information from the fairchild semiconductor data sheet for the lm555/ne555/sa555 single timer (as archived on ben eater’s website)rev 1.0.3 2002
front page
Features
- High Current Drive Capability (200mA)
- Adjustable Duty Cycle
- Temperature Stability of 0.005%/degC
- Timing From uSec to Hours
- Turn off Time Less Than 2uSec
Applications
- Precision Timing
- Pulse Generation
- Time Delay Generation
- Sequential Timing
Description
The xx555 is a highly stable controller capable of producing accurate timing pulses. With a monostable operation, the time delay is controlled by one external resistor and one capacitor. With an a stable operation, the frequency and duty cycle are accurately controlled by two external resistors and one capacitor.
8-DIP / 8-SOP : pin 1 is labeled as the front-right lead with the length of the body of the chip aiming away from the viewer. there may be a marking on the upper side of the package near to the viewer, but it is not clear
Internal Block Diagram
GND 1 - R -+- R -+- R - 8 VCC
|
Trigger 2 - - 7 Discharge
Output 3 - 6 Threshold
Reset 4. - 5 Control Voltage
the resistor triplet from gnd to vcc are arranged in a 1/3rd 2/3rds voltage divider . There are two triangles labeled Comp. that connect to the lower and higher voltage divisions. The first Comp has its + input to the 1/3rd division and its - input to 2 Trigger. The output goes to an internal block labeled F/F . The second Comp. has its - input to the 2/3rd division and its + from 6 Threshold. Its output goes to a different side of F/F.
Output 3 comes from a block labeled OutPut Stage which itself comes from F/F.
Reset goes to the bottom of a T with a diagonal line coming off each top. The right diagonal is an arrow pointing at the T and stems from an open circle labeled Vref. The left diagonal goes to F/F.
5 Control Voltage is also connected to the negative lead of the second Comp, and hence wired into the resistor line from VCC to GND (on the high end).
7 discharge goes to another T with diagonals. It is on the right diagonal which lacks an arrow. The left diagonal has an arrow pointing away and goes to a ground symbol. The T is labeled Discharging Tr. The bottom goes to F/F .
Page 2
Absolute Maximum Ratings (T_A = 25degC)
Parameter Symbol Value Unit
Supply Voltage V_CC 16 V
Lead Temperature (Soldering 10sec) T_LEAD 300 degC
Power Dissipation P_D 600 mW
Operating Temperature Range
LM555/NE555 T_OPR 0 ~ +70 degC
SA555 -40 ~ +85
Storage Temperature Range T_STG -65 ~ +150 degC
Page 3
Electrical Characteristics
(T_A = 25degC, V_CC = 5 ~ 15V, unless otherwise specified)
Parameter Symbol
Supply Voltage V_CC
Supply Current (Low Stable)(Note1) I_CC
… wow that’s a lot of data to try to format on mobile, lots of voltage and error specs on page 3, footnotes at the bottom. This is important stuff if designing a circuit to use this!
Page 4
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