lc72135m Sanyo Semiconductor Corporation, lc72135m Datasheet - Page 17

• Manufacturer Part Number: lc72135m
• Description: Pll Frequency Synthesizer For Electronic Tuning
• Manufacturer: Sanyo Semiconductor Corporation

IF Counter Structure
The LC72135M IF counter is a 20-bit binary counter that accepts an IF input from either the HCTR pin (for FM or AM IF
counting) or the LCTR/I1 pin (for AM IF counting). The result of the count can be read out serially through the DO pin
starting with the MSB.
The IF frequency (Fc) is measured by determining how many pulses were input to an IF counter in a specified
measurement period, GT.
Fc =
1. IF Counter Frequency Calculation Examples
GT1
0
0
1
1
• When the measurement period (GT) is 32 ms, the count (C) is 53980 hexadecimal (342400 decimal):
• When the measurement period (GT) is 8 ms, the count (C) is E10 hexadecimal (3600 decimal):
GT
IF frequency (Fc) = 342400 32 ms = 10.7 MHz
IF frequency (Fc) = 3600 8 ms = 450 kHz
C
GT0
0
1
0
1
Measurement period (GT) (ms)
(C = Fc GT)
32
64
4
8
Measurement time
Wait time (t
C: Count value (number of pulses)
3 to 4
3 to 4
7 to 8
7 to 8
LC72135M
WU
) (ms)
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