Analog Devices Inc./Maxim Integrated MAX6309UK27D2+

Overview

MAX6309UK27D2+ 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 down to VCC = 1V, features 8µA supply current, and provides 20ms minimum reset timeout - ideal for dual-voltage embedded systems requiring reliable power-on and brownout reset in portable equipment.

For engineers reviewing the MAX6309UK27D2+ datasheet, MAX6309UK27D2+ pinout, MAX6309UK27D2+ application, or MAX6309UK27D2+ equivalent, key selection criteria include its factory-trimmed 2.7V VCC threshold with ±2.5% tolerance over –40°C to +85°C, MR input with internal 63.5kΩ pull-up, immunity to fast VCC transients (<100ns), and guaranteed RESET assertion during VCC drop below 1V.

Technical Context

The MAX6309UK27D2+ implements a precision bandgap reference (1.23V ±0.03V) to compare VCC against its factory-programmed 2.7V threshold via an internal resistor divider, while RST IN operates independently with the same reference. Its push/pull RESET output sources up to 800µA at VCC > 4.25V and sinks 3.2mA, enabling direct interface with µP reset pins without external pull-ups.

Reset assertion occurs when VCC falls below 2.7V × (1 − 2.5%) or RST IN drops below 1.23V (±0.03V), with hysteresis of 2.5mV on RST IN and 2×VTH on VCC. The internal timer enforces a minimum 20ms (D2) timeout after all monitored voltages recover, and MR deassertion triggers the same timeout period.

Key Specifications

Pinout & Package

MAX6309UK27D2+ is housed in a lead-free 5-pin SOT23 package (outline 21-0057, footprint 90-0174), with 0.95mm pitch, 2.9mm × 1.6mm body, and 1.1mm max height - suitable for space-constrained PCB layouts in handheld devices.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6309UK27D3+, the MAX6309UK27D2+ offers faster system recovery after power interruption; compared with TPS3808G125DBVR, it provides greater flexibility in multirail systems and operator control via MR, at the cost of slightly higher quiescent current.

Availability

MAX6309UK27D2+ is available at Aetrix Electronics and suitable for portable computers, industrial controllers, battery-powered sensors, and multivoltage embedded systems requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for MAX6309UK27D2+ 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, with emphasis on high-reliability industrial and automotive markets.

The MAX6305–MAX6313 family was engineered specifically for multivoltage microprocessor supervision in space-constrained, battery-sensitive systems - delivering factory-trimmed accuracy, ultra-low power, and integrated transient immunity without external components.

FAQ

What is the exact factory-programmed VCC reset threshold for MAX6309UK27D2+?

The MAX6309UK27D2+ has a factory-trimmed VCC reset threshold of 2.7V with ±2.5% tolerance over the full operating temperature range (–40°C to +85°C), as confirmed in the Electrical Characteristics table under "Reset Threshold (VTH)" for MAX6309E variants. This value is laser-trimmed during manufacturing and does not require external calibration.

Does MAX6309UK27D2+ support monitoring of auxiliary voltage rails beyond VCC?

Yes, MAX6309UK27D2+ includes a dedicated RST IN pin that compares an external voltage to a precise 1.23V internal reference. By connecting a resistor divider from the auxiliary rail to RST IN and GND, designers can monitor secondary supplies such as 1.8V or 2.5V - a capability explicitly documented in the Adjustable Reset Inputs section and functional diagram.

What is the function of the MR pin on MAX6309UK27D2+ and how is it implemented?

The MR (Manual Reset) pin on MAX6309UK27D2+ is an active-low input that forces RESET assertion when pulled below VIH (0.7×VCC). It features an internal 63.5kΩ pull-up resistor, allowing direct connection to a momentary switch tied to GND. The datasheet specifies a 1.5µs minimum pulse width and guarantees glitch rejection of 0.1µs transients - eliminating need for external debounce circuitry.

Can MAX6309UK27D2+ operate reliably during severe VCC voltage transients?

Yes, MAX6309UK27D2+ is specifically designed to ignore fast VCC transients: the Typical Operating Characteristics graph "Maximum Transient Duration vs. VCC Reset Threshold Overdrive" shows it rejects negative-going glitches <100ns wide even with 100mV overdrive. This immunity is achieved through internal filtering and is guaranteed across temperature per the device's design specification.

What are the absolute maximum ratings for VCC and other pins on MAX6309UK27D2+?

Per the Absolute Maximum Ratings table, MAX6309UK27D2+ accepts VCC from –0.3V to +6V, and all other pins from –0.3V to (VCC + 0.3V). Continuous power dissipation is 571mW in SOT23 at +70°C, derating 7.1mW/°C above that. Exceeding these limits may cause permanent damage - they are stress ratings only, not operational conditions.