Analog Devices Inc./Maxim Integrated MAX6868UK46D6L+T

Overview

The MAX6868UK46D6L+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%), 1200ms minimum reset timeout, and integrated watchdog timer with 209s typical timeout. It monitors VCC, responds to manual reset (MR), and triggers reset on watchdog timeout - designed for battery-critical systems like glucose monitors and portable medical devices.

For engineers reviewing the MAX6868UK46D6L+T datasheet, MAX6868UK46D6L+T pinout, MAX6868UK46D6L+T application, or MAX6868UK46D6L+T equivalent, this device delivers guaranteed reset validity down to VCC = +1.1V, immunity to short VCC transients (<40µs at 100mV overdrive), and dual-function supervision (voltage + watchdog) without external components.

Technical Context

The MAX6868UK46D6L+T implements a precision bandgap-based voltage monitor with 2.5% threshold tolerance and 0.5% hysteresis, coupled with a temperature-stable RC-based watchdog timer that clears on any WDI edge and expires after 209s (typ). Its internal 10kΩ MR pullup and glitch rejection (200ns) enable robust manual reset handling in noisy environments.

This variant belongs to the MAX6867–MAX6869 family, which features WDI on Pin 1 and MR on Pin 3, with active-low push-pull RESET on Pin 4 and VCC on Pin 5 - distinct from earlier families where RESET occupies Pin 1. The D6 suffix specifies 600–1200ms reset timeout, and L suffix selects long watchdog timeout (95–487s, typ 209s).

Key Specifications

Pinout & Package

Package: 5-pin SOT23 (lead-free, +T suffix), 2.9mm × 1.6mm × 1.1mm body, 0.95mm pitch.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6867UK46D6L+T and TPS3839G33DBVR, the MAX6868UK46D6L+T uniquely combines 4.625V precision threshold, 1200ms configurable reset hold time, and 209s watchdog in a push-pull output configuration - making it the sole option among these three for high-reliability 4.5V+ systems requiring both voltage and software supervision without external components.

Availability

MAX6868UK46D6L+T is available at Aetrix Electronics and suitable for glucose monitors, patient vital sign loggers, industrial handheld scanners, and smart smoke detectors requiring stable component supply across extended production lifecycles.

Supply support for MAX6868UK46D6L+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 MAX6867–MAX6869 family targets ultra-low-power, safety-critical embedded systems - delivering nanopower supervision with integrated watchdog to meet IEC 62304 and ISO 13485 reliability requirements in portable medical electronics.

FAQ

What is the exact reset threshold voltage of the MAX6868UK46D6L+T?

The MAX6868UK46D6L+T has a factory-trimmed reset threshold of +4.625V, with guaranteed tolerance of ±2.5% over -40°C to +85°C. This value is confirmed in Table 2 (Threshold Suffix Guide) of the datasheet, where suffix "46" corresponds to 4.625V nominal. The device asserts reset when VCC falls below this threshold and holds reset for the full timeout period after VCC rises above it.

Does the MAX6868UK46D6L+T require external components for basic operation?

No, the MAX6868UK46D6L+T operates autonomously with no external components required. Its internal 10kΩ MR pullup, precision voltage reference, and RC-based watchdog timer eliminate the need for external resistors, capacitors, or trimming networks. Only a 0.1µF VCC bypass capacitor is recommended for noise suppression - not mandatory for functionality but strongly advised for robustness in real-world PCB layouts.

How does the watchdog timer in the MAX6868UK46D6L+T clear and expire?

The MAX6868UK46D6L+T watchdog timer clears on any rising or falling edge at the WDI pin (Pin 1), and also clears automatically when RESET is asserted or MR is pulled low. It expires only if WDI remains static (high or low) for longer than the specified timeout - 209s typical (L-suffix). Once expired, it triggers a full reset pulse for the 1200ms timeout period. The timer does not run while RESET is asserted.

Can the MAX6868UK46D6L+T guarantee reset validity when VCC drops below 1.5V?

Yes, the MAX6868UK46D6L+T guarantees valid reset assertion down to VCC = +1.1V, as explicitly stated in the Electrical Characteristics table. At VCC ≥1.1V and ISINK = 50µA, VOL remains ≤0.3V for the active-low push-pull RESET output. This ensures reliable MCU reset signaling even during severe brownout conditions where many competing supervisors cease functioning.

What is the pin configuration difference between MAX6868UK46D6L+T and MAX6864UK46D6L+T?

The MAX6868UK46D6L+T places WDI on Pin 1 and RESET on Pin 4, whereas MAX6864UK46D6L+T places RESET on Pin 1 and WDI on Pin 4 - a swapped pinout confirmed in the Pin Configurations diagram (page 16) and Selector Guide (page 16). This difference makes them non-pin-compatible; PCB layout must be verified against the correct variant's top-view schematic before substitution.