Analog Devices Inc./Maxim Integrated MAX6309UK46D3+T

Overview

MAX6309UK46D3+T from Maxim Integrated is a 5-pin SOT23 programmable supervisory circuit that monitors VCC (factory-set 4.6V reset threshold) and an external undervoltage input (RST IN), asserts active-low push/pull RESET during out-of-tolerance conditions, and features manual-reset (MR) input and 140ms minimum reset timeout. It draws only 8µA supply current and guarantees valid RESET down to VCC = 1V - ideal for multivoltage embedded systems requiring reliable power-on reset and brownout protection.

For engineers reviewing the MAX6309UK46D3+T datasheet, MAX6309UK46D3+T pinout, MAX6309UK46D3+T application, or MAX6309UK46D3+T equivalent, key selection considerations include its factory-programmed 4.6V VCC threshold (±2.5% over temperature), 140ms reset timeout, MR input with 63.5kΩ internal pull-up, immunity to fast VCC transients (<100ns), and compatibility with 3.3V/5V mixed-rail systems.

Technical Context

The MAX6309UK46D3+T implements dual-supply monitoring: primary VCC supervision via an internal factory-trimmed resistor divider (nominal 4.6V threshold), and secondary undervoltage monitoring on RST IN referenced to a 1.23V internal bandgap. Its push/pull RESET output drives both high and low without external components, eliminating need for pull-up resistors in most µP interfaces.

Reset assertion is triggered when either VCC drops below 4.6V × (1 − 2.5%) or RST IN falls below 1.23V (with hysteresis of 2.5mV); reset remains asserted for ≥140ms after all monitored voltages recover. The MR input provides TTL/CMOS-compatible manual reset with glitch rejection (0.1µs) and guaranteed 500ns MR-to-RESET delay.

Key Specifications

Pinout & Package

MAX6309UK46D3+T is housed in a RoHS-compliant, lead-free 5-pin SOT23 package (outline U5+1, land pattern 90-0174), measuring 2.9mm × 1.6mm × 1.1mm - suitable for space-constrained PCB layouts in portable and industrial modules.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6312UK46D3+T, MAX6309UK46D3+T offers lower cost and smaller footprint but omits overvoltage detection; versus TPS3808G33DBVR, it provides flexible dual-rail supervision at higher quiescent current but enables robust multivoltage system design.

Availability

MAX6309UK46D3+T is available at Aetrix Electronics and suitable for industrial PLCs, medical patient monitors, automotive body control modules, and network infrastructure equipment requiring stable component supply with guaranteed long-term availability.

Supply support for MAX6309UK46D3+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 demanding industrial, automotive, and communications applications - emphasizing reliability, low power, and integration.

The MAX6305–MAX6313 family delivers programmable supervisory circuits optimized for multivoltage embedded systems, combining factory-set thresholds, manual reset, and dual-input monitoring in minimal SOT23 packaging.

FAQ

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

The MAX6309UK46D3+T has a nominal VCC reset threshold of 4.6V, with tolerance of ±2.5% over the full operating temperature range (−40°C to +85°C). This value is factory-trimmed using an internal resistor divider and corresponds to entry "46" in Table 1 of the datasheet. At +25°C, the typical threshold is 4.630V, with min/max bounds of 4.514V and 4.746V respectively.

Does MAX6309UK46D3+T support monitoring a 3.3V supply in addition to its 5V VCC input?

Yes, MAX6309UK46D3+T supports monitoring a 3.3V supply via its RST IN pin. By connecting a resistor divider from the 3.3V rail to RST IN and ground, the device triggers reset when the divided voltage falls below its internal 1.23V comparator threshold. For a 3.3V rail, a common divider uses R1 = 1.0MΩ and R2 = 604kΩ, yielding ~1.23V at RST IN when VIN = 3.3V.

What is the function of the MR pin on MAX6309UK46D3+T and how should it be interfaced?

The MR (manual reset) pin on MAX6309UK46D3+T is an active-low input that forces RESET assertion when pulled below 0.8V. It features an internal 63.5kΩ pull-up resistor, so a normally-open momentary switch from MR to GND provides full manual reset functionality without external components. The pin rejects glitches <0.1µs and guarantees 500ns propagation delay from MR low to RESET assertion.

Can MAX6309UK46D3+T operate with a VCC supply below 4.6V?

No - MAX6309UK46D3+T requires VCC ≥ 4.71V (4.6V × 1.025) to operate correctly, as specified in the Electrical Characteristics table. Below this voltage, the internal trimmed divider cannot reliably compare against the 4.6V threshold. However, once asserted, RESET remains valid down to VCC = 1V, ensuring controlled release during brownout recovery.

What is the purpose of the 140ms reset timeout (D3) in MAX6309UK46D3+T?

The D3 suffix denotes a factory-programmed minimum reset timeout of 140ms, which ensures the RESET signal stays active long enough for microprocessors and peripherals to fully initialize after power-up or brownout recovery. This duration exceeds JEDEC JESD76B recommendations for 8-bit and 16-bit µCs and accommodates slow-ramping supplies in industrial power systems.