Analog Devices Inc./Maxim Integrated MAX6729KATGD3+

Overview

The MAX6729KATGD3+ from Maxim Integrated is a triple-voltage microprocessor supervisory circuit in an 8-pin SOT23 package, monitoring VCC1 (primary), VCC2 (secondary), and RSTIN (auxiliary) supply rails with factory-trimmed thresholds of 4.625V (VTH1), 3.075V (VTH2), and 626.5mV reference for RSTIN. It provides push-pull active-low reset output (RST), manual reset input (MR), watchdog timer (35s startup / 1.12s normal timeout), and power-fail input/output (PFI/PFO) with push-pull PFO. Used in multivoltage telecom and industrial systems requiring reliable brownout detection and orderly shutdown.

For engineers reviewing the MAX6729KATGD3+ datasheet, MAX6729KATGD3+ pinout, MAX6729KATGD3+ application, or MAX6729KATGD3+ equivalent, key selection criteria include its triple-supply monitoring capability, guaranteed reset validity down to VCC1/VCC2 = 0.8V, 14µA typical supply current at 3.6V, 210ms (min) reset timeout, and integrated push-pull PFO for direct power-fail interrupt generation without external pullup.

Technical Context

The MAX6729KATGD3+ implements dual independent voltage comparators for VCC1 and VCC2, plus a dedicated high-impedance RSTIN comparator referenced to a 626.5mV internal bandgap. Its power-fail function uses the same 626.5mV reference on PFI to drive a push-pull PFO output with 2µs propagation delay.

It features a dual-mode watchdog timer: a 35s minimum initial timeout after any reset event (power-up, MR, or watchdog expiry), followed by a 1.12s minimum normal timeout triggered by WDI edge transitions. Reset assertion is latched and held for 210ms minimum after all monitored voltages exceed thresholds or MR releases.

Key Specifications

Pinout & Package

MAX6729KATGD3+ is housed in an 8-pin SOT23-8 package (2.0mm × 2.1mm × 1.25mm profile) with gull-wing leads, RoHS-compliant and lead-free (+T suffix).

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6728KA+T and TPS3808G33DBVR, the MAX6729KATGD3+ uniquely delivers push-pull PFO for direct interrupt assertion, factory-trimmed triple-threshold supervision, and dual-mode watchdog - enabling robust power sequencing, predictive shutdown, and software hang recovery in space-constrained industrial and telecom designs.

Availability

MAX6729KATGD3+ is available at Aetrix Electronics and suitable for telecom line cards, industrial PLCs, battery-backed routers, and medical imaging subsystems requiring stable component supply across extended product lifecycles.

Supply support for MAX6729KATGD3+ 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, mixed-signal, and power management ICs for industrial, automotive, communications, and computing markets.

The MAX6715–MAX6729 family delivers ultra-low-voltage, multi-rail supervisory circuits optimized for space-constrained systems needing reliable power monitoring, manual reset, watchdog, and power-fail alerting without external components.

FAQ

What is the exact reset timeout period for MAX6729KATGD3+?

The MAX6729KATGD3+ has a minimum reset timeout period of 210ms, as indicated by the "D3" suffix in its part number. This value is factory-trimmed and guaranteed over -40°C to +85°C. The actual timeout may vary slightly due to temperature and supply voltage but remains ≥210ms under all operating conditions specified in the datasheet. This ensures sufficient hold time for microprocessor initialization before release.

Does MAX6729KATGD3+ support monitoring a 1.2V core supply?

Yes, MAX6729KATGD3+ supports monitoring a 1.2V core supply via its VCC2 input, which accepts secondary supply voltages from 0.9V to 3.3V. Its factory-trimmed VTH2 threshold is 3.075V - intended for 3.3V rails - but the device also provides the RSTIN input with a 626.5mV internal reference, enabling precise monitoring of lower rails like 1.2V using an external resistor divider (e.g., R1=1.87MΩ, R2=1.24MΩ yields ~1.2V trip point). The MAX6729KATGD3+ datasheet confirms RSTIN operation down to 0.62V.

Can MAX6729KATGD3+ generate a power-fail interrupt without external components?

Yes, MAX6729KATGD3+ can generate a power-fail interrupt without external components using its push-pull PFO output. When the PFI input falls below its 626.5mV threshold (set via external resistor divider), PFO asserts low directly - no pullup resistor required. This allows direct connection to a µP's interrupt pin. In contrast, open-drain alternatives like MAX6728 require an external pullup. The MAX6729KATGD3+'s push-pull PFO simplifies design and improves noise immunity in high-speed interrupt paths.

What is the watchdog behavior after power-on reset for MAX6729KATGD3+?

After power-on reset, MAX6729KATGD3+ enters a 35s minimum startup watchdog mode. During this period, the WDI input must transition at least once to exit startup mode and enter the 1.12s minimum normal timeout mode. If no WDI edge occurs within 35s, the watchdog expires and asserts RST. This architecture prevents premature timeouts during lengthy firmware initialization. Once in normal mode, each WDI edge resets the 1.12s timer - failure to update within that window triggers reset. This dual-mode behavior is intrinsic to the MAX6729KATGD3+ silicon.

Is MAX6729KATGD3+ compatible with 1.8V I/O systems?

Yes, MAX6729KATGD3+ is fully compatible with 1.8V I/O systems. Its MR input accepts logic-low levels ≤0.3×VCC1 (so ≤0.54V at VCC1=1.8V) and logic-high levels ≥0.7×VCC1 (≥1.26V), meeting standard 1.8V CMOS thresholds. The push-pull RST and PFO outputs drive to ≥0.8×VCC1 when high (≥1.44V) and ≤0.4V when low - compatible with 1.8V µP reset and interrupt inputs. All electrical characteristics, including 14µA supply current, are validated down to VCC1=1.8V per the datasheet.