Sony CXA1741Q Datasheet

CXA1741Q

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IF Amplifier for Analog Cellular Communications

Description

The CXA1741Q is an analog cellular(TACS/

NTACS) FM IF IC which incorporates an IF filter.

Features

• Incorporates a ceramic filter function, which is

normally mounted externally.

• Quadrature detection discriminator function.

• This IC has almost all IF functions and is ideal for

reduction in set size because of few external parts
required.

• The built-in filter permits mode changeover
between TACS and NTACS.

• Wide operating voltage range (2.7 V to 3.6 V) and
low current consumption (Icc=10 mA (typ.) when
Vcc= 3 V).

• Wide range and excellent temperature
characteristics for the RSSI (receiving signal
strength indicator).

Absolute Maximum Ratings (Ta = 25°C)

• Supply voltage VCC 5V

•Operating temperature Topr –35 to +85 °C

• Storage temperature Tstg –65 to +150 °C

• Allowable power dissipation

Operating Conditions

Supply voltage VCC 2.7 to 3.6 V

40 pin QFP (Plastic)

PD 500 mW

Applications

Ideally suited for cellular phones, particularly hand-

held sets.

Structure

Bipolar silicon monolithic IC

Sony reserves the right to change products and specifications without prior notice. This information does not convey any license by
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.

—1—

E94245-TE

Block Diagram and Pin Configuration

CXA1741Q

(Top View)

T4

T5

CC1

V

GND1

T6

FADJ1

FADJ2

SGND

BPFPS1

31

32

33

34

35

36

37

38

39

T3

BIAS

MIXADJ1

PSN

PSN

BPF0

BPF1

MIXADJ2

MIXPS

MIXER

LIM DET

GND

MIXIN

1/2 OSC

AGC

RSSI

CC

V

IFPS

23 22 212425262730 2829

RF AMP

IFIN

GND

20

19

18

17

16

15

14

13

12

XTALIN

XTALOUT

AGCPS

VREF

RSSIPS

T2

RSDETPS

T1

GND2

BPFPS2

40

11

CC2

V

1 2 3 4 5 6 7 8 9 10

NC

BPFO

SW(TACS/NTACS)

AUDIO

RSSI

IF2

LIMPS

GADJ(RSSI)

Note) Pins 21 and 25 are connected via the IC internal wiring.

Pins 12, 21 and Pins 25, 34 are connected via IC internal resistors.
When designing a PCB, ensure that all GND pins of IC are connected to the GND on PCB with its
connection wiring distance minimized.

—2—

CXA1741Q

Pin No. Symbol

Pin voltage I/O
DC AC

1SW0V

TACS OPEN

( )

NTACS HIGH

(3 V)

2NC
3 BPFO 1.8 V
4
5

resistance

31

34

Equivalent circuit Description

Changeover switch for

20µA

built-in filter.
TACS for Low; NTACS for

50k

1

50k

VREF

GND

High.

Not internally connected.
BPF output monitor. Not
used normally. Connected
to the LIM and RSSI inputs
in the IC.

33

6 AUDIO 2.1 V

B.P.F
N.F.B Network

LIM

RSSI

147

11

3
4

5

34

Outputs an AUDIO signal
which is FM-detected.

—3—

1k

6

12

CXA1741Q

Pin No. Symbol

7 RSSI 1.2 V

8 GADJ 0.2 V

Pin voltage I/O

DC AC

resistance

Equivalent circuit Description

RSSI output. Outputs a

11

DC voltage in accordance
with the signal input to the
RF amplifier.

147

7

12

Adjusts the RSSI amplifier
gain (varies the resistance
so as to obtain a linear
RSSI output).

8

147

147

7

9 IF2 0.9 V

10 LIMPS 1.8 V

147

11

12

Limiter operation monitor.
Not used normally.

9

Connects a limiter

11

integrating capacitor.

10

—4—

12

CXA1741Q

Pin No. Symbol

11 VCC2 3.0 V

12 GND2 0 V
13 T1

14 RSDETPS 1.4 V

15 T2

Pin voltage I/O
DC AC

resistance

Equivalent circuit Description

Power supply. Supplies
current to the LIM, DET,
and RSSI circuits.
Ground.
IC operation check.

Connects an RSSI detector
integrating capacitor.

11

147

14

12

IC operation check.

16 RSSIPS 1.8 V

17 VREF 1.3 V

reference voltage
used in the
internal circuit

11

16

12

Connects an RSSI
integrating capacitor.

Monitor for the reference

33

voltage used in the internal
circuit.

17

When connected to an
external capacitor, this pin
also functions to lower the
reference voltage dynamic
impedance.

34

—5—

CXA1741Q

Pin No. Symbol

18 AGCPS 0.2 V

19 XTALOUT 2.9 V

20 XTALIN 2.9 V

Pin voltage I/O

DC AC

resistance

VREF

20

Equivalent circuit Description

Connects an AGC

33

integrating capacitor.

18

34

15

Connect a crystal oscillator
to form a Colpitts-type

24

147

10k

15p

10k

oscillator circuit.
When an external
oscillator is used, its input

19

must be connected to Pin

20.

21 GND 0 V
22 IFIN 1.3 V

23 IFPS 1.3 V

24 VCC 3.0 V

25 GND 0 V

25

22

VREF

21

Ground.
RF amplifier input. The
relationship between IFIN

24

(Pin 22) and IFPS (Pin 23)
is designed so that the IC
internal stray capacitance

23

1.5k1.5k

is small.
Therefore, if Pins 22 and
23 are used for balance
input, the common-mode

2521

rejection deteriorates.

Power supply.
Supplies current to the RF
AMP, MIXER, OSC, and
1/2 DIVIDER circuits.
Ground.

—6—

CXA1741Q

Pin No. Symbol

26 MIXIN 1.3 V

27 MIXPS 1.3 V

28 MIX ADJ2 0.1 V

29 MIX ADJ1 0.1 V

Pin voltage I/O
DC AC

resistance

Equivalent circuit Description

27

26

MIXER

4k 4k 4k 4k

28

RF AMP

29

RF AMP output monitor.
Connected to the MIXER
input in the IC.

Balance adjustment for
mixers 1 and 2.

30 T3
31 T4
32 T5
33 VCC1 3.0 V

34 GND1 0 V
35 T6

36 FADJ1 2.2 V

37 FADJ2 1.5 V

660

147

36
37

147

660

IC operational check.

Power supply.
Supplies current to the PSN,
BPF, and BIAS circuits.
Ground.
IC operational check.

When the resistance value
of an external resistor
connected between Pins
36 and 37 is varied, the
center frequency of the
BPF in the IC changes
accordingly.

—7—