SDIP24-P-300-1.78 查看數據表（PDF） - Toshiba

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SDIP24-P-300-1.78

3V AM/FM 1 Chip Tuner IC (for Digital Tuning System)

Toshiba 

TA2149BN/BFN

Application Note

1. AM Low-Cut Circuit

· The AM Low-Cut action is carried out by the bypass of the high frequency

component of the positive-feedback signal at the AF AMP stage.

The external capacitor: C3 by-pass this component.

· The cut-off frequency fL is determined by the internal resistance

22 kW (Typ.) and the external capacitor C3 as following;

f

L

=

2

´

p

´

1

22 ´103

´

C3

(Hz)

22 kW

22 kW

3

R

C3

· In the case of the AM Low-Cut function is not needed, set up the value of C3 over 1 mF.

In the condition of C3 >= 1 mF, the frequency characteristic has flat response at the low frequency.

· It is possible to reduce the recovered output level at AM mode, by additional resistance between the pin 3

and GND line.

2. FM Detection Circuit

For the FM detection circuit, detection coil is able to use instead of ceramic discriminator.

Recommended circuit and recommended coil are as follows. (In this case, please take care that Vin (lim.)

falls a little.)

VCC

10

VCC

3

4

2

1

6

Pin 10

Test

Co

Frequency (pF)

10.7 MHz

51

Qo

Turns

Wire

1-2 2-3 1-3 4-6 (mmf)

Reference

45

¾

¾ 30 ¾ 0.08UEW

Toko Co., Ltd.

600BEAS-10018Z

3. FM/AM switch and forced monaural switch.

· FM/AM switchover and stereo/forced monaural switchover are done by pin 13 and pin 14.

· FM/AM switch (pin 13)

V13: Low (Active Low, Vth = 0.2 V (Typ.), Ith 30 mA (Typ.) ® AM

V13: OPEN

® FM

· Stereo/forced monaural switch (pin 14)

V14: Low (Active Low, Vth = 0.2 V (Typ.), Ith 30 mA (Typ.)® Forced Monaural

V14: OPEN

® Stereo

VCC

VCE (sat)

VCE (sat)

14

13

8

2001-12-21

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