Analog Devices Inc./Maxim Integrated MAX6724UTLTD3+

Overview

MAX6724UTLTD3+ from Maxim Integrated is a triple-voltage microprocessor supervisory circuit in SOT23-6 package, monitoring VCC1 (4.625V threshold), VCC2 (3.075V threshold), and an externally adjustable third supply via RSTIN (626.5mV reference). It asserts active-low push-pull reset for ≥210ms after any monitored voltage drops below threshold or manual reset is triggered, and supports watchdog timeout with 35s startup/1.12s normal mode. Used in multivoltage telecom power systems requiring reliable brownout detection and orderly restart.

For engineers reviewing the MAX6724UTLTD3+ datasheet, MAX6724UTLTD3+ pinout, MAX6724UTLTD3+ application, or MAX6724UTLTD3+ equivalent, key selection criteria include its dual-supply monitoring capability with factory-trimmed thresholds, guaranteed reset validity down to VCC1/VCC2 = 0.8V, push-pull RST output referenced to VCC1, and integrated watchdog timer with long initial timeout - all critical for battery-backed industrial controllers and embedded servers.

Technical Context

The MAX6724UTLTD3+ implements independent voltage comparators for VCC1 and VCC2, plus a high-impedance RSTIN input tied to a 626.5mV internal reference, enabling precise third-supply monitoring via external resistor divider. Its reset logic combines OR-ed fault conditions (VCC1/VCC2 undervoltage, RSTIN low, MR low) with a monostable timeout circuit ensuring minimum 210ms reset assertion.

This device uses BiCMOS process with 1072 transistors and features a dual-mode watchdog: 35s minimum startup period after reset, followed by 1.12s minimum normal timeout upon first WDI edge detection. Reset outputs are push-pull, referenced to VCC1, and guaranteed functional at VCC1 or VCC2 ≥ 0.8V - enabling operation during deep brownout conditions.

Key Specifications

Pinout & Package

MAX6724UTLTD3+ is housed in a 6-pin SOT23-6 package (2.9mm × 1.6mm × 1.1mm), surface-mount, lead-free (+T suffix), with gull-wing leads and standard JEDEC MO-178 footprint.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar triple-voltage supervisory applications.

Compared with MAX6724UTLTD3+, MAX6720UTLTD3+ omits RSTIN but matches all other electrical and timing specs - making it viable only in dual-supply designs. TPS3808G33DBVR requires redesign to replicate triple monitoring, lacks watchdog, and forces external pullup - significantly increasing BOM count and layout complexity.

Availability

MAX6724UTLTD3+ is available at Aetrix Electronics and suitable for telecom power systems, industrial PLCs, server BMCs, and portable medical devices requiring stable component supply, guaranteed long-term availability, and full traceability.

Supply support for MAX6724UTLTD3+ 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, communications, and computing markets.

The MAX6715–MAX6729 family was designed specifically for multivoltage embedded systems needing compact, ultra-low-power supervision with factory-trimmed accuracy and flexible fault response - targeting space-constrained, battery-sensitive, and reliability-critical applications.

FAQ

What is the exact reset threshold voltage for VCC1 and VCC2 on the MAX6724UTLTD3+?

The MAX6724UTLTD3+ has factory-trimmed reset thresholds of 4.625V (±125mV) for VCC1 and 3.075V (±75mV) for VCC2, as defined by the "LT" suffix per Maxim's Reset Voltage Threshold Suffix Guide. These values are measured at TA = +25°C and guaranteed over -40°C to +85°C with 20ppm/°C tempco. The MAX6724UTLTD3+ uses these fixed thresholds without external adjustment.

Does the MAX6724UTLTD3+ support watchdog functionality, and what are its timing modes?

Yes, the MAX6724UTLTD3+ includes a dual-mode watchdog timer with a 35s minimum startup timeout after any reset event (power-up, MR, or watchdog timeout), followed by a 1.12s minimum normal timeout after the first valid WDI transition. This architecture prevents false timeouts during boot while ensuring rapid detection of software hangs during steady-state operation. The MAX6724UTLTD3+ requires no external components to enable this feature.

How is the third supply voltage monitored on the MAX6724UTLTD3+?

The MAX6724UTLTD3+ monitors a third supply via the RSTIN pin, which connects to an internal 626.5mV precision reference. A resistor divider (e.g., R1=100kΩ, R2=20kΩ) scales the target supply (e.g., 1.2V) to match this reference. When the divided voltage falls below 626.5mV, RST asserts. The MAX6724UTLTD3+ specifies RSTIN input current ≤±25nA, enabling high-resistance dividers that minimize system power draw.

What is the reset output type and drive capability of the MAX6724UTLTD3+?

The MAX6724UTLTD3+ features a push-pull active-low RST output referenced to VCC1. It sinks up to 3.2mA while maintaining VOL ≤0.4V (at VCC1 ≥4.5V) and sources up to 800µA while maintaining VOH ≥0.8×VCC1. This eliminates the need for an external pullup resistor and ensures robust interfacing with µP reset inputs across varying VCC1 levels - a key advantage over open-drain alternatives like the MAX6723UTLTD3+.

Is the MAX6724UTLTD3+ guaranteed to operate correctly at very low supply voltages?

Yes, the MAX6724UTLTD3+ guarantees valid reset output logic state when either VCC1 or VCC2 remains ≥0.8V - verified across -40°C to +85°C. This brownout resilience is achieved through internal biasing and comparator design, allowing the MAX6724UTLTD3+ to assert reset reliably even as primary supplies collapse, unlike many supervisors that fail below 1.2V or 1.8V.