LC72121, 72121M, 72121V
Structure of the IF Counter
The LC72121 IF counter is a 20-bit binary counter, and takes the IF signal from the IFIN pin as its input. The result of
the count can be read out serially, MSB first, from the DO pin.
Measurement time
GT1
GT0
Measurement time (GT)
Wait time (tWU
3 to 4 ms
)
0
0
1
1
0
1
0
1
4 ms
8
3 to 4 ms
32
7 to 8 ms
64
7 to 8 ms
The IF frequency (Fc) is measured by determining how many pulses were input to the IF counter in the stipulated
measurement time, GT.
C
GT
Fc =—— (C = Fc x GT)
C: Counted value (the number of pulses)
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.
IF frequency (F ) = 342400 ÷ 32 ms = 10.7 MHz
C
• When the measurement time (GT) is 8 ms and the counted value (C) is E10 (hexadecimal) or 3600 decimal.
IF frequency (F ) = 3600 ÷ 8 ms = 450 kHz
C
No. 5815-15/22
SANYO [ SANYO SEMICON DEVICE ]
