Analog Devices Inc./Maxim Integrated MAX6858UK27D1+T

Overview

The MAX6858UK27D1+T from Maxim Integrated is a nanopower microprocessor supervisory circuit in a 5-pin SOT23 package, providing voltage monitoring, manual reset input, and reset assertion with 2.7V factory-trimmed threshold and 10ms minimum timeout. It asserts an active-low push-pull RESET output when VCC drops below 2.7V or MR is pulled low, and guarantees valid reset operation down to VCC = +1.1V. It is designed for ultra-low-power portable systems such as glucose monitors and battery-powered medical devices.

For engineers reviewing the MAX6858UK27D1+T datasheet, MAX6858UK27D1+T pinout, MAX6858UK27D1+T application, or MAX6858UK27D1+T equivalent, key selection criteria include its 170nA typical supply current, 2.7V reset threshold tolerance (±2.5%), immunity to short VCC transients, no external components requirement, and compatibility with 1.2V–5.5V supply rails.

Technical Context

The MAX6858UK27D1+T implements a precision bandgap-based voltage monitor with hysteresis (0.5% of VTH) and a digital timeout counter that holds RESET asserted for ≥10ms after VCC rises above the 2.7V threshold and MR deasserts. Its internal 10kΩ MR pullup enables direct connection to momentary switches without external biasing.

Unlike watchdog-equipped variants (e.g., MAX6864), the MAX6858UK27D1+T omits WDI functionality and I.C. pins-instead using Pins 1 and 2 as internally connected (I.C.) terminals tied to GND for enhanced noise immunity. It supports only push-pull active-low RESET output and lacks CT or WDI logic inputs.

Key Specifications

Pinout & Package

Package: 5-pin SOT23-5, lead-free, RoHS-compliant.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TPS3836K27DBVR and MAX6369K27+T, the MAX6858UK27D1+T delivers superior energy efficiency (170nA vs. >1µA), guaranteed reset validity down to 1.1V, and integrated noise-suppression I.C. pins - making it uniquely suited for long-life, safety-critical portable medical devices.

Availability

MAX6858UK27D1+T is available at Aetrix Electronics and suitable for glucose monitors, patient vital sign recorders, and low-power wearable sensors requiring stable component supply across extended production lifecycles.

Supply support for MAX6858UK27D1+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 demanding applications in industrial, medical, and communications markets.

The MAX685x family was engineered specifically for nanopower supervisory functions in battery-constrained portable medical and sensor equipment, prioritizing ultra-low ICC, deep-brownout resilience, and robust transient immunity.

FAQ

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

The MAX6858UK27D1+T has a factory-trimmed reset threshold of 2.700V, with guaranteed tolerance of ±2.5% (2.633V to 2.768V) over -40°C to +85°C. This value is confirmed in Table 2 (Threshold Suffix Guide) of the datasheet, where suffix "27" corresponds to 2.7V nominal. The device guarantees valid reset assertion down to VCC = +1.1V, independent of threshold drift.

Does the MAX6858UK27D1+T include a watchdog timer function?

No, the MAX6858UK27D1+T does not include a watchdog timer. It belongs to the MAX6858 subfamily, which provides only voltage monitoring and manual reset (MR) functionality - unlike MAX6864–MAX6869 variants that integrate WDI inputs. The MAX6858UK27D1+T pinout omits WDI and uses Pins 1 and 2 as internally connected (I.C.) terminals for noise suppression.

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

Pins 1 and 2 of the MAX6858UK27D1+T are labeled I.C. (Internally Connected) and must be externally connected to GND. This configuration enhances noise immunity by shunting high-frequency interference away from the internal voltage reference and timing circuitry. The datasheet explicitly states: "For increased noise immunity, connect I.C. to GND." Failure to tie both pins to ground may degrade reset threshold accuracy under EMI stress.

Can the MAX6858UK27D1+T drive a reset input directly without a pullup resistor?

Yes, the MAX6858UK27D1+T features a push-pull active-low RESET output, meaning it actively drives LOW and HIGH states without requiring an external pullup. When RESET is deasserted, it sources sufficient current (VOH ≥ 0.8×VCC at ISOURCE = 200µA) to meet standard CMOS input thresholds. This eliminates the need for external components - a key advantage over open-drain alternatives like the MAX6856.

What is the minimum reset timeout period for the MAX6858UK27D1+T?

The MAX6858UK27D1+T has a fixed minimum reset timeout period of 10ms (suffix D1), as defined in Table 4 (Reset Timeout Periods). This value is guaranteed over full temperature and voltage range (1.2V–5.5V, -40°C to +85°C). The actual timeout varies from 10ms (min) to 25ms (max), with typical behavior centered at 15ms - ensuring sufficient time for µP core and peripherals to stabilize post-power-up.