la1145 Sanyo Semiconductor Corporation, la1145 Datasheet - Page 10

• Manufacturer Part Number: la1145
• Description: Fm If System Quadrature Detector For Car Radio
• Manufacturer: Sanyo Semiconductor Corporation

3.
1)
2)
As can be seen from the above circuit diagrams, the time constant during detuning is determined by the internal PNP
resistance, the NPN collector resistance and the capacitance of the externally- mounted capacitor. This time constant is
determined by the external resistance R
required search time.
Narrow-band SD output circuit
An IF count circuit is provided for equipment compatibility for the European marketplace. However, if the band is made
narrow using only the SD circuit, there is a tendency for the number of erroneous stops caused by an undesired signal to
increase. To prevent this, two threshold voltages should be used to control the SD circuit.
Current path during detuning
Current return path from detuning
Band Mute Characteristics (1)
Without C
Frequency, f – kHz
SD sensitivity setting
17
AFC
and capacitor C. This time constant,
Mute driver pin for the 2nd threshold voltage.
LA1145, 1145M
The input/output current from pin 8 becomes zero during return.
With C
17
Band Mute Characteristics (2)
= 10000 pF
Frequency, f – kHz
= R
AFC
SD output
C, must be set depending on the
No. 2725-10/17