Application information

TSH512

14/31

Doc ID 8120 Rev 7

4

Application information

This section gives application information for some typical applications.

4.1

Infrared stereo transmitter application (stereo headphones)

In this application, shown in Figure 21, the hi-fi stereo audio is amplified and level regulated

by ALC. The carrier of each transmitter TX1 or TX2 of the TSH512 is modulated in FM and

buffered to drive the LED.

Figure 21.

Hi-fi stereo headphone block diagram

The audio signals are transmitted on the left and the right channels using 2.8- and 2.3-MHz

carriers. The VOX activates the TX1 transmitter when the audio signal is present

(Figure 22).

Audio

amp1

Audio

amp2

LNA

LNA + ALC

LNA + ALC

SBY

buffer1

buffer2

RX2

RX1

Line inputs

Right

channel

Left

channel

Vcc

LED

photodiode

filter

filter

2.3 MH z

2.8 MH z

Vcc: 2.3 to 5.5V

Current < 15 mA

TSH512

TSH511

20 mW / 16

Ω

20 mW / 16

Ω

Power supply:

2.3 to 5.5V

Icc < 20 mA stereo

IR stereo HiFi transmitter

Headphone side

HiF

i s

ter

eo

:

2.3

&

2.

8 M

Hz

ca

rrie

rs

VOX

TX1

TX2

RX2

RX1

LED

filter

20 mW / 16

Ω

20 mW / 16

Ω

:

:

VOX

TX1

TX2