
I1
I1
(4)
V
V
Gain 2
+
O
+
2 x 150 kW
V
R
V
I2
I2
(5)
If summing left and right inputs with a gain of 1 V/V, use R
I1
= R
I2
= 300 kΩ.
11
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