Analog Devices Inc./Maxim Integrated MAX6337US18D3-T

Overview

MAX6337US18D3-T from Maxim Integrated is an ultra-low-voltage, open-drain microprocessor supervisory circuit designed for 1.8V power supply monitoring in space-constrained embedded systems. It asserts an active-low RESET signal when VCC falls below 1.80V (±1.8% at +25°C, ±3% over -40°C to +125°C) or when the debounced manual-reset input (MR) is asserted, with a guaranteed minimum 100ms reset timeout period and valid operation down to VCC = 1.0V. Used in portable equipment and automotive controllers requiring reliable brownout detection.

For engineers reviewing the MAX6337US18D3-T datasheet, MAX6337US18D3-T pinout, MAX6337US18D3-T application, or MAX6337US18D3-T equivalent, key selection criteria include its 1.8V factory-trimmed reset threshold, open-drain output structure for bidirectional µP reset pin interfacing, 3.3µA typical supply current at 1.8V, and guaranteed reset assertion validity down to VCC = 1.0V - critical for low-power battery-operated designs.

Technical Context

The MAX6337US18D3-T implements a precision voltage comparator with factory-trimmed 1.80V threshold and built-in immunity to fast VCC transients (e.g., ≤24µs at 100mV overdrive). Its reset timeout is fixed at ≥100ms (nominal), determined by internal RC timing and stable over temperature (±10% variation from -40°C to +125°C).

It features a debounced MR input with 20kΩ internal pull-up, enabling direct connection of a momentary switch to GND without external components. The open-drain RESET output requires an external pull-up resistor and supports wired-OR configurations with µP bidirectional reset pins such as the Motorola 68HC11.

Key Specifications

Pinout & Package

MAX6337US18D3-T is housed in a 4-pin SOT143 package (3.0mm × 1.6mm × 0.9mm), optimized for high-density PCB layouts in portable and automotive electronics.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6337US18D3-T, the MAX6336US18D3-T offers lower minimum VCC (0.7V vs. 1.0V) but lacks open-drain flexibility, while the MAX812TEUS29D3-T targets higher-voltage rails and cannot accurately supervise 1.8V supplies - making MAX6337US18D3-T uniquely suited for low-voltage, shared-bus reset architectures.

Availability

MAX6337US18D3-T is available at Aetrix Electronics and suitable for portable medical sensors, automotive body control modules, industrial IoT edge nodes, and smart energy metering requiring stable component supply and long-term lifecycle support.

Supply support for MAX6337US18D3-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 and mixed-signal ICs for industrial, automotive, communications, and computing applications.

The MAX6335/MAX6336/MAX6337 family delivers ultra-low-voltage, low-power µP supervisory circuits with factory-trimmed thresholds and integrated manual reset - targeting space- and power-constrained embedded systems where reliability and minimal external components are critical.

FAQ

What is the factory-trimmed reset threshold voltage for MAX6337US18D3-T?

The MAX6337US18D3-T has a factory-trimmed reset threshold of 1.80V, with a tolerance of ±1.8% at +25°C and ±3% over the full operating temperature range of -40°C to +125°C. This value is laser-trimmed during production and specified in Table 1 of the datasheet; it enables precise supervision of 1.8V logic supplies without external calibration.

Does MAX6337US18D3-T require an external pull-up resistor on the RESET pin?

Yes, MAX6337US18D3-T requires an external pull-up resistor on the RESET pin because it features an open-drain active-low output. The resistor connects RESET to the target logic rail (e.g., VCC or I/O voltage), establishing the high-state voltage level. Typical values range from 10kΩ to 100kΩ, balancing speed, power, and noise immunity - no pull-up is needed for push/pull variants like MAX6336US18D3-T.

What is the minimum supply voltage at which MAX6337US18D3-T guarantees correct reset assertion?

MAX6337US18D3-T guarantees correct reset assertion and output state validity down to VCC = 1.0V. This is explicitly stated in the datasheet and differentiates it from the MAX6335/MAX6336 variants, which are guaranteed only to 0.7V. Below 1.0V, the open-drain output may lose sinking capability, risking indeterminate reset states.

Can MAX6337US18D3-T interface directly with a Motorola 68HC11 microcontroller?

Yes, MAX6337US18D3-T is specifically cited in the datasheet as compatible with the Motorola 68HC11 due to its open-drain RESET output. The device connects directly to the µP's bidirectional reset pin using a single external pull-up resistor, allowing either the supervisor or the µP to assert reset - a key advantage over push/pull alternatives that cannot share the reset line.

What is the reset timeout period for MAX6337US18D3-T, and is it adjustable?

The MAX6337US18D3-T has a factory-programmed nominal reset timeout period of 100ms (minimum), as indicated by the "D3" suffix in the part number. This timing is fixed by internal RC elements and is not user-adjustable. The timeout remains stable across temperature (±10% variation), ensuring consistent processor initialization timing in varying environmental conditions.