Analog Devices Inc./Maxim Integrated MAX6734KAYHD3+

Overview

The MAX6734KAYHD3+ from Maxim Integrated is a triple-voltage microprocessor supervisor IC with independent watchdog timer, monitoring VCC1 (4.375V nominal), VCC2 (2.625V nominal), and an adjustable RSTIN input (626mV threshold). It features open-drain RST and WDO outputs, manual reset input (MR), and a 140ms–280ms reset timeout period. It is used in multivoltage embedded systems to ensure reliable power-on initialization and runtime fault detection.

For engineers reviewing the MAX6734KAYHD3+ datasheet, MAX6734KAYHD3+ pinout, MAX6734KAYHD3+ application, or MAX6734KAYHD3+ equivalent, key selection considerations include its dual fixed-threshold + adjustable third-supply monitoring capability, 14µA typical supply current at +3.6V, -40°C to +85°C operation, SOT23-8 package, and compatibility with manual reset and watchdog-driven system recovery.

Technical Context

The MAX6734KAYHD3+ implements a triple-supply supervisory architecture: two factory-set voltage monitors (VCC1 = 4.375V, VCC2 = 2.625V) and one high-impedance adjustable comparator input (RSTIN, 626mV reference) for monitoring a third rail down to +0.63V via external resistor divider. Its reset logic asserts active-low RST when any monitored voltage falls below threshold, MR is pulled low, or RSTIN drops below 626mV.

The device integrates a dual-mode watchdog timer: a 35s minimum startup delay after reset enables full system boot, followed by a 1.12s minimum normal-mode timeout. WDI edge detection clears the timer; absence of transitions triggers open-drain WDO assertion. Both RST and WDO are open-drain, requiring external pullups.

Key Specifications

Pinout & Package

SOT23-8 package: 2.9mm × 1.6mm body, 0.95mm height, gull-wing leads, lead (Pb)-free (RoHS compliant).

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6734KALTD3+, the MAX6734KAYHD3+ offers tighter VCC1/VCC2 thresholds optimized for +3.3V/1.8V systems, while TPS3808G33DBVR lacks RSTIN and dual fixed monitoring-making it unsuitable as a drop-in replacement but viable for simplified designs.

Availability

MAX6734KAYHD3+ is available at Aetrix Electronics and suitable for telecom infrastructure, industrial control, and medical imaging applications requiring stable component supply, guaranteed -40°C to +85°C operation, and RoHS-compliant packaging.

Supply support for MAX6734KAYHD3+ 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 MAX6730–MAX6735 family was engineered specifically for robust, low-power microprocessor supervision in multivoltage embedded systems-emphasizing accurate threshold detection, flexible watchdog timing, and minimal external component count.

FAQ

What is the exact reset threshold voltage for VCC1 and VCC2 on the MAX6734KAYHD3+?

The MAX6734KAYHD3+ has factory-set reset thresholds: VCC1 = 4.375V (±125mV) and VCC2 = 2.625V (±125mV), per the 'YH' suffix in its part number. These values are guaranteed over -40°C to +85°C and include 0.5% hysteresis. The RSTIN input uses a precise 626mV internal reference for third-rail monitoring.

Does the MAX6734KAYHD3+ support manual reset, and how is it implemented?

Yes, the MAX6734KAYHD3+ includes an active-low manual reset input (MR) on Pin 7. It features an internal 50kΩ pullup to VCC1, accepts 1µs minimum pulse width, and rejects noise spikes under 100ns. Driving MR low forces RST assertion for the full reset timeout period (140–280ms), making it ideal for field service or test-mode resets without power cycling.

What is the watchdog timeout behavior of the MAX6734KAYHD3+ during system startup?

The MAX6734KAYHD3+ implements a dual-mode watchdog: after any reset event (power-up, brownout, or MR), it enters a 35s minimum startup delay (tWD-L) to allow full system initialization. Once the first valid WDI edge occurs-or after 35s expires-it switches to normal mode with a 1.12s minimum timeout (tWD-S), enabling rapid lockup detection during steady-state operation.

Can the MAX6734KAYHD3+ monitor a +1.0V supply, and how is that configured?

Yes, the MAX6734KAYHD3+ can monitor a +1.0V supply using its RSTIN pin (Pin 5). Since RSTIN compares against a fixed 626mV internal reference, connect a resistive voltage divider from the +1.0V rail to RSTIN such that the divided voltage equals 626mV at the pin. For example, use R1 = 600kΩ and R2 = 1MΩ to scale +1.0V down to ~625mV, ensuring accuracy within tolerance.

What package type and RoHS status does the MAX6734KAYHD3+ use?

The MAX6734KAYHD3+ is supplied in an 8-pin SOT23 package (2.9mm × 1.6mm), lead (Pb)-free and RoHS compliant, indicated by the '+' suffix. Its thermal characteristics include θJA = 180°C/W and θJC = 60°C/W, supporting reliable operation in compact, thermally constrained designs without heatsinking.