U2514B Datasheet, PDF (4/15 Pages) TEMIC Semiconductors – AM/FM Receiver for Digital Tuning with FM-Stereo Decoder

U2514B
AMIN
AMIN
1
VREF
AMSADJ
12418
9 AMSADJ
GNDRF
I _AGC
12417
Figure 8.
GND
Figure 6.
The AM antenna coil is connected between AMIN (Pin 1)
and VREF (Pin 14). In order to ensure that the AGC
W^{operates correctly, a coil impedance of approximately 25}
k is necessary.
AMOSC
7 AMOSC
The ceramic resonator of the stereo decoder PLL circuit
is used as a stop signal detector for AM signals. For this
purpose, the parallel resonance frequency of the
resonator, which is unloaded about 456 kHz, is reduced
by an internal load capacitor down to 455 kHz. Therefore,
the AM IF must be 455 kHz. The internal loading
capacitor is defined by the current through AMSADJ
(Pin 9) to GND. An external resistor is connected
between AMSADJ (Pin 9) and GND. It allows the
alignment of the stop signal center frequency. The width
of the stop window is typicaly 800 Hz. If AM search-
mode is not activated, the pin is internally pulled to
ground.
VREF
6k
IFOUT
10 IFOUT
AM_ON
FM
AM
12419
Figure 7.
GNDRF
Figure 9.
12420
The AM oscillator has to be loaded by an external tank
referred to VREF (Pin 14). If reduction of the oscillator
voltage is necessary, this may be achieved by a parallel
resistor.
The IF output (IFOUT Pin 10) of both the FM and the AM
mixer has to be loaded into external IF-tank circuits
refered to VREF (Pin 14). Q-factor of IF coils must not be
lower than 50.
4 (15)
TELEFUNKEN Semiconductors
Preliminary Information
Rev. A2, 04-Nov-96