Analog Devices Inc./Maxim Integrated MAX6309UK46D4+

Overview

MAX6309UK46D4+ from Maxim Integrated is a 5-pin SOT23 programmable supervisory IC that monitors VCC and one adjustable undervoltage input (RST IN), asserts active-low push/pull RESET when either falls below its threshold, and features factory-set 4.63V VCC reset threshold with ±2.5% tolerance over -40°C to +85°C and 1120ms minimum reset timeout. It draws only 8µA supply current and guarantees valid RESET output down to VCC = 1V - ideal for multivoltage embedded control systems requiring robust brownout protection.

For engineers reviewing the MAX6309UK46D4+ datasheet, MAX6309UK46D4+ pinout, MAX6309UK46D4+ application, or MAX6309UK46D4+ equivalent, key selection considerations include its dual-supply monitoring capability (VCC + RST IN), manual-reset input with internal 63.5kΩ pull-up, immunity to fast transients, guaranteed operation at VCC as low as 1V, and compatibility with 3.3V/5V mixed-rail systems.

Technical Context

The MAX6309UK46D4+ implements a precision bandgap reference (1.23V) to compare VCC against a factory-trimmed internal voltage divider and RST IN against the same reference via external resistor networks. Its reset generator includes a temperature-stable RC timer for the 1120ms timeout period, with propagation delay under 500ns from MR assertion to RESET activation.

This device operates across VCC = (VTH + 2.5%) to +5.5V - i.e., 4.75V to 5.5V for its 4.63V threshold - and supports manual reset with TTL/CMOS-compatible logic levels. The push/pull RESET output sources up to 800µA and sinks up to 3.2mA, ensuring reliable drive into microcontroller reset pins without external pull-ups.

Key Specifications

Pinout & Package

MAX6309UK46D4+ is housed in a lead-free 5-pin SOT23 package (outline U5+1), measuring 2.9mm × 1.6mm × 1.1mm, with gull-wing leads suitable for automated reflow assembly.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6309UK46D3+, the MAX6309UK46D4+ provides significantly longer reset assertion for complex boot sequences; versus TPS3808G33DBVR, it offers flexible dual-supply monitoring and manual reset - critical for field-serviceable or safety-critical embedded systems.

Availability

MAX6309UK46D4+ is available at Aetrix Electronics and suitable for industrial PLCs, medical patient monitors, automotive body control modules, point-of-sale terminals, and multivoltage embedded systems requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for MAX6309UK46D4+ 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) is a semiconductor company specializing in high-performance analog, mixed-signal, and power management ICs for industrial, automotive, communications, and computing applications.

The MAX6305–MAX6313 family was designed specifically for multivoltage microprocessor supervision in space-constrained, battery-sensitive, and thermally demanding systems - delivering precision reset thresholds, ultra-low quiescent current, and dual-input flexibility in SOT23 packaging.

FAQ

What is the exact factory-set reset threshold voltage for MAX6309UK46D4+?

The MAX6309UK46D4+ 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. It is specified to remain stable with 40ppm/°C drift and includes 2.5mV hysteresis to prevent chatter near threshold.

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

Yes, MAX6309UK46D4+ includes a dedicated MR (manual reset) input on pin 4. It features an internal 63.5kΩ pull-up resistor to VCC, accepts TTL- or CMOS-level logic lows, requires a minimum 1.5µs pulse width for reliable assertion, and provides 0.1µs glitch rejection. When pulled low, MAX6309UK46D4+ asserts RESET for the full 1120ms timeout period after MR returns high - enabling hardware-initiated system recovery without firmware involvement.

Can MAX6309UK46D4+ monitor a second voltage rail besides VCC?

Yes, MAX6309UK46D4+ monitors a second rail via its RST IN input (pin 3), which compares an externally divided voltage to an internal 1.23V reference. By connecting a resistor divider from the secondary rail (e.g., 3.3V) to RST IN and GND, users can program a custom undervoltage threshold independent of the 4.63V VCC setting - enabling true dual-rail supervision in systems with mixed 5V/3.3V domains.

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

MAX6309UK46D4+ guarantees valid RESET output down to VCC = 1V. Below this level, the push/pull driver's sourcing/sinking capability degrades, but within the specified 4.75V–5.5V operating range (defined by VTH + 2.5%), RESET maintains full logic-level compliance: VOH ≥ 0.8 × VCC at 500µA source, VOL ≤ 0.3V at 3.2mA sink. This ensures robust interface with modern µPs even during marginal brownout conditions.

Is MAX6309UK46D4+ compatible with lead-free PCB assembly processes?

Yes, MAX6309UK46D4+ is supplied in RoHS-compliant, lead-free packaging (indicated by the "+" suffix). Its SOT23-5 package is rated for reflow soldering at peak temperatures up to +260°C, matching standard lead-free process profiles. The device meets JEDEC J-STD-020 moisture sensitivity level (MSL) requirements and does not require special baking or handling prior to assembly - simplifying manufacturing for high-reliability electronics production.