Analog Devices Inc./Maxim Integrated MAX6445UK26L+

Overview

MAX6445UK26L+ from Maxim Integrated is a dual-manual-reset, fixed-threshold microprocessor supervisor IC with 2.625V VCC reset threshold, 6.72s extended MR1/MR2 setup period, push-pull active-low RESET output, and guaranteed operation from -40°C to +85°C. It monitors a single supply (VCC) and asserts reset when voltage drops below threshold or when both manual inputs are held low for ≥6.72s - used in set-top boxes and cable modems to prevent nuisance resets from front-panel switches.

For engineers reviewing the MAX6445UK26L+ datasheet, MAX6445UK26L+ pinout, MAX6445UK26L+ application, or MAX6445UK26L+ equivalent, key selection criteria include its dual extended-setup manual reset architecture, 2.625V precision threshold, 210ms typical reset timeout, low 6µA supply current, and SOT23-5 package compatibility with space-constrained consumer electronics designs.

Technical Context

The MAX6445UK26L+ implements a dual-input, synchronized manual reset logic requiring simultaneous assertion of MR1 and MR2 for ≥6.72s to trigger a one-shot 140ms–280ms RESET pulse. Its internal 50kΩ pullup on both MR1 and MR2 eliminates external components while ensuring immunity to sub-6.72s switch bounces.

VCC monitoring uses a precision bandgap-based comparator with 60ppm/°C tempco and 2×VTH hysteresis (≈5.25mV at 2.625V). RESET remains asserted for 210ms (typ) after VCC recovers above threshold, guaranteeing valid reset hold time across the full -40°C to +85°C industrial temperature range.

Key Specifications

Pinout & Package

Package: 5-pin SOT23 (U5+1), 2.9mm × 1.6mm footprint, surface-mount, RoHS-compliant lead(Pb)-free.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6445UK26L+, MAX6445UK26T+ offers faster manual reset activation but sacrifices nuisance immunity, while TPS3808G33DBVR reduces quiescent current by 60% but removes dual-input security - making MAX6445UK26L+ optimal for consumer UIs requiring deliberate, tamper-resistant reset sequences.

Availability

MAX6445UK26L+ is available at Aetrix Electronics and suitable for set-top boxes, cable modems, DVD players, and industrial media players requiring stable component supply, long-life design assurance, and qualified industrial-temperature operation.

Supply support for MAX6445UK26L+ 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, communications, and consumer applications, with expertise in power management and supervisory circuits.

The MAX6443–MAX6452 family was engineered specifically for consumer electronics and networking equipment requiring robust, glitch-immune reset supervision with configurable manual reset timing and low quiescent current.

FAQ

What is the exact reset threshold voltage of the MAX6445UK26L+?

The MAX6445UK26L+ has a factory-set VCC reset threshold of 2.625V, with a guaranteed range of 2.55V to 2.70V at +25°C and ±0.075V tolerance over temperature. This value is defined by the "26" suffix per Table 1 in the datasheet and applies to the primary VCC monitor - no external resistor divider is needed for this function. The MAX6445UK26L+ does not include RSTIN, so it monitors only VCC.

How does the dual manual reset functionality work on the MAX6445UK26L+?

The MAX6445UK26L+ requires both MR1 and MR2 pins to be driven low simultaneously for at least 6.72 seconds (the "L" suffix) to assert the RESET output. Neither input alone triggers reset; both must meet the extended setup period. This dual-input requirement prevents accidental resets from single-button presses and is ideal for service-mode entry or factory recovery sequences in consumer devices.

Is the MAX6445UK26L+ pin-compatible with other parts in the MAX6443–MAX6452 family?

Yes, the MAX6445UK26L+ uses the 5-pin SOT23 (U5+1) package and shares identical pinout with all MAX6445/46/47/48 variants. Pin 1 = GND, Pin 2 = VCC, Pin 3 = MR1, Pin 4 = RESET, Pin 5 = MR2. However, functional differences exist - e.g., MAX6447/48 add immediate-reset MR2 capability, and MAX6449–6452 add RSTIN - so electrical compatibility depends on selected features, not just pin layout.

What is the minimum VCC voltage at which the MAX6445UK26L+ guarantees valid RESET output?

The MAX6445UK26L+ guarantees correct RESET output logic state (low when asserted, high when deasserted) for VCC ≥ 1.0V. Below 1.0V, current-sinking capability degrades, and RESET may float. For applications requiring valid reset down to 0V, a 100kΩ pulldown resistor is recommended on the push-pull RESET output - but this is not needed for standard operation within the 1.0V–5.5V operating range.

Does the MAX6445UK26L+ support open-drain RESET output?

No, the MAX6445UK26L+ features a push-pull RESET output only, as indicated by the "+" suffix and confirmed in the Ordering Information table (MAX6445UKxxL+ = push-pull). Open-drain variants exist in the family (e.g., MAX6446UK26L+) but require different part numbers. The push-pull output drives high actively and does not require an external pullup resistor.