Analog Devices Inc./Maxim Integrated MAX213EWI

Introduction to the MAX213EWI RS-232 Transceiver

The MAX213EWI, developed by Analog Devices Inc./Maxim Integrated, is part of an advanced family of RS-232 transceiver ICs tailored for robust and compact serial communication interfaces. Housed in a 28-pin SOIC package, the MAX213EWI integrates four drivers and five receivers, making it ideal for applications requiring multiple RS-232 channels on a single device. With its +5V single-supply operation and integrated charge-pump circuitry, the MAX213EWI eliminates the need for bulky ±12V supplies, streamlining design and reducing component count in a wide range of industrial and portable systems.

Highlights and Performance Advantages of the MAX213EWI

The MAX213EWI introduces several critical features that simplify board design and enhance overall system performance:

Integrated dual charge-pump voltage converter enables single-supply operation at +5V, eliminating the space and complexity of external voltage rails traditionally required for RS-232.

Low external capacitance requirements (four 0.1μF capacitors) reduce board real estate and sourcing concerns.

Offers 75μW ring indicator monitoring with two active receivers in shutdown mode, providing both power savings and system monitoring.

Its shutdown function lowers supply current dramatically, supporting portable and battery-operated designs with efficient power management.

The device is available in wide SOIC and SSOP packages, supporting high-density layouts and saving up to 40% PCB area compared to conventional SO packages.

Robust ESD protection, large signal swing capabilities, and input logic compatibility (CMOS and TTL thresholds) ensure reliable operation even in electrically noisy environments.

Technical Data and Electrical Properties of the MAX213EWI

Selection engineers will find the MAX213EWI’s technical profile suited for demanding design requirements:

Operating supply voltage: +5V ±10%

Guaranteed EIA/TIA-232E compliant output swing: ±5V minimum under full load and temperature range; typical swing ±8V with a 5kΩ load.

Receiver input thresholds: +0.8V (guaranteed, +0.6V in shutdown), far tighter than the ±3V defined by the RS-232 standard, improving noise margin and versatility.

Propagation delay: 1μs (typical); in shutdown, selected receivers maintain operation with a delay of 4μs.

Shutdown supply current: 15μA (with limited ring indication operational in shutdown).

Input tolerance: Receivers can withstand ±30V.

Operating temperature range: -40°C to +85°C (E-grade).

Short-circuit protection on all outputs and robust power dissipation ratings for reliable operation in industrial applications.

Operational Overview and Internal Design of the MAX213EWI

Internally, the MAX213EWI is partitioned into three core sections: the charge-pump voltage converters, four RS-232 drivers (transmitters), and five RS-232 receivers.

The dual charge-pump voltage converter employs a two-stage process—first doubling the input +5V to generate +10V and then inverting this +10V to -10V. This architecture obviates the traditional ±12V rails, consolidating all voltage conversion internally and minimizing the need for high-voltage capacitors.

The RS-232 transmitters are designed with on-chip CMOS and TTL-compatible input logic, supporting unconnected inputs via integrated pullups. Output swings are compliant with EIA/TIA-232E, and power consumption is further reduced via intelligent output disablement during shutdown.

RS-232 receiver channels convert incoming signals to CMOS logic levels, supporting both inverting outputs and guaranteed tight switching thresholds. Inputs exhibit substantial hysteresis for noise immunity and defined behavior for both open and grounded lines.

Usage Modes and Control Options of the MAX213EWI

The MAX213EWI incorporates flexible power and signaling modes:

Shutdown Mode: Reduces supply current for low-power standby; disables all charge pumps and transmitters. Receivers R4 and R5 continue to operate, enabling crucial system-level external activity monitoring.

Receiver Enable (EN): Allows selective high-impedance operation, enabling direct bus connection to shared, three-state buses without contention risk.

Fast Wake Time: Exiting shutdown mode takes under 2ms, ensuring readiness for time-sensitive serial communication.

Fault Tolerance: Transmitter and receiver outputs handle output clamping, short circuits, and voltage reversals, providing fault robustness.

Design Guidelines for the MAX213EWI

When integrating the MAX213EWI, careful attention should be given to:

Capacitor selection: Ceramic capacitors (≥0.1μF) are recommended, with higher capacitance possible to improve ripple and noise performance at V+ and V-. Mode of use and temperature dependencies should be considered to avoid capacitance degradation.

Power supply decoupling: For applications sensitive to noise, the VCC decoupling capacitor should match the charge-pump capacitor value.

Drive capability: Each transmitter is specified for a single receiver load; for multi-drop configurations, parallel transmitters as per datasheet guidance.

Power supply sequencing: If external V+ arises after VCC (relevant for MAX201/MAX209), series-diodes may be necessary to prevent reverse biasing.

Shutdown exit dynamics: Upon leaving shutdown, the drivers become active rapidly and reliably, ensuring no transients or ringing on outputs.

Engineering Applications and Use Cases for the MAX213EWI

The MAX213EWI finds its place in a range of system environments, including portable data-acquisition devices, handheld diagnostic equipment, and communication subsystems within industrial control units. For example, in battery-powered field equipment, the selective shutdown with ring indication allows these devices to monitor host systems or modems while maximizing battery life—a vital feature where power budgets are tight.

In noisy factory-floor installations, the combination of tight receiver thresholds and input hysteresis improves signal integrity, reducing false triggers and improving RS-232 link reliability. The compact 28-SOIC or SSOP package fits well into dense system layouts, a significant advantage for engineers balancing performance and board area constraints.

Alternative or Substitute Devices for the MAX213EWI

Engineers seeking alternatives or considering pin-compatible upgrades for the MAX213EWI should examine several models within the Analog Devices/Maxim Integrated RS-232 family:

MAX211: Offers similar features and pin count, but with different channel ratios (4 drivers/4 receivers); also available in 28-pin packages.

MAX205 and MAX203: These models provide integrated charge-pump capacitors; use no external capacitors for applications with ultra-tight board space.

MAX200–MAX209 Series: Provides varying numbers of drivers and receivers and may allow selection for optimized channel count and shutdown features.

MAX206 and MAX208: For designers needing singleor dual-supply options or alternative package footprints.

For migration or second-source strategies, consult the full series selector guide, considering the required driver/receiver ratio, feature sets (like shutdown, ring indication), and package constraints.

Conclusion

The MAX213EWI RS-232 transceiver from Analog Devices Inc./Maxim Integrated stands out for its integrated voltage-conversion, compact multi-channel design, enhanced power-management features, and robust compliance with industry standards. For system architects and procurement professionals, the MAX213EWI offers a well-documented, reliable, and space-efficient solution for modern RS-232 communication needs—balancing board area, power, and performance across diverse engineering environments. Its combination of circuit simplicity, application flexibility, and proven electrical robustness makes it an essential device in the toolkit of engineers designing or maintaining high-reliability serial interfaces.