Sony CXA1991N Datasheet

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E95925B8Y

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any implication or otherwise under any patents or other right. Application circuits shown, if any, are typical examples illustrating the
operation of the devices. Sony cannot assume responsibility for any problems arising out of the use of these circuits.

Absolute Maximum Ratings (Ta=25 °C)

• Supply voltage VCC 14 V

• Operating temperature Topr –20 to +75 °C

• Storage temperature Tstg –65 to +150 °C

• Allowable power dissipation

PD 400 mW

Operating Conditions

Supply voltage VCC 1.8 to 4.5 V

Description

The CXA1991N is a tuner IC designed for use in
FM pagers and FM multiplex broadcasting. A
receiver system can be configured by using the
digital data output, in combination with a decoder. It
has a battery save function and ultra-low power
consumption.

Features

• Ultra-low power consumption

(ID = 1.2 mA for FM; ID = 0.8 mA for AM; VCC = 3 V)

• LED drive circuit for tuning

• Battery save function

• Few external parts

Applications

• Tuners for FM multiplex broadcasting

• FM pagers

FM Pager/FM Multiplex Tuner

20 pin SSOP (Plastic)

Block Diagram

1 2 3 4 5 6 7 8 9

10

20 19 18 17 16 15 14 12 11

AM FRONT END

FM FRONT END

13

REG

METER

BATTERY

SAVE CONT

FM IF DET

AM IF, IF DET

AGC

AGC BUFF

FE OUT

GND 1

FM IN

AM IN

FM RF

FM MIX

REG

FM OSC

AM OSC

TUNE

AM IF

AGC

FM IF

BAND

GND 2

DISCRI

V

CC

B.S

DET OUT

AFC

CXA1991N

For the availability of this product, please contact the sales office.

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CXA1991N

Pin Description (VCC=3 V, Ta=25 °C)

Pin
No.

1

2

9

3

4

5

6

7

Symbol

AM IF IN

AGC

DET OUT

FM IF IN

BAND

GND2

DISCRI

VCC

Pin voltage (V)

FM AM

1.1 1.1

0.3 0.4

0.9 0.7

1.1 0

1.1 0

0 0

2.0 2.4

3.0 3.0

Description

AM IF input pin.

Connected to a capacitor.

Detection output pin.

FM IF input pin.

AM/FM band switching pin.
AM when grounded, FM when
open.

IF system ground.

Connected to phase shift circuit
and ceramic discriminator.

Equivalent circuit

220k

1

330

3 4

VCC VCC

2k

6

1.1k

V

CC

130

2

9

130 100k

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CXA1991N

Equivalent circuit

200k

10

REG

13

VCC

11

8

160k

550k

12

REG

VCC

14

Pin
No.

8

10

13

11

12

14

Symbol

BS

AFC

FM OSC

TUNE

AM OSC

REG

Pin voltage (V)

FM AM

1.0 0.7

1.1 1.1

1.1 1.1

1.1 1.1

1.1 1.1

Description

Controls battery save via
microcomputer.
High = Active, Low = Save

AFC varicap pin.

FM local oscillation circuit.

AM/FM tuning indicator drive
circuit.

AM local oscillation circuit.

Regulator output pin.

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CXA1991N

Pin

No.

15

16

18

17

19

20

Symbol

FM MIX

FM RF

FM RF IN

AM RF IN

GND1

FE OUT

Pin voltage (V)

FM AM

1.1 1.1

1.1 1.1

2.2 2.4

1.1 1.1

0 0

0.6 1.5

Equivalent circuit Description

Load for mixer which resonates
at 10.7 MHz from internal
capacitance and external coil.

FM RF amplifier circuit which is
connected to RF tank circuit

FM RF amplifier circuit which is
FM RF input.

AM RF input which is
connected to bar antenna.

Front-end ground.

AM/FM IF output pin which is
connected to IF filter.

VCC

5k

REG

18

16

50k

VCC

FM Block

3k

20

15

AM Block

VCC

17

VCC

15

10k

REG

11p