SIT3491EESD from SIT, in a SOP-14. 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	NC	unconnected	No internal connection. Leave floating.
2	RO	output	Receiver output. When /RE is low: RO = H if A-B >= -10mV, RO = L if A-B <= -200mV. CMOS logic-level output referenced to VCC/GND.
3	/RE	input	Receiver output enable, active low. /RE = L enables the receiver (RO active); /RE = H puts RO in high-impedance. /RE = H together with DE = L puts the device into low-power shutdown.
4	DE	input	Driver output enable, active high. DE = H enables the driver (Y/Z active); DE = L puts Y/Z in high-impedance. /RE = H together with DE = L puts the device into low-power shutdown.
5	DI	input	Driver input. DI = L drives Y low and Z high; DI = H drives Y high and Z low. CMOS logic input; VIH >= 2.0V, VIL <= 0.8V.
6	GND	power_in	Ground return. Tie to system ground; both GND pins (6 and 7) must be connected.
7	GND	power_in	Ground return. Tie to system ground; both GND pins (6 and 7) must be connected.
8	NC	unconnected	No internal connection. Leave floating.
9	Y	output	Driver non-inverting (in-phase) differential output to the RS-485/RS-422 bus. High-impedance when DE = L. ±15kV HBM ESD protected.
10	Z	output	Driver inverting (anti-phase) differential output to the RS-485/RS-422 bus. High-impedance when DE = L. ±15kV HBM ESD protected.
11	B	input	Receiver inverting differential input from the RS-485/RS-422 bus. Common-mode range -7V to +12V; RIN(min) = 96 kΩ (1/8 unit load). ±15kV HBM ESD protected.
12	A	input	Receiver non-inverting differential input from the RS-485/RS-422 bus. Common-mode range -7V to +12V; RIN(min) = 96 kΩ (1/8 unit load). ±15kV HBM ESD protected.
13	VCC	power_in	Supply voltage pin. May be tied to VCC (3V ≤ VCC ≤ 5.5V) together with pin 14, or left unconnected. Bypass with a 0.1 μF ceramic capacitor to GND when connected.
14	VCC	power_in	Primary supply pin, 3V ≤ VCC ≤ 5.5V. Bypass with a 0.1 μF ceramic capacitor to GND. Absolute max VCC = +7V.

Key specifications

Parameter	Value
Manufacturer	SIT
Package	SOP-14
Category	Interface
Pins	14

Ordering variants

Same part, different packaging or reel option.

SIT3491EESD

CAD (KiCad official)

Symbol: SIT3491EESD
Footprint: Package_SO:SOIC-14_3.9x8.7mm_P1.27mm
3D model: SOP-14 (KiCad packages3D, STEP)

Provenance

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

Datasheet: SIT datasheet (12 pp, sha256 c171fa9cb090a1ee, retrieved 2026-08-17, tier: lcsc)
Datasheet language: Chinese. Pin names, descriptions, and specs on this page were extracted and translated to English by ds2sf; the linked PDF is the manufacturer original.
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