1
S
R
R1
TRIG
THRES
V
CC
CONT
RESET
OUT
DISCH
GND
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4
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SLFS022I –SEPTEMBER 1973–REVISED SEPTEMBER 2014
xx555 Precision Timers
1 Features 3 Description
These devices are precision timing circuits capable of
1
• Timing From Microseconds to Hours
producing accurate time delays or oscillation. In the
• Astable or Monostable Operation
time-delay or mono-stable mode of operation, the
• Adjustable Duty Cycle
timed interval is controlled by a single external
resistor and capacitor network. In the a-stable mode
• TTL-Compatible Output Can Sink or Source
of operation, the frequency and duty cycle can be
Up to 200 mA
controlled independently with two external resistors
• On Products Compliant to MIL-PRF-38535,
and a single external capacitor.
All Parameters Are Tested Unless Otherwise
The threshold and trigger levels normally are two-
Noted. On All Other Products, Production
thirds and one-third, respectively, of V
CC
. These
Processing Does Not Necessarily Include
levels can be altered by use of the control-voltage
Testing of All Parameters.
terminal. When the trigger input falls below the trigger
level, the flip-flop is set, and the output goes high. If
2 Applications
the trigger input is above the trigger level and the
• Fingerprint Biometrics threshold input is above the threshold level, the flip-
flop is reset and the output is low. The reset (RESET)
• Iris Biometrics
input can override all other inputs and can be used to
• RFID Reader
initiate a new timing cycle. When RESET goes low,
the flip-flop is reset, and the output goes low. When
the output is low, a low-impedance path is provided
between discharge (DISCH) and ground.
The output circuit is capable of sinking or sourcing
current up to 200 mA. Operation is specified for
supplies of 5 V to 15 V. With a 5-V supply, output
levels are compatible with TTL inputs.
Device Information
(1)
PART NUMBER PACKAGE BODY SIZE (NOM)
PDIP (8) 9.81 mm × 6.35 mm
SOP (8) 6.20 mm × 5.30 mm
xx555
TSSOP (8) 3.00 mm × 4.40 mm
SOIC (8) 4.90 mm × 3.91 mm
(1) For all available packages, see the orderable addendum at
the end of the datasheet.
4 Simplified Schematic
1
An IMPORTANT NOTICE at the end of this data sheet addresses availability, warranty, changes, use in safety-critical applications,
intellectual property matters and other important disclaimers. PRODUCTION DATA.
