LMC555CMMX from Texas Instruments, in a VSSOP-8-0.65mm. 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 (0 V) for the device. Connect to the negative supply rail.
2	TRIG	input	Trigger input. A negative pulse below 1/3 V+ on this pin sets the internal flip-flop, driving OUT high and starting the timing cycle.
3	OUT	output	Push-pull timer output. Swings between GND and V+ and can source or sink load current (typ. up to ~50 mA at V+ = 15 V).
4	RESET	input	Active-low reset. Pulling below ~0.7 V forces OUT low and discharges the timing capacitor regardless of TRIG. Tie to V+ when unused.
5	CONT	input	Control voltage. Provides access to the internal 2/3 V+ threshold reference; can be driven externally to modulate timing or pulse width. Typically bypassed to GND via a 10 nF capacitor when unused.
6	THRES	input	Threshold input. When the voltage on this pin exceeds 2/3 V+, the internal flip-flop is reset, driving OUT low and turning on the discharge transistor.
7	DISCH	output	Discharge. Open-drain output from an internal N-channel MOSFET; used to discharge the external timing capacitor when OUT is low.
8	V+	power_in	Positive supply voltage, 1.5 V to 15 V. Bypass to GND with a 100 nF ceramic capacitor placed close to the pin.

Key specifications

Parameter	Value
Manufacturer	Texas Instruments
Package	VSSOP-8-0.65mm
Category	RTC
Pins	8

Ordering variants

Same part, different packaging or reel option.

LMC555CMMX
LMC555CMMXCMX
LMC555CMMXCN

CAD (KiCad official)

Symbol: LMC555CMMX
Footprint: Package_SO:VSSOP-8_2.3x2mm_P0.5mm
3D model: VSSOP-8-0.65mm (KiCad packages3D, STEP)

3D model downloads

Two STEP files. Same geometry, different body top:

File	Size	Use it when
`lmc555cmmx.step`	122 KB	You want the bare part, or you mark your own boards.
`lmc555cmmx-etched.step`	1.9 MB	You want the part with `LMC555CMMX` already on it.

The marking in the etched file is real recessed geometry cut into the solid, not a texture or a decal: 479 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 (32 pp, sha256 23c01b550f0a28cb, 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