Analog Devices Inc./Maxim Integrated MAX6451UT26L+

Overview

MAX6451UT26L+ from Maxim Integrated is a dual-supply microprocessor reset supervisor IC with one fixed-threshold (2.625V) and one adjustable-threshold (0.63V reference) voltage monitor, extended manual reset setup period (6.72s), active-low push-pull RESET output, and operation over –40°C to +85°C. It prevents nuisance resets in consumer electronics and industrial equipment by requiring sustained button press before asserting reset.

For engineers reviewing the MAX6451UT26L+ datasheet, MAX6451UT26L+ pinout, MAX6451UT26L+ application, or MAX6451UT26L+ equivalent, key selection considerations include its 2.625V VCC threshold, 6.72s MR1 setup timeout, 0.63V RSTIN reference for external voltage monitoring, 6µA supply current, and SOT23-6 package compatibility with space-constrained embedded designs.

Technical Context

The MAX6451UT26L+ integrates two independent reset comparators: one factory-trimmed at 2.625V for VCC monitoring and one high-impedance RSTIN input referenced to 0.63V for externally adjustable thresholds via resistor divider. Its dual manual reset architecture combines MR1 (extended 6.72s low-time requirement) and MR2 (immediate rising-edge-triggered one-shot pulse), enabling both intentional system reset and smart-card-detect functionality without external debouncing.

Reset assertion follows strict timing hierarchy: VCC or RSTIN falling below threshold triggers 210ms typical timeout; MR1 held low ≥6.72s asserts RESET for ≥140ms; MR2 rising edge immediately pulses RESET for ≥140ms, with internal 210ms debounce on MR2 deassertion to prevent false triggers during card removal. All logic states remain valid down to VCC = 1.0V.

Key Specifications

Pinout & Package

MAX6451UT26L+ is housed in a 6-pin SOT23 package (U6+1 outline, 90-0175 land pattern), measuring 2.9mm × 1.6mm × 1.1mm, suitable for high-density PCB layouts.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6452UT26L+, the MAX6451UT26L+ offers integrated push-pull drive eliminating external components; versus TPS3808G33DBVR, it delivers essential dual-supply supervision and programmable threshold flexibility at the cost of higher quiescent current.

Availability

MAX6451UT26L+ is available at Aetrix Electronics and suitable for set-top boxes, DVD players, smart card readers, industrial PLCs, and medical devices requiring stable component supply across automotive-grade temperature ranges and long product lifecycles.

Supply support for MAX6451UT26L+ 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, communications, and consumer applications.

The MAX6443–MAX6452 family delivers robust, low-power microprocessor supervision with extended manual reset immunity-targeting reliability-critical embedded systems where false resets compromise user experience or safety.

FAQ

What is the exact reset threshold voltage for VCC on the MAX6451UT26L+?

The MAX6451UT26L+ has a factory-set VCC reset threshold of 2.625V, with guaranteed limits of 2.55V (min) and 2.70V (max) over temperature. This value is encoded in the "26" suffix per Maxim's ordering convention and applies specifically to the VCC monitor channel-not the RSTIN input, which uses a separate 0.63V internal reference.

Does the MAX6451UT26L+ support monitoring a 1.8V supply?

Yes-the MAX6451UT26L+ can monitor a 1.8V supply using its RSTIN pin. By connecting an external resistor divider to RSTIN, the 0.63V internal reference sets the trip point: for example, a 1.8V threshold requires R1 = 1.85MΩ when R2 = 250kΩ. The VCC pin remains dedicated to its fixed 2.625V threshold and cannot be repurposed for 1.8V monitoring.

How does the MR2 pin function on the MAX6451UT26L+?

The MR2 pin on the MAX6451UT26L+ is an active-high, edge-triggered manual reset input. A rising edge (low-to-high transition) immediately pulses the RESET output low for ≥140ms. Unlike MR1, MR2 requires no setup time. Its internal 210ms debounce on release prevents false triggers during mechanical switch bounce or smart card removal events.

Is the MAX6451UT26L+ pin-compatible with other devices in the MAX6443–MAX6452 family?

The MAX6451UT26L+ uses a 6-pin SOT23 package and shares identical pinout with MAX6449UTxx+, MAX6450UTxx+, and MAX6452UTxx+. However, it is not pin-compatible with 4-pin (MAX6443/MAX6444) or 5-pin (MAX6445–MAX6448) variants due to differing pin counts and RSTIN/MR2 assignments. Always verify package code (U6+1) and functional table before substitution.

What is the minimum VCC voltage required for valid RESET output operation in the MAX6451UT26L+?

The MAX6451UT26L+ guarantees valid RESET output logic down to VCC = 1.0V. Below this, current-sinking capability degrades rapidly. For applications requiring RESET validity down to 0V, a 100kΩ pulldown resistor must be added to the RESET pin-but only when using the push-pull variant (like MAX6451UT26L+), not open-drain versions.