LC72121MA
Continued from preceding page.
Pin name
Pin No.
Type
Function
• PLL charge pump output
A high level is output when the frequency of the local oscillator signal
Charge pump
PD
19
divided by N is higher than the reference frequency, and a low level
output
is output when that frequency is lower. This pin goes to the
highimpedance state when the frequencies match.
AIN
AOUT
Low-pass filter
20
• Connections for the MOS transistor used for the PLL active low-pass
amplifier
21
filter.
transistor
VSSa
22
Ground
• Ground for the low-pass filter MOS transistor
Equivalent circuit
• The input frequency range is 0.4 to 15MHz
• The signal is passed directly to the IF counter.
IFIN
13
IF counter
• The result is output, MSB first, through the DO pin.
• Four measurement periods are supported: 4, 8, 32, and 64ms.
12
NC
NC pin
• No connection
-
23
No.A2009-7/24