PT8A2515 Datasheet, PDF (2/6 Pages) Pericom Semiconductor Corporation – Simple Timer

PT8A2515
Simple Timer
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Pin Configuration
OSC 1
GND 2
VCC 3
PT8A2515
SOT23-5
5 NC
4 Relay
Pin Description
Pin No.
TO-94
1
2
SOT23-5
4
3
3
1
4
2
-
5
Pin Name
Relay
VCC
OSC
GND
NC
I/O
Description
O Relay output, high active
I Power supply
I/O
Oscillator's Frequency of 8.192KHz with an external R1, C1.
As input, requires a negative pulse to active “Reset” function.
I Ground
- Not connected
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 at timer, it will reset the timer; when timer is
out, it will reset the timer and restart the output.
Timer circuit
This circuit will provide a timer to logic control circuit. When
Fosc = 8.192 KHz, timer output is 245720/8192=30s.
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 180Hz 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.
2013-07-0010
PT0272-3 08/01/13
2