Analog Devices Inc./Maxim Integrated MAX6858UK27D1+

Overview

The MAX6858UK27D1+ from Maxim Integrated is a nanopower microprocessor supervisory circuit in a 5-pin SOT23 package, featuring ultra-low 170nA typical supply current, factory-trimmed 2.7V reset threshold (±2.5%), and 10ms minimum reset timeout period. It monitors VCC, asserts active-low push-pull RESET on undervoltage or manual reset, and guarantees valid reset output down to VCC = +1.1V - ideal for battery-powered glucose monitors and portable medical devices.

For engineers reviewing the MAX6858UK27D1+ datasheet, MAX6858UK27D1+ pinout, MAX6858UK27D1+ application, or MAX6858UK27D1+ equivalent, this page delivers verified electrical parameters, exact pin functions, real-world use cases in low-power embedded systems, and two confirmed alternative parts with documented functional and timing differences.

Technical Context

The MAX6858UK27D1+ implements a precision voltage monitor with hysteresis (0.5% of VTH) and a fixed 10ms reset timeout timer. Its internal 10kΩ MR pullup enables direct CMOS-level manual reset triggering without external components.

Unlike watchdog-equipped variants (e.g., MAX6864–MAX6869), the MAX6858UK27D1+ omits WDI and CT pins - it has no watchdog timer or selectable timeout, and its I.C. pins (1 & 2) are internally connected and must be tied to GND for noise immunity.

Key Specifications

Pinout & Package

Package: 5-pin SOT23 (2.9mm × 1.6mm × 1.1mm), lead-free, -40°C to +85°C operating range.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6854UK27D1+, the MAX6858UK27D1+ removes MR functionality and adds dual I.C. pins tied to GND - reducing pin count overhead while improving noise immunity. Versus TPS3836K27DBVR, it delivers 7× lower supply current and deeper brownout coverage, critical for multi-year battery operation.

Availability

MAX6858UK27D1+ is available at Aetrix Electronics and suitable for glucose monitors, portable ECG devices, and wireless pulse oximeters requiring stable component supply across long-lifecycle medical programs.

Supply support for MAX6858UK27D1+ 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 systems.

The MAX6854–MAX6869 family delivers nanopower supervisory circuits optimized for battery-critical portable medical and handheld electronics - prioritizing ultra-low ICC, guaranteed brownout coverage, and minimal external component count.

FAQ

What is the exact reset threshold voltage of the MAX6858UK27D1+?

The MAX6858UK27D1+ has a factory-trimmed reset threshold of 2.7V with ±2.5% tolerance, meaning the actual VTH falls between 2.633V and 2.768V at +25°C. This value is fixed and non-adjustable; it is specified under VCC falling conditions and includes 0.5% hysteresis to prevent chatter near the threshold. The '27' suffix in the part number directly encodes this 2.7V nominal threshold per Maxim's Threshold Suffix Guide.

Does the MAX6858UK27D1+ include a watchdog timer or manual reset input?

No, the MAX6858UK27D1+ does not include a watchdog timer or manual reset (MR) input. Unlike MAX6864–MAX6869 or MAX6854–MAX6856 variants, it omits both WDI and MR pins. Instead, pins 1 and 2 are labeled I.C. (internally connected) and must be externally tied to GND to ensure noise immunity - a key differentiator confirming its simplified, MR-free supervisory role.

What is the function of the I.C. pins on the MAX6858UK27D1+?

Pins 1 and 2 of the MAX6858UK27D1+ are marked I.C. (Internally Connected) and serve solely to improve noise immunity. They are shorted together internally and must be externally connected to GND on the PCB. Leaving them floating degrades transient immunity and may cause erratic reset behavior. This design choice replaces the MR pin found on other family members, reducing pin count while enhancing robustness in electrically noisy portable systems.

Can the MAX6858UK27D1+ operate reliably down to 1.1V supply voltage?

Yes, the MAX6858UK27D1+ guarantees valid RESET output down to VCC = +1.1V - a critical specification for deep brownout recovery. Below this voltage, RESET remains asserted but is no longer guaranteed to drive correctly. This capability ensures the host microcontroller receives a clean, deterministic reset signal even during severe battery sag, preventing undefined states or partial execution that could corrupt memory or sensors.

Is the MAX6858UK27D1+ pin-compatible with other SOT23-5 supervisory ICs?

The MAX6858UK27D1+ uses a nonstandard SOT23-5 pinout: pins 1 and 2 are I.C. (tie to GND), pin 3 is GND, pin 4 is RESET, and pin 5 is VCC. It is not pin-compatible with MAX6854/MAX6855/MAX6856 (which place RESET on pin 1 or 4 with MR on pin 3) or with TPS3836/TPS3837/TPS3838 (which place RESET on pin 1). Direct replacement requires PCB layout revision to accommodate the unique I.C./GND/RESET/VCC arrangement.