MAX3218EAP+T

Overview

The MAX3218EAP+T is a low-power RS-232 transceiver manufactured by Analog Devices Inc./Maxim Integrated, housed in a 20-pin SSOP package. It operates from a single supply voltage ranging from 1.8V to 4.25V and supports data rates up to 120kbps. The device integrates two drivers and two receivers with an AutoShutdown feature that reduces supply current to 1µA when no valid signal is detected. Operating temperature range is -40°C to +85°C.

Feature Summary

• AutoShutdown functionality minimizes power consumption by disabling the onboard power supply and drivers when invalid receiver input levels are sensed.
• Integrated switch-mode DC-DC converter generates internal ±6.5V rails from a single low-voltage supply without requiring external voltage regulators.
• Three-state receiver outputs allow multiple devices with different interface standards to share the same bus via wire-OR connections.

Applications

• Battery-powered EIA/TIA-232E and V.28/V.24 communications interfaces
• Subnotebook computers and personal digital assistants (PDAs)
• Hand-held equipment and cellular phones

Procurement Notes

Verify the specific suffix 'EAP' confirms the extended industrial temperature range (-40°C to +85°C) and SSOP package type. Confirm RoHS compliance status for lead-free requirements. Ensure the ordering quantity matches the tape-and-reel packaging format indicated by the '+T' designation.

Selection Notes

Select this component for applications requiring direct operation from alkaline, NiCd, or NiMH battery cells without additional regulation. Consider the external inductor and diode requirements for the charge pump circuitry. Evaluate system wake-up timing constraints relative to the AutoShutdown detection delay.

Part Context

This part belongs to the MAX3218 family of RS-232 transceivers designed for low-power serial communication. The 'E' suffix denotes the industrial temperature grade, while 'AP' specifies the 20-pin shrink small-outline package. The '+T' indicates a lead-free, RoHS-compliant version supplied in a reel.

Replacement Considerations

MAX3218CAP+T

FAQ

How does the AutoShutdown feature determine when to enter low-power mode?

The device enters shutdown after sensing invalid RS-232 voltage levels on both receiver inputs for typically 30µs, which occurs if the cable is disconnected or peripheral transmitters are off.

What external components are required for the onboard DC-DC converter?

The circuit requires a 15µH inductor, a fast recovery diode (such as 1N6050), and three capacitors (C1=0.47µF, C2=1µF, C3=1µF) to generate the necessary ±6.5V supply rails.

Can the receivers remain active while the transmitters are shut down?

Yes, during AutoShutdown, both receivers can remain active to monitor external devices, or they can be disabled under logic control via the FORCEON pin.