U4255BM
AM/FM Receiver IC
Description
The U4255BM is an integrated AM/FM front end circuit
in BICMOS technology. It contains a double conversion
system for FM and an up/down conversion circuit
for AM (IF1 = 10.7 MHz, IF2 = 450 kHz). A complete
automatically aligned high performance AM/FM tuner
can be built together with the PLL U4256BM. This ICs
are designed for high performance car radio applications.
Electrostatic sensitive device.
Observe precautions for handling.
Features
D
FM-double conversion system
D
Integrated second IF filter with software controlled
bandwidth
D
Completely integrated FM demodulator
D
Soft mute and multipath noise cancellation
D
Receiving condition analyzer
D
AM up/down conversion system
D
AM preamplifier with AGC and stereo capability
D
3-wire bus controlled
D
Stop signal generation for AM and FM
D
Automatic alignment possible
Block Diagram
AMPLPF
IF1AMI
V3
IF2IN
MX2OB
MX1OA
IF1FMI
IF1REF
IF1OUT MX2IN
MX2OA
V3P
MX1OB
8
7
AMAGC
6
AMVREG
AGC
43 44
38
39
33
AM
FM
IF2OUT
20
30 29 26
23 24
28
27
AM
dem.
MX1AMA
MX1AMB
41
3
AM
V3
AGC
32
OPLPF
36
35
IFAGCL
IFAGCCH
GNDMX
MX1FMB
MX1FMA
4
2
1
FM
AGC
Automatic
adjustment 37 FMADJ
OSCOUT
16
Divider
Adj.
chan.
OSC
V3
Bus
Bandgap
22
MX2LO
10
ADJAC
Multi鈥?/div>
path
11
FM
dem.
Soft
mute
GNDOSC
15
Stop
MPX
OSCE 14
OSCB 13
INT
21
40
INT MULTIP
34
SMUTE
Dev.
ana.
31
DEV
12 25 42 9
17 18 19
5
GND
EN
DATA FMAGC
METER
V57
VS
CLK
Figure 1. Block diagram
Ordering Information
Extended Type Number
U4255BM-AFN
U4255BM-AFNG3
Rev. A2, 11-Oct-00
Package
SSO44
SSO44
Tube
Taped and reeled
1 (14)
Remarks
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