Analog Devices Inc./Maxim Integrated MAX6865UK43D5L+T

Overview

The MAX6865UK43D5L+T from Maxim Integrated is a nanopower microprocessor supervisory circuit in a 5-pin SOT23 package, combining voltage monitoring (4.193V factory-trimmed reset threshold), manual reset input (MR), and watchdog timer (209s typical timeout) with ultra-low 170nA typical supply current. It asserts an active-high push-pull RESET signal during VCC brownout, MR assertion, or watchdog timeout, and holds reset for 300ms minimum after recovery - ideal for battery-powered glucose monitors and portable medical devices requiring long shelf life and reliable power-on reset.

For engineers reviewing the MAX6865UK43D5L+T datasheet, MAX6865UK43D5L+T pinout, MAX6865UK43D5L+T application, or MAX6865UK43D5L+T equivalent, key selection criteria include its 4.193V reset threshold, 300ms reset timeout (D5 option), 209s watchdog period (L suffix), active-high push-pull output, and guaranteed reset validity down to VCC = +1.1V - all critical for low-voltage, safety-critical embedded systems.

Technical Context

This device implements a precision bandgap-based voltage monitor with ±2.5% threshold accuracy over -40°C to +85°C, coupled with a digitally controlled watchdog timer that clears on any WDI edge and expires if WDI remains static beyond 209s (typ). The internal reset timeout generator uses a temperature-stable RC oscillator, delivering 300ms (min) assertion time independent of VCC within 1.2V–5.5V operating range.

The MR input features 10kΩ internal pullup, 1µs minimum pulse width support, and 200ns glitch rejection; RESET output drives high to VCC with 0.8×VCC VOH at 500µA source current, and remains valid down to VCC = 1.1V - enabling robust operation during deep brownout conditions common in coin-cell or energy-harvesting systems.

Key Specifications

Pinout & Package

Package: 5-pin SOT23-5, lead-free, surface-mount, 2.9mm × 1.6mm footprint.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6865UK43D5S+T, the MAX6865UK43D5L+T provides 63× longer watchdog timeout for extended firmware operations; versus TPS3837K33DBVR, it delivers 9.4× lower supply current and integrated watchdog - making it uniquely suited for long-duration, safety-critical medical monitoring.

Availability

MAX6865UK43D5L+T is available at Aetrix Electronics and suitable for glucose monitors, patient vital sign recorders, and wireless medical telemetry requiring stable component supply across extended production lifecycles and strict regulatory traceability.

Supply support for MAX6865UK43D5L+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, mixed-signal, and power management ICs for demanding industrial, medical, and communications applications.

The MAX6865UK43D5L+T belongs to the MAX68xx nanopower supervisory family, engineered specifically for ultra-low-power, safety-critical portable medical electronics where battery longevity and fault resilience are non-negotiable.

FAQ

What is the exact reset threshold voltage of the MAX6865UK43D5L+T?

The MAX6865UK43D5L+T has a factory-trimmed reset threshold of 4.193V, with guaranteed limits of 4.095V (min) and 4.305V (max) over -40°C to +85°C. This value is defined by the "43" suffix per Maxim's Threshold Suffix Guide (Table 2) and is laser-trimmed during production - no external adjustment is possible or required for the MAX6865UK43D5L+T.

Does the MAX6865UK43D5L+T require external components for basic operation?

No, the MAX6865UK43D5L+T requires no external components for core supervision: MR has a built-in 10kΩ pullup, RESET is push-pull active-high (no pullup needed), and VCC should be bypassed with a 0.1µF capacitor to GND per datasheet recommendation. No timing resistors, capacitors, or voltage dividers are necessary - the MAX6865UK43D5L+T functions autonomously from power-on.

How does the watchdog timer in the MAX6865UK43D5L+T behave during reset assertion?

While RESET is asserted (low for active-low variants, high for the MAX6865UK43D5L+T's active-high output), the internal watchdog timer is halted and does not count. It resumes timing only after RESET deasserts. This prevents spurious timeouts during power-up or manual reset - the MAX6865UK43D5L+T's watchdog exclusively monitors firmware health during normal µP operation.

Can the MAX6865UK43D5L+T supervise a 1.8V microcontroller supply?

Yes, the MAX6865UK43D5L+T operates from 1.2V to 5.5V and guarantees RESET validity down to VCC = +1.1V, making it fully compatible with 1.8V systems. However, its 4.193V reset threshold is intended for monitoring higher rails (e.g., 4.2V battery or 3.3V LDO output); for direct 1.8V supervision, a different threshold variant (e.g., MAX6865UK18D5L+T) would be required - the MAX6865UK43D5L+T is not suitable for 1.8V rail monitoring.

What is the meaning of the 'L' suffix in MAX6865UK43D5L+T?

The 'L' suffix in MAX6865UK43D5L+T specifies the watchdog timeout period: 'L' denotes the long timeout option (95–487s, 209s typical), whereas 'S' would indicate short timeout (1.5–7.75s, 3.3s typical). This suffix is exclusive to MAX6864–MAX6869 devices and is positioned after the reset timeout code ('D5') - confirming the MAX6865UK43D5L+T delivers minute-scale watchdog coverage for extended firmware routines.