LMC555CMX from Texas Instruments, in a SOIC-8. Pinout and pin descriptions extracted from the manufacturer datasheet by ds2sf; symbol, footprint, and 3D from KiCad-official CAD.

Pinout

Pin	Name	Type	Function
1	GND	power_in	Ground reference voltage. All voltages in the datasheet are measured with respect to this pin.
2	TRIG	input	Trigger input (active low). Responsible for transition of the flip-flop from set to reset. A negative-going pulse below 1/3 Vcc sets the output high. Typical trigger voltage ~1.67 V at Vs = 5 V; trigger current ~10 pA.
3	OUT	output	Output driven waveform. CMOS/TTL-compatible push-pull output rated to source/sink up to ~50 mA at 5 V supply (tested at -10 mA / 50 mA output current levels).
4	RESET	input	Active-low reset input. Negative pulse applied to this pin disables or resets the timer. When not used for reset purposes it should be tied to V+ to avoid false triggering. VRES typ 0.7 V at Vs = 1.5 V (Vs must be >= 2.0 V if RESET is used at -20 degC or below).
5	CTRL	input	Control voltage input. Sets the threshold and trigger comparator levels (nominally 2/3 Vcc). Typically bypassed to GND with a 0.01 uF capacitor; can be driven externally to modulate the output waveform.
6	THRES	input	Threshold input. Compares the applied voltage against the internal 2/3 Vcc reference; when exceeded, the flip-flop is reset and the output goes low. Threshold input current ~10 pA at Vs = 5 V.
7	DISCH	output	Open-drain discharge output. Discharges the external timing capacitor between intervals (in phase with OUT). Toggles from high-impedance to low when the timing capacitor voltage reaches 2/3 Vcc. Discharge saturation voltage typ 150 mV at IDIS = 10 mA (Vs = 5 V).
8	V+	power_in	Positive supply voltage with respect to GND. Recommended operating range 1.5 V to 15 V (absolute max 15 V). Typical supply current 100 uA at Vs = 5 V.

Key specifications

Parameter	Value
Manufacturer	Texas Instruments
Package	SOIC-8
Category	RTC
Pins	8

Ordering variants

Same part, different packaging or reel option.

LMC555CMX
LMC555CMXIM
LMC555CMXIMX
LMC555CMXCMM
LMC555CMXCMMX
LMC555CMXIMM
LMC555CMXIMMX
LMC555CMXCN
LMC555CMXN
LMC555CMXTP
LMC555CMXTPX

CAD (KiCad official)

Symbol: LMC555CMX
Footprint: Package_SO:SOIC-8_3.9x4.9mm_P1.27mm
3D model: SOIC-8 (KiCad packages3D, STEP)

3D model downloads

Two STEP files. Same geometry, different body top:

File	Size	Use it when
`lmc555cmx.step`	122 KB	You want the bare part, or you mark your own boards.
`lmc555cmx-etched.step`	1.8 MB	You want the part with `LMC555CMX` already on it.

The marking in the etched file is real recessed geometry cut into the solid, not a texture or a decal: 450 faces against 147 in the bare model. It survives export, section views, and rendering in any CAD tool, and it drops straight into KiCad or Fusion with no extra setup.

Provenance

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

Datasheet: Texas Instruments datasheet (30 pp, sha256 3ac8d41ac202b0b0, 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