JVC PC-X250 Service Manual page 14

PC-X250
LC72131 Pin Functions
Pin No.
Symbol (MFP pin Nos. are
in parentheses.)
V
21 (19)
SS
BO1 7 (6)
BO2 8 (7)
BO3 9 (8)
BO4 10 (9)
IO1 11 (10)
IO2 13 (12)
PD 18 (16)
AIN 19 (17)
AOUT 20 (18)
IFIN 12 (11)
1 - 14
Type
Ground ¥ The LC72131 ground
¥ Dedicated output pins
¥ The output states are determined by BO1 to BO4 bits in
the serial data.
Data: 0 = open, 1 = low
¥ A time base signal (8 Hz) can be output from the BO1
Output port pin. (When the serial data TBC bit is set to 1.)
¥ Care is required when using the BO1 pin, since it has a
higher on impedance that the other output ports (pins
BO2 to BO4).
¥ All output ports are set to the open state following a
power on reset.
¥ I/O dual-use pins
¥ The direction (input or output) is determined by bits IOC1
and IOC2 in the serial data.
Data: 0 = input port, 1 = output port
¥ When specified for use as input ports:
The state of the input pin is transmitted to the controller
over the DO pin.
I/O port Input state: low = 0 data value
¥ When specified for use as output ports:
The output states are determined by the IO1 and IO2
bits in the serial data.
Data: 0 = open, 1 = low
¥ These pins function as input pins following a power on
reset.
¥ PLL charge pump output
When the frequency generated by dividing the local
oscillator frequency by N is higher than the reference
Charge pump
frequency, a high level is output from the PD pin.
output
Similarly, when that frequency is lower, a low level is
output. The PD pin goes to the high impedance state
when the frequencies match.
LPF amplifier ¥ The n-channel MOS transistor used for the PLL active
transistor low-pass filter.
¥ Accepts an input in the frequency range 0.4 to 12 MHz.
¥ The input signal is directly transmitted to the IF counter.
¥ The result is output starting the MSB of the IF counter
IF counter
using the DO pin.
¥ Four measurement periods are supported: 4, 8, 32, and
64 ms.
Functions
high = 1 data value
Circuit configuration
Ñ