Analog Devices Inc./Maxim Integrated MAX6386XS44D3+

Overview

MAX6386XS44D3+ from Maxim Integrated is a low-power, open-drain active-low microprocessor supervisory circuit in 4-pin SC70 package, with factory-set 4.38V reset threshold (±2.5% over -40°C to +125°C), 140ms minimum reset timeout, and debounced manual reset input (MR) featuring internal 63kΩ pullup. It monitors VCC in battery-powered embedded controllers and ensures reliable reset assertion during brownout.

For engineers reviewing the MAX6386XS44D3+ datasheet, MAX6386XS44D3+ pinout, MAX6386XS44D3+ application, or MAX6386XS44D3+ equivalent, key selection criteria include its open-drain output configuration, 140ms VCC reset timeout, 4.38V threshold accuracy, MR debounce capability, and compatibility with 1.8V–5.0V supply rails in space-constrained industrial and portable designs.

Technical Context

The MAX6386XS44D3+ implements a precision bandgap-based voltage comparator with ±2.5% threshold accuracy across -40°C to +125°C and integrates a temperature-stable RC timer for guaranteed 140ms minimum reset assertion after VCC recovery. Its MR input includes internal 63kΩ pullup and 1µs minimum pulse width support, enabling direct switch interfacing without external components.

As an open-drain active-low reset device, MAX6386XS44D3+ requires an external pullup resistor on RESET to define logic-high level and supports mixed-voltage systems via independent VCC monitoring and MR logic-level tolerance (0.3×VCC to 0.7×VCC for VTH < 4V). Reset output remains valid down to VCC = 1.0V.

Key Specifications

Pinout & Package

MAX6386XS44D3+ uses a 4-pin SC70 package (X4-1 footprint, 1.0mm × 1.3mm × 0.6mm, lead-free), optimized for high-density PCB layouts in portable electronics.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6326XR46D3+, MAX6386XS44D3+ adds MR functionality at identical package size but trades 0.25V higher threshold; versus TPS3808G33DBVR, it offers adjustable threshold and MR at higher ICC and looser accuracy - optimal for 4.3V rail supervision with user-reset capability.

Availability

MAX6386XS44D3+ is available at Aetrix Electronics and suitable for industrial PLCs, medical wearables, automotive body controllers, and smart energy meters requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for MAX6386XS44D3+ 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 demanding industrial, automotive, and medical applications, emphasizing low power, high reliability, and small form factor.

MAX6386XS44D3+ belongs to the MAX6381–MAX6390 family of single-supply µP supervisors engineered for low-voltage, low-power embedded systems where deterministic reset timing and robust brownout protection are critical.

FAQ

What is the exact reset threshold voltage of MAX6386XS44D3+ and how is it specified?

The MAX6386XS44D3+ has a factory-set nominal reset threshold of 4.38V, with a tolerance of ±2.5% over the full operating temperature range of -40°C to +125°C. This value is defined by the "44" suffix in the part number and confirmed in the Reset Thresholds table of the datasheet. The actual threshold falls between 4.27V (min) and 4.48V (max) at temperature extremes, ensuring reliable detection of brownout on 4.5V rails.

Does MAX6386XS44D3+ require an external pullup resistor on the RESET pin, and why?

Yes, MAX6386XS44D3+ requires an external pullup resistor on the RESET pin because it features an open-drain active-low output. Without the pullup, the RESET line would float high when deasserted, risking undefined logic states. A typical 10kΩ to 100kΩ resistor to the target supply rail (e.g., 3.3V) ensures proper voltage levels and enables wired-OR reset bus configurations shared with other devices.

What is the function and electrical behavior of the MR pin on MAX6386XS44D3+?

The MR pin on MAX6386XS44D3+ is an active-low manual reset input with an internal 63kΩ pullup resistor to VCC. Driving MR below 0.3×VCC for ≥1µs forces reset assertion; reset remains active for the full 140ms timeout after MR is released. This eliminates external debounce components and supports direct connection to momentary switches or logic outputs in battery-powered systems.

How does MAX6386XS44D3+ behave when VCC drops below 1.0V, and what design guidance applies?

MAX6386XS44D3+ guarantees correct reset output logic state only down to VCC = 1.0V. Below this, the internal circuitry may not operate reliably. For applications requiring valid reset signaling all the way to 0V, a pullup resistor on RESET (for active-high systems) or pulldown (for active-low) is recommended - though this method is incompatible with MAX6386XS44D3+'s open-drain output, so system-level power sequencing must ensure VCC stays ≥1.0V during critical reset windows.

Is MAX6386XS44D3+ pin-compatible with legacy Maxim reset ICs like MAX809, and what does that mean for design reuse?

MAX6386XS44D3+ is listed as pin-compatible with MAX809/MAX810/MAX803 and several MAX63xx variants, meaning its 4-pin SC70 footprint matches those parts electrically and mechanically. However, due to differences in reset threshold (4.38V vs. 2.93V/3.08V/4.63V), output type (open-drain vs. push-pull), and MR inclusion, direct substitution requires verification of timing, voltage margins, and external circuit changes - especially pullup resistor addition for open-drain operation.