Analog Devices Inc./Maxim Integrated MAX803LEXR+T

Overview

MAX803LEXR+T from Maxim Integrated is a 3-pin SC70-packaged microprocessor supervisory circuit with open-drain active-low RESET output, designed to monitor +5V power supplies. It asserts reset when VCC falls below 4.63V (typ), holds reset for ≥140ms after VCC recovers, operates down to VCC = 1V, draws only 12μA supply current, and is AEC-Q100 qualified for automotive use.

For engineers reviewing the MAX803LEXR+T datasheet, MAX803LEXR+T pinout, MAX803LEXR+T application, or MAX803LEXR+T equivalent, key selection criteria include reset threshold accuracy (±1.5% over temperature), open-drain output compatibility with bidirectional μP reset pins, guaranteed operation at VCC = 1V, transient immunity to 20μs/100mV glitches, and automotive-grade qualification in SC70 package.

Technical Context

The MAX803LEXR+T implements a precision voltage comparator with 30ppm/°C tempco to detect VCC droop below its 4.63V nominal threshold. Its reset timeout is internally timed to guarantee ≥140ms assertion after power-up, independent of external components.

Reset assertion is immune to fast transients-negative-going VCC excursions of ≤100mV amplitude are tolerated up to 20μs duration without false triggering. The open-drain output requires an external pullup resistor, enabling level-shifting to higher-voltage logic domains while maintaining compatibility with μPs having bidirectional reset I/O.

Key Specifications

Pinout & Package

MAX803LEXR+T is housed in a 3-pin SC70 package (package code X3+2), with 0.65mm pitch, 1.25mm × 0.85mm footprint, and 0.95mm height - optimized for space-constrained automotive and portable designs.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX803LEXR+T, MAX809LEXR+T simplifies design by eliminating the pullup resistor but sacrifices level-shifting capability, while TLV803E33DBVR serves a different voltage class entirely and cannot replace the 4.63V automotive supervisory function.

Availability

MAX803LEXR+T is available at Aetrix Electronics and suitable for automotive engine control units, industrial programmable logic controllers, and portable medical diagnostic devices requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for MAX803LEXR+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 automotive, industrial, communications, and computing markets.

The MAX803 family delivers highly accurate, low-power reset supervision for microprocessors in harsh environments - specifically engineered for automotive-grade reliability with AEC-Q100 qualification and extended temperature operation.

FAQ

What is the exact reset threshold voltage of the MAX803LEXR+T and how stable is it over temperature?

The MAX803LEXR+T has a nominal reset threshold of 4.63V with ±1.5% tolerance over the full -40°C to +125°C operating range. Its temperature coefficient is 30ppm/°C, meaning the threshold drifts less than 0.014V across the entire temperature span. This stability is verified per AEC-Q100 test conditions and ensures consistent reset behavior in automotive under-hood applications where thermal cycling is severe. The MAX803LEXR+T uses laser-trimmed internal references to achieve this precision without external calibration.

Does the MAX803LEXR+T require an external pullup resistor, and what value is recommended?

Yes, the MAX803LEXR+T requires an external pullup resistor on its open-drain RESET pin because it cannot drive high actively. A 10kΩ to 100kΩ resistor is recommended, connected to the target logic supply (e.g., 3.3V or 5V). Lower values improve noise immunity and rise time but increase static current; higher values reduce current but slow edge transitions. The MAX803LEXR+T datasheet specifies RESET leakage <1μA when deasserted, so even 100kΩ yields negligible voltage drop. This flexibility enables level-shifting - e.g., monitoring a 5V rail while pulling RESET to a 3.3V domain.

Can the MAX803LEXR+T operate reliably at VCC = 1V, and what happens to RESET output below that?

Yes, the MAX803LEXR+T guarantees correct RESET output behavior down to VCC = 1V - the open-drain output remains capable of sinking ≥1.2mA while asserted. Below 1V, the internal circuitry loses drive strength, and RESET transitions to a high-impedance state. In most systems, this is acceptable because μPs and peripherals are nonfunctional below 1V. However, if deterministic low-state maintenance is required down to 0V, a 100kΩ pull-down resistor on RESET is recommended, as documented in Maxim's Application Note for the MAX803LEXR+T.

How does the MAX803LEXR+T handle fast transients on the VCC line, and what is its immunity specification?

The MAX803LEXR+T is designed to ignore fast negative-going VCC transients: it tolerates excursions of up to 100mV below the 4.63V threshold for durations ≤20μs without asserting reset. This immunity is achieved through internal filtering and comparator hysteresis, validated across temperature. The specification is measured per the test method in the MAX803LEXR+T datasheet Figure 1, using controlled pulse injection. A 0.1μF ceramic capacitor placed close to the VCC pin further enhances immunity by shunting high-frequency noise before it reaches the supervisor's input.

Is the MAX803LEXR+T pin-compatible with other members of the MAX803/MAX809/MAX810 family, and what are the key mechanical constraints?

The MAX803LEXR+T uses the SC70-3 package (X3+2), which shares identical pinout (GND, RESET, VCC) and footprint with all SC70-packaged variants in the MAX803/MAX809/MAX810 families, including MAX809LEXR+T and MAX810LEXR+T. However, output type differs: MAX803LEXR+T is open-drain, while MAX809LEXR+T is push-pull active-low and MAX810LEXR+T is push-pull active-high. Mechanical constraints include 0.65mm lead pitch, 1.25mm × 0.85mm body size, and 0.95mm max height - requiring fine-pitch reflow profiles and stencil aperture design per Maxim's land pattern AN6436.