MAX3221ECUE+T from Maxim Integrated, in a TSSOP-16. Pinout and pin descriptions extracted from the manufacturer datasheet (extract_pins, cross-checked by a second model); symbol, footprint, and 3D from KiCad-official CAD.

Pinout

Pin	Name	Type	Function
1	EN	input	Receiver enable control: drive low for normal operation, drive high to force the receiver outputs (R_OUT) into a high-impedance state.
2	C1+	passive	Positive terminal of the voltage doubler charge-pump capacitor (C1, 0.1µF for 3.3V operation).
3	V+	power_out	+5.5V generated by the charge pump over the +3.0V to +5.5V VCC range.
4	C1-	passive	Negative terminal of the voltage doubler charge-pump capacitor.
5	C2+	passive	Positive terminal of the inverting charge-pump capacitor.
6	C2-	passive	Negative terminal of the inverting charge-pump capacitor.
7	V-	power_out	-5.5V generated by the inverting charge pump over the +3.0V to +5.5V VCC range.
8	R1IN	input	RS-232 receiver input, rated for an input voltage range of ±25V.
9	R1OUT	output	TTL/CMOS inverting three-state receiver output, high-impedance when EN is high.
10	INVALID	output	Output of the valid signal detector: goes high when a valid RS-232 level is present on any receiver input, and is low otherwise.
11	T1IN	input	TTL/CMOS transmitter input; the transmitter inputs do not have pull-up resistors.
12	FORCEON	input	Drive high to override the automatic circuitry and keep transmitters and charge pump on (FORCEOFF must be high).
13	T1OUT	output	RS-232 transmitter output, forced to high impedance when FORCEOFF is driven low or AutoShutdown senses invalid levels on all receiver inputs.
14	GND	power_in	Ground reference.
15	VCC	power_in	+3.0V to +5.5V supply voltage.
16	FORCEOFF	input	Force-off input, active low: drive low to shut down the transmitters, receivers, and on-board charge pump, overriding AutoShutdown and FORCEON.

Key specifications

Parameter	Value
Manufacturer	Maxim Integrated
Package	TSSOP-16
Category	Interface ICs
Pins	16

Electrical characteristics

Limits as printed in the datasheet (page.json metadata.characteristics carries them as data).

Parameter	Symbol	Min	Typ	Max	Unit	Conditions	Page
Input Logic Threshold Low				0.8	V		2
Input Logic Threshold High		2.4			V		2
Output Voltage Low				0.4	V	IOUT = 1.6mA	2
Input Leakage Current		-1	0.01	1	µA	T_IN, EN, FORCEON, FORCEOFF	2
Output Leakage Current (receiver)		-10	0.05	10	µA	R_OUT receivers disabled	2
Supply Current, AutoShutdown Disabled	ICC		0.3	1	mA	FORCEON = FORCEOFF = VCC, no load	2
Supply Current, Shutdown	ICC		1	10	µA	FORCEOFF = GND, all R_IN = GND	2
Supply Current, AutoShutdown	ICC		1	10	µA	FORCEON = GND, FORCEOFF = VCC, all R_IN open	2
INVALID Output Voltage Low				0.4	V	IOUT = 1.6mA	2
Receiver Input Threshold to INVALID Output Low		-0.3		0.3	V		2
Receiver Input Threshold to INVALID Output High		-2.7		2.7	V		2
Output Short-Circuit Current		-60		60	mA		3
Output Leakage Current (transmitter)		-25		25	µA	VOUT = ±12V, VCC = 0 or 3V to 5.5V, transmitters disabled	3
Output Resistance		300			Ω	VCC = V+ = V- = 0, TOUT = ±2V	3
Output Resistance (upper limit)				10	MΩ	VCC = V+ = V- = 0, TOUT = ±2V	3
Output Voltage Swing		-5	5.4		V	All transmitter outputs loaded with 3kΩ to ground	3
Input Threshold Low			0.6	1.2	V	VCC = 3.3V	3
Input Threshold Low			0.8	1.5	V	VCC = 5.0V	3
Input Threshold High			1.5	2.4	V	VCC = 3.3V	3
Input Threshold High			1.8	2.4	V	VCC = 5.0V	3
Input Resistance		3	5	7	kΩ		3
Input Voltage Range		-25		25	V		3
ESD Protection, Human Body Model		-15		15	kV		3
ESD Protection, IEC 1000-4-2 Contact Discharge		-8		8	kV		3
ESD Protection, IEC 1000-4-2 Air-Gap Discharge		-15		15	kV		3
Receiver Positive or Negative Threshold to INVALID High	tINVH			1	µs	VCC = 5V, Figure 5b	3
Receiver Positive or Negative Threshold to INVALID Low	tINVL			30	µs	VCC = 5V, Figure 5b	3
Receiver or Transmitter Edge to Transmitters Enabled	tWU			100	µs	VCC = 5V, Figure 5b	3
Maximum Data Rate		250			kbps		4
Transition-Region Slew Rate		6		30	V/µs	VCC = 3.3V, RL = 3kΩ to 7kΩ, TA = +25°C, one transmitter switching	4
Receiver Skew	/tPHL - tPLH/			50	ns		4
Transmitter Skew	/tPHL - tPLH/			100	ns		4
Receiver Output Enable Time				200	ns	Normal operation	4
Receiver Output Disable Time				200	ns	Normal operation	4
VCC to GND	VCC	-0.3		6	V		2
V+ to GND	V+	-0.3		7	V	Note 1	2
V- to GND	V-	-7		0.3	V	Note 1	2
V+ + /V-/				13	V	Note 1	2
T_IN, EN, FORCEON, FORCEOFF to GND		-0.3		6	V		2
R_IN to GND		-25		25	V		2
T_OUT to GND		-13.2		13.2	V		2
R_OUT, R2OUTB, INVALID to GND		-0.3			V	Upper limit printed as VCC + 0.3V	2
Storage Temperature Range	TSTG	-65		160	°C		2
Lead Temperature (soldering, 10s)				300	°C	10s	2
Soldering Temperature (reflow)				260	°C		2
Operating Temperature Range	TA	0		70	°C	MAX32_ EC _ grade (MAX3221ECUE)	2
Supply Voltage	VCC	3		5.5	V		2
Charge-pump capacitor C1 minimum	C1	0.22			µF	VCC = 3.0V to 5.5V (Table 3)	12
Charge-pump capacitor C2, C3, C4 minimum	C2, C3, C4	1			µF	VCC = 3.0V to 5.5V (Table 3)	12

CAD (KiCad official)

Symbol: MAX3221ECUE+T
Footprint: Package_SO:TSSOP-16_4.4x5mm_P0.65mm
3D model: TSSOP-16 (KiCad packages3D, STEP)
3D model files: max3221ecue-t-etched.step / max3221ecue-t-etched.glb carry the MPN laser-etched on the die in a toggleable Adom.LaserEtch group (Fusion-ready); max3221ecue-t.step / max3221ecue-t.glb are the bare package body.

Provenance

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

Datasheet: Maxim Integrated datasheet (19 pp, sha256 05825bd0ffbc0555, retrieved 2026-10-31, tier: manufacturer)
Extractor: parts-factory 2.0.0 / extract_pins 0.3, primary claude-haiku-5-5 (text), consensus claude-sonnet-5-5 (agreed), guards: pin_guards 0.1: passed. Pins are checked against the footprint pad set and their cited datasheet pages before publish.
CAD: KiCad official libraries (CC-BY-SA 4.0).

Datasheet PDF

MAX3221ECUE+T

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3D Model

Symbol & Footprint

Schematic Symbol

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Datasheet

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