lc72134m Sanyo Semiconductor Corporation, lc72134m Datasheet - Page 19

• Manufacturer Part Number: lc72134m
• Description: Dual Pll Frequency Synthesizer For Fm Tuner Systems
• Manufacturer: Sanyo Semiconductor Corporation

Structure of the IF Counter
The LC72134M IF counter is a 20-bit binary counter, and takes the IF signal from the IFIN1 or IFIN2/I1 pin as its input.
The result of the count can be read out serially MSB first from the DO pin.
The IF frequency (FC) is measured by determining how many pulses were input to the IF counter in the stipulated measurement time, GT.
IF Counter Frequency Measurement Examples
• When the measurement time (GT) is 32 ms and the counted value (C) is 53980 (hexadecimal) or 342,400 decimal.
• When the measurement time (GT) is 8 ms and the counted value (C) is E10 (hexadecimal) or 3600 decimal.
IF frequency (FC) = 342400 32 ms = 10.7 MHz
IF frequency (FC) = 3600 8 ms = 450 kHz
GT1
Fc = —— (C = Fc
0
0
1
1
GT
C
GT0
0
1
0
1
Measurement time (GT)
GT)
4 ms
32
64
C: Counted value (the number of pulses)
8
Measurement time
Wait time (t
3 to 4 ms
3 to 4
7 to 8
7 to 8
WU
)
LC72134M
No. 5814-19/27