PT8A2516 Datasheet, PDF (3/6 Pages) Pericom Semiconductor Corporation – Simple Timer

|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Block Diagram
OSC/^OR^SE^CSET _Oscillator
PT8A2516
Simple Timer
Simple Timer ^{|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||}
Time r
Power On _VCC
Re s et
Ke y
Logic control
scan
Circuit
GND
S ys te m
Oscillator
Output
Drive r
RELAY
Function Description (Refer to Block Diagram)
The chip mainly includes: Power on reset circuit, Logic
control circuit, Output driver circuit, Key scan circuit, timer
circuit, external R/C oscillator circuit and internal oscillator
circuit etc.
Power on reset circuit
Internal power on reset circuit will reset all the logic circuit
and the timer; it will clear all output pins when power on.
Logic control circuit
The logic circuit will carries out all the logic control function.
It will check OSC pin status, then control the output drive
circuit, when timer is out, it will pull down Relay pin to
release relay.
Output driver circuit
The pin Relay will drive a relay.
Key scan circuit
This circuit will detect “Reset/Restart” key at OSC have a low
negative pulse, it will active the corresponding work status.
When IC worked normal, it will reset the timer; when timer is
out, it will reset the timer and restart the output.
External R/C Oscillator circuit
This will produce a system frequency depend on external
resistor and cap, the frequency is about 8.192 KHz when
R1=47 KΩ and C1=332. (Refer to Fig 1).
Note: The system frequency with external resistor and cap
must be between 200Hz to 20 KHz.
Internal oscillator
An on-chip RC oscillator with frequency about 256 KHz is
used to check the input signal and the wrong statue of
external RC oscillator.
QTM
In order to make the manufacturer’s test convenient, quick
test mode is designed to speed up the test.
QTM can be accessed by pressing button (reset) over 3s once
power on. It can exit automatically after quick test timer is
expired; system comes back normal operation after quick test
mode.
Timer
1hr
16hr
QTM timer
2s
32s
Timer circuit
This circuit will provide a timer to logic control circuit. When
Fosc = 8.192 KHz, timer output is 29486400/8192=1hrs.
2014-04-0002
PT0273-4
04/09/2014
3