MAX3320TCAP+

Overview

The MAX3320TCAP+ is a true RS-232 transceiver with an integrated power-on reset circuit, operating from a +3V to +5.5V supply. It features two drivers and two receivers supporting data rates up to 250kbps. The device utilizes AutoShutdown Plus technology to achieve a low shutdown supply current of 4µA. It includes a precise power-supply supervisor with a minimum 100ms reset pulse width and guarantees valid RESET output down to VCC = 1V. The component is housed in a 20-pin SSOP package and operates within a commercial temperature range of 0°C to +70°C.

Feature Summary

• Integrates a microprocessor supervisory circuit that asserts a reset signal when the supply voltage drops below a preset threshold
• Features proprietary low-dropout transmitter output stage enabling true RS-232 performance with dual charge pumps
• Includes AutoShutdown Plus functionality that reduces supply current to 4µA after 30 seconds of inactivity
• Provides an active-low RESET output guaranteed to be in the correct state for VCC down to 1V

Applications

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

Procurement Notes

Verify the specific suffix 'T' corresponds to the required reset threshold voltage of 3.08V before procurement. Confirm the 'CAP+' designation indicates the 20-pin SSOP package and commercial temperature range (0°C to +70°C). Ensure compatibility with the system's logic families and check for any obsolete status or lifecycle changes directly from Analog Devices documentation.

Selection Notes

Select this part when a combined RS-232 interface and power supervision solution is needed for battery-operated devices. The 3.08V reset threshold is suitable for systems where the supply rail may dip slightly below nominal levels but requires stable monitoring. Consider the 4µA shutdown current for applications requiring extended battery life during idle periods.

Part Context

This component belongs to the MAX3320A/B/L/T family of true RS-232 transceivers. The specific 'T' suffix differentiates it by its power-on reset threshold voltage compared to other variants like the MAX3320A (4.25V) or MAX3320B (2.85V). All members share the same core transceiver architecture and pinout.

Replacement Considerations

Direct replacements include other MAX3320 variants such as MAX3320ACAP+, MAX3320BCAP+, or MAX3320LCAP+. These parts share identical electrical characteristics and pinouts but differ only in the internal power-on reset threshold voltage setting.

FAQ

What is the function of the INVALID output?

The INVALID output asserts when no valid RS-232 levels are present on any receiver inputs for at least 90µs, indicating the absence of a valid signal.

How does AutoShutdown Plus work?

AutoShutdown Plus monitors receiver and transmitter inputs; if no activity is detected for 30 seconds, the transmitters shut off and the supply current drops to 4µA until a valid transition occurs.

What capacitors are required for the charge pump?

The device requires four external 0.1µF capacitors for operation at 3.3V. Different values may be required for other supply voltages as specified in the datasheet tables.