Analog Devices Inc./Maxim Integrated MAX6309UK46D3+

Overview

MAX6309UK46D3+ from Maxim Integrated is a 5-pin SOT23 programmable supervisory IC 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 features 140ms minimum reset timeout, 8µA supply current, and guaranteed RESET validity down to VCC = 1V. Used in multivoltage embedded systems for reliable power-on and brownout reset control.

For engineers reviewing the MAX6309UK46D3+ datasheet, MAX6309UK46D3+ pinout, MAX6309UK46D3+ application, or MAX6309UK46D3+ equivalent, key selection criteria include factory-trimmed 4.63V VCC threshold tolerance (±2.5% over -40°C to +85°C), MR input with 63.5kΩ internal pull-up, RST IN comparator reference of 1.23V, and immunity to sub-200ns VCC transients.

Technical Context

The MAX6309UK46D3+ implements a triple-monitor architecture: internal factory-trimmed resistor divider sets VCC reset threshold at 4.63V; external voltage divider on RST IN compares against 1.23V reference; MR input provides logic-controlled reset initiation. All three inputs independently trigger the same internal reset generator.

Its push/pull RESET output drives high/low without external pull-up, sourcing ≥0.8×VCC at 500µA and sinking ≤0.3V at 1.2mA. The 140ms timeout (D3 variant) is factory-programmed and stable across temperature (±1% variation), enabling deterministic system initialization timing in portable and industrial controllers.

Key Specifications

Pinout & Package

Package: 5-pin SOT23 (U5+1), RoHS-compliant lead-free, 1.6mm × 2.9mm footprint, 1.1mm height.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6312UK46D3+, the MAX6309UK46D3+ omits overvoltage detection but retains identical VCC/RST IN/MR functionality and timing-making it optimal for cost-sensitive 5V systems needing only undervoltage and manual reset. Versus TPS3808G33DBVR, it supports higher threshold, triple-input supervision, and push/pull drive-critical for multivoltage industrial designs.

Availability

MAX6309UK46D3+ is available at Aetrix Electronics and suitable for industrial PLC controllers, portable medical monitors, automotive body control modules, and network edge routers requiring stable component supply and long-term production continuity.

Supply support for MAX6309UK46D3+ 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 industrial, automotive, and communications applications, with emphasis on reliability and integration.

The MAX6305–MAX6313 family delivers programmable supervisory circuits optimized for multivoltage embedded systems requiring simultaneous monitoring of primary and auxiliary rails with minimal external components.

FAQ

What is the exact factory-programmed VCC reset threshold for MAX6309UK46D3+?

The MAX6309UK46D3+ has a factory-trimmed VCC reset threshold of 4.63V, with ±2.5% tolerance over the full operating temperature range (-40°C to +85°C). This value is confirmed in Table 1 of the datasheet and corresponds to the "46" suffix in the part number. The MAX6309UK46D3+ uses an internal resistor divider to achieve this precise threshold without external calibration.

Does MAX6309UK46D3+ support manual reset functionality, and how is it implemented?

Yes, the MAX6309UK46D3+ includes a dedicated MR (manual reset) input on pin 4. It is active-low and features an internal 63.5kΩ pull-up resistor, allowing direct connection of a momentary switch to ground. When pulled low, MR forces RESET assertion for the full 140ms timeout period after release. This function is fully integrated-no external pull-up or debounce components are required for basic operation.

What is the purpose of the RST IN pin on MAX6309UK46D3+, and what voltage does it monitor?

The RST IN pin (pin 3) on the MAX6309UK46D3+ is an adjustable undervoltage comparator input referenced to an internal 1.23V threshold. It monitors external power rails (e.g., 3.3V, 2.5V) using an external resistor divider. When the divided voltage falls below 1.23V, the MAX6309UK46D3+ asserts RESET independently of the VCC monitor-enabling dual-rail supervision in multivoltage systems.

How does the RESET output of MAX6309UK46D3+ differ from open-drain alternatives?

The MAX6309UK46D3+ features an active-low push/pull RESET output (pin 1), unlike open-drain variants that require an external pull-up. It actively drives low (≤0.3V at 1.2mA) and high (≥0.8×VCC at 500µA), eliminating BOM cost and board area for pull-up resistors. This architecture ensures faster rise/fall times and deterministic logic levels-even under light or no load-making it ideal for driving modern microcontrollers with low-threshold RESET pins.

What is the guaranteed operating temperature range for MAX6309UK46D3+?

MAX6309UK46D3+ is rated for operation from -40°C to +85°C, as indicated by the "E" prefix omission (i.e., non-E version). Its electrical specifications-including 4.63V threshold accuracy, 140ms timeout stability, and RESET output performance-are fully guaranteed across this industrial temperature range. The device uses design techniques (e.g., ppm/°C threshold drift control) to maintain specification compliance without derating.