Analog Devices Inc./Maxim Integrated MAX6309UK30D4+T

Overview

The MAX6309UK30D4+T from Maxim Integrated is a 5-pin SOT23 programmable supervisory circuit that monitors VCC (factory-set 3.0V reset threshold), an external undervoltage input (RST IN), and a manual-reset input (MR) to assert an active-low push/pull RESET signal. It features 1120ms minimum reset timeout, 8µA supply current, guaranteed RESET validity down to VCC = 1V, and immunity to fast VCC transients. It is used in multivoltage embedded systems requiring reliable power-on and brownout reset control.

For engineers reviewing the MAX6309UK30D4+T datasheet, MAX6309UK30D4+T pinout, MAX6309UK30D4+T application, or MAX6309UK30D4+T equivalent, key selection considerations include its factory-trimmed 3.0V ±2.5% VCC threshold, D4 (1120ms min) timeout, push/pull output drive capability, MR input with 63.5kΩ internal pull-up, and operation across 0°C to +70°C.

Technical Context

The MAX6309UK30D4+T implements a dual-monitoring architecture: an internal factory-trimmed resistor divider sets the primary VCC reset threshold at 3.0V, while a dedicated RST IN pin accepts an externally programmed undervoltage comparator input referenced to 1.23V. Its push/pull RESET output actively drives both high and low states without requiring an external pull-up.

It integrates a precision reset timeout timer (1120ms min) triggered when all monitored supplies exceed their thresholds, and includes a manual-reset input (MR) with glitch rejection (0.1µs) and internal 63.5kΩ pull-up - enabling direct switch connection without external components. The device guarantees valid RESET assertion down to VCC = 1V and exhibits ±40ppm/°C reset threshold drift.

Key Specifications

Pinout & Package

Package: 5-pin SOT23 (U5+1), RoHS-compliant lead-free, tape-and-reel delivery.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6309UK30D3+T and TPS3808G30DBVR, the MAX6309UK30D4+T uniquely combines extended 1120ms reset hold time, dual-supply monitoring (VCC + RST IN), and manual reset in a single SOT23-5 package - making it optimal for complex embedded systems requiring robust, multi-condition reset assurance.

Availability

MAX6309UK30D4+T is available at Aetrix Electronics and suitable for industrial PLC controllers, portable medical monitors, automotive infotainment head units, network router power management, and multivoltage embedded control systems requiring stable component supply and long-term production continuity.

Supply support for MAX6309UK30D4+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 demanding industrial, computing, and communications applications.

The MAX6305–MAX6313 product line delivers highly integrated, low-power supervisory circuits optimized for multivoltage embedded systems requiring simultaneous monitoring of primary and auxiliary rails with configurable reset timing and manual intervention capability.

FAQ

What is the factory-set VCC reset threshold for MAX6309UK30D4+T?

The MAX6309UK30D4+T has a factory-trimmed VCC reset threshold of 3.0V, specified with ±2.5% tolerance over the full operating temperature range (−40°C to +85°C). This value is encoded in the "30" portion of the part number and is implemented using an internal precision resistor divider. The device asserts RESET when VCC falls below this threshold and holds it active for the full 1120ms timeout period after VCC recovers above 3.0V.

Does MAX6309UK30D4+T require an external pull-up resistor on the RESET pin?

No, the MAX6309UK30D4+T does not require an external pull-up resistor because it features an active-low push/pull RESET output. This output can both sink up to 3.2mA and source up to 0.8×VCC, enabling direct drive of microcontroller reset pins without additional components. This design reduces board space, lowers BOM cost, and improves noise immunity compared to open-drain alternatives.

What is the function of the RST IN pin on MAX6309UK30D4+T?

The RST IN pin on the MAX6309UK30D4+T is an adjustable undervoltage reset input referenced to an internal 1.23V comparator threshold. When used with an external resistor divider, it allows monitoring of a second supply rail (e.g., 12V, 24V, or another 3.3V domain) independently of the primary VCC rail. If the voltage at RST IN falls below 1.23V, the device immediately asserts RESET regardless of VCC status - providing true dual-rail fault coverage.

How does the manual-reset (MR) input behave on MAX6309UK30D4+T?

The MR input on the MAX6309UK30D4+T is an active-low, internally pulled-up (63.5kΩ typical) pin that forces RESET assertion when driven low. RESET remains active for the full 1120ms timeout period after MR returns high, ensuring reliable processor reset. The pin accepts TTL- or CMOS-level signals and rejects glitches shorter than 0.1µs. No external debounce components are needed, though a 0.1µF capacitor to GND is recommended in electrically noisy environments.

What is the minimum VCC voltage at which MAX6309UK30D4+T guarantees valid RESET output?

The MAX6309UK30D4+T guarantees valid RESET output down to VCC = 1V. Below this level, the push/pull driver's sourcing/sinking capability degrades significantly. For applications requiring RESET validity down to 0V, a 100kΩ pull-down resistor between RESET and GND is recommended to hold the line low during deep brownout - a configuration validated in Maxim's application notes for the MAX6309UK30D4+T.