Analog Devices Inc./Maxim Integrated MAX6309UK46D4-T

Overview

MAX6309UK46D4-T from Maxim Integrated is a 5-pin SOT23 programmable supervisory circuit that monitors VCC (factory-set 4.63V threshold), an external undervoltage input (RST IN), and a manual-reset input (MR) to assert an active-low push/pull RESET signal. It guarantees valid reset down to VCC = 1V, features 8µA supply current, and provides 1120ms minimum reset timeout. It is used in multivoltage embedded systems requiring reliable power-on and brownout reset control.

For engineers reviewing the MAX6309UK46D4-T datasheet, MAX6309UK46D4-T pinout, MAX6309UK46D4-T application, or MAX6309UK46D4-T equivalent, key selection considerations include its factory-programmed 4.63V ±2.5% VCC reset threshold, 1120ms timeout, push/pull RESET output with 0.3V VOL at 1.2mA sink, MR input with 63.5kΩ internal pullup, and immunity to fast VCC transients.

Technical Context

The MAX6309UK46D4-T implements a precision bandgap reference (1.23V) to compare VCC against a factory-trimmed internal voltage divider, yielding a nominal 4.63V reset threshold with ±2.5% tolerance over -40°C to +85°C. Its RST IN input accepts externally divided voltages referenced to the same 1.23V comparator, enabling monitoring of secondary supplies.

It integrates a digital timeout counter that holds RESET asserted for ≥1120ms after all monitored inputs exceed their thresholds, and supports manual reset via MR - which forces RESET low while pulled low and maintains assertion for the full timeout after release. The push/pull output drives both high and low without external components.

Key Specifications

Pinout & Package

MAX6309UK46D4-T is housed in a 5-pin SOT23 package (outline U5+1, land pattern 90-0174), optimized for space-constrained PCB layouts and automated assembly.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6309UK46D4-T, the D3 variant reduces reset hold time for speed-critical designs, while TPS3808G33DBVR trades multi-input flexibility and long timeout for ultra-low current and lower cost in simple 3.3V applications.

Availability

MAX6309UK46D4-T is available at Aetrix Electronics and suitable for industrial controllers, portable medical devices, automotive infotainment units, and networked sensor nodes requiring stable component supply across extended production lifecycles.

Supply support for MAX6309UK46D4-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 and mixed-signal ICs for power management, sensing, and interface applications in industrial, computing, and communications markets.

The MAX6305–MAX6313 family delivers highly integrated, low-power supervisory circuits with factory-programmable thresholds and timeouts - engineered specifically for multivoltage embedded systems needing robust, component-minimized reset control.

FAQ

What is the exact factory-programmed VCC reset threshold for MAX6309UK46D4-T?

The MAX6309UK46D4-T has a nominal VCC reset threshold of 4.63V, with ±2.5% tolerance over the full operating temperature range (-40°C to +85°C). This value is factory-trimmed using an internal voltage divider and corresponds to the "46" in the part number per Table 1 of the datasheet. The actual measured threshold falls between 4.514V and 4.746V at room temperature.

Does MAX6309UK46D4-T support manual reset functionality, and how is it implemented?

Yes, MAX6309UK46D4-T includes a dedicated MR (manual reset) input on pin 4. Driving MR low forces the RESET output active (low) for the duration of the low pulse plus the full 1120ms timeout period after MR returns high. An internal 63.5kΩ pullup resistor allows direct connection of a momentary switch to GND without external components, simplifying board design.

What is the RESET output structure of MAX6309UK46D4-T, and why does it matter?

MAX6309UK46D4-T features an active-low push/pull RESET output (pin 1), meaning it actively drives both high and low states without requiring an external pull-up resistor. This ensures fast, deterministic transitions and compatibility with bidirectional µP reset pins. It sinks 1.2mA while maintaining ≤0.3V and sources up to 0.8×VCC, eliminating layout overhead and improving noise immunity versus open-drain alternatives.

Can MAX6309UK46D4-T monitor a second voltage rail besides VCC?

Yes, MAX6309UK46D4-T includes an RST IN input (pin 3) that compares an externally divided voltage against an internal 1.23V reference. By connecting a resistor divider from a secondary supply (e.g., 3.3V) to RST IN and GND, users can configure undervoltage detection at any threshold - for example, 3.0V - enabling dual-rail supervision in a single 5-pin package.

What is the minimum VCC voltage at which MAX6309UK46D4-T guarantees valid RESET output?

MAX6309UK46D4-T guarantees valid RESET output down to VCC = 1.0V. Below this level, the push/pull driver's sinking/sourcing capability degrades, but within the specified 1.0V–5.5V operating range, RESET remains a well-defined logic-low or logic-high signal. This ensures deterministic µP reset behavior even during severe brownout conditions before complete power loss.