U2514B Datasheet, PDF (7/15 Pages) TEMIC Semiconductors – AM/FM Receiver for Digital Tuning with FM-Stereo Decoder

CERES
VREF
MPXIN
24
10 k
MPXIN
U2514B
20
CERES
50 k
12452
60 k
Figure 20.
GND
Figure 18.
The MPX signal is applied to MPXIN (Pin 24). It is fed
W ^{to the stereo decoder. The input resistance into Pin 24 is}
approximately 10 k . It is recommended to align the
channel separation by an RC network between MPXIN
12449
and MPXOUT (Pin 25) due to the tolerances in group
delay of the IF filter.
MPXOUT
VREF
A ceramic resonator of 456 kHz parallel resonance
frequency (at 30 pF chip internal load capacitance) is
connected between CRES (Pin 20) and GND (necessary
for the pilot regeneration). It should be mounted very
close to Pin 20 in order to avoid spurios radiation. In the
AM (V26 < 1.1 V) search (V22 < 0.8 V) mode, the
resonator is used for stop signal generation. The parallel
resonance frequency is then reduced down to 455 kHz by
adjusting the current into Pin 9 AMSADJ.
25
MPXOUT
GND
12451
LPF
21
Figure 21.
In order to drive both the compensation network to
MPXIN (Pin 24) and an optional RDS decoder, the
MPXOUT (Pin 25) has a low output impedance. The dc
25 k
VREF
level is 1.2 V in FM mode (depending on the
discriminator coil alignment) and 0.7 to 1.5 V in AM
mode (depending on the signal level).
OUTR/OUTL
LPF
VREF
18,19
12450
OUTL
OUTR
12453
Figure 19.
Figure 22.
A PLL circuit is used for the pilot regeneration of the
stereo decoder. Therefore, a loopfilter consisting of an RC
network is connected between LPF (Pin 21) and GND.
The open collector output of OUTR/OUTL (Pin 18/19)
W requires an external resistor of about 4.7 k to ground.
The de-emphasis may be achieved by an additional
parallel capacitor.
TELEFUNKEN Semiconductors
7 (15)
Rev. A2, 04-Nov-96
Preliminary Information