Analog Devices Inc./Maxim Integrated MAX6309UK42D3-T

Overview

MAX6309UK42D3-T from Maxim Integrated is a 5-pin SOT23 programmable supervisory IC that monitors VCC (factory-set to 4.20V ±2.5%), an adjustable undervoltage input (RST IN), and a manual reset (MR) input, asserting an active-low push/pull RESET output for microprocessor systems requiring reliable power-on, brownout, and manual reset control. It features 140ms minimum reset timeout, 8µA supply current, and guaranteed RESET validity down to VCC = 1V.

For engineers reviewing the MAX6309UK42D3-T datasheet, MAX6309UK42D3-T pinout, MAX6309UK42D3-T application, or MAX6309UK42D3-T equivalent, this device serves as a precision, low-power, multi-input reset supervisor for multivoltage embedded systems where VCC monitoring at 4.2V, external rail supervision, and operator-initiated reset are required with minimal board space and no external components.

Technical Context

The MAX6309UK42D3-T implements a factory-trimmed internal voltage divider to monitor VCC against a precise 4.20V threshold (±2.5% over -0°C to +70°C), while its RST IN pin compares an external voltage divider to a 1.23V internal reference for configurable undervoltage detection. Its MR input includes a 63.5kΩ internal pull-up and guarantees reset assertion during low pulses ≥1.5µs.

This device uses a push/pull RESET output structure capable of sourcing 0.8×VCC at 500µA and sinking 0.3V at 1.2mA, enabling direct interface with µP reset pins without external pull-ups. The 140ms reset timeout (D3 variant) is factory-programmed and exhibits <±1% variation over temperature.

Key Specifications

Pinout & Package

MAX6309UK42D3-T is housed in a 5-pin SOT23 package (outline U5+1, land pattern 90-0174), measuring 2.9mm × 1.6mm × 1.1mm, optimized for high-density PCB layouts in space-constrained portable and embedded applications.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6309UK42D3-T, the D2 variant reduces reset hold time for faster boot cycles but sacrifices margin for slow peripherals, while TLV803EC29DBZR trades configurability and supervision flexibility for lower unit cost and simpler qualification in basic single-rail designs.

Availability

MAX6309UK42D3-T is available at Aetrix Electronics and suitable for industrial PLC modules, medical patient monitors, automotive infotainment head units, network edge routers, and portable test equipment requiring stable component supply across extended production lifecycles.

Supply support for MAX6309UK42D3-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) is a semiconductor company specializing in high-performance analog, mixed-signal, and power management ICs for industrial, computing, communications, and consumer markets.

The MAX6305–MAX6313 family was designed specifically for multivoltage microprocessor systems needing simultaneous monitoring of primary VCC, auxiliary rails, and manual reset-delivering precision, low power, and compact packaging without external components.

FAQ

What is the exact factory-programmed VCC reset threshold for MAX6309UK42D3-T?

The MAX6309UK42D3-T has a factory-programmed VCC reset threshold of 4.20V, specified with ±2.5% tolerance over the 0°C to +70°C operating temperature range. This value is laser-trimmed during production using an internal voltage divider and corresponds to the "42" in the part number per Table 1 of the datasheet. The threshold remains stable with 40ppm/°C drift and includes 2.5mV hysteresis to prevent chatter near the trip point.

Does MAX6309UK42D3-T support monitoring of a second voltage rail besides VCC?

Yes, MAX6309UK42D3-T supports monitoring of a second voltage rail via its RST IN pin, which compares an externally applied voltage (set by a resistor divider) to a precise 1.23V internal reference. When the divided input falls below 1.23V, the device asserts RESET. This allows supervision of auxiliary supplies such as 12V, 24V, or negative rails-provided the divider scales the target voltage to match the 1.23V threshold.

What is the function and electrical behavior of the MR pin on MAX6309UK42D3-T?

The MR pin on MAX6309UK42D3-T is a manual reset input with an internal 63.5kΩ pull-up resistor. Driving MR low for ≥1.5µs forces RESET assertion for the full 140ms timeout period, even if VCC remains stable. The pin accepts TTL- or CMOS-level logic and requires no external debounce. Its absolute maximum rating is -0.3V to (VCC + 0.3V), so MR should be powered from the same supply as VCC to avoid ESD structure conduction during brownout.

Can MAX6309UK42D3-T operate reliably when VCC drops below 2.0V?

Yes, MAX6309UK42D3-T guarantees valid RESET output down to VCC = 1.0V, meaning the push/pull driver maintains defined logic levels (VOH ≥ 0.8×VCC at 500µA, VOL ≤ 0.3V at 1.2mA) throughout that range. Below 1.0V, output behavior is not specified. This capability ensures deterministic reset assertion during gradual brownout events common in battery-powered systems before complete power collapse.

Is MAX6309UK42D3-T pin-compatible with other devices in the MAX6305–MAX6313 family?

Yes, MAX6309UK42D3-T shares identical SOT23-5 pinout and package dimensions with all members of the MAX6305–MAX6313 family, including MAX6306, MAX6307, MAX6310, MAX6312, and MAX6313. Pin functions (RESET, GND, RST IN, MR, VCC) are consistent across variants. However, functional differences exist-such as presence/absence of OVRST IN or push/pull vs. open-drain output-so electrical compatibility must be verified per application requirements.