Texas Instruments SN75C3221PWR

Overview

SN75C3221PWR from Texas Instruments is a single-channel RS-232 line driver and receiver IC operating from 3-V to 5.5-V supply, supporting up to 1 Mbit/s data rate with ±15-kV HBM ESD protection on bus pins and auto-powerdown enabling <1 μA standby current. It integrates dual charge-pump circuitry to generate ±5.5-V RS-232 levels from a single supply and is used in portable computing interfaces requiring low-power serial communication.

For engineers reviewing the SN75C3221PWR datasheet, SN75C3221PWR pinout, SN75C3221PWR application, or SN75C3221PWR equivalent, key selection considerations include its TSSOP-16 package, 3–5.5-V operation, auto-powerdown activation logic (FORCEON low / FORCEOFF high), INVALID output for RS-232 signal presence detection, and compatibility with 0.1-μF external capacitors.

Technical Context

The SN75C3221PWR implements a dual-stage charge-pump architecture to generate ±5.5-V supplies (V+ and V−) from a single 3–5.5-V VCC input, enabling full RS-232 voltage compliance without dual supplies. Its driver delivers slew rates from 18 V/μs to 150 V/μs and supports 1-Mbit/s signaling under 250-pF load conditions.

Receiver thresholds are asymmetric: VIT+ = 1.6–2.4 V and VIT− = 0.6–1.4 V (depending on VCC), with 0.5-V hysteresis; the INVALID output asserts low when RIN remains within −0.3 V to +0.3 V for >30 μs, indicating invalid RS-232 signal presence. Power management is controlled via FORCEON/FORCEOFF pins and enabled EN pin.

Key Specifications

Pinout & Package

TSSOP-16 package (PW), 10.3 mm × 7.50 mm body size, 1.2-mm max height, RoHS-compliant NIPDAU lead finish, MSL Level-1.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar RS-232 transceiver applications.

Compared with SN65C3221PWR, SN75C3221PWR trades extended temperature range for lower cost and optimized commercial availability; versus MAX3221EUP+, it provides hardware INVALID signaling and tighter thermal resistance (108.0°C/W vs. ~120°C/W), improving reliability in thermally constrained handheld designs.

Availability

SN75C3221PWR is available at Aetrix Electronics and suitable for industrial PCs, wired networking infrastructure, and battery-powered systems requiring stable component supply, long-term lifecycle support, and RoHS-compliant TSSOP packaging.

Supply support for SN75C3221PWR includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Texas Instruments is a global semiconductor leader delivering analog, embedded processing, and connectivity solutions for industrial, automotive, and communications markets.

The SN75C3221PWR belongs to TI's RS-232 transceiver product line, designed specifically for low-power, single-supply serial interface applications in portable and commercial computing equipment.

FAQ

What is the operating temperature range for the SN75C3221PWR?

The SN75C3221PWR is specified for operation from 0 °C to 70 °C, making it suitable for commercial-grade computing and networking equipment. This differs from the SN65C3221PWR, which supports −40 °C to 85 °C for industrial environments. The SN75C3221PWR's thermal resistance is 108.0°C/W (Junction-to-Ambient), confirming its suitability for moderate-power-density PCB layouts without forced air cooling.

How does the auto-powerdown feature work on the SN75C3221PWR?

The SN75C3221PWR enters auto-powerdown when FORCEON is low and FORCEOFF is high; it then monitors RIN and disables DOUT if no valid RS-232 signal (|RIN| < 2.7 V for >30 μs) is detected. This reduces supply current to 1 μA typical. Activation is automatic - applying a valid signal to RIN wakes the driver within 100 μs (ten). The INVALID pin reflects this state, going low during invalid-signal conditions.

Can the SN75C3221PWR operate with a 3.3-V supply while interfacing with 5-V logic inputs?

Yes, the SN75C3221PWR accepts 5-V logic levels on DIN, FORCEON, FORCEOFF, and EN pins even when VCC = 3.3 V. This 5-V tolerant input capability eliminates external level shifters in mixed-voltage systems. Input leakage current remains ±1 μA maximum across the full operating range, ensuring minimal loading on upstream drivers.

What external components are required for SN75C3221PWR operation?

The SN75C3221PWR requires four 0.1-μF ceramic capacitors (C1+, C1−, C2+, C2−) for its dual charge-pump circuit - no electrolytic or tantalum capacitors needed. With VCC = 3.3 V ± 0.3 V, all four caps are 0.1 μF; at 5 V ± 0.5 V, C1 is 0.047 μF and C2–C4 are 0.33 μF. Layout guidelines specify 14-mil trace widths and tight capacitor placement near pins 2, 4, 5, and 6 to minimize EMI.

Is the SN75C3221PWR pin-compatible with other members of the C3221 family?

Yes, the SN75C3221PWR shares identical pinout and function mapping with SN65C3221PWR and SN75C3221DBR (SSOP-16). All variants use the same logic diagram, registerless control scheme, and timing behavior. Differences are limited to temperature grade (0–70°C vs. −40–85°C) and package (TSSOP vs. SSOP), allowing direct substitution where thermal and mechanical constraints permit.