STMicroelectronics ST3243ECTR-E

Overview

ST3243ECTR-E from STMicroelectronics is a ±15 kV ESD-protected, 3–5.5 V, 400 kbps RS-232 transceiver with auto power-down, featuring 3 drivers, 5 receivers, dual charge-pump circuitry, and R2OUTB always-active wake-up capability. It delivers true RS-232 voltage levels (±5.4 V) from low supply voltages and supports battery-powered portable computing interfaces.

For engineers reviewing the ST3243ECTR-E datasheet, ST3243ECTR-E pinout, ST3243ECTR-E application, or ST3243ECTR-E equivalent, key selection criteria include guaranteed 250 kbps data rate, 1 µA auto power-down current, ±8 kV IEC 1000-4-2 contact ESD protection, TSSOP28 package compatibility, and FORCEON/FORCEOFF control logic for power-state management.

Technical Context

The ST3243E implements a dual charge-pump architecture to generate ±5.5 V rails (V+ and V−) from a single 3.0–5.5 V supply, enabling full RS-232 compliance without external high-voltage sources. Its proprietary low-dropout transmitter output stage ensures ±5 V minimum swing into 3 kΩ loads across temperature and supply variation.

Auto power-down is triggered by absence of valid RS-232 signal at any receiver input, verified via the INVALID output and controlled by FORCEON/FORCEOFF logic states. Receiver R2OUTB remains active during shutdown to detect wake-up events, supporting serial port sleep/wake protocols in portable systems.

Key Specifications

Pinout & Package

TSSOP28 (Thin Shrink Small Outline Package, 28-pin), 9.7 mm × 6.4 mm body, 0.65 mm pitch, ECOPACK® compliant, tape-and-reel packaging (2500 units/reel).

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 ST3243ECTR-E uniquely combines 400 kbps capability, 1 µA auto power-down, dedicated wake-up output (R2OUTB), and dual hardware control (FORCEON/FORCEOFF) in a single TSSOP28 device-enabling lower-system-power, higher-integration serial interfaces.

Availability

ST3243ECTR-E is available at Aetrix Electronics and suitable for notebook computers, battery-powered handheld terminals, industrial printers, and point-of-sale peripheral adapters requiring stable component supply, ESD-hardened RS-232 connectivity, and ultra-low-power serial interface design.

Supply support for ST3243ECTR-E 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, digital, and mixed-signal ICs for automotive, industrial, and consumer markets.

The ST3243E belongs to ST's RS-232 transceiver product line, engineered specifically for low-voltage, low-power, ESD-robust serial communication in portable and space-constrained embedded systems.

FAQ

What is the minimum external capacitor value required for ST3243ECTR-E at 3.3 V supply?

At 3.0–3.6 V supply, ST specifies a minimum 0.1 µF for C1 (V+ pump) and C2–C4 (V− pump and bypass). These values ensure stable charge-pump operation and meet the ±5.4 V output swing guarantee across temperature and load. Using smaller capacitors risks undershoot, reduced drive strength, or failure to enter auto power-down.

How does the INVALID output behave during auto power-down activation?

The INVALID output goes LOW when no RS-232 signal (±2.7 V threshold) is detected on any R1IN–R5IN input for >30 µs. This LOW state, combined with FORCEON = low and FORCEOFF = high, triggers auto power-down. The INVALID signal remains LOW until a valid level reappears, at which point it transitions HIGH within 0.2 µs to initiate wake-up.

Can ST3243ECTR-E drive an RS-232 cable longer than 15 meters?

Yes-when loaded with ≤1000 pF capacitance and terminated with 3 kΩ, ST3243ECTR-E maintains 250 kbps data rate over cables up to 30 m per EIA/TIA-232-F. Its 6 V/µs slew rate and ±5.4 V swing provide sufficient noise margin; however, signal integrity beyond 15 m depends on cable quality, grounding, and ambient noise-not device limitation.

Is R2OUTB truly always active-even during FORCEOFF = low shutdown?

No-R2OUTB is only always active during auto power-down (FORCEOFF = high, FORCEON = low, no valid signal). When FORCEOFF = low, both drivers and receivers (except R2OUTB) are disabled, but R2OUTB is also forced inactive. Only R2IN remains electrically connected to enable wake-up detection upon FORCEOFF release.