Analog Devices Inc./Maxim Integrated MAX6389LT22D3+T

Overview

MAX6389LT22D3+T from Maxim Integrated is a low-power microprocessor supervisory circuit with open-drain active-low reset output, factory-set 2.19V VCC reset threshold (±2.5% over -40°C to +125°C), 140ms minimum reset timeout, and auxiliary RESET IN input for dual-voltage monitoring. It consumes only 3μA at +1.8V and guarantees valid reset state down to VCC = 1V, serving in battery-powered embedded controllers and industrial power-monitoring systems.

For engineers reviewing the MAX6389LT22D3+T datasheet, MAX6389LT22D3+T pinout, MAX6389LT22D3+T application, or MAX6389LT22D3+T equivalent, key selection criteria include its 2.19V threshold accuracy, 140ms VCC timeout, open-drain output requiring external pullup, RESET IN comparator referenced to +1.27V, and operation across -40°C to +125°C.

Technical Context

The MAX6389LT22D3+T implements a precision bandgap-based voltage monitor for VCC and a separate high-impedance comparator for the RESET IN pin, both feeding into a digital timeout timer. Its reset assertion logic triggers on either VCC falling below 2.19V or RESET IN dropping below 1.27V, with independent glitch rejection (100ns) and transient immunity against negative-going VCC spikes.

This device uses BiCMOS process technology to achieve 3μA supply current at 1.8V while maintaining ±2.5% threshold accuracy over full temperature range and guaranteeing reset output validity down to VCC = 1V - enabling reliable brownout detection in ultra-low-power systems without external supervision.

Key Specifications

Pinout & Package

MAX6389LT22D3+T is housed in a 6-pin μDFN package (2mm × 2mm, 0.5mm pitch) with wettable flanks, RoHS-compliant and lead-free.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar microprocessor reset applications.

Compared with MAX6389LT22D3+T, the MAX6389XS22D3+T offers identical electrical performance in a smaller 4-pin SC70 package but omits RESET IN functionality, while TLV803EB22DBZR provides basic reset supervision at lower cost but sacrifices threshold accuracy, temperature range, and dual-supply capability.

Availability

MAX6389LT22D3+T is available at Aetrix Electronics and suitable for industrial PLC controllers, battery-powered IoT sensors, automotive body control modules, and medical portable diagnostic devices requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for MAX6389LT22D3+T includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Maxim Integrated (now part of Analog Devices) designs precision analog, mixed-signal, and power-management ICs for demanding industrial, automotive, and communications applications.

The MAX6381–MAX6390 family delivers ultra-low-power, high-accuracy microprocessor supervisory circuits optimized for battery longevity and robust operation in harsh thermal and electrical environments.

FAQ

What is the exact reset threshold voltage of MAX6389LT22D3+T and how stable is it over temperature?

The MAX6389LT22D3+T has a factory-set VCC reset threshold of 2.19V nominal, with guaranteed ±2.5% accuracy over the full operating temperature range of -40°C to +125°C. This stability is achieved through laser-trimmed bandgap references and BiCMOS process design, making MAX6389LT22D3+T suitable for automotive and industrial applications where supply margin is tight.

Does MAX6389LT22D3+T support monitoring of a second voltage rail, and how is it implemented?

Yes, MAX6389LT22D3+T includes a dedicated RESET IN pin that connects to an internal +1.27V comparator. To monitor a second voltage, apply the target rail to RESET IN through a resistor divider - for example, use R1 = 100kΩ and R2 = 100kΩ to set a 2.54V threshold. The MAX6389LT22D3+T asserts reset if either VCC falls below 2.19V or the divided RESET IN voltage drops below 1.27V.

What is the function of the two N.C. pins on the 6-pin μDFN package of MAX6389LT22D3+T?

Pins 3 and 5 on the MAX6389LT22D3+T's 6-pin μDFN package are No Connection (N.C.) terminals - they are not bonded internally and serve no electrical function. Per Maxim's land pattern guidelines, these pins may be left floating or connected to GND for mechanical stability and thermal relief, but must never be tied to active signals or supply rails.

Can MAX6389LT22D3+T operate reliably when VCC drops below 1.8V, and what is the minimum functional voltage?

Yes, MAX6389LT22D3+T is fully specified down to VCC = 1.0V and guarantees correct reset output logic state (valid high-impedance or asserted low) at all voltages ≥1.0V. Its 3μA supply current at 1.8V scales downward as VCC decreases, enabling fail-safe brownout detection even during deep undervoltage events - a key capability distinguishing MAX6389LT22D3+T from many competing supervisors.

Is MAX6389LT22D3+T pin-compatible with other members of the MAX6381–MAX6390 family, and which variants share the same 6-pin μDFN footprint?

MAX6389LT22D3+T shares the identical 6-pin μDFN package (L611+1 land pattern) with MAX6381LTxxDx+T, MAX6382LTxxDx+T, MAX6383LTxxDx+T, MAX6384LTxxDx+T, MAX6385LTxxDx+T, MAX6386LTxxDx+T, MAX6387LTxxDx+T, MAX6388LTxxDx+T, and MAX6390LTxxDx+T. However, pin functions differ: MAX6389LT22D3+T uses Pin 4 for RESET IN and Pins 3/5 as N.C., whereas MAX6384–MAX6386 use Pin 3 for MR and MAX6390 uses Pin 3 for MR with different timeout timing.