Analog Devices Inc./Maxim Integrated MAX6735KAWGD3+T

Overview

MAX6735KAWGD3+T from Maxim Integrated is a triple-voltage microprocessor supervisor IC with independent watchdog output, monitoring VCC1 (+3.075V threshold), VCC2 (+2.313V threshold), and an adjustable RSTIN input (626mV reference). It features push-pull RESET and WDO outputs, 210ms reset timeout, manual reset input, and operates across –40°C to +85°C - used in multivoltage embedded systems requiring reliable power-on reset and lockup recovery.

For engineers reviewing the MAX6735KAWGD3+T datasheet, MAX6735KAWGD3+T pinout, MAX6735KAWGD3+T application, or MAX6735KAWGD3+T equivalent, key selection considerations include its triple-supply monitoring capability, push-pull active-low reset and watchdog outputs, factory-set dual fixed thresholds plus adjustable third input, 210ms timeout, and SOT23-8 package compatibility with space-constrained industrial and telecom designs.

Technical Context

The MAX6735KAWGD3+T implements a triple-monitor architecture: two factory-trimmed voltage comparators for VCC1 and VCC2, plus a high-impedance adjustable comparator on RSTIN referenced to an internal 626mV bandgap. Its reset logic asserts RST low when any monitored supply falls below its threshold or MR is pulled low, holding assertion for the full 210ms timeout after recovery.

It integrates a dual-mode watchdog timer: a 35s minimum startup delay after reset enables safe system initialization, followed by a 1.12s minimum normal-mode timeout triggered by missing edges on WDI. The push-pull WDO and RST outputs eliminate external pullups and support direct interfacing with bidirectional μP reset pins when used with a 10kΩ series resistor.

Key Specifications

Pinout & Package

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

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6734KAWGD3+T and TPS3808G33DBVR, the MAX6735KAWGD3+T uniquely delivers triple-supply supervision with push-pull outputs and independent watchdog functionality in one SOT23-8 package - enabling higher integration, reduced layout complexity, and faster fault response in multirail embedded systems.

Availability

MAX6735KAWGD3+T is available at Aetrix Electronics and suitable for telecom equipment, industrial PLCs, network switches, and medical point-of-care devices requiring stable component supply, long-term lifecycle support, and guaranteed RoHS-compliant sourcing.

Supply support for MAX6735KAWGD3+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 industrial, automotive, communications, and computing markets.

The MAX6730–MAX6735 family was engineered for high-reliability embedded systems needing simultaneous multi-rail voltage supervision, deterministic reset timing, and robust watchdog protection - targeting applications where system uptime and fail-safe behavior are critical.

FAQ

What is the exact reset threshold voltage for VCC1 on the MAX6735KAWGD3+T?

The MAX6735KAWGD3+T has a factory-set VCC1 reset threshold of +3.075V (falling edge), corresponding to the "TW" suffix in Maxim's threshold coding scheme. This value is guaranteed over –40°C to +85°C with ±1.5% tolerance and 20ppm/°C tempco. The threshold is internally trimmed and does not require external calibration.

Does the MAX6735KAWGD3+T support monitoring a 1.0V supply using the RSTIN pin?

Yes, the MAX6735KAWGD3+T supports monitoring a 1.0V supply via RSTIN using a resistive voltage divider. With its internal 626mV reference, a 1.0V rail requires a divider ratio of ~1.597:1 (e.g., 10.2kΩ top, 1kΩ bottom). The RSTIN input draws only ±25nA, enabling high-resistance dividers that minimize power loss while maintaining accuracy.

What is the function of the WDI pin on the MAX6735KAWGD3+T, and how should it be driven?

The WDI (Watchdog Input) pin on the MAX6735KAWGD3+T must receive periodic rising or falling edges to prevent watchdog timeout. It is not a pulse-input pin - edges should occur at least once every 1.12s (min) during normal operation. Driving WDI high/low at strategic program points (e.g., start of main loop) ensures detection of hangs. Leaving WDI unconnected asserts WDO low continuously.

How does the reset timeout period of 210ms (D3) affect system behavior during power-up?

The 210ms reset timeout (D3 suffix) ensures the MAX6735KAWGD3+T holds RST low for at least 140ms and up to 280ms after all monitored supplies exceed their thresholds. This accommodates slow-ramping DC-DC converters and provides margin for clock stabilization and memory initialization before releasing the microprocessor from reset - preventing premature code execution.

Can the MAX6735KAWGD3+T operate reliably if VCC1 drops to +0.85V?

Yes, the MAX6735KAWGD3+T guarantees valid reset assertion down to VCC1 = +0.8V. At +0.85V, both the internal comparators and reset driver remain fully functional, ensuring RST remains asserted during brownout conditions. This specification is production-tested and enables robust operation in systems with marginal or fluctuating input supplies.