Analog Devices Inc./Maxim Integrated MAX6726KASHD3+

Overview

MAX6726KASHD3+ from Maxim Integrated is a triple-voltage microprocessor supervisory circuit in an 8-pin SOT23 package, monitoring VCC1 (4.625V threshold), VCC2 (3.075V threshold), and RSTIN (adjustable down to 0.626V) with 210ms reset timeout, push-pull RST output, manual reset input, and watchdog timer - used for reliable power-up sequencing and brownout protection in multivoltage embedded systems.

For engineers reviewing the MAX6726KASHD3+ datasheet, MAX6726KASHD3+ pinout, MAX6726KASHD3+ application, or MAX6726KASHD3+ equivalent, key selection criteria include its dual-supply monitoring capability (1.8–5.0V primary, 0.9–3.3V secondary), guaranteed reset validity down to VCC = 0.8V, 14µA typical supply current at 3.6V, and integrated watchdog with 35s startup / 1.12s normal timeout.

Technical Context

The MAX6726KASHD3+ implements independent voltage comparators for VCC1 and VCC2 with factory-trimmed thresholds (4.625V and 3.075V), plus a high-impedance RSTIN input referenced to a 626.5mV internal bandgap reference, enabling precise third-voltage monitoring via external resistor divider. Its reset logic asserts active-low RST for ≥210ms after any monitored supply recovers.

It integrates a dual-mode watchdog timer: 35s minimum initial timeout after reset events (supporting complex boot sequences), transitioning to 1.12s minimum normal timeout after first WDI edge detection; MR input features internal 50kΩ pullup and 200ns response, while RST output is push-pull referenced to VCC1 with VOL ≤ 0.4V at 3.2mA sink.

Key Specifications

Pinout & Package

MAX6726KASHD3+ uses an 8-pin SOT23-8 package (2.0mm × 2.1mm footprint, 1.1mm height), optimized for space-constrained PCB layouts in portable and networking equipment.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6725KAHED3+, MAX6726KASHD3+ provides push-pull RST for direct µP interface without pullup, while versus TPS3808G33DBVR it delivers full triple-supply supervision, adjustable monitoring, and dual-mode watchdog - making it essential for complex multirail systems requiring coordinated reset and runtime fault detection.

Availability

MAX6726KASHD3+ is available at Aetrix Electronics and suitable for telecom infrastructure, industrial PLCs, portable medical devices, and network switch power sequencing requiring stable component supply, long-term lifecycle support, and guaranteed traceable sourcing.

Supply support for MAX6726KASHD3+ 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) is a semiconductor company specializing in high-performance analog, mixed-signal, and power management ICs for industrial, communications, and computing markets.

The MAX6715–MAX6729 family was designed specifically for ultra-low-voltage, multirail microprocessor supervision in space- and power-constrained systems, integrating precision voltage monitoring, watchdog, manual reset, and power-fail functions into minimal SOT23 footprints.

FAQ

What is the exact reset threshold voltage for VCC1 on the MAX6726KASHD3+?

The MAX6726KASHD3+ has a factory-trimmed VCC1 reset threshold of 4.625V (falling), with ±1.5% tolerance over temperature. This value is encoded in the "SH" suffix per Maxim's Reset Voltage Threshold Suffix Guide and is verified across -40°C to +85°C. The threshold remains stable with 20ppm/°C tempco, ensuring consistent behavior in varying thermal environments. MAX6726KASHD3+ guarantees reset assertion before the 5V rail drops below safe µP operating margins.

Does the MAX6726KASHD3+ support monitoring a third voltage, and how is it configured?

Yes, the MAX6726KASHD3+ supports third-voltage monitoring via its RSTIN pin, which references an internal 626.5mV bandgap. To configure, connect an external resistor divider from the target supply to GND, with the midpoint feeding RSTIN. The monitored threshold is calculated as V_EXT = 626.5mV × (R1 + R2)/R2. MAX6726KASHD3+ maintains <25nA input bias, enabling high-resistance dividers that minimize system power draw without sacrificing accuracy.

What are the watchdog timeout periods supported by the MAX6726KASHD3+?

The MAX6726KASHD3+ implements a dual-mode watchdog: a 35s minimum initial timeout after any reset event (power-up, MR, or watchdog-triggered), followed by a 1.12s minimum normal timeout after the first valid WDI edge. This architecture accommodates lengthy boot sequences while ensuring rapid detection of software hangs during runtime. MAX6726KASHD3+ requires no external components to achieve this timing, and the watchdog clears on any WDI transition - high-to-low or low-to-high.

Is the reset output of the MAX6726KASHD3+ push-pull or open-drain?

The MAX6726KASHD3+ features a push-pull RST output referenced to VCC1, capable of sourcing up to 800µA and sinking up to 3.2mA while maintaining VOL ≤ 0.4V. This eliminates the need for an external pullup resistor in most µP reset interfaces. Unlike open-drain variants (e.g., MAX6725), MAX6726KASHD3+ actively drives both logic states, simplifying PCB layout and improving noise immunity in electrically noisy industrial environments.

What is the minimum supply voltage at which the MAX6726KASHD3+ guarantees valid reset operation?

The MAX6726KASHD3+ guarantees correct reset output logic state down to VCC1 or VCC2 = 0.8V, as specified in the Absolute Maximum Ratings and Electrical Characteristics tables. This ensures reliable brownout detection and controlled shutdown even during deep undervoltage conditions. MAX6726KASHD3+ achieves this via internal biasing schemes that remain functional below typical CMOS logic thresholds, making it suitable for battery-powered systems approaching end-of-life voltage.