TEA2025D

LINEAR INTEGRATED CIRCUIT

UNISONICTECHNOLOGIESCO.,LTD

5 of 8

www.unisonic.com.tw

QW-R107-017,B

■

APPLICATION INFORMATION

Input Capacitor

Input capacitor is PNP type allowing source to be referenced to ground.

In this way no input coupling capacitor is required. However, a series capacitor(0.22µF) to the input side can be

useful in case of noise due to variable resistor contact.

Bootstrap

The bootstrap connection allows to increase the output swing.

The suggested value for the bootstrap capacitors (100µF) avoids a reduction of the output signal also at low

frequencies and low supply voltage.

Voltage Gain Adjust

STEREO MODE

The voltage gain is determined by on-chip resistors R1 and R2 together with the external RfC1 series connected

between pin 8(13) and ground. The frequency response is given approximated by:

=

R1

Rf +R2+

1

JWC1

With Rf=0,C1=100µF, the gain results 46dB with pole at f=32Hz

The purpose of RfI is to reduce the gain. It is recommended to not reduce it under 36dB.

BRIDGE MODE

Rf

C1

R2

50

R1

10K

8(13)

2(19)

Figure 7

The bridge configuration is realized very easily thanks to an internal voltage divider which provides (at pin 1)the CH1

output signal after reduction. It is enough to connect pin8(inverting input of CH 2 )with a capacitor to pin 1 and to

connect to ground the pin 9.

The total gain of the bridge is given by:

=

R1

Rf +R2+

1

JWC1

(1+

R3

R4

R1

R2+R4+

1

JWC1

)

and with the suggested values (C1=C2=100µF,Rf=0)means:

Gv=52dB

R1

10K

Figure 8

R1

10K

R3

5K

R4

50

R2

R2

OUT

OUT

IN

With first pole at f=32Hz