RS2251XTQC16 from Jiangsu RUNIC Tech, in a QFN-16L(3x3). 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	X	passive	Analog Switch 'X' common output/input. Bidirectional analog signal pin connected to one of X0-X7 based on A/B/C address inputs when ENABLE is low. Signal range GND to VCC.
2	X7	passive	Analog switch channel input/output 7. Connected to X when C,B,A = 1,1,1 and ENABLE is low. Bidirectional analog signal, range GND to VCC.
3	X5	passive	Analog switch channel input/output 5. Connected to X when C,B,A = 1,0,1 and ENABLE is low. Bidirectional analog signal, range GND to VCC.
4	ENABLE	input	Active-low digital enable input. When low, one of X0-X7 is connected to X per address inputs; when high, all channels are off. VIH ≥ 1.7V, VIL ≤ 0.5V. Normally connected to GND if permanently enabled.
5	NC	unconnected	No connect. Leave floating or tie as convenient.
6	GND	power_in	Ground. Connect to digital ground / system 0V reference.
7	C	input	Digital Address 'C' input (MSB of channel select). Binary address bit selecting X0-X7. VIH ≥ 1.7V, VIL ≤ 0.5V. Must be held at VCC or GND when unused.
8	B	input	Digital Address 'B' input (middle bit of channel select). Binary address bit selecting X0-X7. VIH ≥ 1.7V, VIL ≤ 0.5V.
9	A	input	Digital Address 'A' input (LSB of channel select). Binary address bit selecting X0-X7. VIH ≥ 1.7V, VIL ≤ 0.5V.
10	X3	passive	Analog switch channel input/output 3. Connected to X when C,B,A = 0,1,1 and ENABLE is low. Bidirectional analog signal, range GND to VCC.
11	X0	passive	Analog switch channel input/output 0. Connected to X when C,B,A = 0,0,0 and ENABLE is low. Bidirectional analog signal, range GND to VCC.
12	X1	passive	Analog switch channel input/output 1. Connected to X when C,B,A = 0,0,1 and ENABLE is low. Bidirectional analog signal, range GND to VCC.
13	X2	passive	Analog switch channel input/output 2. Connected to X when C,B,A = 0,1,0 and ENABLE is low. Bidirectional analog signal, range GND to VCC.
14	VCC	power_in	Positive analog and digital supply voltage input. 2.5V to 5.5V operating range. Decouple locally with a bypass capacitor to GND.
15	X4	passive	Analog switch channel input/output 4. Connected to X when C,B,A = 1,0,0 and ENABLE is low. Bidirectional analog signal, range GND to VCC.
16	X6	passive	Analog switch channel input/output 6. Connected to X when C,B,A = 1,1,0 and ENABLE is low. Bidirectional analog signal, range GND to VCC.
EP	EP	power_in	Exposed thermal pad on package underside. Must be connected to GND.

Key specifications

Parameter	Value
Manufacturer	Jiangsu RUNIC Tech
Package	QFN-16L(3x3)
Category	Comm/UART
Pins	17

Ordering variants

Same part, different packaging or reel option.

RS2251XTQC16
RS2251XTQC16XS16
RS2251XTQC16XSS16
RS2251XTQC16XTSS16

CAD (KiCad official)

Symbol: RS2251XTQC16
Footprint: Package_DFN_QFN:MPS_QFN-16_3x3mm_P0.5mm
3D model: QFN-16L(3x3) (KiCad packages3D, STEP)

Provenance

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

Datasheet: Jiangsu RUNIC Tech datasheet (14 pp, sha256 64ffabd09559d39d, 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