Analog Devices Inc./Maxim Integrated MAX812MEUS

Overview

MAX812MEUS from Maxim Integrated is an active-high microprocessor supervisory circuit in a 4-pin SOT143 package, designed to monitor 4.38V power supplies and assert reset during brownout, power-up, or power-down events. It delivers 6µA supply current, guarantees 140ms minimum reset pulse width, and features manual reset input with internal 20kΩ pull-up for portable and battery-powered µP systems.

For engineers reviewing the MAX812MEUS datasheet, MAX812MEUS pinout, MAX812MEUS application, or MAX812MEUS equivalent, key selection criteria include reset threshold accuracy (±1.5% over temperature), VCC transient immunity (40µs at 125mV overdrive), guaranteed RESET validity down to VCC = 1V, and compatibility with TTL/CMOS logic levels on MR.

Technical Context

The MAX812MEUS implements a precision voltage comparator with factory-trimmed 4.38V reset threshold and 30ppm/°C tempco, coupled to a monostable timer that enforces ≥140ms reset assertion after VCC recovery. Its internal MR pull-up eliminates external components while supporting momentary switch or logic-driven reset initiation.

Reset output behavior is strictly level-sensitive: RESET remains high when VCC < 4.38V or MR is low, and stays high for tRP = 140–560ms after both conditions clear. The device ignores transients ≤40µs (at 125mV overdrive) and operates across -40°C to +85°C with no external capacitors required.

Key Specifications

Pinout & Package

MAX812MEUS uses a 4-pin SOT143 package (4.0 × 2.0 × 1.75 mm), surface-mount, lead-free compatible. Pin 1 = VCC, Pin 2 = MR, Pin 3 = RESET, Pin 4 = GND.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar voltage supervisor applications.

Compared with TPS3124E-43 and ADM6712S-43ARTZ, the MAX812MEUS uniquely balances 4.38V precision, 6µA consumption, integrated MR pull-up, and 140ms reset timing in a legacy-compatible SOT143 footprint - making it optimal for cost-sensitive industrial designs requiring proven field reliability.

Availability

MAX812MEUS is available at Aetrix Electronics and suitable for industrial PLC controllers, portable medical devices, automotive body control modules, smart energy meters, and battery-backed real-time clock systems requiring stable component supply across long production lifecycles.

Supply support for MAX812MEUS 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, with emphasis on power management and interface solutions.

The MAX812MEUS belongs to Maxim's µP supervisory product line, engineered specifically for deterministic reset generation in resource-constrained embedded systems where supply voltage integrity directly impacts firmware stability and safety compliance.

FAQ

What is the exact reset threshold voltage for MAX812MEUS?

The MAX812MEUS has a nominal reset threshold voltage of 4.38V, with guaranteed accuracy of ±1.5% over the full -40°C to +85°C temperature range. This value is factory-trimmed and specified in the Electrical Characteristics table under VTH parameter for the 'M' suffix variant. The threshold is referenced to the VCC pin and remains stable against supply ripple due to internal hysteresis design.

Does MAX812MEUS require external components for basic operation?

No, the MAX812MEUS requires no external components for core supervision functionality. It integrates a 20kΩ internal pull-up resistor on the MR pin and a factory-calibrated voltage reference, enabling direct connection to VCC, GND, MR (via switch or logic), and the µP reset input. Only optional 0.1µF bypass capacitor on VCC is recommended for enhanced transient immunity in noisy environments.

How does the manual reset (MR) input behave on MAX812MEUS?

The MR input on MAX812MEUS is active-low with internal 20kΩ pull-up to VCC. When pulled ≤0.25×VCC, it asserts RESET high immediately and holds it high for ≥140ms after MR returns high. MR accepts TTL/CMOS logic levels and can be driven by open-drain outputs or a momentary switch to GND - no external debounce circuitry is needed due to internal synchronization logic.

Can MAX812MEUS operate reliably at VCC = 1V?

Yes, the MAX812MEUS RESET output remains valid and correctly asserted down to VCC = 1V. Below 1V, the output stage enters high-impedance state, but for VCC ≥1V, VOH is guaranteed ≥0.8×VCC (with ISOURCE = 150µA) and VOL ≤0.4V (with ISINK = 3.2mA), ensuring robust interface with 5V µP reset inputs throughout the operational range.

What is the maximum allowable VCC transient duration that will not trigger reset on MAX812MEUS?

For a 125mV overdrive (VTH – VCC = 125mV), the MAX812MEUS is immune to negative-going VCC transients ≤40µs in duration. This immunity is specified for the L/M versions (including MAX812MEUS) and verified across temperature. Transients exceeding this width or magnitude will cause the internal comparator to trip and initiate reset, ensuring reliable brownout detection without false triggers.