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부품번호 | BA1442A 기능 |
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기능 | AM radio / FM IF stereo system IC | ||
제조업체 | ROHM Semiconductor | ||
로고 | |||
전체 17 페이지수
Audio ICs
AM radio / FM IF stereo system IC
BA1442A
The BA1442A is an AM radio and FM IF stereo system IC developed for radio cassette players. The FM circuit is com-
prised of a differential IF amplifier, a double-balance type quadrature detector, and a PLL-type stereo MPX circuit. The
AM circuit is comprised of a local oscillator, a double-balanced mixer, an IF amplifier, a detector, and an AGC circuit.
FApplications
Radio cassette players
FFeatures
1) The “S” curve characteristic of the FM detector can
be used for upper heterodyne (“N” curve) operation.
2) Audio high cut and low cut can be used to improve the
AM fidelity.
3) A reference voltage supply is provided to ensure
good frequency stability in the shortwave bands.
4) Good FM stability.
5) Built-in damping resistor (3.3kΩ) for the quadrature
coil.
6) The FM MPX uses a Laser Locked Loop, making
adjustment of the VCO and addition of external
components unnecessary.
7) Built-in forced monaural function for the MPX (VCO
stops, LED off).
8) VCO of the MPX is switched off during AM opera-
tion.
9) The stereo indicator pin has a constant drive cur-
rent, and a current limiting resistor is not required.
10) Few external components required.
FAbsolute maximum ratings (Ta = 25_C)
FRecommended operating conditions (Ta = 25_C)
337
Audio ICs
BA1442A
340
4페이지 Audio ICs
BA1442A
(7) AM AGC circuit
AGC is applied to the input shunt, mixer , and IF circuits.
The AGC reduces the mixer and IF circuit current, and
according the DC level of the detector output, reduces
the gain to control the output at a fixed level. In addition,
an input shunt is provided to prevent distortion caused by
strong input signals. The AGC pin is also used as the
MPX PLL filter pin. For this reason, when there is no in-
put, the AGC voltage becomes Vreg (pin 19), and when
there is a strong input signal, it is about Vreg - 0.2V.
(8) AM / FM detector circuits
There is one pin for both detector outputs (pin 6), and the
AM / FM switching is done internally. The output imped-
ance is 5kΩ, and the DC output is 1.3V.
(9) The FM MPX circuit uses a PLL to recover the ste-
reo. For FM, the input from pin 7 is switched by the de-
coder and output on pin 11 (L channel) and pin 12 (R
channel). In the case of AM, the input is from pin 8, and
this is output through to pins 11 and 12. The audio fidelity
is improved by the low-pass filter comprised of the capac-
itor connected between pins 6 and 8 and the input imped-
ance of pin 8 (20kΩ). The input / output gain for both AM
and FM is about 6dB. The VCO has been laser trimmed
on the chip to set its time constant. External components
and re-adjustment are not required.
FApplication example
343
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구매 문의 | 일반 IC 문의 : 샘플 및 소량 구매 ----------------------------------------------------------------------- IGBT, TR 모듈, SCR 및 다이오드 모듈을 포함한 광범위한 전력 반도체를 판매합니다. 전력 반도체 전문업체 상호 : 아이지 인터내셔날 사이트 방문 : [ 홈페이지 ] [ 블로그 1 ] [ 블로그 2 ] |
부품번호 | 상세설명 및 기능 | 제조사 |
BA1442A | AM radio / FM IF stereo system IC | ROHM Semiconductor |
DataSheet.kr | 2020 | 연락처 | 링크모음 | 검색 | 사이트맵 |