la1145 Sanyo Semiconductor Corporation, la1145 Datasheet - Page 9

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

SD Output Circuit
1.
2.
LA1145 SD output differs from the LA1140’s pin substitute SD output as shown below. The SD output on the LA1145 does
not operate in conjunction with the soft mute characteristics.
1)
2)
As shown, the SD output is the logical AND of the band mute and S-meter comparator outputs.
Signal search using the SD output circuit
2-1 The transition response characteristics of the SD output circuit depends on the time constants of pins 15, 16, 17 and 8.
2-2 Band mute range circuit time constant (pin 8)
LA1140
LA1145
As the SD output transition response characteristics are determined by the pin with the largest time constant, erroneous
stopping will result when a search time is less than the largest one.
An equivalent circuit to the band circuit is shown below.
Hole detector
Signal meter
Hole detector
Signal meter
Band mute
Bandmute
Mute switch circuit
LA1145, 1145M
Comparator
Exhibit hysteresis
Mute driver
Mute driver
output
output
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