LC72F3781 Datasheet, PDF (11/17 Pages) Sanyo Semicon Device – CMOS IC Electronic tuning radio for car audio ETR Controller

Continued from preceding page.
Pin name Pin No.
I/O
HCTR
90
I
LCTR
89
I
SNS
88
I
HOLD
87
I
LC72F3781
Pin explanation
Universal counter and general-purpose input shared function input port.
The IOS1 instruction is used for switching between the universal
counter and general- purpose input functions.
• When used for frequency measurement :
The universal counter function is set up with the IOS1 instruction.
The counter is controlled using UCS and UCC instructions.
Since this pin functions as an AC amplifier in this mode, the input
signal must be input with capacitor coupling.
• When used as a general-purpose input pin :
The general-purpose input function is set up with the IOS1
instruction.
Data is read from the port using the INR (b0) instruction.
Input is disabled in Backup mode. (The input pin will be pulled down.)
The universal counter function is selected after a power on reset.
Universal counter (frequency or period measurement) and general-
purpose input shared function input port.
The IOS1 instruction is used for switching between the universal
counter and general-purpose input functions.
• When used for frequency measurement :
The universal counter function is set up with the IOS1 instruction.
Set up LCTR frequency measurement mode with the UCS
instruction, and control operation with the UCC instruction.
Since this pin functions as an AC amplifier in this mode, the input
signal must be input with capacitor coupling.
• When used for period measurement :
The universal counter function is set up with the IOS1 instruction.
Set up LCTR frequency measurement mode with the UCS
instruction, and control operation with the UCC instruction.
Since the bias feedback resistor is disconnected in this mode, the
input signal must be input with DC coupling.
• When used as a general-purpose input pin :
The general-purpose input port function is set up with the IOS1
instruction.
Data is read from the port using the INR (b1) instruction.
Input is disabled in Backup mode. (The input pin will be pulled down.)
The universal counter function (HCTR frequency measurement mode)
is selected after a power on reset.
Voltage sense and general-purpose input shared function port.
This input circuit is designed with a low input threshold voltage.
• When used as a voltage sense input :
The pin is used to test for power failures on the return from Backup
mode.
Application can test this condition using the internal SNS flip-flop.
The SNS flip-flop can be tested with the TST instruction.
(This usage requires external components, capacitors and resistors.
For the sample application circuit, see the user’s manual.)
• When used as a general-purpose input port :
When used as a general-purpose input port the pin state can be
tested with the TST instruction.
Unlike the other input ports, input to this pin is not disabled in Backup
mode and after a power on reset. As a result, through currents must
be taken into account when designing applications that use this pin as
a general-purpose input.
Power supply monitor (with interrupt function)
This is designed with a high input threshold voltage.
This pin is normally connected to the ACC line and used for power off
detection.
When a power off state is detected, the HOLDON flag and the hold
interrupt request flag will be set.
To enter Backup mode, execute a CKSTP instruction when the HOLD
pin is low. Set this pin high to clear Backup mode.
Equivalent circuit
PLL Stop instruction
ILC05536
ILC05539
ILC05539
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No.0459-11/17