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Summing Two Single-Ended Input Signals

Gain 1 +

V

O

V

I1

+

2 x 150 kW

R

I1

V

V

(11)

Gain 2 +

V

O

V

I2

+

2 x 150 kW

R

I2

V

V

(12)

C

I1 +

1

2p R

I1

f

c1

(13)

C

I2 +

1

2p R

I2

f

c2

(14)

C

P +

C

I1 )

C

I2

(15)

R

P +

R

I1

R

I2

R

I1 )

R

I2

(16)

_

+

IN-

IN+

PWM

H-

Bridge

Internal

Oscillator

To Battery

GND

Bias

Circuitry

Filter-Free Class D

SHUTDOWN

Single-Ended

Input 2

Single-Ended

Input 1

Component Location

TPA2006D1

SLOS498 – SEPTEMBER 2006

Four resistors and three capacitors are needed for summing single-ended input signals. The gain and corner

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 26. Application Schematic With TPA2006D1 Summing Two Single-Ended Inputs

Place all the external components very close to the TPA2006D1. The input resistors need to be very close to the

TPA2006D1 input pins so noise does not couple on the high impedance nodes between the input resistors and

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

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