U4275B Datasheet, PDF (3/12 Pages) TEMIC Semiconductors – FM-Receiving Condition Analyser and Multipath Noise Cancellation

TELEFUNKEN Semiconductors
U4275B
MPXIN / MPXOUT
V_S
50 kW
MPXIN
The function unit MNC can be controlled externally via
this pin. Blanking occurs when the voltage at the MUTE
pin falls below 1 V. A voltage in the range VS/2 > 1 V
defines the switching threshold as from which multipath
interference is signalled at pin INT.
CRIN
50 kW
V_S
V_S
60 kW
MPXOUT
60 kW
94 8649
V_S
200 mA
CRIN
40 kW
94 8652
94 8650
The MPX signal is fed directly from the FM demodulator
to input MPXIN and is available amplified by a factor of
1.5 at MPXOUT. The MPX signal is blanked out in the
event of multipath interference or when MUTE is
activated externally in the circuit part MNC (Multipath
Noise Canceller). In all other cases, the MPX signal
passes through the IC unchanged.
The internal one-pin oscillator is connected to CRIN with
a 456 kHz ceramic resonator. The 456 kHz reference
frequency is used for calibrating the filters and generating
pulses at INT.
ANAOUT
+5V
GND2
GND2 is the reference potential for the MPX signal.
GND2 should be connected directly with the ground
terminal of the IF FM demodulator to ensure a high
signal-to-noise ratio of the MPX signal.
MUTE
MUTE
ANAOUT
94 8653
60 mA
Analyzer output. DC values are available at this pin that
characterize the respective reception situation. The
output voltage is limited to max. 5 V. ANAOUT is a
multiplex output, i.e. the value for the fieldstrength, level
of multipath interference or level of common channel
interference is applied to this output depending on
addressing. ANAOUT can be switched to the
high-impedance state by means of OE.
94 8651
Rev. A1: 14.03.1995
Preliminary Information
3