STMicroelectronics ST232ACD

Overview

ST232ACD 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 supply current at no load-ideal for portable computers and battery-powered RS-232 networks.

For engineers reviewing the ST232ACD datasheet, ST232ACD pinout, ST232ACD application, or ST232ACD equivalent, key selection criteria include its ultra-low power consumption, integrated charge-pump voltage generation requiring only four 0.1 µF capacitors, wide ±30 V receiver input range, and operation across 0 to 70 °C ambient temperature.

Technical Context

The ST232ACD integrates two independent RS-232 transmitters and receivers in one SO-16 package, using on-chip charge-pump circuitry to generate ±V_CC-derived voltages (V+ and V−) from a single 5 V rail. Its logic-side I/O is TTL/CMOS-compatible, while the RS-232 side supports full ±30 V input tolerance and ±9 V output swing under 3 kΩ load.

It features fast signal timing: 12 V/µs typical slew rate on transmitter outputs and sub-microsecond propagation delays (0.1 µs receiver, 1.3 µs transmitter), enabling reliable high-speed serial communication without external level-shifting components or ±12 V supplies.

Key Specifications

Pinout & Package

ST232ACD is housed in a 16-pin SOIC (SO-16) package with 1.27 mm pitch, RoHS-compliant and ECOPACK® certified. Pin numbering follows standard top-view orientation with pin 1 marked by a notch or dot.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX232ACPE+ and SP3232ECA-L, the ST232ACD offers optimal balance of low power (1.5 mA), proven 5 V-only compatibility, and SO-16 drop-in replacement capability-making it ideal for cost-sensitive, volume-manufactured commercial equipment where legacy footprint retention matters.

Availability

ST232ACD is available at Aetrix Electronics and suitable for portable computers, low-power modems, and interface translation applications requiring stable component supply and long-term sourcing continuity.

Supply support for ST232ACD 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 microcontrollers, analog ICs, power management, and interface solutions for automotive, industrial, and consumer markets.

The ST232 series belongs to ST's legacy RS-232 transceiver product line, engineered specifically for single-supply, low-power serial communication in commercial-grade embedded systems and peripheral interfaces.

FAQ

What external components are required for ST232ACD operation?

The ST232ACD requires exactly four 0.1 µF ceramic capacitors (C1–C4) for internal charge-pump voltage generation-no inductors, transformers, or additional regulators are needed. These capacitors connect between pins C1+/C1−, C2+/C2−, V+, and V− as specified in the application circuit. All capacitors must be rated for ≥10 V and placed close to the IC for stable operation.

Does ST232ACD support true RS-232 voltage levels with a 5 V supply?

Yes. Using its internal charge-pump architecture, the ST232ACD generates V+ (~10 V) and V− (~−5 V) from a single 5 V supply, delivering ±9 V differential output swing into a 3 kΩ load-fully compliant with EIA/TIA-232-F electrical specifications for driver output voltage magnitude and symmetry.

Can ST232ACD operate with 3.3 V logic inputs?

No. The ST232ACD's transmitter inputs (T1IN/T2IN) and receiver outputs (R1OUT/R2OUT) are TTL/CMOS-compatible with V_CC = 5 V, meaning logic-high threshold is 1.4–2.0 V and logic-low is 0.8–1.4 V. While 3.3 V logic may function marginally, ST specifies operation only with 5 V logic levels; for 3.3 V systems, use the SP3232ECA-L or similar 3.3 V–5.5 V compatible transceivers.

Is ST232ACD pin-compatible with older ST232 variants like ST232CD?

Yes. The ST232ACD is a direct replacement for the ST232CD in SO-16 packaging, sharing identical pinout, electrical characteristics, and functional behavior. Both operate from 4.5–5.5 V, require four 0.1 µF capacitors, and deliver ±9 V output swing. No PCB redesign or firmware changes are needed when upgrading from ST232CD to ST232ACD.