MAX3320AEAP+

Overview

The MAX3320AEAP+ is a true RS-232 transceiver integrated with a microprocessor power-on reset circuit, manufactured by Analog Devices Inc./Maxim Integrated. It operates on a single +3V to +5.5V supply and supports data rates up to 250kbps. The device features AutoShutdown Plus technology, reducing supply current to 4µA during inactivity. It includes two drivers and two receivers within a 20-pin SSOP package. The integrated reset circuit provides a minimum 100ms pulse width for the A suffix threshold of 4.25V.

Feature Summary

• Integrates an RS-232 transceiver with a dedicated microprocessor power-on reset supervisor.
• Features AutoShutdown Plus functionality that reduces supply current to 4µA when inputs are inactive.
• Includes a proprietary low-dropout transmitter output stage enabling true RS-232 performance from a single supply.
• Provides precise monitoring of power-supply voltages with guaranteed valid reset states down to VCC = 1V.

Applications

• Palmtop Computers
• Portable/Battery-Powered Equipment
• Hand-Held Equipment

Procurement Notes

Verify the specific ordering suffix against the datasheet table to confirm the reset threshold voltage. The 'E' suffix indicates operation across the -40°C to +85°C temperature range. Confirm pin-out compatibility with the 20-pin SSOP footprint before integration into existing designs.

Selection Notes

Select this component when a combined RS-232 interface and system supervision circuit is required to minimize board space. The choice of the 'A' suffix dictates a 4.25V reset threshold, suitable for standard 5V logic systems. Ensure external charge-pump capacitors meet the minimum capacitance requirements specified for the operating voltage.

Part Context

This part belongs to the MAX3320A/B/L/T family of low-power RS-232 transceivers. The family differentiates parts primarily through their reset threshold voltages and operating temperature ranges. The MAX3320AEAP+ specifically targets industrial and commercial applications requiring extended temperature stability alongside low-power standby modes.

Replacement Considerations

Direct substitutes within the same series include MAX3320BEAP+, MAX3320LEAP+, and MAX3320TEAP+. These variants share identical electrical characteristics and pinouts but differ in the internal reset comparator threshold voltage settings.

FAQ

What is the function of the INVALID output?

The INVALID output asserts low when no valid RS-232 signal levels are present on any receiver input for at least 90µs, indicating a disconnected cable or inactive peripheral.

How does AutoShutdown Plus operate?

When FORCEOFF is high and FORCEON is low, the device monitors inputs. If all receiver and transmitter inputs remain inactive for 30 seconds, the internal power supply and drivers shut off, reducing current to 4µA until activity resumes.

What is the reset threshold for the MAX3320AEAP+?

The 'A' suffix corresponds to a reset threshold of 4.25V (typical), ensuring the RESET signal activates if VCC drops below this level.