UM3232EESE from Union Semiconductor, in a SOP-16. 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	C1+	passive	Positive terminal of the voltage-doubler charge-pump capacitor C1 (0.1µF typical).
2	V+	power_out	Positive voltage generated by the internal charge pump (approximately +2×VCC). Bypass to GND with a 0.1µF capacitor.
3	C1-	passive	Negative terminal of the voltage-doubler charge-pump capacitor C1 (0.1µF typical).
4	C2+	passive	Positive terminal of the inverting charge-pump capacitor C2 (0.1µF typical).
5	C2-	passive	Negative terminal of the inverting charge-pump capacitor C2 (0.1µF typical).
6	V-	power_out	Negative voltage generated by the internal charge pump (approximately -2×VCC). Bypass to GND with a 0.1µF capacitor.
7	T2OUT	output	RS-232 driver 2 output. Swings between V+ and V- levels, typically ±5V minimum into a 3kΩ load.
8	R2IN	input	RS-232 receiver 2 input. Accepts ±30V, input resistance 3-7kΩ, thresholds ~0.8V/1.35V (VCC=3.3V).
9	R2OUT	output	RS-232 receiver 2 CMOS/TTL logic output. Drives VCC/GND levels, IOUT up to ±10mA.
10	T2IN	input	RS-232 driver 2 logic input. CMOS/TTL levels referenced to VCC; VIL ≤ 0.8V, VIH ≥ 1.6V (VCC=3.3V).
11	T1IN	input	RS-232 driver 1 logic input. CMOS/TTL levels referenced to VCC; VIL ≤ 0.8V, VIH ≥ 1.6V (VCC=3.3V).
12	R1OUT	output	RS-232 receiver 1 CMOS/TTL logic output. Drives VCC/GND levels, IOUT up to ±10mA.
13	R1IN	input	RS-232 receiver 1 input. Accepts ±30V, input resistance 3-7kΩ, thresholds ~0.8V/1.35V (VCC=3.3V).
14	T1OUT	output	RS-232 driver 1 output. Swings between V+ and V- levels, typically ±5V minimum into a 3kΩ load.
15	GND	power_in	Device ground reference.
16	VCC	power_in	Supply voltage input, +3.0V to +5.5V. Bypass to GND with a 0.1µF capacitor.

Key specifications

Parameter	Value
Manufacturer	Union Semiconductor
Package	SOP-16
Category	Interface
Pins	16

Ordering variants

Same part, different packaging or reel option.

UM3232EESE
UM3232EEPE
UM3232EEUE
UM3232EEAE
UM3221EEAE
UM3221EEUE
UM3222EEUE

CAD (KiCad official)

Symbol: UM3232EESE
Footprint: Package_SO:SOIC-16_3.9x9.9mm_P1.27mm
3D model: SOP-16 (KiCad packages3D, STEP)

3D model downloads

Two STEP files. Same geometry, different body top:

File	Size	Use it when
`um3232eese.step`	217 KB	You want the bare part, or you mark your own boards.
`um3232eese-etched.step`	2.7 MB	You want the part with `UM3232EESE` already on it.

The marking in the etched file is real recessed geometry cut into the solid, not a texture or a decal: 663 faces against 267 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: Union Semiconductor datasheet (20 pp, sha256 77562ced1a0ec900, 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