MD8312 from Shanghai Mingda Microelectronics, in a SOT-89-3. 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	VOUT	power_out	Regulated 12V output. Drive with a >=1.0uF low-ESR ceramic capacitor to GND placed close to the pin. Maximum output current 300mA (typ), current-limited around 550mA with foldback. Must not exceed VIN+0.3V or the internal parasitic diode will conduct.
2	GND	power_in	Device ground / return. Quiescent GND current is ~1.5uA (no load) and rises with IOUT (typ 460uA at IOUT=100mA). SOT89 heat-slug tab; connect to the ground plane for thermal dissipation (PD=1000mW, RθJB=100 °C/W).
3	VIN	power_in	Unregulated input supply, 2.2V to 40V (absolute max 45V). Bypass with a >=1.0uF ceramic capacitor to GND close to the pin to avoid oscillation. For the 12V output variant VIN must be at least VOUT + dropout (~1.3V typ at 300mA).

Key specifications

Parameter	Value
Manufacturer	Shanghai Mingda Microelectronics
Package	SOT-89-3
Category	PMIC
Pins	3

Ordering variants

Same part, different packaging or reel option.

MD8312
MD8312A

CAD (KiCad official)

Symbol: MD8312
Footprint: Package_TO_SOT_SMD:SOT-89-3
3D model: SOT-89-3 (KiCad packages3D, STEP)

Provenance

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

Datasheet: Shanghai Mingda Microelectronics datasheet (10 pp, sha256 b90bf74c0495d786, retrieved 2026-08-17, tier: lcsc)
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