SC7422 查看數據表（PDF） - Silan Microelectronics

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产品描述 (功能)

生产厂家

SC7422

2-CH AUDIO POWER AMPLIFIER (2W x 2)

Silan Microelectronics 

SC7422

(Continued)

Pin No. Pin Name

13

Bypass

14

-OUT1

15

VCC

16

+OUT1

I/O

Pin Description

O Half supply voltage ripple rejection

O Inverted loudspeaker output of channel 1

-- Supply

O Non inverted loudspeaker output of channel 1

FUNCTION DESCRIPTION

Gain Setting for Input Stage

The gain for each audio input stage of the SC7422 is set by external resistors R1 and R2 (see typical

application circuit). It is recommended that R1 = R2 = 20kΩ in the application and the gain is 0dB.

If the amplitude of audio input voltage is lower, for example, the peak-peak value is less than 2Vpp, it should be

improve the gain, whereas, it should be reduce the gain. However, the amplitude of audio input voltage is so high

that the output wave would be distortion. Therefore, the amplitude of audio signal source should be checked at

first. And the gain in the application should be set following Table 1.

Table 1 Gain Setting for Input Stage

Operation

Voltage

VCC=3V

The peak-

peak value of

input voltage

VIN <1.25Vpp

VIN <2.5Vpp

VIN <5Vpp

Gain Setting

for Input

Stage

+6dB

0dB

-6dB

Operation

Voltage

VCC=5V

The peak-

peak value of

input voltage

VIN <2Vpp

VIN <4Vpp

VIN <8Vpp

Gain Setting

for

Input Stage

+6dB

0dB

-6dB

Otherwise, the minimum value of input resistor R1 is 10kΩ, in order to ensure proper impedance for input.

32 Steps Volume Control

The SC7422 includes a 32 steps volume controller. It changes the volume gain linearly with 1.5dB per step from

-45dB to 0dB. The volume is controlled by input voltage of DC Vol pin. As the voltage was increasing, the volume

is louder. Table 2 shows the relationship of them.

Table 2 32 Steps Volume Setting

Step

1

2

3

4

5

Volume

(dB)

0

-1.5

-3

-4.5

-6

DC Vol

VH(%)

Vcc

64.4

63.0

61.4

59.8

DC Vol

VL(%)

64.2

62.8

61.2

59.4

57.6

Step

17

18

19

20

21

Volume

(dB)

-24

-25.5

-27

-28.5

-30

DC Vol

VH(%)

38.1

35.6

31.8

29.2

27.6

DC Vol

VL(%)

30.4

29.0

27.4

25.4

23.8

(To be continued)

HANGZHOU SILAN MICROELECTRONICS CO.,LTD

Http: www.silan.com.cn

REV:1.0 2006.11.13

Page 4 of 8

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