Analog Devices Inc./Maxim Integrated MAX6735KAZID3+

Overview

The MAX6735KAZID3+ from Maxim Integrated is a triple-voltage microprocessor supervisor IC with independent watchdog output, monitoring VCC1 (+2.25V nominal), VCC2 (+2.313V nominal), and an adjustable RSTIN input (626mV threshold). It features push-pull RESET and WDO outputs, 140ms–280ms reset timeout (D3 option), and operates across –40°C to +85°C. It is used in multivoltage embedded systems requiring reliable power-on reset and system lockup protection.

For engineers reviewing the MAX6735KAZID3+ datasheet, MAX6735KAZID3+ pinout, MAX6735KAZID3+ application, or MAX6735KAZID3+ equivalent, key selection considerations include its triple-supply monitoring capability, push-pull active-low reset and watchdog outputs, factory-set dual fixed thresholds (Z/V suffixes), adjustable third-voltage input, and SOT23-8 package compatibility with space-constrained industrial and telecom designs.

Technical Context

The MAX6735KAZID3+ implements a triple-threshold supervisory architecture: two factory-trimmed comparators for VCC1 and VCC2 (2.25V and 2.313V respectively), plus a high-impedance RSTIN comparator referenced to a 626mV internal bandgap. Its dual-mode watchdog timer provides a 35s minimum startup delay after reset and a 1.12s minimum normal-mode timeout, cleared by edges on WDI.

Reset assertion is synchronized to voltage recovery: RST remains low for the full D3 timeout period (140–280ms) after all monitored voltages exceed their thresholds and MR releases. The push-pull RST and WDO outputs drive loads directly without external pullups, supporting bidirectional μP reset pins when isolated with a 10kΩ series resistor.

Key Specifications

Pinout & Package

SOT23-8 package: 2.9mm × 1.6mm footprint, 1.1mm height, thermal resistance θJA = 180°C/W, rated for 444.4mW continuous dissipation at +70°C ambient.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6734KAZID3+ and TPS3808G33DBVR, the MAX6735KAZID3+ uniquely combines triple-supply monitoring, push-pull outputs, and manual reset in an 8-pin SOT23-enabling compact, high-integrity supervision where multiple rails and deterministic reset drive are mandatory.

Availability

MAX6735KAZID3+ is available at Aetrix Electronics and suitable for telecom infrastructure, industrial PLCs, medical imaging devices, and automotive infotainment systems requiring stable component supply over extended product lifecycles.

Supply support for MAX6735KAZID3+ 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, communications, and computing applications.

The MAX6730–MAX6735 family was engineered specifically for high-reliability μP-based systems needing multi-rail voltage supervision, deterministic reset timing, and independent watchdog enforcement in minimal footprints.

FAQ

What is the exact reset threshold voltage for VCC1 on the MAX6735KAZID3+?

The MAX6735KAZID3+ has a VCC1 reset threshold of 2.25V (minimum), 2.313V (typical), and 2.375V (maximum), corresponding to the 'Z' suffix in its part number. This threshold is factory-trimmed and guaranteed over the full –40°C to +85°C operating range, with ±20ppm/°C tempco and 0.5% hysteresis referenced to typical value.

Does the MAX6735KAZID3+ support monitoring a third voltage higher than 626mV?

Yes, the MAX6735KAZID3+ supports monitoring voltages above 626mV using its RSTIN pin. Connect a resistive voltage divider between the target supply and GND, with the divider's midpoint fed to RSTIN. The internal 626mV reference compares against the divided voltage, enabling precise supervision of any rail up to VCC1 (e.g., +5V monitored as +3.3V via 2:1 divider).

What is the function of the MR pin on the MAX6735KAZID3+ and how should it be used?

The MR (Manual Reset) pin on the MAX6735KAZID3+ is an active-low input that forces RST assertion when pulled low. It includes a 50kΩ internal pullup to VCC1, so leaving it open defaults to inactive. For hardware reset, connect a momentary switch from MR to GND; no external debounce is needed. MR also clears the watchdog timer and deasserts WDO when asserted.

How does the watchdog timer operate on the MAX6735KAZID3+ during system startup?

The MAX6735KAZID3+ watchdog timer starts in a 35s minimum startup mode after any reset event (power-up, brownout, or MR assertion). This extended initial period allows complete system initialization before watchdog enforcement begins. After the first valid edge on WDI-or after 35s expires-the timer switches to normal mode with a 1.12s minimum timeout, providing rapid hang detection during runtime.

Can the MAX6735KAZID3+ operate reliably when VCC1 drops below 1.0V?

Yes, the MAX6735KAZID3+ guarantees valid reset assertion down to VCC1 = +0.8V. Its internal circuitry maintains proper comparator and output driver functionality across this range. However, for applications requiring RST to remain valid down to 0V, a 100kΩ pulldown resistor from RST to GND is recommended-though this is unnecessary for push-pull outputs like those on the MAX6735KAZID3+.