MAX3386ECUP+

Overview

The MAX3386ECUP+ is a 3.0V-powered EIA/TIA-232 and V.28/V.24 communications interface featuring two receivers and three transmitters. It operates from a +3.0V to +5.5V supply with a maximum data rate of 250kbps. The device includes a dual charge pump requiring four small capacitors for operation. It provides enhanced electrostatic discharge protection rated at ±25kV via the IEC 1000-4-2 Air-Gap Discharge method, ±8kV via Contact Discharge, and ±15kV using the Human Body Model. A dedicated VL pin allows logic-level programming for mixed-voltage systems. The component is housed in a space-saving 20-pin TSSOP package.

Feature Summary

• Features a unique VL pin that enables interoperability in mixed-logic voltage systems by allowing both input and output logic levels to be pin programmable.
• Provides enhanced electrostatic discharge protection on RS-232 inputs and outputs, ensuring robust performance against static electricity without latchup.
• Incorporates a proprietary low-dropout transmitter output stage that delivers true RS-232 performance from a single +3.0V to +5.5V supply.
• Includes a low-power shutdown mode that reduces supply current to less than 1µA while turning off internal charge pumps.

Applications

• Subnotebook and Palmtop Computers
• PDAs and PDA Cradles
• Cell Phone Data Cables
• Battery-Powered Equipment

Procurement Notes

Verify the specific suffix 'C' indicates an operating temperature range of 0°C to +70°C, distinct from the 'E' variant which covers -40°C to +85°C. Confirm RoHS compliance status as indicated by the '+' designation. Ensure the ordering information matches the exact package type and thermal grade required for the target application environment.

Selection Notes

Select this component when interfacing between TTL/CMOS logic and RS-232 ports in battery-operated devices. The separate VL pin is critical for compatibility with host systems operating at logic voltages lower than VCC, such as 1.8V baseband logic in cell phones. Ensure external capacitors meet minimum values specified for the chosen supply voltage to maintain stable charge pump operation.

Part Context

The MAX3386E belongs to Maxim Integrated's family of 3.0V RS-232 transceivers designed for portable electronics. It addresses the need for low power consumption and high ESD immunity in mobile devices like PDAs and cellular phones. The device simplifies system design by integrating a dual charge pump and offering flexible logic level interfacing through the VL pin.

Replacement Considerations

The MAX3386EEUP serves as a direct functional substitute with an extended industrial temperature range (-40°C to +85°C). Verify that the replacement part meets the specific thermal requirements of the application if operating conditions exceed the commercial range of the ECUP variant.

FAQ

How does the VL pin function in mixed-voltage systems?

The VL pin acts as a logic-level supply input that sets the output voltage swing for receiver outputs and defines the input thresholds for transmitters and the shutdown pin. This allows the device to interface directly with various logic families, including those operating at voltages as low as 1.8V.

What are the specific ESD protection ratings for the MAX3386E?

The device offers ±25kV protection using the IEC 1000-4-2 Air-Gap Discharge method, ±8kV using the IEC 1000-4-2 Contact Discharge method, and ±15kV using the Human Body Model. These protections apply to all RS-232 inputs and outputs.

What is the purpose of the third transmitter (T3) in this device?

While two transmitters handle standard full-duplex communication, the third transmitter is specifically designed to generate a Ring Indicator (RI) signal. This alerts the PC's UART to incoming signals from cradled devices like PDAs or cell phones, enabling interrupt-driven servicing.