U4256BM Datasheet, PDF (1/14 Pages) TEMIC Semiconductors – Frequency Synthesizer for Radio Tuning

Frequency Synthesizer for Radio Tuning
U4256BM
Description
The U4256BM is a single chip frequency synthesizer in
BICMOS technology. Together with the AM/FM IC
U4255BM, it performs a complete AM/FM car radio front
end, which is recommended also for RDS (Radio Data
System) applications. It is controlled by 3-wire bus and
contains also Digital to Analog Converters (DACs) for
automatic alignment of the AM/FM tuner.
Features
D Reference oscillator up to 15 MHz (tuned)
D Oscillator buffer output (for AM up/down conversion)
D Two programmable 16-bit dividers
D Fine-tuning steps: AM ≥ 1 kHz, FM ≥ 2 kHz
D Fast response time due to integrated loop push-pull stage
D 3-wire bus (enable, clock and data; 3 V and 5 V micro-
controllers acceptable)
D Four programmable switching outputs (open drain)
D Three DACs for software controlled tuner alignment
D Low power consumption
D High S/N ratio
* D Integrated band gap only one supply voltage
necessary
Block Diagram
Tuning
SWO1 SWO2 SWO3 SWO4
7 8 9 10
OSCIN ¹³
12 Oscillator
OSCOUT
MX2LO ¹⁵
OSC
buffer
17
CLK
DATA ¹⁶
3W–
bus
EN ^{18 interface}
R–
divider
Switching outputs
DAC3
3–bit
VRef
DAC2
DAC1
5
DAC3
4
DAC2
3
DAC1
FMOSCIN ¹⁹
FM–
preamp
20
GNDan
Ordering Information
Extended Type Number
U4256BM-AFS
U4256BM-AFSG3
N–
divider
Phase
detector
Current
sources
Band-gap
14
V5
11
GND
Figure 1. Block diagram
AM/FM
VRef
6
1
VS
PDO
2
PD
96 11799
Package
SSO20
SSO20
Remarks
Taped and reeled
Rev. A2, 03-Nov-98
1 (14)
Preliminary Information