Analog Devices Inc./Maxim Integrated MAX6725KAYHD3+

Overview

MAX6725KAYHD3+ 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 and open-drain RST2 outputs, and integrated watchdog timer - used for reliable power-up sequencing and brownout protection in multivoltage embedded systems.

For engineers reviewing the MAX6725KAYHD3+ datasheet, MAX6725KAYHD3+ pinout, MAX6725KAYHD3+ application, or MAX6725KAYHD3+ equivalent, key selection criteria include dual-supply monitoring with factory-trimmed thresholds, externally adjustable third-voltage supervision, guaranteed reset validity down to VCC = 0.8V, and watchdog startup timing (35s min initial / 1.12s min normal mode).

Technical Context

The MAX6725KAYHD3+ implements independent voltage comparators for VCC1 and VCC2 with ±1.5% threshold accuracy and 20ppm/°C tempco, plus a high-impedance RSTIN input referenced to a 626.5mV internal bandgap. Its dual-mode watchdog uses a long 35s minimum startup period followed by a 1.12s minimum normal timeout, triggered by WDI edge transitions.

Reset assertion is latched and held for a fixed 210ms timeout after any monitored supply recovers; the device guarantees correct reset logic state when either VCC1 or VCC2 ≥ 0.8V, and supports manual reset via MR with 50kΩ internal pullup and 1µs minimum pulse width.

Key Specifications

Pinout & Package

MAX6725KAYHD3+ is housed in an 8-pin SOT23-8 package (2.0mm × 2.1mm × 1.25mm), with exposed pad for thermal enhancement and RoHS-compliant lead-free finish.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6725KAYHD3+, MAX6726KA+T offers identical supervision functionality with dual push-pull outputs for reduced BOM count, while TPS3808G33DBVR provides lower power and cost at the expense of triple-monitoring capability, watchdog, and manual reset - making it a functional subset rather than drop-in replacement.

Availability

MAX6725KAYHD3+ is available at Aetrix Electronics and suitable for industrial PLC controllers, telecom line cards, medical imaging modules, and automotive ADAS ECUs requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for MAX6725KAYHD3+ 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 multivoltage microprocessor systems requiring simultaneous monitoring of primary, secondary, and auxiliary supplies with minimal footprint and guaranteed reset integrity under brownout conditions.

FAQ

What is the exact reset threshold voltage for VCC1 and VCC2 on the MAX6725KAYHD3+?

The MAX6725KAYHD3+ has factory-trimmed reset thresholds of 4.625V for VCC1 and 3.075V for VCC2, with ±1.5% tolerance over the full -40°C to +85°C operating temperature range. These values are encoded in the "YH" suffix per Maxim's Reset Voltage Threshold Suffix Guide and are verified in the Electrical Characteristics table of the official datasheet.

Does the MAX6725KAYHD3+ support monitoring a third voltage, and how is it configured?

Yes, the MAX6725KAYHD3+ supports third-voltage monitoring via the RSTIN pin, which references an internal 626.5mV bandgap. A resistor divider connected between the target supply and ground sets the trip point using the formula V_{EXT_TH} = 626.5mV × (R1 + R2)/R2. The MAX6725KAYHD3+ datasheet confirms RSTIN input current is ±25nA, enabling high-resistance dividers for minimal power draw.

What are the watchdog timeout periods supported by the MAX6725KAYHD3+?

The MAX6725KAYHD3+ implements a dual-mode watchdog: a 35s minimum initial timeout after any reset event (power-up, MR, or watchdog timeout), followed by a 1.12s minimum normal timeout after the first valid WDI edge transition. This architecture is explicitly documented in the "Watchdog Input" section and Electrical Characteristics table of the MAX6725KAYHD3+ datasheet.

What output types does the MAX6725KAYHD3+ provide, and how are they electrically distinguished?

The MAX6725KAYHD3+ provides two reset outputs: Pin 1 (RST) is push-pull, sourcing/sinking current relative to VCC1, while Pin 4 (RST2) is open-drain, requiring an external pullup to VCC2 or another rail. This configuration is confirmed in the Pin Description table and Selector Guide, where MAX6725 is listed with "1" open-drain RST and "1" push-pull RST - matching the physical pin assignments.

Is the MAX6725KAYHD3+ compatible with systems requiring reset assertion below 1.0V supply voltage?

Yes, the MAX6725KAYHD3+ guarantees correct reset output logic state when either VCC1 or VCC2 remains above 0.8V - explicitly stated in the General Description and Absolute Maximum Ratings sections. This enables reliable brownout detection during deep undervoltage events, such as automotive cold-crank conditions, without requiring external level-shifting circuitry.