component

LMC555 CMOS Timer

Public Unreviewed

by Ray

CMOS version of the 555 timer with low power, high frequency, and single-supply operation.

timer555cmoslow-poweroscillatortisoic-8
Overview Files Discover Packages Releases Dependencies Issues Breadcrumbs Pull Requests Activity

3D Model

Open in new tab ↗

Symbol & Footprint

Schematic Symbol

Open full view ↗

PCB Footprint

Open full view ↗
Contents

README

markdown

LMC555

Texas Instruments · Timer · SOIC-8

The LMC555 is a CMOS version of the classic 555 timer. It draws far less current than the bipolar 555, operates from 1.5 V to 15 V, and oscillates up to 3 MHz. Configured as an astable or monostable with an external RC, it generates clocks, pulses, PWM, and time delays with minimal power.

Pinout

Pin Name Type Function
1 GND power_in Ground reference voltage (0 V return for the supply).
2 TRIGGER input Trigger input responsible for transition of the internal flip-flop from set to reset. The output pulse of the timer depends on the amplitude of the external trigger pulse applied to this pin. Trigger threshold is nominally 1/3 V+.
3 OUTPUT output Output driven waveform. Sources/sinks up to 10 mA (VS=5 V) or 50 mA (VS=12 V) to directly drive TTL and CMOS loads.
4 RESET input Active-low reset. A negative pulse applied to this pin disables/resets the timer. When not used for reset purposes, connect this pin to V+ to avoid false triggering. Typical VRES = 0.7 V at VS = 1.5 V.
5 CONTROL_VOLTAGE input Control-voltage input sets the internal threshold and trigger levels (nominally 2/3 V+). An external voltage applied here modulates the output pulse width/waveform. Typically decoupled to ground with 0.01 uF when unused.
6 THRESHOLD input Threshold comparator input; compared against an internal reference of 2/3 V+. The voltage at this pin sets the reset state of the internal flip-flop.
7 DISCHARGE output Open-collector (open-drain) discharge pin that shorts the external timing capacitor to ground between intervals (in phase with OUTPUT). Toggles the output from high to low when THRESHOLD reaches 2/3 V+.
8 V+ power_in Positive supply voltage with respect to ground. Operating range 1.5 V to 15 V.

Key specifications

Parameter Value
Type CMOS timer (555-type)
Supply voltage 1.5 V to 15 V
Max frequency 3 MHz
Supply current 100 uA typ at 5 V
Modes Astable, monostable
Timing External R and C
Operating temperature -40 C to 85 C

Ordering variants

Same part, different packaging or reel option.

  • LMC555D
  • LMC555DGK
  • LMC555P
  • LMC555YBF
  • LMC555YPB

CAD (KiCad official)

  • Symbol: lmc555.kicad_sym
  • Footprint: lmc555.kicad_mod
  • 3D model: SOIC-8 body from KiCad Package_SO/SOIC-8_3.9x4.9mm_P1.27mm.

Provenance

Data extracted from the manufacturer datasheet, not a distributor listing:

  • Datasheet: Texas Instruments datasheet (35 pp, sha256 993be6e487fb5fe6, retrieved 2026-08-17, tier: manufacturer)
  • Extractor: ds2sf (Claude). Every pin and dimension is cited to a datasheet page; it refuses to fabricate.
  • CAD: KiCad official libraries (CC-BY-SA 4.0).

Datasheet PDF