Analog Devices Inc./Maxim Integrated MAX6445UK16L+T

Overview

MAX6445UK16L+T from Maxim Integrated is a dual manual reset microprocessor supervisor IC with fixed 1.575V VCC reset threshold, 6.72s extended setup period for both MR1 and MR2 inputs, push-pull active-low RESET output, and guaranteed operation from -40°C to +85°C in 5-pin SOT23 package. It monitors VCC only (no RSTIN), asserts RESET when VCC drops below threshold or when both MR1/MR2 are held low ≥6.72s, and holds RESET low for 210ms (typ) after recovery.

For engineers reviewing the MAX6445UK16L+T datasheet, MAX6445UK16L+T pinout, MAX6445UK16L+T application, or MAX6445UK16L+T equivalent, key selection criteria include its dual extended-setup manual reset architecture, 1.575V precision threshold, 6.72s tMR timing, push-pull output drive capability, and immunity to short switch closures - critical for set-top boxes, cable modems, and industrial equipment requiring robust system reset control.

Technical Context

The MAX6445UK16L+T implements a dual-input manual reset logic where both MR1 and MR2 must be held low simultaneously for ≥6.72s (tMR) to trigger a one-shot RESET pulse; it ignores transitions shorter than this period. Its internal comparator continuously monitors VCC against a factory-trimmed 1.575V threshold with ±0.045V tolerance and 60ppm/°C tempco.

RESET assertion is synchronized to VCC drop events with 20µs delay (tRD), and deassertion occurs after all monitored supplies exceed their thresholds plus a 210ms timeout (tRP typ). The device uses BiCMOS process, draws only 6µA at 3.6V, and guarantees valid RESET down to VCC = 1.0V.

Key Specifications

Pinout & Package

MAX6445UK16L+T is housed in a 5-pin SOT23 package (package code U5+1, outline 21-0057), with exposed pad not electrically connected. Pin 1 is GND, pin 2 is VCC, pin 3 is MR1, pin 4 is RESET, and pin 5 is MR2 - all pins rated for -0.3V to +6V absolute maximum voltage.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6445UK16K+T (10.08s tMR) and MAX6445UK16S+T (3.36s tMR), the MAX6445UK16L+T provides the optimal balance between accidental press immunity and user experience in mid-tier consumer electronics - its 6.72s window rejects brief contact while remaining practical for service personnel and end users.

Availability

MAX6445UK16L+T is available at Aetrix Electronics and suitable for set-top boxes, cable/DSL modems, and industrial HMIs requiring stable component supply across extended temperature ranges and long product lifecycles.

Supply support for MAX6445UK16L+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, communications, and consumer applications, with emphasis on power management, sensing, and interface solutions.

The MAX6443–MAX6452 family was developed specifically for robust microprocessor supervision in noise-prone consumer and industrial environments, featuring extended manual reset timing to eliminate false triggers from mechanical switch bounce or ESD events.

FAQ

What is the exact reset threshold voltage for MAX6445UK16L+T?

The MAX6445UK16L+T has a factory-trimmed VCC reset threshold of 1.575V, with a guaranteed tolerance of ±0.045V over the full -40°C to +85°C temperature range. This value is confirmed in Table 1 of the datasheet under suffix "16", and applies exclusively to the VCC monitoring function - the device does not include RSTIN and therefore does not support adjustable threshold monitoring.

How does the dual manual reset function work on MAX6445UK16L+T?

The MAX6445UK16L+T requires both MR1 and MR2 inputs to be held low simultaneously for the full 6.72s extended setup period (tMR) before asserting the RESET output. Neither input alone triggers reset; the dual-input requirement is hardwired in silicon and provides immunity to single-point failures or unintended button presses. After assertion, RESET remains low for 210ms (typ) regardless of MR1/MR2 state.

Does MAX6445UK16L+T support open-drain RESET output?

No, MAX6445UK16L+T features a push-pull RESET output only. The "U" in the package code (UK16L+T) indicates SOT23-5 packaging, and the ordering table confirms MAX6445 variants with "U" prefix and no "/V" suffix are push-pull configured. Open-drain versions exist in the family (e.g., MAX6446UK16L+T) but require explicit part number differentiation - MAX6445UK16L+T does not support open-drain operation.

What is the minimum VCC voltage required for MAX6445UK16L+T to guarantee valid RESET output?

MAX6445UK16L+T guarantees valid RESET output logic state down to VCC = 1.0V. Below this voltage, the internal circuitry cannot maintain specified sink current or output voltage levels. The datasheet explicitly states "Guaranteed Valid Reset Down to VCC = 1.0V" as a key feature, and electrical characteristics confirm VOL ≤ 0.3V at ISINK = 1.2mA for VCC ≥ 2.55V and similar performance down to 1.0V.

Can MAX6445UK16L+T monitor an external voltage using RSTIN?

No, MAX6445UK16L+T does not include an RSTIN pin and cannot monitor external voltages. It is a single-supply VCC-only supervisor (per Pin Configuration table and Functional Diagram). RSTIN capability is exclusive to MAX6449–MAX6452 variants (6-pin SOT23), which have dedicated RSTIN terminals and adjustable threshold architecture - MAX6445UK16L+T lacks both the pin and internal comparator circuitry for RSTIN functionality.