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IF Down Converter for Digital Broadcast
Description
The CXA3556N is a one-chip integrated IC that
processes IF signals of a digital broadcast tuner and
includes an AGC amplifier circuit, a mixer circuit, a
local oscillator circuit and an output amplifier circuit.
The package utilizes a 24-pin SSOP suitable for
surface mounting.
Features
• AGC control width that has a 56dB variable range
• Low noise characteristics
• Low distortion characteristics (in par ticular, during
AGC gain reduction)
• Includes switching function between down
converter mode and linear amplifier mode
• Variable output amplifier gain by changing external
resistance
• Includes RF AGC output pin
• Variable RF AGC settings
• AGC control curve characteristics with excellent
linearity
Absolute Maximum Rating (Ta = 25°C)
• Supply voltage Vcc –0.3 to +12 V
• Operating temperature Topr –55 to +150 °C
Operating Conditions
• Supply voltage Vcc 4.75 to 5.25 V
• Operating temperature Topr –25 to +75 °C
CXA3556N
24 pin SSOP (Plastic)
Applications
Digital broadcast tuners
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.
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E02426-PS
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Block Diagram and Pin Configuration
CXA3556N
IFIN1
IFIN2
RFAGC
IREG
VREG
LOB1
LOC1
LOC2
1
2
3
4
5
6
7
8
Comparator
REG
OSC
AGC
Amp.
Mixer
Output
Amp.
AGCIN
24
MODESEL
23
AGCGND
22
AO2
21
AO1
20
GND
19
AGCREF
18
17
E2
LOB2
CC
V
MO1
MO2
9
10
1
11
12
16
15
14
13
E1
AIN2
AIN1
CC
V
2
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Pin Description and Equivalent Circuit
CXA3556N
Pin
No.
Symbol
Pin
voltage
1 IFIN1 1.4V
2 IFIN2 1.4V
3 RFAGC —
10
22
Equivalent circuit Pin description
CC
1
V
1
2
5k
3
5k
AGCGND
IF inputs.
RF AGC voltage output.
Comparator output.
Low level: 0.4V or less
High level: 8V or more
10
22
AGCGND
V
CC1
4 IREG 2.6V
5VREG 3.3V
6 LOB1 2.9V
7 LOC1 3.7V
8 LOC2 3.7V
10
10
22
Connects external resistance
27kΩ.
22
AGCGND
4
V
CC
1
Connects external capacitance
5
AGCGND
6
978
1µF.
V
CC
1
Connects external capacitance
and crystal oscillator.
9 LOB2 2.9V
19
GND
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CXA3556N
Pin
No.
Symbol
10 VCC15V
Pin
voltage
Equivalent circuit Pin description
Power supply.
V
CC
10
1
11 MO1 2.3V
11
12
Mixer output pin.
12 MO2 2.3V
19
GND
13 VCC2 5V Power supply.
CC
1
14 AIN1 1.3V
15 AIN2 1.3V
16 E1 0.6V
10
14
15
200
200
10k
10k
V
Output amplifier circuit inputs.
Gain of output amplifier circuit
can be changed by connecting
external resistance between
Pins 16 and 17.
17 E2 0.6V
18 AGCREF —
19
10
17 16
V
90µA
CC1
18
GND
RF AGC setting voltage
adjustment pin.
Connect external resistance
between Pin 18 and GND and
change the value to change
RF AGC output voltage.
22
AGCGND
19 GND 0V GND
CC
1
V
20 21
Output amplifier output.
20 AO1 2.7V
10
21 AO2 2.7V
19
GND
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