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Pin
Function
24 AFC
25 QD OUT
26 QD IN
27 VREF
LA1867NM
Unit (resistance:Ω, capacitance:F)
Equivalent internal circuit
Note
• R1 is the resistor that determines the band
muting bandwidth.
Increasing R1 reduces the bandwidth.
Decreasing R1 increases the bandwidth.
• Null voltage
When tuned, the voltage between pins 24
and 27 will be 0 V.
V24 – V27 = 0 V
The band muting is turned on when
| V24 – V27 | ≥ 0.7 V.
29 SD pin
SD sensitivity adjustment
30 pin
IF counter buffer
19
Seek/stop switch
The SD output for the pin 30 SD.
R determines the SD sensitivity.
Pin 23 is coupled to the muting drive output.
SD operates when the switch is off.
This pin is used for both the IF counter
buffer (AC output) and the seek/stop switch
(DC input).
It is not coupled to the SD output.
The IF buffer is turned on and off by the pin
19 DC bias level.
Pin 19: high → buffer on, low → buffer off.
No. 4619-10/32