TDA7220 查看數據表（PDF） - STMicroelectronics

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TDA7220

VERY LOW VOLTAGE AM-FM RADIO

STMicroelectronics 

TDA7220

AM-FM SWITCHING

AM-FM switching is achieved by applying a DC voltage at pin 13, to switch the internal reference.

TYPICAL DC VOLTAGE (refer to the test circuit)

Pins 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 Unit

AM 3 1.1 3 1.1 1.1 2.5 3 0.7 1.2 3 0 2.1 2.1 2.9 3 2.9 V

FM 3 0 3 0 0 2.4 3 0 0.9 3 0 3 3 2.7 2.7 2.7 V

APPLICATION SUGGESTION

Recommended values referred to the test circuit of Figure 1

Part

Number

C1

C2 (1)

C3 (1)

C4

C5

C7

C8

C9

C10 (1)

C11

C12

C13

C16

R1 (1)

R2 (1)

R3

R4

R5

R6

Recommended

Value

100µF

100nF

10nF

20nF

20nF

100nF

100nF

10µF

56pF

10nF

100nF

220µF

2.7nF

68Ω

56Ω

330Ω

6.8kΩ

560Ω

13kΩ

Purpose

AGC Bypass

AM Input DC Cut

FM Input DC Cut

FM Amplifier Bypass

FM detector Decoupling

Power Supply Bypass

AGC Bypass

Tuning of the AM

Oscillator at 1455kHz

50ms FM De-emphasis

Output DC Decoupling

Power Supply Decoupling

AM Detector capacitor

FM Input Matching

AM Input Matching

Ceramic Filter Matching

FM Detector Coil Q Setting

FM Detector Load Resistor

AM Detector Coil Q Setting

Smaller than

Recommended Value

Increase of the distortion at

low audio frequency

Reduction of sensitivity

Danger of RF Irradiation

Noise increase of the audio

output

Increase of the distortion at

low audio frequency

Low audio frequency cut

Increase of the distortion at

low frequency

Low suppression of the IF

frequency and harmonics

Audio output decrease and

lower distortion

Audio output decrease and

higher AMR

Lower IF Gain and Lower

AGC Range

Larger than

Recommended Value

Increase of the AGC time

constant

- bandwidth increase

- higher noise

Increase of the AGC time

constant

Increase of the audion

distortion

Audio output increase and

higher distortion

Higher IF Gain and Lower

AGC Range

(1) Only for test circuit.

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