UM3488EESA from Union Semiconductor, in a SOP-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	VCC	power_in	Positive supply input. Operating range 3.135V ≤ VCC ≤ 3.465V (nominal +3.3V ±5%). Absolute maximum +7V. Typical quiescent current 180µA.
2	RO	output	Receiver output. RO is high when the receiver differential input A−B ≥ −50mV, and low when A−B ≤ −200mV. CMOS-level output; VOH ≥ VCC−0.4V at IO=−4mA, VOL ≤ 0.4V at IO=4mA.
3	DI	input	Driver input. A logic low on DI forces the non-inverting output (Y) low and the inverting output (Z) high; a logic high on DI drives Y high and Z low. VIH ≥ 2.0V, VIL ≤ 0.8V, ~100mV input hysteresis.
4	GND	power_in	Device ground reference. All voltages are referred to this pin unless otherwise noted.
5	Y	output	Non-inverting differential driver output (RS-422). Driven high or low relative to Z per DI state, always enabled on UM3488 (no DE pin). ±15kV HBM ESD protected; short-circuit current ±250mA.
6	Z	output	Inverting differential driver output (RS-422), complementary to Y. Always enabled on UM3488. ±15kV HBM ESD protected; short-circuit current ±250mA.
7	B	input	Inverting differential receiver input (RS-422). Together with A forms the receiver differential pair; VTH typ −125mV. Fail-safe guarantees RO=high if the bus is open, shorted, or terminated with no active driver. 1/8-unit-load input (RIN ≥ 96kΩ) allowing 256 transceivers on the bus.
8	A	input	Non-inverting differential receiver input (RS-422). Together with B forms the receiver differential pair. Common-mode range −7V to +12V; ±15kV HBM ESD protected; 1/8-unit-load (RIN ≥ 96kΩ).

Key specifications

Parameter	Value
Manufacturer	Union Semiconductor
Package	SOP-8
Category	Comm/UART
Pins	8

Ordering variants

Same part, different packaging or reel option.

UM3488EESA
UM3488EESAEEPA
UM3488EESAEESE
UM3488EESAEEPE

CAD (KiCad official)

Symbol: UM3488EESA
Footprint: Package_SO:SOIC-8_3.9x4.9mm_P1.27mm
3D model: SOP-8 (KiCad packages3D, STEP)

Provenance

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

Datasheet: Union Semiconductor datasheet (17 pp, sha256 64342b95d538e6d2, 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