ST3243ECTR-E - 3V-5.5V RS-232 Transceiver | STMicroelectronics
MPN: ST3243ECTR-E ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $2.45 | $2.45 |
| 10 | $2.21 | $22.10 |
| 100 | $1.95 | $195.00 |
| 500 | $1.74 | $870.00 |
| 1,000 | $1.55 | $1,550.00 |
ST3243ECTR-E Overview
An RS-232 transceiver is a line driver/receiver IC that translates logic-level (typically 0 V / 3.3 V or 5 V) UART signals between a microcontroller or ASIC and the bipolar ±5 V to ±15 V voltage swings required by the legacy EIA/TIA-232 (V.28) serial communication standard. RS-232 transceivers form a key sub-category of interface ICs in the broader power management and signal conditioning hierarchy (line driver/receiver → transceiver → interface IC → signal chain semiconductor). They remain ubiquitous in industrial control, point-of-sale, instrumentation, and embedded console ports where asymmetric voltage levels and proven noise rejection are required over short cable runs.
The ST3243ECTR-E integrates three RS-232 drivers and five RS-232 receivers - an asymmetric 3/5 channel count that fits UART-to-LTE flows, debug consoles, and legacy serial equipment ports. ESD protection reaches ±15kV on the human-body model and ±8kV on IEC 1000-4-2 contact discharge, exceeding the typical ±2kV HBM level on standard UART transceivers. The device also includes a guaranteed 6 V/µs slew rate, auto power-down circuitry that drops quiescent current to microampere levels when no valid RS-232 activity is detected, and 3-state receiver outputs for bus sharing.
Architecturally, the part uses an on-chip dual charge-pump with four small external capacitors (typically 100 nF) to generate the positive and negative RS-232 supplies from a single 3 V to 5.5 V rail. The CMOS-level TTL/CMOS-compatible inputs interface directly with modern microcontrollers running from 3.3 V or 5 V without level shifters. The auto power-down mode reduces supply variation while idle, extending battery life in portable applications.
Typical applications include service and console ports on embedded systems, point-of-sale (POS) terminals, industrial programmable-logic-controller (PLC) serial links, networking equipment console management ports, and battery-powered handheld test instruments. The wide 3 V to 5.5 V supply range and rugged ±15kV ESD make it well suited to factory-floor environments.
When designing with this device, place the four charge-pump capacitors (V+ to GND, V- to GND, C1+/C1-, C2+/C2-) as close to the IC pins as possible with minimal trace inductance. Decouple VCC with a 0.1 µF ceramic capacitor. Note that the ST3243ECTR-E industrial grade operates from 0 °C to +70 °C; for -40 °C to +85 °C operation, choose the ST3243EBTR-E extended-grade variant.
This page synthesizes distributor pricing, drop-in alternatives, and practical design notes not found in the manufacturer datasheet.
Drop-in alternatives for ST3243ECTR-E — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
ST3243EBTR-E
✅ Drop-In📋 Reference alternative (not in catalog)
ST3243ECTR
✅ Drop-In📋 Reference alternative (not in catalog)
TRS3243ECPWR
✅ Drop-In📋 Reference alternative (not in catalog)
MAX3243EIPW
✅ Drop-In📋 Reference alternative (not in catalog)
MAX3243ECPW
✅ Drop-In📋 Reference alternative (not in catalog)
ST3243ECTR-E Specifications
| Number of Drivers | 3 |
| Number of Receivers | 5 |
| Protocol | RS-232 (EIA/TIA-232, V.28/V.24) |
| Supply Voltage | 3 V to 5.5 V |
| Maximum Data Rate | 400 kbps |
| ESD Protection (HBM) | ±15 kV |
| ESD Protection (IEC 1000-4-2 Contact) | ±8 kV |
| Slew Rate | 6 V/µs |
| Charge-pump Capacitors Required | 4 external (typical 100 nF) |
| Auto Power-Down | Yes |
| Receiver Output Type | 3-state (tri-state) |
| Operating Temperature | 0 °C to +70 °C |
| Package | 28-TSSOP (0.173, 4.40 mm Width) |
| Mounting Type | Surface Mount |
| Packaging | Tape & Reel (TR) |
| RoHS Status | Compliant |
ST3243ECTR-E Pin Configuration
| Pin 1 | C2+ — Charge-pump capacitor 2 positive terminal |
| Pin 2 | C2- — Charge-pump capacitor 2 negative terminal |
| Pin 3 | V- — Negative charge-pump output (reservoir cap to GND) |
| Pin 4 | DIN1 — Driver 1 TTL/CMOS input |
| Pin 5 | DOUT1 — Driver 1 RS-232 output |
| Pin 6 | DIN2 — Driver 2 TTL/CMOS input |
| Pin 7 | DOUT2 — Driver 2 RS-232 output |
| Pin 8 | DIN3 — Driver 3 TTL/CMOS input |
| Pin 9 | DOUT3 — Driver 3 RS-232 output |
| Pin 10 | V+ — Positive charge-pump output (reservoir cap to GND) |
| Pin 11 | C1+ — Charge-pump capacitor 1 positive terminal |
| Pin 12 | C1- — Charge-pump capacitor 1 negative terminal |
| Pin 13 | VCC — Positive supply (3 V to 5.5 V) |
| Pin 14 | GND — Ground |
| Pin 15 | ROUT1 — Receiver 1 TTL/CMOS output (3-state) |
| Pin 16 | RIN1 — Receiver 1 RS-232 input |
| Pin 17 | ROUT2 — Receiver 2 TTL/CMOS output (3-state) |
| Pin 18 | RIN2 — Receiver 2 RS-232 input |
| Pin 19 | ROUT3 — Receiver 3 TTL/CMOS output (3-state) |
| Pin 20 | RIN3 — Receiver 3 RS-232 input |
| Pin 21 | ROUT4 — Receiver 4 TTL/CMOS output (3-state) |
| Pin 22 | RIN4 — Receiver 4 RS-232 input |
| Pin 23 | ROUT5 — Receiver 5 TTL/CMOS output (3-state) |
| Pin 24 | RIN5 — Receiver 5 RS-232 input |
| Pin 25 | EN — Receiver enable (active low, with auto power-down) |
| Pin 26 | READY — Auto power-down ready output |
| Pin 27 | STATUS — Auto power-down status flag |
| Pin 28 | FORCEON — Force auto power-down off (active high) |
Typical Applications
ST3243ECTR-E is suitable for 6 applications: Embedded UART Debug Console Port, Point-of-Sale (POS) Terminal Serial Link, Industrial PLC and Factory Automation Serial Port, Networking Equipment Console Port, Battery-Powered Handheld Test Instrument, Medical Diagnostic Equipment Serial Interface.
Embedded UART Debug Console Port
The ST3243ECTR-E's 3-driver/5-receiver channel count and 400 kbps data rate make it ideal for embedded UART debug ports on evaluation boards, single-board computers, and industrial controllers. The ±15 kV ESD protection tolerates repeated cable insertion by field engineers, while the 3 V to 5.5 V supply matches modern 3.3 V MCUs without level shifters. The auto power-down mode drops quiescent current when no host terminal is connected, extending battery life in portable debug equipment. Typical pairing is with an STM32F4 host UART, four 100 nF charge-pump caps, and a DB9 connector carrying TD, RD, RTS, CTS, plus DTR/DSR/DCD/RI handshake lines.
Recommended
Point-of-Sale (POS) Terminal Serial Link
The ST3243ECTR-E is widely deployed in POS terminals connecting receipt printers, barcode scanners, cash drawers, and customer displays over EIA/TIA-232. Its ±15 kV ESD withstand protects against ESD discharge from cable handling and static-prone retail environments, while the 400 kbps data rate supports older serial peripherals without bottleneck. The wide 3 V to 5.5 V input range enables direct connection to either legacy 5 V logic or modern 3.3 V POS controller ASICs. Auto power-down extends battery life in mobile POS units during idle periods. The 28-TSSOP footprint fits in the compact mainboards typical of retail terminals.
Recommended
Industrial PLC and Factory Automation Serial Port
In factory automation, the ST3243ECTR-E bridges PLCs, motor drives, and operator panels over EIA/TIA-232 multidrop links. Its ±8 kV IEC 1000-4-2 contact ESD rating meets the surge and electrostatic discharge requirements typical of plant-floor installations, and the -40 °C to +85 °C industrial temperature grade (BTR variant) handles uncontrolled-temperature cabinets. The 400 kbps rate covers all standard PLC communication speeds up to 115.2 kbps with substantial overhead, while the 28-TSSOP footprint enables dense multi-port serial modules.
Recommended
Networking Equipment Console Port
Routers, switches, and base stations commonly include an RS-232 console port for out-of-band management access. The ST3243ECTR-E's 3 V to 5.5 V supply simplifies power-tree design across both 3.3 V and 5 V platforms, and its 3-driver/5-receiver channel count fully supports the full modem channel plus RI/DSR/DCD handshake lines required by management software. The ±15 kV ESD protects the technician-accessible RJ45-to-DB9 console cable insertion of a service, and the 400 kbps rate enables high-speed firmware recovery and diagnostic transfers during field service.
Recommended
Battery-Powered Handheld Test Instrument
The ST3243ECTR-E's auto power-down mode drops quiescent current to microampere levels when no valid RS-232 activity is detected, which is critical for battery-powered multimeters, oscilloscopes, and field service tools that spend most of their time idle. The single 3 V to 5.5 V supply runs directly from a Li-ion cell without boost converters. The 400 kbps data rate supports firmware updates and measurement log uploads via USB-to-RS-232 dongles, and the small 28-TSSOP footprint fits inside compact handheld enclosures.
Recommended
Medical Diagnostic Equipment Serial Interface
The ST3243ECTR-E interfaces legacy medical instruments - patient monitors, blood analyzers, and imaging systems - that still expose EIA/TIA-232 ports for data export and service diagnostics. Its ±15 kV ESD withstand protects against the static discharge that accumulates on equipment moved between clinical rooms. The 400 kbps rate supports export of patient records and waveform data to external systems. The single 3 V to 5.5 V supply enables integration into 3.3 V system-on-chip designs without external level translation.
Recommended
Recommended Products Summary
Engineering reference data for ST3243ECTR-E — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | ST3243EBTR-E | ST3243ECTR | TRS3243ECPWR | MAX3243EIPW | MAX3243ECPW |
|---|---|---|---|---|---|---|
| Package | 28-TSSOP (0.173, 4.40 mm Width) | 28-TSSOP (0.173, 4.40 mm Width) - same | 28-TSSOP (0.173, 4.40 mm Width) - same | 28-TSSOP - same | 28-TSSOP - same | 28-TSSOP - same |
| Brand | STMicroelectronics | STMicroelectronics | STMicroelectronics | Texas Instruments | Analog Devices | Analog Devices |
| Number of Drivers / Receivers | 3 / 5 | 3 / 5 | 3 / 5 | 3 / 5 | 3 / 5 | 3 / 5 |
| Supply Voltage | 3 V to 5.5 V | 3 V to 5.5 V | 3 V to 5.5 V | 3 V to 5.5 V | 3 V to 5.5 V | 3 V to 5.5 V |
| Maximum Data Rate | 400 kbps | 400 kbps | 400 kbps | 250 kbps | 120 kbps (EIPW) / 1 Mbps (EUI) | 120 kbps |
| ESD Protection (HBM) | ±15 kV | ±15 kV | ±15 kV | ±15 kV | ±15 kV | ±15 kV |
| Auto Power-Down | Yes | Yes | Yes | Yes | Yes (AutoShutdown Plus) | No |
| Operating Temperature | 0 °C to +70 °C | -40 °C to +85 °C | 0 °C to +70 °C | 0 °C to +70 °C | -40 °C to +85 °C | 0 °C to +70 °C |
| Charge-Pump Capacitors Required | 4 external (typical 100 nF) | 4 external (typical 100 nF) | 4 external (typical 100 nF) | 4 external (typical 100 nF) | 4 external (typical 100 nF) | 4 external (typical 100 nF) |
Key Differentiators
- Highest data rate among cross-brand equivalents (vs TRS3243ECPWR)
- Auto power-down for battery-powered designs (vs MAX3243ECPW)
- Industry-standard 28-TSSOP pinout with second sources from TI and Maxim (vs MAX3243EIPW)
Design Notes
Always place the four charge-pump capacitors (C1+, C1-, C2+, C2-, V+, V-) as close to the IC pins as possible. Traces longer than 5 mm introduce inductance that can destabilize the charge-pump oscillator and cause RS-232 output voltage droop at high data rates. Use 100 nF ceramic X7R/X5R capacitors rated for at least 16 V to handle the generated ±5.5 V rails with adequate margin.
Decouple VCC (pin 13) with a 0.1 µF ceramic capacitor as close as possible to the pin. According to the STMicroelectronics datasheet, the device draws charge-pump switching transients that couple back into VCC - bulk decoupling on the board supply rail is also recommended. Place a small ferrite bead in series with VCC if the device shares a rail with sensitive analog circuits to attenuate charge-pump noise ripple.
Route the RS-232 driver outputs (DOUT1-3) and receiver inputs (RIN1-5) as differential pairs with matching trace lengths to minimize skew. Keep TTL/CMOS logic-side traces (DIN1-3, ROUT1-5, EN, FORCEON, READY, STATUS) short and isolated from the RS-232 high-voltage traces to avoid crosstalk. Place the DB9 connector and ESD protection TVS array near the board edge with chassis ground reference.
Do not exceed the maximum capacitive load on RS-232 driver outputs. The EIA/TIA-232 standard specifies a maximum 2500 pF load; cables and connectors plus parasitic board capacitance must remain below this limit. Cables longer than 30 m may require a lower-capacitance grade cable or buffering to maintain the 6 V/µs slew rate. Confirm that downstream receivers are EIA/TIA-232 compliant if you must exceed standard limits.
For the auto power-down feature, the FORCEON pin should be tied high through a pull-up resistor to keep the device active; tie it LOW to allow auto power-down based on the READY output. Receiver outputs are 3-state - ensure bus-sharing logic (EN pin) does not float. Unused receiver inputs should be tied to GND to prevent oscillation; unused driver inputs should be tied to VCC to force output low.
Compliance Information
RoHS compliant per STMicroelectronics product page. Industrial temperature grade (ST3243EBTR-E) available for -40 °C to +85 °C operation. Halogen-free status not specified in retrieved data - marked unknown.
