a3848eeq Allegro MicroSystems, Inc., a3848eeq Datasheet

a3848eeq

Manufacturer Part Number

a3848eeq

Description

Dual-conversion Am Receiver

Manufacturer

Allegro MicroSystems, Inc.

Datasheet

1.A3848EEQ.pdf (3 pages)

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REGULATOR

WB AGC 1 IN

MIX 1 OUT

3848

DUAL-CONVERSION AM RECEIVER

AFC OUT

Supply Voltage, V

Package Power Dissipation, P

Operating Temperature Range,

Storage Temperature Range,

MIX 1 IN

RESET

STOP

ABSOLUTE MAXIMUM RATINGS

FSI

. . . . . . . . . . . . . . .

REG

AGC

REF

DET

. . . . . . . . . . . . . . 12 V

SUB

-40 C to +105 C

-65 C to +150 C

Dwg. No. PS-012-1

. . . . 1.2 W

MIX 2 OUT

AGC (MUTE)

CRYSTAL

AGC RATE 2

MIX 2 OUT

MIX 2 E

MIX 2

BYPASS

Dwg. PS-012-1

DUAL-CONVERSION AM RECEIVER

3848

tuned AM receiver (ETR), the A3848EEQ includes two balanced

mixers, a crystal local oscillator, an L/C-tuned local oscillator, oscillator

buffer, IF amplifier, AM detector, scan control detectors, and a switch-

able voltage regulator. This dual-conversion device typically mixes the

incoming RF up to a first IF of 10.7 MHz, then down to 450 kHz, and

then detects the audio. The addition of a JFET matched to a whip

antenna, RF low-pass filter, IF selectivity, and audio stages gives a

complete AM radio which can be used in automotive receivers. The

frequency-detecting stop circuit is also capable of recovering narrow-

band FM, making it useful for scanners or weather band radio applica-

tions. Two AGC and field-strength indicator modes provide special

features for scanning.

for establishing a valid stop. Tuning accuracy (frequency criterion) is

established by evaluating phase shift across the detector coil. The

circuitry is similar to that used in FM discriminators. Because this

detection system is phase operated, it remains effective even in the

presence of strong signals, which can cause false stops in systems

using narrow-band filters. The amplitude criterion for stop is deter-

mined by evaluating the IF level. It includes a unique circuit that

removes the effect of the AGC action. This allows the AGC tuning

components to be selected for low-frequency audio performance

without compromising scanning speed.

field-strength indicator (FSI) is provided for controlling signal-depen-

dent functions such as stereo blending. A fast AGC mode (AGC

RESET high) resets the AGC holding capacitors to maximum gain.

This mode allows cataloging station strengths quickly during a band

sweep.

plastic, leaded chip carrier (PLCC) for surface-mount applications and

is rated for operation over the temperature range of -40 C to +105 C

are available on special order.

FEATURES

Always order by complete part number: A3848EEQ .

Low Noise Figure

Balanced Mixers

High Dynamic Range First Mixer

Providing the AM signal processing functions for an electronically

The A3848EEQ uses the dual criteria of frequency and amplitude

In the normal AGC mode (AGC RESET low), a slow, narrow-band

This AM signal processor is packaged in a rectangular, 32-lead,

Field-Strength Indicator

Buffered Oscillator

Fast Scan Mode

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a3848eeq Summary of contents

Page 1

... MIX MIX The A3848EEQ uses the dual criteria of frequency and amplitude MIX 2 21 for establishing a valid stop. Tuning accuracy (frequency criterion) is BYPASS established by evaluating phase shift across the detector coil. The circuitry is similar to that used in FM discriminators. Because this ...

Page 2

... Mod = 3 kHz peak deviation Ref mV, V for out 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 W Copyright © 1993, Allegro MicroSystems, Inc MHz 10.7 MHz, o if1 Limits Min Typ Max — — 1.0 6.0 — 6.0 10 — ...

Page 3

... V =3% THD, Mod = 90% out Allegro MicroSystems, Inc. reserves the right to make, from time to time, such departures from the detail specifications as may be required to permit improvements in the design of its products. The information included herein is believed to be accurate and reliable. However, Allegro MicroSystems, Inc. assumes no responsibil- ity for its use ...

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