Analog Devices Inc./Maxim Integrated MAX6865UK46D3L+T

Overview

The MAX6865UK46D3L+T from Maxim Integrated is a nanopower microprocessor supervisory circuit in a 5-pin SOT23 package, featuring ultra-low 170nA typical supply current, a factory-trimmed 4.625V reset threshold (±2.5%), 300ms minimum reset timeout, and integrated watchdog timer with 209s typical timeout. It asserts active-low push-pull RESET during VCC brownout, manual reset, or watchdog expiration-used in battery-powered medical monitors and portable instrumentation.

For engineers reviewing the MAX6865UK46D3L+T datasheet, MAX6865UK46D3L+T pinout, MAX6865UK46D3L+T application, or MAX6865UK46D3L+T equivalent, key selection criteria include guaranteed reset validity down to VCC = +1.1V, immunity to short VCC transients (<40µs at 100mV overdrive), MR input glitch rejection (200ns), and compatibility with noisy low-power systems requiring long watchdog intervals.

Technical Context

This device integrates three core functions: precision voltage monitoring with hysteresis (0.5% of VTH), a manual reset input with internal 10kΩ pullup and 1µs minimum pulse width, and a watchdog timer that clears on any WDI edge and expires if WDI remains static beyond 209s (typ). The reset output remains asserted for ≥300ms after VCC rises above threshold and MR deasserts.

It operates across -40°C to +85°C with supply voltage range 1.2V–5.5V, delivers VOL ≤ 0.3V at ISINK = 1.2mA (VCC ≥ 2.12V), and maintains VOH ≥ 0.8×VCC at ISOURCE = 500µA-enabling direct interface with 1.8V/2.5V/3.3V µP reset inputs without level-shifting.

Key Specifications

Pinout & Package

Package: 5-pin SOT23-5, lead-free, surface-mount. Pinout validated per MAX6865 functional diagram and pin description table (page 8 of datasheet).

Key Features

Applications

Equivalent & Alternatives

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

Compared with TPS3836K33DBVR and STM6823RWX6F, the MAX6865UK46D3L+T uniquely combines 4.625V precision threshold, 300ms timeout, 209s watchdog, and 170nA current in a standard 5-pin SOT23-enabling single-chip brownout + hang protection in space-constrained battery systems.

Availability

MAX6865UK46D3L+T is available at Aetrix Electronics and suitable for portable medical devices, industrial handhelds, smart energy meters, and battery-backed data loggers requiring stable component supply across extended product lifecycles.

Supply support for MAX6865UK46D3L+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 power, sensing, and interface applications in industrial, medical, and communications markets.

The MAX68xx family targets ultra-low-power microprocessor supervision in battery-critical systems, emphasizing nanoscale current consumption, wide VCC range, and integrated watchdog functionality without external components.

FAQ

What is the exact reset threshold voltage of the MAX6865UK46D3L+T?

The MAX6865UK46D3L+T has a factory-trimmed reset threshold of +4.625V with ±2.5% tolerance over temperature (–40°C to +85°C), corresponding to suffix "46" per Table 2 in the datasheet. This value is guaranteed at VCC falling and includes 0.5% hysteresis to prevent chatter near threshold. The MAX6865UK46D3L+T maintains this accuracy without external calibration components.

Does the MAX6865UK46D3L+T require external components for basic operation?

No, the MAX6865UK46D3L+T requires no external components for core supervision functionality. Its internal 10kΩ MR pullup, precision bandgap reference, and RC-based timing eliminate need for resistors or capacitors. A 0.1µF ceramic bypass capacitor on VCC is recommended for noise immunity but not strictly required for DC operation. The MAX6865UK46D3L+T achieves full functionality in minimal footprint.

How does the watchdog timer in the MAX6865UK46D3L+T behave during reset assertion?

While RESET is asserted (low), the MAX6865UK46D3L+T watchdog timer is disabled and does not count. It resumes timing only after RESET deasserts. The timer clears on any WDI edge (rising or falling), MR assertion, or RESET assertion-ensuring reliable recovery from firmware lockups. With L-suffix, the MAX6865UK46D3L+T provides 209s typical timeout, validated across temperature.

Can the MAX6865UK46D3L+T operate reliably at VCC = 1.2V?

Yes, the MAX6865UK46D3L+T is fully specified from VCC = 1.2V to 5.5V. At 1.2V, it draws ~190nA supply current and guarantees RESET assertion validity down to VCC = +1.1V. Output drive strength is reduced at low VCC (e.g., VOL ≤ 0.3V at ISINK = 50µA), but sufficient for interfacing with modern ultra-low-voltage µPs. The MAX6865UK46D3L+T maintains timing and threshold accuracy across this range.

What is the function of Pin 4 (WDI) on the MAX6865UK46D3L+T?

Pin 4 (WDI) is the watchdog input terminal of the MAX6865UK46D3L+T. It monitors µP activity: if WDI remains static (high or low) longer than the 209s timeout, the device asserts RESET. Each rising or falling edge on WDI clears the timer. WDI accepts CMOS-level signals, requires ≥150ns pulse width, and draws ≤20nA leakage. This pin enables fail-safe supervision of firmware execution in safety-critical portable devices using the MAX6865UK46D3L+T.