TRS3221EIPWR from Texas Instruments, in a TSSOP-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	EN	input	Active-low receiver enable. When EN is low, ROUT is active; when EN is high, ROUT is high-impedance. Logic input referenced to VCC.
2	C1+	passive	Positive terminal of the charge-pump flying capacitor C1 (0.1 µF typical; 0.047 µF at VCC = 3.3 V). Used by the internal doubler to generate V+.
3	V+	power_out	Regulated +5.5-V (typ) charge-pump output. Bypass to GND with C3 (0.1 µF typical, 0.33 µF at VCC = 5 V). Absolute max +7 V.
4	C1-	passive	Negative terminal of the charge-pump flying capacitor C1. Paired with C1+ to develop V+.
5	C2+	passive	Positive terminal of the charge-pump flying capacitor C2 (0.1 µF typical, 0.33 µF at VCC = 5 V). Used by the internal inverter to generate V-.
6	C2-	passive	Negative terminal of the charge-pump flying capacitor C2. Paired with C2+ to develop V-.
7	V-	power_out	Regulated -5.4-V (typ) inverted charge-pump output. Bypass to GND with C4 (0.1 µF typical, 0.33 µF at VCC = 5 V). Absolute max -7 V.
8	RIN	input	RS-232 receiver input. Accepts ±25-V RS-232 line levels with 3-kΩ to 7-kΩ input resistance (5 kΩ typ). Provides ±15-kV IEC 61000-4-2 ESD protection.
9	ROUT	output	TTL/CMOS receiver output derived from RIN. High-impedance when EN is high. VOH = VCC - 0.1 V typ, VOL = 0.4 V max.
10	INVALID	output	Active-low RS-232 signal-present status output. Low when RIN sits between -0.3 V and 0.3 V for more than 30 µs (invalid data); high when a valid RS-232 signal is present.
11	DIN	input	TTL/CMOS driver input. Accepts 5-V logic with 3.3-V supply. VIH >= 2 V (VCC=3.3 V) or 2.4 V (VCC=5 V); VIL <= 0.8 V.
12	FORCEON	input	Auto-powerdown override input. When FORCEON is high and FORCEOFF is high, auto-powerdown is disabled and the driver is always on. Used with FORCEOFF to select powerdown modes (see function table).
13	DOUT	output	RS-232 driver output. Swings to ±5.4 V (typ) into a 3-kΩ load; high-impedance when the driver is powered off. ±15-kV IEC ESD protected.
14	GND	power_in	Ground reference for the device. All voltages referenced to this pin.
15	VCC	power_in	Positive supply input, 3 V to 5.5 V. Bypass to GND with a 0.1-µF capacitor (0.047 µF at VCC = 3.3 V). Absolute max 6 V.
16	FORCEOFF	input	Active-low forced-off input. When FORCEOFF is low (and EN is high), both driver and receiver are shut off and supply current drops to about 1 µA. Must be high for normal operation.

Key specifications

Parameter	Value
Manufacturer	Texas Instruments
Package	TSSOP-16
Category	Interface
Pins	16

Ordering variants

Same part, different packaging or reel option.

TRS3221EIPWRECPW
TRS3221EIPWRECPWR
TRS3221EIPWR
TRS3221EIPWRECDB
TRS3221EIPWRECDBR
TRS3221EIPWREIDB
TRS3221EIPWREIDBR

CAD (KiCad official)

Symbol: TRS3221EIPWR
Footprint: Package_SO:TSSOP-16_4.4x5mm_P0.65mm
3D model: TSSOP-16 (KiCad packages3D, STEP)

3D model downloads

Two STEP files. Same geometry, different body top:

File	Size	Use it when
`trs3221eipwr.step`	205 KB	You want the bare part, or you mark your own boards.
`trs3221eipwr-etched.step`	2.8 MB	You want the part with `TRS3221EIPWR` already on it.

The marking in the etched file is real recessed geometry cut into the solid, not a texture or a decal: 696 faces against 255 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: Texas Instruments datasheet (19 pp, sha256 c3f6bd8a698d6c21, retrieved 2026-08-17, tier: manufacturer)
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