STMicroelectronics ST232ACTR

Overview

ST232ACTR from STMicroelectronics is a dual-transmitter/dual-receiver RS-232 interface IC operating from a single 5 V supply, compliant with EIA/TIA-232 and V.28 standards. It delivers ±9 V transmitter output swing, 400 kbps data rate, 0.1 µs receiver propagation delay, and draws only 1.5 mA typical supply current-enabling low-power portable RS-232 communication in space-constrained designs.

For engineers reviewing the ST232ACTR datasheet, ST232ACTR pinout, ST232ACTR application, or ST232ACTR equivalent, key selection criteria include its TSSOP16 package, ±30 V receiver input tolerance, 12 V/µs slew rate, 3–7 kΩ load compatibility, and requirement for only four 0.1 µF external capacitors.

Technical Context

The ST232ACTR integrates charge-pump voltage doublers and inverters to generate ±9 V RS-232 signal levels from 5 V, eliminating need for ±12 V supplies. Its dual transceivers operate independently with TTL/CMOS-compatible logic interfaces on both sides.

Receiver inputs feature ±30 V common-mode range and 0.5 V hysteresis, ensuring robust noise immunity in electrically noisy environments. Transmitter outputs are short-circuit protected with ±22 mA current limit and 300 Ω output impedance.

Key Specifications

Pinout & Package

TSSOP16 (Thin Shrink Small Outline Package, 5 mm × 4.4 mm, 0.65 mm pitch) with exposed pad for thermal enhancement and mechanical stability in automated assembly.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX3232ESE+ and SP3232EEN-L, the ST232ACTR offers lowest active supply current (1.5 mA), native 5 V-only operation, and TSSOP16 packaging-making it optimal for compact, battery-sensitive RS-232 nodes where ±12 V is unavailable.

Availability

ST232ACTR is available at Aetrix Electronics and suitable for portable medical diagnostics, industrial PLC serial interfaces, and low-power modem design requiring stable component supply across extended production cycles.

Supply support for ST232ACTR 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

STMicroelectronics is a global semiconductor leader headquartered in Geneva, Switzerland, designing and manufacturing analog, microcontroller, power, and sensor solutions for industrial, automotive, and consumer markets.

The ST232 series belongs to ST's legacy RS-232 transceiver product line, engineered specifically for ultra-low-power, single-supply 5 V RS-232 interfacing in portable and space-constrained embedded systems.

FAQ

What external components are required for ST232ACTR operation?

The ST232ACTR requires exactly four 0.1 µF ceramic capacitors (C1–C4) for charge-pump operation-no inductors, transformers, or additional regulators. These connect between pins C1+/C1−, C2+/C2−, V+, and V−. A 10 µF bulk capacitor and 0.1 µF ceramic decoupling capacitor on VCC are also recommended for stable operation.

Does ST232ACTR support automatic power-down or shutdown mode?

No, the ST232ACTR does not include a shutdown pin or automatic power-down feature. It operates continuously when powered. For applications requiring standby current reduction, external power gating using a low-leakage MOSFET on VCC is necessary-typical active current remains fixed at 1.5 mA (typ) under no-load conditions.

Can ST232ACTR interface directly with 3.3 V microcontrollers?

Yes-its TTL/CMOS input thresholds (VIH = 1.4 V min, VIL = 0.8 V max) and output voltage levels (VOH = 3.5 V min, VOL = 0.4 V max at 3.2 mA) are fully compatible with 3.3 V logic. No level-shifting circuitry is needed, though VCC must remain at 5 V to sustain ±9 V RS-232 output swing.

What is the maximum recommended RS-232 cable length for ST232ACTR at 400 kbps?

At 400 kbps, ST232ACTR supports up to 15 m of standard 24 AWG twisted-pair cable with proper termination. This is enabled by its 12 V/µs slew rate and ±9 V output swing, which maintain signal integrity above the RS-232 ±3 V detection threshold even after attenuation and noise coupling over distance.