+

100W

R

6

100W

1kW

1kW

½

TLV2376

½

TLV2376

10 F

m

10 F

m

C

2

33 F

m

10 F

m

10kW

+

R

1

2.7kW

R

9

4.7kW

R

8

4.7kW

33 F

m

D

1

5.1V

2

R

7

100W

C

3

33 F

m

3

2

3

1

1

R

G

R

10

6.8kW

R

11

6.8kW

3.3kW

3.3kW

Phantom Power

(Provides power source for microphone)

48V

1 F

m

INA163

-15V

+15V

Microphone

Typical microphone input circuit used in mixing consoles.

Low-level differential audio signal

is transmitted differentially on the

same cable as power to the microphone.

Panasonic

WM-034CY

Copyright © 2016, Texas Instruments Incorporated

17

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www.ti.com

SBOS755 – OCTOBER 2016

Product Folder Links: TLV376 TLV2376 TLV4376

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Copyright © 2016, Texas Instruments Incorporated

Application Information (continued)

8.1.5 Phantom-Powered Microphone

The circuit shown in Figure 28 depicts how a remote microphone amplifier can be powered by a phantom source

on the output side of the signal cable. The cable serves double duty, carrying both the differential output signal

from and dc power to the microphone amplifier stage.

A TLV2376 serves as a single-ended input to a differential output amplifier with a 6-dB gain. Common-mode bias

for the two op amps is provided by the dc voltage developed across the electret microphone element. A 48-V

phantom supply is reduced to 5.1 V by the series 6.8-k

Ω resistors on the output side of the cable, and the 4.7 kΩ

and zener diode on the input side of the cable. AC coupling blocks the different dc voltage levels from each other

on each end of the cable.

An INA163 instrumentation amplifier provides differential inputs and receives the balanced audio signals from the

the input circuitry used in mixing consoles.

Figure 28. Phantom-Powered Electret Microphone