Analog Devices Inc./Maxim Integrated MAX6445UK29L+T

Overview

MAX6445UK29L+T from Maxim Integrated is a dual manual reset microprocessor supervisor IC with fixed 2.925V VCC reset threshold, extended 6.72s 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 provides system reset assertion during brownout or power-up, used in set-top boxes and cable modems where nuisance resets from front-panel switches must be avoided.

For engineers reviewing the MAX6445UK29L+T datasheet, MAX6445UK29L+T pinout, MAX6445UK29L+T application, or MAX6445UK29L+T equivalent, key selection criteria include its dual extended-setup manual reset inputs, 2.925V precision reset threshold, 6.72s minimum button-hold time, 210ms typical reset timeout, and SOT23-5 package compatibility with industrial and consumer embedded systems requiring high noise immunity and low 6µA quiescent current.

Technical Context

The MAX6445UK29L+T implements a dual-input manual reset architecture where both MR1 and MR2 must be held low simultaneously for ≥6.72s to trigger a one-shot 140ms–280ms RESET pulse. Its internal 50kΩ pullup on each MR input enables direct connection to mechanical switches without external components.

VCC monitoring uses a precision bandgap-based comparator with 60ppm/°C tempco and 2×VTH hysteresis. RESET remains asserted for 210ms (typ) after VCC recovers above 2.925V, ensuring stable processor initialization during supply ramp-up or transient recovery.

Key Specifications

Pinout & Package

Package: 5-pin SOT23 (U5+1), footprint compatible with industry-standard 0.95mm pitch land pattern (Maxim outline 21-0057).

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6445UK29S+T, the MAX6445UK29L+T provides stronger protection against accidental resets via its longer 6.72s setup period, while versus TPS3808G33DBVR it delivers unique dual-MR functionality essential for secure service access and industrial HMI safety protocols.

Availability

MAX6445UK29L+T is available at Aetrix Electronics and suitable for set-top boxes, cable modems, industrial HMIs, and medical infusion pumps requiring stable component supply across extended temperature ranges and long product lifecycles.

Supply support for MAX6445UK29L+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 industrial, automotive, communications, and computing markets.

The MAX6443–MAX6452 family was engineered specifically for microprocessor reset supervision in noise-prone consumer and industrial equipment, emphasizing extended manual reset immunity, low quiescent current, and guaranteed operation down to 1.0V VCC.

FAQ

What is the exact reset threshold voltage of the MAX6445UK29L+T?

The MAX6445UK29L+T has a factory-trimmed VCC reset threshold of 2.925V, with guaranteed limits of 2.85V (min) and 3.00V (max) over the full -40°C to +85°C operating range. This value is defined by the "29" suffix per Table 1 in the datasheet and applies specifically to the MAX6445UK29L+T, not other variants in the family.

Does the MAX6445UK29L+T support adjustable voltage monitoring via RSTIN?

No, the MAX6445UK29L+T does not include an RSTIN pin or adjustable threshold capability. It is a single-supply fixed-threshold supervisor (MAX6445 variant), as confirmed by the Pin Description table and Functional Diagram - only MAX6449–MAX6452 devices feature RSTIN.

What is the function of the two manual reset inputs (MR1 and MR2) on the MAX6445UK29L+T?

On the MAX6445UK29L+T, both MR1 and MR2 are active-low manual reset inputs requiring simultaneous assertion for ≥6.72s (L suffix) to generate a one-shot RESET pulse. Neither input functions independently; the dual-input requirement prevents accidental resets and enables secure service-mode activation in applications like set-top boxes and medical devices.

Can the MAX6445UK29L+T operate with a 1.8V supply voltage?

Yes, the MAX6445UK29L+T operates across VCC = 1.0V to 5.5V. At 1.8V, it maintains full functionality: the 2.925V reset threshold remains valid (monitoring higher rails via external divider is not supported), RESET output drives low to <0.3V with 50µA sink, and manual reset timing is preserved. However, VCC must be ≥2.925V for reset deassertion to occur.

Is the RESET output of the MAX6445UK29L+T open-drain or push-pull?

The MAX6445UK29L+T features a push-pull RESET output, as indicated by the "U" prefix in the ordering code (MAX6445UK29L+T) and confirmed in the Pin Description table and Ordering Information section. This eliminates the need for an external pullup resistor in standard 3.3V logic interfaces, unlike open-drain variants such as MAX6446.