Texas Instruments MAX3221CPWR

Overview

MAX3221CPWR from Texas Instruments is a 3-V to 5.5-V single-driver, single-receiver RS-232 transceiver with ±15-kV HBM ESD protection on bus pins, 250-kbps data rate capability, automatic power-down (1 µA standby current), and integrated dual charge-pump circuit requiring only four 0.1-µF capacitors. It interfaces UART logic to legacy RS-232 ports in space-constrained portable systems.

For engineers reviewing the MAX3221CPWR datasheet, MAX3221CPWR pinout, MAX3221CPWR application, or MAX3221CPWR equivalent, key selection criteria include its TSSOP-16 package footprint, 3.3-V/5-V supply compatibility, INVALID status output for receiver signal validation, and automatic driver disable during RS-232 inactivity - critical for battery-powered industrial and mobile designs.

Technical Context

The MAX3221CPWR implements a dual-stage charge-pump architecture generating ±5.5-V rails from a single 3.3-V or 5-V supply, enabling full RS-232 voltage compliance without external high-voltage sources. Its receiver features hysteresis (0.5 V) and input thresholds of ±2.7 V (valid) and ±0.3 V (invalid), with INVALID output asserting low after >30 µs of indeterminate RIN voltage.

Driver operation supports 30-V/µs slew rate control and 150–250 kbps signaling; receiver propagation delay is 150 ns (typical) with 50-ns pulse skew. Power management is governed by FORCEON/FORCEOFF logic inputs, enabling automatic driver disable when no valid RS-232 signal is detected at RIN.

Key Specifications

Pinout & Package

TSSOP-16 (PW) package, 5.00 mm × 4.40 mm body size, 0.65-mm lead pitch, RoHS-compliant NIPDAU 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 SN65C3221IPWR and MAX3232CPWR, the MAX3221CPWR delivers optimal cost and footprint efficiency for single-channel, moderate-speed RS-232 links where automatic power-down and INVALID status are prioritized over raw speed or channel count.

Availability

MAX3221CPWR is available at Aetrix Electronics and suitable for industrial handheld terminals, medical point-of-care devices, and PLC HMI panels requiring stable component supply across multi-year production cycles.

Supply support for MAX3221CPWR 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 company specializing in analog and embedded processing technologies, with leadership in interface, power management, and signal chain solutions.

The MAX3221 product line delivers robust, low-power RS-232 transceivers optimized for battery-operated and space-constrained industrial, medical, and test equipment applications.

FAQ

What is the maximum data rate supported by the MAX3221CPWR?

The MAX3221CPWR supports a maximum data signaling rate of 250 kbps under recommended operating conditions with 1000-pF load capacitance and 3-kΩ termination. This rate is validated per TIA/EIA-232-F and maintains full RS-232 voltage compliance (±5.4 V). The MAX3221CPWR achieves this while delivering 30-V/µs driver slew rate control to reduce EMI - making it suitable for reliable communication in electrically noisy industrial environments.

Does the MAX3221CPWR require external high-voltage supplies?

No, the MAX3221CPWR does not require external high-voltage supplies. It integrates a dual charge-pump circuit that generates ±5.5-V internal rails from a single 3.0-V to 5.5-V VCC supply. Only four 0.1-µF external ceramic capacitors are needed - eliminating the need for discrete DC-DC converters or transformer-based isolation in most RS-232 implementations. This capability is fully implemented in the MAX3221CPWR's TSSOP-16 package.

How does the automatic power-down feature function in the MAX3221CPWR?

The MAX3221CPWR automatically disables its driver and reduces supply current to 1 µA when FORCEON is low and FORCEOFF is high, and no valid RS-232 signal (|RIN| > 2.7 V or < –2.7 V) is detected for >30 µs. The INVALID output goes low to indicate this condition. This behavior is intrinsic to the MAX3221CPWR's internal state machine and requires no firmware polling - enabling true hands-off power savings in portable and always-on embedded systems.

Can the MAX3221CPWR interface directly with 3.3-V logic while operating from a 5-V supply?

Yes, the MAX3221CPWR accepts 5-V-tolerant logic inputs (DIN, FORCEON, FORCEOFF, EN) even when powered from a 3.3-V supply - a key design feature confirmed in its datasheet's Recommended Operating Conditions table. This allows seamless integration into mixed-voltage systems where host controllers operate at 3.3 V but retain 5-V-compatible GPIOs. The MAX3221CPWR's input leakage remains ±1 µA across both supply configurations.

What is the purpose of the INVALID output pin on the MAX3221CPWR?

The INVALID output on the MAX3221CPWR is an active-high status indicator that asserts high when a valid RS-232 signal (|RIN| > 2.7 V or < –2.7 V) is present, and goes low when RIN remains within ±0.3 V for more than 30 µs - signaling loss of valid line activity. This pin enables hardware-driven wake-up interrupts or link-status monitoring without CPU polling, and is functional independently of FORCEON/FORCEOFF states. Its behavior is guaranteed across the full 0°C to 70°C temperature range of the MAX3221CPWR.