21-03-2012, 01:49 PM
LM555/NE555/SA555
NE555.pdf (Size: 149.22 KB / Downloads: 26)
Features
• High Current Drive Capability (200mA)
• Adjustable Duty Cycle
• Temperature Stability of 0.005%/°C
• Timing From μSec to Hours
• Turn off Time Less Than 2μSec
Applications
• Precision Timing
• Pulse Generation
• Time Delay Generation
• Sequential Timing
Description
The LM555/NE555/SA555 is a highly stable controller
capable of producing accurate timing pulses. With
monostable operation, the time delay is controlled by one
external resistor and one capacitor. With astable operation,
the frequency and duty cycle are accurately controlled with
two external resistors and one capacitor.
Application Information
When the low signal input is applied to the reset terminal, the timer output remains low regardless of the threshold voltage or
the trigger voltage. Only when the high signal is applied to the reset terminal, timer's output changes according to threshold
voltage and trigger voltage.
When the threshold voltage exceeds 2/3 of the supply voltage while the timer output is high, the timer's internal discharge Tr.
turns on, lowering the threshold voltage to below 1/3 of the supply voltage. During this time, the timer output is maintained
low. Later, if a low signal is applied to the trigger voltage so that it becomes 1/3 of the supply voltage, the timer's internal
discharge Tr. turns off, increasing the threshold voltage and driving the timer output again at high.