BA1442A 데이터 시트보기 (PDF) - ROHM Semiconductor

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BA1442A

AM radio / FM IF stereo system IC

ROHM Semiconductor 

Audio ICs

BA1442A

Pin 18: AM antenna (L3)

The input impedance of pin 18 is 10kΩ. The AM antenna

earth point is Vreg; make the voltage at pin 18 the same

as the pin 19 (Vreg) potential. If there is a voltage drop,

local oscillator leakage to the mixer output will increase.

Pin 19: Reference power supply bypass capacitors (C18

and C19)

Connect the low-frequency bypass capacitor (C18) and

the high-frequency bypass capacitor (C19).

Pin 20: AM oscillator coil (L4)

To improve the startup oscillation characteristics, a 100Ω

resistor (built-in) is connected in series with the coil. If the

shortwave oscillation startup characteristics are poor,

connect an additional resistor (47Ω to 100Ω) in series

with the coil. Make the earth point for the oscillator coil pin

19 (Vreg). The relationship between the S / N ratio and

sensitivity at 20dB S / N against pin 20 oscillation voltage

is shown in Fig. 11.

Pin 16: AM ceramic filter (CF2)

The input impedance of pin 16 is 3kΩ, so it should be con-

nected to a ceramic filter that has an output impedance

of 3kΩ. The connection distance between the ceramic fil-

ter and pin 16 should be as short as possible.

Pin 17: AM IFT (T2)

The output impedance of pin 17 is 100kΩ. The IFT earth

point is VCC; make the voltage at pin 17 the same as the

pin 3 (VCC) potential. The connection distance between

the IFT and pin 17 should be as short as possible.

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