Analog Devices Inc./Maxim Integrated MAX6740XKSHD3

Overview

The MAX6740XKSHD3 from Maxim Integrated is a triple-voltage microprocessor supervisor IC with two factory-trimmed reset thresholds (VTH1 = 2.925V, VTH2 = 2.188V) and one adjustable RSTIN input (488mV threshold), open-drain RESET output, manual reset detect function, and 150ms minimum reset timeout. It monitors I/O supply (VCC1), core supply (VCC2), and an external rail via RSTIN in portable, multivoltage embedded systems.

For engineers reviewing the MAX6740XKSHD3 datasheet, MAX6740XKSHD3 pinout, MAX6740XKSHD3 application, or MAX6740XKSHD3 equivalent, key selection criteria include triple-supply monitoring capability, 6µA quiescent current, SC70-5 package size, manual reset detect timing (tDEB = 37.5–75ms), and compatibility with low-voltage core rails down to 0.788V.

Technical Context

The MAX6740XKSHD3 implements independent voltage comparators for VCC1, VCC2, and RSTIN against precision internal references (±1.5% over temperature), with hysteresis of 0.5% to reject supply transients. Its reset logic asserts active-low RESET when any monitored input falls below its threshold and holds it for ≥150ms after all inputs recover.

It features an integrated 50kΩ pullup on the open-drain RESET pin enabling pushbutton-driven manual reset detection without external components, debounced internally for 37.5–75ms. The device operates from 1.0V to 5.5V on VCC1 and supports VCC2 monitoring from 0.752V to 3.150V per suffix configuration.

Key Specifications

Pinout & Package

MAX6740XKSHD3 uses a 5-pin SC70-5 package with exposed pad (not electrically connected). 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-supply supervisor applications.

Compared with MAX6743XKSHD3, the MAX6740XKSHD3 provides essential manual reset detect via internal pullup-critical for pushbutton integration-while TPS3808G33DBVR omits the third monitoring channel entirely, limiting applicability in complex multivoltage architectures.

Availability

MAX6740XKSHD3 is available at Aetrix Electronics and suitable for portable/battery-powered equipment, multivoltage systems, and notebook computers requiring stable component supply with guaranteed long-term availability.

Supply support for MAX6740XKSHD3 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 management, sensing, and interface applications.

The MAX6736–MAX6745 family was developed specifically for low-power, space-constrained multivoltage microprocessor supervision in portable and embedded systems.

FAQ

What is the exact reset threshold voltage for VCC1 on the MAX6740XKSHD3?

The MAX6740XKSHD3 has a factory-trimmed VCC1 reset threshold of 2.925V (±1.5%) over the -40°C to +85°C temperature range. This value is defined by the "S" suffix in the part number and is verified per Table 1 of the datasheet. The threshold remains stable across operating conditions, ensuring reliable reset assertion for 3.0V nominal I/O supplies.

Does the MAX6740XKSHD3 support manual reset functionality, and how is it implemented?

Yes, the MAX6740XKSHD3 supports manual reset detection via its open-drain RESET pin, which includes an internal 50kΩ pullup resistor to VCC1. When a pushbutton connects RESET to GND, the device detects the low state, debounces it for 37.5–75ms, and holds RESET low for the full 150ms timeout period after release-no external components required.

What is the purpose of the RSTIN pin on the MAX6740XKSHD3, and what voltage range can it monitor?

The RSTIN pin on the MAX6740XKSHD3 provides a third monitoring channel with a fixed 0.488V internal reference. Using an external resistor divider, it can supervise any supply rail from 0.5V up to 5.0V. For example, a 1.2V rail can be monitored by setting R1/R2 to achieve 0.488V at RSTIN when the rail drops to its fail threshold.

How does the MAX6740XKSHD3 handle simultaneous faults on multiple supply rails?

The MAX6740XKSHD3 asserts RESET immediately if any monitored input (VCC1, VCC2, or RSTIN) falls below its respective threshold. Once asserted, RESET remains low until all three inputs exceed their thresholds for the full 150ms timeout period. If any input dips again during timeout, the timer restarts-ensuring robust fault recovery.

Is the MAX6740XKSHD3 compatible with lead-free PCB assembly processes?

Yes, the MAX6740XKSHD3 is available in lead-free packaging. To order the RoHS-compliant version, replace the standard "-T" suffix with "+T" (e.g., MAX6740XKSHD3+T). The SC70-5 package is rated for standard reflow profiles including JEDEC J-STD-020 moisture sensitivity level 1.