Analog Devices Inc./Maxim Integrated MAX6726KARVD3+

Overview

MAX6726KARVD3+ from Maxim Integrated is a triple-voltage microprocessor supervisory circuit in an 8-pin SOT23 package, monitoring VCC1 (primary), VCC2 (secondary), and RSTIN (auxiliary) supply rails with factory-trimmed thresholds of 2.925V (VTH1), 2.188V (VTH2), and 626.5mV (RSTIN reference). It provides push-pull active-low RST and RST2 outputs, manual reset input (MR), watchdog timer (1.12s normal / 35s startup timeout), and guaranteed reset validity down to VCC1 or VCC2 = 0.8V - used in multivoltage embedded systems requiring reliable power-on reset and brownout detection.

For engineers reviewing the MAX6726KARVD3+ datasheet, MAX6726KARVD3+ pinout, MAX6726KARVD3+ application, or MAX6726KARVD3+ equivalent, key selection considerations include its triple-supply monitoring capability, 210ms (min) reset timeout, push-pull output drive referenced to VCC1/VCC2, -40°C to +85°C industrial temperature range, and compatibility with low-voltage core/I/O domains in telecom, computing, and portable equipment.

Technical Context

The MAX6726KARVD3+ implements dual independent voltage comparators for VCC1 and VCC2, plus a dedicated high-impedance RSTIN comparator with 626.5mV internal reference, enabling precise third-rail monitoring via external resistor divider. Its reset logic asserts RST and RST2 simultaneously on any threshold violation and holds both outputs low for a minimum 210ms timeout after all monitored voltages recover.

This device integrates a dual-mode watchdog timer: a 35s (min) initial timeout after reset enables full system boot, followed by a 1.12s (min) normal mode requiring periodic WDI transitions. MR input features internal 50kΩ pullup to VCC1 and 200ns propagation delay, while RST/RST2 outputs are push-pull with VOH ≥ 0.8×VCC and VOL ≤ 0.4V at 3.2mA sink.

Key Specifications

Pinout & Package

MAX6726KARVD3+ is housed in an 8-pin SOT23-8 package (2.0mm × 2.1mm × 1.25mm), optimized for space-constrained PCB layouts while supporting thermal performance up to +85°C ambient.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6726KARVD3+, MAX6725KAURD3+ offers identical supervision functionality but requires external pullups due to open-drain outputs, while TPS3808G33DBVR reduces feature set (no RSTIN, MR, or watchdog) and package size to lower BOM cost in simpler dual-rail systems.

Availability

MAX6726KARVD3+ is available at Aetrix Electronics and suitable for telecom infrastructure, industrial PLCs, portable medical devices, and consumer set-top boxes requiring stable component supply, long-term lifecycle support, and guaranteed industrial temperature operation.

Supply support for MAX6726KARVD3+ 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, mixed-signal, and power management ICs for demanding industrial, automotive, and communications applications.

The MAX6715–MAX6729 family delivers ultra-low-voltage, multi-rail supervisory circuits targeting space-constrained, battery-powered, and multivoltage embedded systems needing robust power-on reset and brownout protection.

FAQ

What is the exact reset timeout period of the MAX6726KARVD3+?

The MAX6726KARVD3+ has a minimum reset timeout period of 210ms, specified by the "D3" suffix in its part number. This value is guaranteed over the full -40°C to +85°C operating temperature range and ensures sufficient hold time for microprocessor and peripheral initialization before release. The actual timeout may vary slightly with temperature and supply voltage but remains ≥210ms under all specified conditions.

Does the MAX6726KARVD3+ support monitoring a third voltage rail?

Yes, the MAX6726KARVD3+ supports third-rail monitoring via its RSTIN/PFI pin, which uses a precise 626.5mV internal reference voltage. By connecting an external resistor divider from the target supply to GND with RSTIN at the midpoint, users can configure custom reset thresholds down to 0.62V. This feature enables supervision of auxiliary rails such as battery backup, analog sensors, or FPGA configuration supplies.

How does the watchdog timer operate in the MAX6726KARVD3+?

The MAX6726KARVD3+ incorporates a dual-mode watchdog timer: a 35s (minimum) startup timeout after power-on or reset, followed by a 1.12s (minimum) normal timeout once the first valid WDI transition occurs. This architecture accommodates lengthy boot sequences while providing rapid response to software hangs. The timer resets on any rising or falling edge at WDI and asserts RST/RST2 if no transition occurs within the active timeout window.

What are the output drive capabilities of RST and RST2 on the MAX6726KARVD3+?

RST and RST2 are push-pull outputs referenced to VCC1 and VCC2 respectively. Each can source ≥200µA at VOH ≥ 0.8×VCC and sink ≥3.2mA at VOL ≤ 0.4V. This eliminates external pullup resistors and allows direct connection to microprocessor reset inputs. The outputs remain valid even when VCC1 or VCC2 drops to 0.8V, ensuring deterministic behavior during brownout recovery.

Can the MAX6726KARVD3+ be used in systems with bidirectional reset pins?

Yes, the MAX6726KARVD3+ is compatible with microprocessors featuring bidirectional reset I/O. Its push-pull RST and RST2 outputs provide strong logic levels that prevent contention. For robust interfacing, a 4.7kΩ series resistor between RST and the µP's reset pin is recommended to isolate driver strength and accommodate bidirectional signaling without risk of latch-up or excessive current draw.