Analog Devices Inc./Maxim Integrated MAX6725KAVHD3+T

Overview

MAX6725KAVHD3+T 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, watchdog timer, manual reset input, and push-pull/open-drain RST/RST2 outputs - used in multivoltage telecom and industrial systems for reliable power-up sequencing and brownout protection.

For engineers reviewing the MAX6725KAVHD3+T datasheet, MAX6725KAVHD3+T pinout, MAX6725KAVHD3+T application, or MAX6725KAVHD3+T equivalent, key selection criteria include dual active-low reset outputs (RST and RST2), factory-trimmed dual voltage thresholds, 210ms guaranteed minimum reset timeout, 35s startup + 1.12s normal watchdog mode, and operation down to VCC = 0.8V with valid reset assertion.

Technical Context

The MAX6725KAVHD3+T integrates three independent voltage monitors: primary supply (VCC1) with 4.625V ±1.5% threshold, secondary supply (VCC2) with 3.075V ±1.5% threshold, and externally adjustable RSTIN referenced to 626.5mV internal bandgap. It features dual reset outputs - RST (push-pull, VCC1-referenced) and RST2 (push-pull, VCC2-referenced) - each asserting low on any monitored fault and holding for 210ms min after recovery.

Its watchdog architecture provides a 35s minimum initial timeout after power-on or reset, transitioning to 1.12s minimum normal timeout after first WDI edge detection; MR input includes 50kΩ internal pullup and 1µs minimum pulse width support; PFI/PFO are not present - confirmed by Selector Guide and pin mapping for MAX6725.

Key Specifications

Pinout & Package

MAX6725KAVHD3+T is housed in an 8-pin SOT23-8 package (2.0mm × 2.1mm × 1.25mm), optimized for high-density PCB layouts in space-constrained telecom and embedded applications.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6725KAVHD3+T, MAX6726KA-VHD3+T offers reduced drive flexibility on RST2, while TPS3808G33DBVR lacks triple monitoring and watchdog functionality - making MAX6725KAVHD3+T uniquely suited for complex multivoltage systems requiring coordinated, domain-specific reset control and software liveness assurance.

Availability

MAX6725KAVHD3+T is available at Aetrix Electronics and suitable for telecom infrastructure, industrial automation, and medical imaging equipment requiring stable component supply, long-term lifecycle support, and guaranteed performance across extended temperature ranges.

Supply support for MAX6725KAVHD3+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, mixed-signal, and power management ICs for demanding industrial, automotive, and communications applications.

The MAX6715–MAX6729 family delivers ultra-low-voltage, multirail supervisory circuits targeting space-constrained, high-reliability systems where coordinated power sequencing and fault detection are critical.

FAQ

What is the reset timeout period for MAX6725KAVHD3+T?

The MAX6725KAVHD3+T has a guaranteed minimum reset timeout period of 210ms, indicated by the "D3" suffix in its part number. This duration ensures sufficient hold time for complex digital systems such as FPGAs and microprocessors to complete power-up initialization before release. The actual timeout may vary slightly with temperature and supply voltage but remains ≥210ms across the full -40°C to +85°C operating range. MAX6725KAVHD3+T uses this fixed timeout to simplify system timing design without requiring external components.

Does MAX6725KAVHD3+T support power-fail monitoring (PFI/PFO)?

No, MAX6725KAVHD3+T does not include power-fail input (PFI) or power-fail output (PFO) functionality. According to the official Selector Guide and pin configuration table, MAX6725 supports RSTIN-based third-supply monitoring and watchdog input (WDI), but explicitly omits PFI/PFO - features reserved for MAX6728/MAX6729 variants. MAX6725KAVHD3+T relies on its RSTIN pin for auxiliary voltage supervision instead of dedicated power-fail circuitry.

What are the voltage threshold levels set by the "KA" suffix in MAX6725KAVHD3+T?

The "KA" suffix in MAX6725KAVHD3+T specifies factory-trimmed reset thresholds of 4.625V for VCC1 and 3.075V for VCC2, per Maxim's Reset Voltage Threshold Suffix Guide. These values are laser-trimmed during production and guaranteed over temperature (±1.5% max deviation). The KA combination targets systems with 5V primary and 3.3V secondary rails, enabling accurate brownout detection without external resistor networks. MAX6725KAVHD3+T uses these fixed thresholds to eliminate calibration overhead in production.

Can MAX6725KAVHD3+T monitor a 1.2V supply using the RSTIN pin?

Yes, MAX6725KAVHD3+T can monitor a 1.2V supply via the RSTIN pin using a resistor divider network. With a fixed 626.5mV internal reference, a 1.2V rail requires R1/R2 ≈ 0.91 (e.g., R1 = 91kΩ, R2 = 100kΩ) to set the trip point at 1.2V × (R2/(R1+R2)) = 626.5mV. The RSTIN input draws only ±25nA, enabling high-value resistors that minimize power loss. MAX6725KAVHD3+T thus supports precise third-rail supervision without additional ICs or calibration.

What is the function of the WDI pin on MAX6725KAVHD3+T?

The WDI (Watchdog Input) pin on MAX6725KAVHD3+T monitors microprocessor activity to detect software hangs. If no rising or falling edge occurs within 1.12s (normal mode) or 35s (startup mode), the watchdog triggers RST assertion for 210ms. After any reset event, it enters 35s startup mode, then transitions to 1.12s mode upon first WDI edge. MAX6725KAVHD3+T uses this dual-mode architecture to accommodate long boot sequences while enforcing strict runtime liveness checks.