Analog Devices Inc./Maxim Integrated MAX6740XKYHD3

Overview

The MAX6740XKYHD3 from Maxim Integrated is a triple-voltage microprocessor supervisor IC with two factory-trimmed reset thresholds (VTH1 = 2.188V, VTH2 = 1.575V) and one adjustable RSTIN input (488mV threshold), open-drain RESET output, manual reset detect function, and 150ms minimum reset timeout period. It monitors I/O and core supply rails in portable multivoltage systems and asserts reset if any monitored voltage falls below its threshold.

For engineers reviewing the MAX6740XKYHD3 datasheet, MAX6740XKYHD3 pinout, MAX6740XKYHD3 application, or MAX6740XKYHD3 equivalent, key selection criteria include its SC70-5 package footprint, 6µA quiescent current, dual fixed + single adjustable voltage monitoring capability, pushbutton-compatible manual reset detect, and -40°C to +85°C industrial temperature range.

Technical Context

The MAX6740XKYHD3 implements a triple-supply supervisory architecture with independent comparators for VCC1 (2.188V threshold), VCC2 (1.575V threshold), and RSTIN (488mV internal reference). Its reset logic combines ORed fault detection across all three inputs with a single 150ms timeout timer that restarts on any new threshold violation.

It features an integrated 50kΩ internal pullup on the open-drain RESET pin for manual reset detect functionality, eliminating external components when interfacing with momentary pushbuttons. The device operates from 1.2V to 5.5V supply range and guarantees valid reset state down to VCC1 ≥ 1.2V.

Key Specifications

Pinout & Package

MAX6740XKYHD3 uses a 5-pin SC70-5 package with 0.65mm pitch, measuring 1.6mm × 1.6mm × 0.9mm (max height). Pin 1 is RESET (open-drain active-low), Pin 2 is GND, Pin 3 is RSTIN (adjustable threshold input), Pin 4 is VCC2 (secondary supply monitor), and Pin 5 is VCC1 (primary supply monitor).

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6740XKYHD3, MAX6743XKYHD3 trades manual reset convenience for stronger push-pull drive, while TPS3808G33DBVR reduces integration by omitting the adjustable third monitor - making MAX6740XKYHD3 optimal for compact triple-rail designs demanding minimal BOM count and pushbutton simplicity.

Availability

MAX6740XKYHD3 is available at Aetrix Electronics and suitable for portable medical sensors, notebook power management, industrial handheld terminals, and GPS tracking modules requiring stable component supply with guaranteed long-term availability.

Supply support for MAX6740XKYHD3 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 power, sensing, and interface applications in industrial, automotive, and computing markets.

The MAX6736–MAX6745 product line delivers ultra-low-power, space-efficient microprocessor supervisors optimized for battery-powered and multivoltage embedded systems requiring reliable power-on reset and supply monitoring.

FAQ

What is the exact reset threshold voltage for VCC1 on the MAX6740XKYHD3?

The MAX6740XKYHD3 has a factory-trimmed VCC1 reset threshold of 2.188V, with ±0.05V tolerance over the full -40°C to +85°C temperature range. This value is confirmed in Table 1 of the datasheet under suffix "Y", and applies specifically to the MAX6740XKYHD3 variant - not the broader MAX6740 family. The threshold remains stable across supply voltages from 1.2V to 5.5V.

Does the MAX6740XKYHD3 support manual reset functionality, and how is it implemented?

Yes, the MAX6740XKYHD3 supports manual reset via its RESET pin, which features an internal 50kΩ pullup resistor to VCC1. When a momentary switch connects RESET to GND, the device detects the low pulse and holds RESET low for the full 150ms timeout period after release. This eliminates external pullup components and simplifies PCB layout compared to traditional MR-input supervisors.

What is the purpose of the RSTIN pin on the MAX6740XKYHD3, and what voltage range can it monitor?

The RSTIN pin on the MAX6740XKYHD3 provides a third adjustable voltage monitoring input with a precise 0.488V internal reference. Using an external resistor divider, it can monitor supply voltages from 0.5V up to 5.5V. For example, a 100kΩ/10kΩ divider enables monitoring of a 5.5V rail, while a 10kΩ/1kΩ divider supports 0.55V - making MAX6740XKYHD3 suitable for ultra-low-voltage SoC cores and analog bias supplies.

How does the MAX6740XKYHD3 handle simultaneous voltage faults across VCC1, VCC2, and RSTIN?

The MAX6740XKYHD3 uses OR-logic across all three monitored inputs: RESET asserts low if *any* of VCC1, VCC2, or RSTIN falls below its respective threshold. The 150ms timeout timer starts upon first fault detection and resets on any subsequent threshold violation - ensuring reset remains asserted until all three supplies remain above their thresholds for a continuous 150ms window, preventing spurious releases during recovery.

Is the MAX6740XKYHD3 compatible with bidirectional microprocessor reset pins?

Yes, the MAX6740XKYHD3's open-drain RESET output is fully compatible with bidirectional µP reset I/O pins. Its 50kΩ internal pullup ensures proper logic-high idle state, and the open-drain structure prevents contention when the µP drives the line low. No series resistor is needed - unlike push-pull supervisors - simplifying interface design and reducing component count in systems like ARM Cortex-M based controllers.