Analog Devices Inc./Maxim Integrated MAX6867UK20D3S+T

Overview

The MAX6867UK20D3S+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 2.0V reset threshold (±2.5%), 300ms minimum reset timeout, and integrated watchdog timer with 3.3s typical timeout. It monitors VCC, responds to manual reset (MR), and asserts active-low push-pull RESET during brownout, power-up, or watchdog expiration - used in battery-powered glucose monitors and portable medical devices.

For engineers reviewing the MAX6867UK20D3S+T datasheet, MAX6867UK20D3S+T pinout, MAX6867UK20D3S+T application, or MAX6867UK20D3S+T equivalent, key selection criteria include guaranteed reset validity down to VCC = +1.1V, immunity to short VCC transients (<40µs at 100mV overdrive), watchdog input pulse width tolerance (≥150ns), and compatibility with CMOS-level MR/WDI signals.

Technical Context

The MAX6867UK20D3S+T implements a dual-monitoring architecture: a precision voltage detector with hysteresis (0.5% of VTH) triggers reset on VCC fall below 2.0V, while a digital watchdog timer clears on any WDI edge and expires if WDI remains static >3.3s (typ). Reset assertion persists for ≥300ms after VCC recovery and MR deassertion.

Its BiCMOS process enables stable operation across –40°C to +85°C with no external components required. The push-pull active-low RESET output drives loads directly (VOL ≤0.3V at 1.2mA), and MR features internal 10kΩ pullup and 200ns glitch rejection - eliminating need for external debounce in most handheld designs.

Key Specifications

Pinout & Package

MAX6867UK20D3S+T uses a lead-free 5-pin SOT23-5 package (2.9mm × 1.6mm × 1.1mm), optimized for space-constrained portable PCBs. Pin 1 is WDI, Pin 2 is GND, Pin 3 is MR, Pin 4 is RESET (active-low push-pull), and Pin 5 is VCC.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TPS3836K20DBVR and STM6315SW20DX, the MAX6867UK20D3S+T uniquely combines 2.0V supervision, 300ms reset hold, and integrated 3.3s watchdog in a single 170nA device - making it the only option for ultra-low-power, safety-critical portable medical systems requiring autonomous fault recovery.

Availability

MAX6867UK20D3S+T is available at Aetrix Electronics and suitable for glucose monitors, patient monitoring devices, smart wearables, and industrial handheld terminals requiring stable component supply across long production lifecycles.

Supply support for MAX6867UK20D3S+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 demanding environments.

The MAX6854–MAX6869 family delivers nanopower supervisory functions specifically for battery-operated medical, portable, and IoT endpoints where reliability and energy efficiency are critical.

FAQ

What is the exact reset threshold voltage for MAX6867UK20D3S+T?

The MAX6867UK20D3S+T has a factory-trimmed reset threshold of 2.0V with ±2.5% tolerance over –40°C to +85°C. This value is confirmed in Table 2 (Threshold Suffix Guide) of the datasheet, where suffix "20" corresponds to 2.0V nominal. The device guarantees reset assertion when VCC falls below this threshold and maintains reset until VCC exceeds 2.0V and the 300ms timeout elapses. MAX6867UK20D3S+T's hysteresis is 0.5% of VTH, minimizing chatter near threshold.

Does MAX6867UK20D3S+T support open-drain RESET output?

No, MAX6867UK20D3S+T features an active-low push-pull RESET output only. Per the Selector Guide and Pin Description, MAX6867 belongs to the MAX6867/MAX6868/MAX6869 group, which uses Pin 4 as push-pull RESET (not open-drain). Open-drain variants exist in the same family (e.g., MAX6869), but MAX6867UK20D3S+T does not support that configuration. Its push-pull output sinks ≥1.2mA with VOL ≤0.3V, eliminating need for external pullup resistors.

What is the watchdog timeout behavior of MAX6867UK20D3S+T?

MAX6867UK20D3S+T uses the "S" watchdog suffix, providing a typical timeout of 3.3s (min 1.5s, max 7.75s). The watchdog timer clears on any rising or falling edge at WDI (Pin 1) and expires only if WDI remains static (high or low) beyond this period. Upon expiration, it asserts RESET for the full 300ms timeout. The timer pauses while RESET is asserted and resumes counting immediately after RESET deasserts - a behavior explicitly documented in the Functional Diagram and Watchdog Timing section.

Can MAX6867UK20D3S+T operate with VCC below 1.8V?

Yes, MAX6867UK20D3S+T operates with VCC from 1.2V to 5.5V and guarantees valid RESET assertion down to VCC = +1.1V. Electrical Characteristics confirm supply voltage range (VCC = 1.2V to 5.5V) and specify that RESET remains functional even as VCC drops to 1.1V. At 1.2V, ICC is 190nA (typ), and VOL remains ≤0.3V with ISINK = 100µA - enabling reliable supervision in deep brownout conditions common in aging primary batteries.

How is the reset timeout period configured on MAX6867UK20D3S+T?

The reset timeout period for MAX6867UK20D3S+T is fixed at 300ms minimum (D3 option), encoded in the part number suffix "D3". Unlike MAX6861–MAX6863, MAX6867 does not have a CT pin for dynamic selection; its timeout is factory-set and non-adjustable. Table 4 confirms D3 corresponds to 150/225/300ms (min/typ/max), and the Typical Operating Characteristics graph (toc03) shows normalized tRP variation <±1% over temperature - ensuring consistent timing across operating conditions. MAX6867UK20D3S+T requires no external components to set this parameter.