MAX3243CWI+ - 3/5 RS-232 Transceiver | Analog Devices
MPN: MAX3243CWI+ ✓ ActiveMAX3243CWI+ Overview
An RS-232 transceiver is an interface IC that converts logic-level digital signals into RS-232 line levels and converts received RS-232 signals back into CMOS-compatible logic. This bidirectional level-conversion function places the MAX3243CWI+ between a host controller or data-processing equipment and an external serial port. Its three-driver, five-receiver arrangement is particularly suited to DE-9 serial interfaces and equipment requiring additional receive channels for status, handshake, or ring-detection signals.
Key features include a 3V-to-5.5V operating range, 250 kbps maximum signaling rate, and ±15 kV ESD protection on serial-port connections. AutoShutdown helps reduce power consumption when the connected RS-232 port has no valid activity. The INVALID output remains available to report the status of received RS-232 signals, while ROUT2B provides a second receiver output for applications that need an additional input or status function.
The MAX3243CWI+ uses Maxim Integrated’s RS-232 interface architecture and is offered in a 28-pin SOIC package. Its driver and receiver organization supports asymmetric port requirements without requiring five separate line-driver circuits. The 3V-to-5.5V supply range makes the device usable in both legacy 5V serial equipment and modern embedded systems operating from lower-voltage rails.
Typical applications include DE-9 RS-232 ports, industrial serial adapters, point-of-sale equipment, instrumentation, data acquisition systems, and embedded control systems. In a typical design, logic-level TX and RX signals connect to the transceiver, while the protected driver outputs connect through the external DB-9 connector or another RS-232 connector. Additional receiver inputs can monitor modem-control or equipment-status lines.
Designers should account for the voltage drop across the RS-232 line, use protection appropriate to the connector environment, and maintain the supply and ground connections required by the manufacturer interface guidance. The AutoShutdown behavior should also be verified against the system’s power-management strategy, especially when a disconnected or idle connector must be recognized reliably.
This page consolidates verified manufacturer and distributor information, package-level alternatives, technical comparisons, and practical design guidance for engineers evaluating the MAX3243CWI+ in 3V-to-5.5V RS-232 interface designs.
Drop-in alternatives for MAX3243CWI+ — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
MAX3243EWI+
✅ Drop-In📋 Reference alternative (not in catalog)
SP3243EHCA-L/TR
✅ Drop-In📋 Reference alternative (not in catalog)
MAX3243CWI+ Specifications
| Product Type | Multichannel RS-232 transceiver |
| Supply Voltage Range | 3 V to 5.5 V |
| Maximum Data Rate | 250 kbps |
| Line Drivers | 3 |
| Line Receivers | 5 |
| Driver/Receiver Functions | 3/5 |
| ESD Protection | ±15 kV HBM on serial-port connections |
| Power Management Feature | AutoShutdown |
| INVALID Output | Always enabled |
| ROUT2B Output | Always enabled |
| Package | 28-pin SOIC |
| Mounting Type | Surface mount |
| Signal Family | RS-232 |
MAX3243CWI+ 28-pin soic Pin Configuration Guide
Pin configuration for MAX3243CWI+ (28-pin soic package). Pin numbering, functions, and connection diagrams are defined in the manufacturer datasheet. Refer to it for the exact footprint and soldering guidelines.
No detailed pinout data available for MAX3243CWI+.
Refer to the datasheet for full pin configuration.
Typical Applications
MAX3243CWI+ is suitable for 6 applications: DE-9 Serial Port Interface, Industrial Serial Adapter, Data Acquisition Equipment, Point-of-Sale Terminal, Embedded Instrumentation Interface, Serial Port Debug Adapter.
DE-9 Serial Port Interface
The MAX3243CWI+ fits a DE-9 serial interface because it provides three line drivers and five line receivers in one 28-pin SOIC package. The three-driver side supports transmit data and selected control functions, while the five-receiver channels can handle incoming data, status, and handshake signals. Its 250 kbps maximum rate covers conventional RS-232 equipment, while the 3 V-to-5.5 V supply range allows the same transceiver to serve both 5 V peripherals and lower-voltage embedded controllers.
Recommended
Industrial Serial Adapter
The MAX3243CWI+ is suitable for industrial serial adapters that translate host logic levels to RS-232 while monitoring several return or status lines. Its three transmitters and five receivers reduce the number of separate interface ICs required around a DE-9 connector. The verified ±15 kV HBM ESD rating adds protection at the line-driver and receiver interface, while AutoShutdown can lower consumption when the remote equipment does not present a valid signal.
Recommended
Data Acquisition Equipment
The MAX3243CWI+ can provide a robust control and status path in data-acquisition systems that communicate with external instruments over RS-232. The 250 kbps rate supports common command and measurement-data transfers, and the five receiver channels are useful for acknowledging equipment states or monitoring remote signals. Its 3 V minimum supply allows deployment with modern controller rails, while the 28-pin SOIC package simplifies assembly on conventional industrial controller boards.
Recommended
Point-of-Sale Terminal
A point-of-sale terminal can use the MAX3243CWI+ to interface a main controller with a receipt printer, scanner, or customer-display accessory connected through RS-232. Three transmit channels and five receive channels support both command traffic and peripheral-status reporting. AutoShutdown is useful when accessories are intermittently connected because it can reduce transceiver power when no valid receive signal is sensed, although the system should confirm the behavior against its accessory-power strategy.
Recommended
Embedded Instrumentation Interface
The MAX3243CWI+ is a practical choice for embedded instrumentation that must communicate with legacy test equipment through RS-232. Its 3 V-to-5.5 V operating range supports modern embedded processors and established 5 V instruments, while the 28-pin SOIC package is widely compatible with industrial assembly methods. The always-enabled INVALID output can provide host-visible receive-status information, and the five-receiver count allows additional lines to be monitored without five separate receiver packages.
Recommended
Serial Port Debug Adapter
The MAX3243CWI+ can serve as the interface in a debug adapter that converts a host UART into a full RS-232 port and exposes multiple return signals for troubleshooting. The 250 kbps rate is adequate for conventional serial-console traffic, and the three transmitters can support more than one outbound control function. AutoShutdown and the always-enabled INVALID signal help the host distinguish inactive or disconnected conditions, supporting reliable peripheral detection in service and test environments.
Recommended
Recommended Products Summary
Engineering reference data for MAX3243CWI+ — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | MAX3243EWI+ | SP3243EHCA-L/TR |
|---|---|---|---|
| Package | 28-pin SOIC | 28-pin SOIC | 28-pin SOIC |
| Brand | Analog Devices | Analog Devices | MaxLinear |
| Maximum Data Rate | 250 kbps | 250 kbps | 460 kbps |
Key Differentiators
- Three-driver and five-receiver organization (vs MAX3243EWI+)
- Defined 250 kbps operating rate (vs SP3243EHCA-L/TR)
- Automatic power reduction and receive-status reporting (vs SP3243EHCA-L/TR)
Design Notes
Confirm the transceiver supply rail remains within the verified 3 V to 5.5 V range under transient and startup conditions. When AutoShutdown is used, review the INVALID output behavior against the host power-management logic because INVALID remains enabled even when the transceiver detects no valid receive activity. Avoid designing the external interface around an undocumented shutdown threshold or delay; verify those details in the manufacturer data sheet.
Place the transceiver and its required charge-pump and bypass components close to the associated connector and logic interface. Keep RS-232 driver and receiver traces away from sensitive analog or high-speed digital paths. Provide a low-impedance return path for every RS-232 signal and follow the complete manufacturer application circuit, including all required capacitors and network connections, rather than using only the functional block diagram.
Do not treat a ±15 kV HBM device rating as permission to omit connector-level and enclosure-level ESD protection. RS-232 cables can accumulate substantial electrostatic charge before reaching the PCB, and the rated device protection is not a substitute for a complete system strategy. Also verify the exact pinout and capacitor network from the manufacturer documentation because the supplied verification data identifies the 28-pin package but does not provide a complete pin-by-pin table.
Compliance Information
The supplied verification data does not explicitly state RoHS, REACH, lead-free, halogen-free, or conflict-minerals status. The MAX3243 is an interface IC and is therefore not treated as an AEC-Q100-qualified automotive device based on the available information.