Analog Devices Inc./Maxim Integrated MAX6309UK27D1

Overview

MAX6309UK27D1 from Maxim Integrated is a 5-pin SOT23 programmable supervisory IC that monitors VCC (factory-set threshold 2.7V ±2.5%), an adjustable undervoltage input (RST IN), and a manual-reset input (MR) to assert an active-low push/pull RESET output. It guarantees valid reset assertion down to VCC = 1V, features 8µA supply current, and provides 1ms minimum reset timeout. It is used in multivoltage embedded systems requiring reliable power-on and brownout reset for microprocessors.

For engineers reviewing the MAX6309UK27D1 datasheet, MAX6309UK27D1 pinout, MAX6309UK27D1 application, or MAX6309UK27D1 equivalent, key selection considerations include its factory-trimmed 2.7V VCC threshold, MR input with internal 63.5kΩ pull-up, immunity to fast VCC transients, and guaranteed RESET validity at low VCC - critical for portable and battery-powered microcontroller systems.

Technical Context

The MAX6309UK27D1 implements a dual-monitoring architecture: one internal factory-trimmed voltage divider sets the primary VCC reset threshold at 2.7V, while a separate comparator monitors the external RST IN pin against a 1.23V reference. Its push/pull RESET output drives both high and low without external components, eliminating need for pull-up resistors in most designs.

It integrates a precision reset timeout timer (D1 = 1ms min), supports manual reset via MR (TTL/CMOS compatible, 1.5µs minimum pulse width), and maintains guaranteed operation across -40°C to +85°C. The device ignores transients ≤100ns on VCC and RST IN due to internal filtering, and its ±25nA input leakage enables high-impedance resistor-divider programming of auxiliary thresholds.

Key Specifications

Pinout & Package

MAX6309UK27D1 is housed in a 5-pin SOT23 package (outline U5+1, land pattern 90-0174), optimized for space-constrained PCB layouts in portable electronics. The compact 2.9mm × 1.6mm footprint supports high-density routing and automated assembly.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6309UK27D2 and TPS3808G125DBVR, the MAX6309UK27D1 uniquely combines factory-set 2.7V supervision, 1ms fast timeout, manual reset, and auxiliary undervoltage monitoring in one SOT23-5 package - making it optimal for cost-sensitive, feature-rich embedded reset management.

Availability

MAX6309UK27D1 is available at Aetrix Electronics and suitable for portable computers, multivoltage industrial controllers, and battery-powered intelligent instruments requiring stable component supply across extended production lifecycles.

Supply support for MAX6309UK27D1 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, automotive, and communications markets.

The MAX6305–MAX6313 family was engineered specifically for multirail microprocessor supervision in space-constrained, low-power systems - delivering factory-programmable thresholds, integrated timing, and robust transient immunity in minimal SOT23-5 packaging.

FAQ

What is the factory-programmed VCC reset threshold for MAX6309UK27D1?

The MAX6309UK27D1 has a factory-programmed VCC reset threshold of 2.7V, with tolerance of ±2.5% over the full operating temperature range (-40°C to +85°C). This value is laser-trimmed during manufacturing and corresponds to the "27" in the part number. The threshold is referenced to an internal voltage divider and does not require external calibration. MAX6309UK27D1 guarantees reliable detection of VCC drops below 2.7V across all qualified conditions.

Does MAX6309UK27D1 support manual reset functionality?

Yes, MAX6309UK27D1 includes a dedicated MR (manual reset) input on pin 4. It is active-low, features an internal 63.5kΩ pull-up resistor to VCC, and requires a minimum pulse width of 1.5µs at temperature extremes. When pulled low, MAX6309UK27D1 asserts RESET for the full timeout period (1ms minimum) after MR returns high. This allows simple integration of momentary switches or logic signals without external components.

What is the RESET output structure of MAX6309UK27D1?

MAX6309UK27D1 features an active-low push/pull RESET output on pin 1. Unlike open-drain variants, it actively drives both high and low states - sourcing up to 800µA and sinking up to 3.2mA (at VCC > 4.25V). This eliminates the need for an external pull-up resistor and ensures strong, deterministic reset signaling to microcontrollers, even under noisy or high-capacitance load conditions. MAX6309UK27D1 maintains this capability down to VCC = 1V.

Can MAX6309UK27D1 monitor a second voltage rail besides VCC?

Yes, MAX6309UK27D1 includes an RST IN input (pin 3) designed to monitor a secondary voltage rail. It compares the applied voltage - typically set via an external resistor divider - to an internal 1.23V reference. This enables precise undervoltage supervision of auxiliary supplies such as 1.8V, 3.3V, or custom rails. The ±25nA input leakage ensures minimal error in high-impedance divider networks, and MAX6309UK27D1's transient immunity extends to this input as well.

What is the minimum VCC voltage at which MAX6309UK27D1 guarantees valid RESET assertion?

MAX6309UK27D1 guarantees valid RESET assertion down to VCC = 1.0V. Below this level, the push/pull driver's sourcing/sinking capability degrades, but within the specified 1.0V–5.5V operating range, RESET remains a robust logic-level signal. This specification ensures reliable reset behavior during deep brownout conditions common in battery-powered systems, and is explicitly tested and guaranteed - not just characterized - across temperature for MAX6309UK27D1.