Application information

TSH511

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7

Application information

This section provides application information for some typical applications.

7.1

Infrared stereo headphone application

The right side of Figure 21 shows the block diagram of an infrared stereo receiver using the

TSH511. The sensitive LNA, directly connected to the photo diode, does not require an

external pre-amplifier. After filtering, the amplified signals are limited and demodulated with

quadrature demodulators. The two integrated audio buffers directly drive the stereo

function fades out the audio when the incoming infrared signal is low. The standby inputs

SBY1 and SBY2 enable only one receiver for the mono applications.

Figure 21.

Hi-fi stereo headphone block diagram

The infrared carriers are detected by the photo diode and the signal is directly amplified by

the TSH511. Each receiver has a standard bandpass filter (filters F1 & F2) to select the

2.3MHz and 2.8MHz carriers. After the FM demodulators, the potentiometer P1 controls the

volume levels. The stereo headphones are directly connected to the integrated audio

buffers. The potentiometer P2 allows adjustment of the sensitivity of the Squelch. The

Squelch function fades in and fades out the audio signal, depending on the level of the

2.8MHz carrier.

Audio

buffer1

Audio

buffer2

LNA

LNA + ALC

LNA + ALC

TX2

TX1

VOX

SBY

buffer1

buffer2

RX2

RX1

Line inputs

Right

channel

Left

channel

Vcc

LED

photodiode

filter

filter

2.3 MHz

2.8 MHz

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

(Television)

IR stereo HiFi receiver

(Headphones)

Hi

Fi

ste

re

o:

2.3

&

2.8

MH

z c

ar

rie

rs

Audio

buffer1

Audio

buffer2

LNA

LNA + ALC

LNA + ALC

TX2

TX1

VOX

SBY

buffer1

buffer2

RX2

RX1

Line inputs

Right

channel

Left

channel

Vcc

LED

photodiode

filter

filter

2.3 MHz

2.8 MHz

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

(Television)

IR stereo HiFi receiver

(Headphones)

Hi

Fi

ste

re

o:

2.3

&

2.8

MH

z c

ar

rie

rs