Analog Devices Inc./Maxim Integrated MAX809LEUR

Overview

MAX809LEUR from Maxim Integrated is a 3-pin SOT23-packaged microprocessor supervisory circuit with push-pull active-low RESET output, 4.63V reset threshold (±1.5% over -40°C to +105°C), 140ms minimum reset timeout, 12µA supply current, and guaranteed reset validity down to VCC = 1V. It monitors +5V power supplies in embedded controllers and portable systems requiring reliable power-on reset assertion.

For engineers reviewing the MAX809LEUR datasheet, MAX809LEUR pinout, MAX809LEUR application, or MAX809LEUR equivalent, this page delivers verified electrical parameters, thermal performance data, package dimensions, real-world interface guidance for µP reset pins, and validated alternative options for industrial and automotive-grade reset supervision.

Technical Context

The MAX809LEUR implements a precision voltage comparator with 30ppm/°C tempco and built-in hysteresis to detect VCC drops below 4.63V, asserting RESET until VCC remains above threshold for ≥140ms. Its push-pull output drives CMOS inputs directly without external pullup resistors.

It features transient immunity against negative-going VCC glitches as short as 20µs at 100mV overdrive, and guarantees correct logic state for VCC ≥1V - enabling robust operation during brownout recovery and low-voltage sequencing in battery-powered equipment.

Key Specifications

Pinout & Package

MAX809LEUR is housed in a RoHS-compliant 3-pin SOT23 package (package code U3-1), measuring 2.9mm × 1.6mm × 1.1mm, with gull-wing leads optimized for automated reflow assembly and high-density PCB layouts.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX809LEUR, MAX809TEUR+T shifts reset activation to 3.08V - making it incompatible for +5V systems - while TPS3808G01DBVR offers superior accuracy and lower current but sacrifices integration by requiring an external timing capacitor.

Availability

MAX809LEUR is available at Aetrix Electronics and suitable for industrial PLC controllers, automotive body control modules, and portable medical monitors requiring stable component supply, long-lifecycle support, and AEC-Q200-aligned reliability.

Supply support for MAX809LEUR 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) is a semiconductor company specializing in analog, mixed-signal, and power management ICs for industrial, automotive, and communications markets.

The MAX803/MAX809/MAX810 family was designed specifically for cost-sensitive, space-constrained microprocessor reset supervision - delivering precision threshold detection, guaranteed timing, and minimal external components in sub-3mm packages.

FAQ

What is the exact reset threshold voltage of the MAX809LEUR and how tightly is it specified?

The MAX809LEUR has a nominal reset threshold of 4.63V, with a guaranteed tolerance of ±1.5% over its full operating temperature range of -40°C to +105°C. This specification ensures the device asserts RESET before the monitored +5V supply falls below 4.5V, providing deterministic behavior for Intel- and ARM-based microcontrollers requiring precise brownout detection. The MAX809LEUR's 30ppm/°C tempco further restricts drift to less than 15mV across temperature, supporting stable operation in automotive and industrial environments.

Does the MAX809LEUR require an external pullup resistor on its RESET pin?

No, the MAX809LEUR does not require an external pullup resistor because it features a push-pull active-low RESET output. Unlike open-drain variants such as the MAX803L, the MAX809LEUR actively drives the RESET line low during assertion and high during deassertion using internal transistors. This eliminates external components, reduces board space, and ensures fast, clean transitions compatible with standard CMOS reset inputs found on most microcontrollers and FPGAs.

Can the MAX809LEUR operate reliably when the VCC supply drops below 2.0V?

Yes, the MAX809LEUR guarantees correct RESET logic state down to VCC = 1.0V, meaning it continues to assert or deassert the RESET signal accurately even as the supply collapses toward shutdown. Below 1.0V, the output enters high-impedance mode - but for all practical design purposes within its specified 1.2V to 5.5V operating range, the MAX809LEUR maintains full functionality, including 140ms timeout accuracy and 4.63V threshold detection.

How does the MAX809LEUR handle fast transients on the VCC line?

The MAX809LEUR incorporates comparator hysteresis and transient filtering to reject short-duration negative-going VCC glitches. Specifically, it ignores transients ≤20µs wide when the supply dips 100mV below the 4.63V threshold - a capability verified in Figure 1 of the official datasheet. This immunity prevents spurious resets caused by switching regulator noise or ESD coupling, making the MAX809LEUR suitable for noisy industrial and automotive power domains without requiring additional RC filtering.

What is the package type and lead finish of the MAX809LEUR?

The MAX809LEUR uses a 3-pin SOT23 package (package code U3-1), measuring 2.9mm × 1.6mm × 1.1mm, with gull-wing leads and a lead(Pb)-free, RoHS-compliant finish denoted by the "+" suffix in the full orderable part number MAX809LEUR+T. This package supports standard reflow profiles up to +260°C and is qualified for automated pick-and-place assembly in high-volume manufacturing environments.