Analog Devices Inc./Maxim Integrated MAX6386LT31D3+

Overview

The MAX6386LT31D3+ from Maxim Integrated is a low-power microprocessor supervisory circuit with open-drain active-low reset output, factory-set 3.08V reset threshold (±2.5% over -40°C to +125°C), 140ms minimum VCC reset timeout, and debounced manual reset input (MR) featuring internal 63kΩ pullup. It monitors single supply voltage in battery-powered embedded systems requiring reliable power-on reset and brownout protection.

For engineers reviewing the MAX6386LT31D3+ datasheet, MAX6386LT31D3+ pinout, MAX6386LT31D3+ application, or MAX6386LT31D3+ equivalent, key selection criteria include its 3.08V threshold accuracy, 140ms reset hold time, MR debounce capability, open-drain output compatibility with mixed-voltage logic, and operation down to VCC = 1.0V with guaranteed reset state validity.

Technical Context

This device implements a precision bandgap-based reset comparator with ±2.5% threshold accuracy across -40°C to +125°C and 60ppm/°C tempco. Its internal timer generates a fixed 140ms minimum reset assertion period after VCC rises above 3.08V or after MR release.

The MR input accepts TTL/CMOS logic levels, includes internal 63kΩ pullup, and provides 1µs minimum pulse width detection with 100ns glitch rejection. The open-drain RESET output requires an external pullup and sinks up to 3.2mA at VCC ≥ 4.5V while maintaining VOL ≤ 0.4V.

Key Specifications

Pinout & Package

MAX6386LT31D3+ is housed in a 4-pin SC70 package (outline 21-0098, land pattern 90-0187), measuring 2.0mm × 2.1mm × 0.95mm, with exposed pad for thermal enhancement.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6326XR31D3+T and TPS3808G33DBVR, the MAX6386LT31D3+ uniquely combines 3.08V precision threshold, 140ms timeout, open-drain flexibility, and integrated MR input in a 4-pin SC70 - making it optimal for space-constrained, manually resettable embedded systems requiring mixed-voltage compatibility.

Availability

MAX6386LT31D3+ is available at Aetrix Electronics and suitable for industrial PLC controllers, medical wearable sensors, automotive body control modules, and IoT edge gateways requiring stable component supply with guaranteed long-term availability.

Supply support for MAX6386LT31D3+ 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 and mixed-signal ICs for industrial, automotive, communications, and computing markets.

The MAX6381–MAX6390 family delivers low-power, high-accuracy μP reset supervision for battery-operated and harsh-environment systems, emphasizing factory-trimmed thresholds, wide temperature operation, and compact packaging.

FAQ

What is the exact reset threshold voltage of the MAX6386LT31D3+ and how stable is it over temperature?

The MAX6386LT31D3+ has a factory-set nominal reset threshold of 3.08V, with guaranteed accuracy of ±2.5% over the full operating temperature range of -40°C to +125°C. Its temperature coefficient is 60ppm/°C, meaning the threshold drifts less than 15mV across the entire range. This stability ensures reliable brownout detection in industrial and automotive applications where supply rails may vary with ambient conditions. The MAX6386LT31D3+ maintains this performance without requiring external calibration components.

Does the MAX6386LT31D3+ require an external pullup resistor on the RESET pin, and why?

Yes, the MAX6386LT31D3+ requires an external pullup resistor on the RESET pin because it features an open-drain active-low output. The internal transistor can only sink current to ground; it cannot source current to pull the line high. A typical value is 10kΩ connected between RESET and the system's logic rail (e.g., 3.3V). This configuration enables wired-OR functionality, level translation, and compatibility with multiple voltage domains - a key advantage over push-pull alternatives. Without the pullup, RESET remains floating and undefined.

How does the manual reset (MR) input of the MAX6386LT31D3+ function, and what external components are needed?

The MR input of the MAX6386LT31D3+ is an active-low signal with an internal 63kΩ pullup resistor to VCC, so no external pullup is required. To initiate a reset, drive MR low using a momentary switch to GND or compatible logic output. The device debounces MR internally - rejecting glitches shorter than 100ns - and asserts RESET for the full 140ms timeout after MR is released. For noisy environments, a 0.1μF capacitor from MR to GND adds immunity. The MAX6386LT31D3+ guarantees correct MR operation down to VCC = 1.0V.

What is the minimum supply voltage at which the MAX6386LT31D3+ guarantees valid RESET output behavior?

The MAX6386LT31D3+ guarantees valid RESET output logic state down to VCC = 1.0V. Below this voltage, the internal circuitry may not operate reliably, and RESET behavior is unspecified. This 1.0V lower limit enables robust operation during severe brownout events common in battery-powered systems nearing end-of-life. Unlike some supervisors that fail silently, the MAX6386LT31D3+ ensures the reset signal remains asserted (low) until VCC recovers sufficiently - preventing premature MCU execution. This specification is tested and guaranteed across temperature.

Is the MAX6386LT31D3+ pin-compatible with older Maxim reset ICs like the MAX809 or MAX6326?

No, the MAX6386LT31D3+ is not pin-compatible with MAX809 (3-pin SOT-23) or MAX6326 (3-pin SOT-23), as it uses a 4-pin SC70 package with VCC, RESET, MR, and GND arranged differently. However, it is functionally compatible and listed in the datasheet as pin-compatible with other members of the MAX6384–MAX6390 series in the same 4-pin SC70 configuration (e.g., MAX6384XS31D3+). Board redesign is required to migrate from 3-pin to 4-pin packages, but schematic logic remains identical due to shared functional architecture and timing characteristics.