Document
CXA1741Q
IF Amplifier for Analog Cellular Communications For the availability of this product, please contact the sales office.
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). Applications Ideally suited for cellular phones, particularly handheld sets. Structure Bipolar silicon monolithic IC 40 pin QFP (Plastic)
Absolute Maximum Ratings (Ta = 25°C) • Supply voltage VCC 5 V • Operating temperature Topr –35 to +85 °C • Storage temperature Tstg –65 to +150 °C • Allowable power dissipation PD 500 mW Operating Conditions Supply voltage
VCC
2.7 to 3.6
V
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
CXA1741Q
Block Diagram and Pin Configuration (Top View)
MIXADJ1
MIXADJ2
MIXPS
MIXIN
IFPS
GND
30 T4 31
29
28
27
26
25
24
VCC
23
22
IFIN
T3
21 20 XTALIN
PSN T5 32 PSN VCC1 33 MIXER
RF AMP 19 XTALOUT
GND
18 AGCPS 17 VREF 16 RSSIPS 15 T2 14 RSDETPS 13 T1 12 GND2 11 VCC2 10
GND1 34 BPF0 T6 35
1/2
OSC
AGC FADJ1 36 FADJ2 37
BPF1 RSSI
SGND 38
BIAS LIM DET
BPFPS1 39
BPFPS2 40
1
SW(TACS/NTACS)
2
NC
3
BPFO
4
5
6
AUDIO
7
RSSI
8
GADJ(RSSI)
9
IF2
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—
LIMPS
CXA1741Q
Pin No. 1
Symbol SW TACS NTACS
Pin voltage DC AC 0V OPEN HIGH (3 V)
I/O resistance
31
Equivalent circuit
Description Changeover switch for built-in filter. TACS for Low; NTACS for High.
(
)
20µA
50k 1 50k
VREF GND
34
2 3 4 5
NC BPFO
1.8 V
Not internally connected. BPF output monitor. Not used normally. Connected to the LIM and RSSI inputs in the IC.
33
147
3 4 5
34
B.P.F N.F.B Network
LIM
RSSI
6
AUDIO
2.1 V
11
Outputs an AUDIO signal which is FM-detected.
1k
6
12
—3—
CXA1741Q
Pin No. 7
Symbol RSSI
Pin voltage DC AC 1.2 V
I/O resistance
Equivalent circuit
Description RSSI output. Outputs a DC voltage in accordance with the signal input to the RF amplifier.
11
147
7
12
8
GADJ
0.2 V
Adjusts the RSSI amplifier gain (varies the resistance so as to obtain a linear RSSI output).
147
8
147
7
9
IF2
0.9 V
11
Limiter operation monitor. Not used normally.
147
9
12
10
LIMPS
1.8 V
11
Connects a limiter integrating capacitor.
10
12
—4—
CXA1741Q
Pin No. 11
Symbol VCC2
Pin voltage DC AC 3.0 V
I/O 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.
12 13 14
GND2 T1
0V
RSDETPS 1.4 V
11
147 14
12
15 16
T2 RSSIPS 1.8 V
11
IC operation check. Connects an RSSI integrating capacitor.
16
12
17
VREF
1.3 V
33 17
34 reference voltage used in the internal circuit
Monitor for the reference voltage used in the internal circuit. When connected to an external capacitor, this pin also functions to lower the reference voltage dynamic impedance.
—5—
CXA1741Q
Pin No. 18
Symbol AGCPS
Pin voltage DC AC 0.2 V
I/O resistance
Equivalent circuit
Description Connects an AGC integrating capacitor.
33
18 VREF
34 15
19
XTALOUT 2.9 V
24 147 20 10k 15p 10k 19
20
XTALIN
2.9 V
Connect a crystal oscillator to form a Colpitts-type oscillator circuit. When an external oscillator is used, its input must be connected to Pin 20.
25
21
21 22
GND IFIN
0V 1.3 V
24
23
IFPS
1.3 V
22 1.5k 1.5k
23
VREF 21 25
Ground. RF amplifier input. The relationship between IFIN (Pin 22) and IFPS (Pin 23) is designed so that the IC internal stray capacitance is small. Therefore, if Pins 22 and 23 are used for balance input, the common-mode rejection deteriorates. Power supply. Supplies current to the RF AMP, MIXER, OSC, and 1/2 DIVIDER circuits. Ground.
24
VCC
3.0 V
25
GND
0V
—6—
CXA1741Q
Pin No. 26
Symbol MIXIN
Pin voltage DC AC 1.3 V
I/O resistance
Equivalent circuit
Description RF AMP output monitor. Connected to the MIXER input in the IC.
27
2.