Analog Devices Inc./Maxim Integrated MAX6309UK31D3+T

Overview

MAX6309UK31D3+T from Maxim Integrated is a 5-pin SOT23 programmable supervisory circuit that monitors VCC (factory-set 3.08V threshold) and an external undervoltage input (RST IN), asserts active-low push/pull RESET during brownout or manual reset, and features 140ms minimum reset timeout. It draws only 8µA supply current and guarantees valid RESET output down to VCC = 1V - used in portable computers and multivoltage embedded systems for reliable power-on and fault recovery.

For engineers reviewing the MAX6309UK31D3+T datasheet, MAX6309UK31D3+T pinout, MAX6309UK31D3+T application, or MAX6309UK31D3+T equivalent, key selection criteria include its factory-trimmed 3.08V ±2.5% VCC reset threshold, 140ms min timeout, manual-reset input with internal 63.5kΩ pull-up, immunity to fast VCC transients, and guaranteed operation from -40°C to +85°C.

Technical Context

The MAX6309UK31D3+T implements a dual-monitoring architecture: one path uses an internal factory-trimmed resistor divider to monitor VCC against a 3.08V threshold, while a second path compares an external voltage at RST IN to a precise 1.23V internal reference. Its reset generator includes a temperature-stable RC timer delivering 140ms minimum timeout after all monitored supplies return to regulation.

It features a push/pull active-low RESET output capable of sourcing 0.8×VCC and sinking 0.3V at 1.2mA, a manual-reset input (MR) with glitch rejection (0.1µs), and guaranteed reset assertion even as VCC falls to 1V - enabling robust brownout detection without external components.

Key Specifications

Pinout & Package

MAX6309UK31D3+T is housed in a lead-free 5-pin SOT23 package (outline U5+1), measuring 2.9mm × 1.6mm × 1.1mm, with gull-wing leads optimized for automated PCB assembly and thermal performance in space-constrained applications.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6309UK31D2+T and TPS3808G33DBVR, the MAX6309UK31D3+T uniquely balances extended 140ms reset hold time, dual-supply monitoring capability (VCC + RST IN), and manual reset support - making it optimal for complex embedded systems requiring robust, configurable power supervision without design compromises.

Availability

MAX6309UK31D3+T is available at Aetrix Electronics and suitable for portable computers, industrial controllers, and intelligent instruments requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for MAX6309UK31D3+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 - serving industrial, computing, and communications markets since 1983.

The MAX6305–MAX6313 family was engineered specifically for multivoltage microprocessor supervision in space- and power-constrained systems, emphasizing factory-programmable thresholds, transient immunity, and zero-external-component operation.

FAQ

What is the factory-programmed reset threshold voltage for MAX6309UK31D3+T?

The MAX6309UK31D3+T has a factory-trimmed VCC reset threshold of 3.08V, specified with ±2.5% tolerance over the full -40°C to +85°C operating temperature range. This value is encoded in the "31" suffix per Maxim's ordering convention (Table 1), and is implemented using an internal precision resistor divider - eliminating the need for external calibration components in the MAX6309UK31D3+T design.

Does MAX6309UK31D3+T support manual reset functionality?

Yes, the MAX6309UK31D3+T includes a dedicated MR (manual reset) input on pin 4. It features an internal 63.5kΩ pull-up resistor, accepts TTL- or CMOS-level logic lows, requires a minimum 1.5µs pulse width, and holds RESET active for the full 140ms timeout period after MR returns high. This allows direct connection to a momentary switch to ground without external debounce circuitry in the MAX6309UK31D3+T implementation.

What is the reset timeout period for MAX6309UK31D3+T, and how is it set?

The MAX6309UK31D3+T provides a factory-programmed minimum reset timeout period of 140ms, indicated by the "D3" suffix in the part number. This value is fixed at wafer sort and does not require external timing components. The internal RC-based timer ensures consistent reset assertion duration across temperature and supply voltage variations - a key reliability feature of the MAX6309UK31D3+T.

Can MAX6309UK31D3+T monitor a second voltage rail besides VCC?

Yes, the MAX6309UK31D3+T includes an adjustable RST IN input (pin 3) that compares an external voltage to a precise 1.23V internal reference. By connecting a resistor divider from the secondary rail (e.g., 1.8V or 2.5V) to RST IN, designers can configure undervoltage detection for a second supply - extending the supervision capability beyond the factory-set 3.08V VCC threshold in the MAX6309UK31D3+T.

What package type and RoHS status does MAX6309UK31D3+T use?

The MAX6309UK31D3+T is supplied in a lead-free 5-pin SOT23 package (package code U5+1), compliant with RoHS Directive 2011/65/EU. The "+T" suffix explicitly denotes lead-free termination, and the device meets JEDEC J-STD-020 moisture sensitivity level 1 (MSL-1) requirements - confirming its suitability for standard reflow soldering processes in the MAX6309UK31D3+T production flow.