Analog Devices Inc./Maxim Integrated MAX6309UK46D4

Overview

MAX6309UK46D4 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 (MR) to assert an active-low push/pull RESET output. It guarantees valid reset assertion down to VCC = 1V, features 8µA supply current, and provides a 1120ms minimum reset timeout period. It is used in multivoltage embedded systems requiring reliable power-on and brownout reset control.

For engineers reviewing the MAX6309UK46D4 datasheet, MAX6309UK46D4 pinout, MAX6309UK46D4 application, or MAX6309UK46D4 equivalent, key selection considerations include its factory-trimmed 4.63V VCC reset threshold (±2.5% over temperature), 1120ms timeout, push/pull RESET output capable of sourcing/sinking at VCC ≥ 2.5V, MR input with internal 63.5kΩ pull-up, and immunity to fast VCC transients.

Technical Context

The MAX6309UK46D4 implements a precision bandgap reference and comparator architecture to monitor VCC via an internal factory-trimmed resistor divider, delivering a nominal 4.63V reset threshold with ±2.5% tolerance over –40°C to +85°C. Its RST IN input compares external voltages against a 1.23V internal reference, enabling configurable undervoltage monitoring of auxiliary rails.

It integrates a digital timeout counter that holds RESET asserted for ≥1120ms after all monitored supplies stabilize, and includes a debounced manual-reset input (MR) that forces reset on logic-low assertion and sustains it for the full timeout period after release. The push/pull RESET output ensures robust drive capability without external pull-ups.

Key Specifications

Pinout & Package

SOT23-5 package: compact 2.9mm × 1.6mm surface-mount outline with gull-wing leads, RoHS-compliant lead-free option available (+T suffix).

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6309UK46D3 and TPS3808G33DBVR, the MAX6309UK46D4 uniquely combines a precise 4.63V VCC threshold, 1120ms timeout, push/pull RESET, MR input, and RST IN in one SOT23-5 package - making it the only option supporting multirail, long-boot, and operator-reset requirements simultaneously.

Availability

MAX6309UK46D4 is available at Aetrix Electronics and suitable for industrial PLCs, medical infusion pumps, automotive body control modules, and network router power management requiring stable component supply and guaranteed long-term availability.

Supply support for MAX6309UK46D4 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, medical, and communications applications, emphasizing reliability, low power, and integration.

The MAX6305–MAX6313 family delivers highly configurable, low-quiescent-current supervisory circuits for multivoltage embedded systems - engineered to replace discrete reset solutions with guaranteed timing, temperature stability, and transient immunity.

FAQ

What is the exact factory-programmed VCC reset threshold for MAX6309UK46D4?

The MAX6309UK46D4 has a factory-trimmed VCC reset threshold of 4.63V nominal, with a tolerance of ±2.5% over the full operating temperature range of –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 MAX6309UK46D4 uses an internal resistor divider to achieve this precise threshold without external components.

Does MAX6309UK46D4 support manual reset functionality, and how is it implemented?

Yes, the MAX6309UK46D4 includes a dedicated MR (manual reset) input on pin 4. A logic-low signal on MR forces the RESET output active for the full timeout period (≥1120ms) after MR returns high. The pin features an internal 63.5kΩ pull-up resistor, allowing direct connection of a momentary switch to ground with no external parts. The MAX6309UK46D4 MR input accepts TTL- or CMOS-level signals depending on system VCC.

What is the guaranteed minimum reset timeout period for MAX6309UK46D4, and how is it set?

The MAX6309UK46D4 guarantees a minimum reset timeout period of 1120ms, as indicated by the "D4" suffix in the part number. This timeout is factory-programmed and does not require external capacitors or resistors. The internal timer begins counting only after all monitored supplies (VCC and RST IN) exceed their respective thresholds, ensuring deterministic release timing critical for reliable µP boot sequences.

Can MAX6309UK46D4 monitor a second voltage rail besides VCC?

Yes, the MAX6309UK46D4 monitors a second voltage rail via its RST IN input (pin 3), which 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 configure undervoltage detection for rails such as 3.3V, 2.5V, or 1.8V. This dual-monitoring capability is intrinsic to the MAX6309UK46D4 and requires no additional ICs.

What output drive capability does the RESET pin of MAX6309UK46D4 provide?

MAX6309UK46D4 features an active-low push/pull RESET output (pin 1) that both sinks and sources current. At VCC ≥ 2.5V, it sinks up to 1.2mA with VOL ≤ 0.3V and sources up to 0.8×VCC with VOH ≥ 0.8×VCC. This eliminates the need for an external pull-up resistor and ensures robust interfacing with µP reset inputs, including bidirectional I/O pins. The MAX6309UK46D4 RESET output remains valid down to VCC = 1V.