Analog Devices Inc./Maxim Integrated MAX6855UK26D3+T

Overview

The MAX6855UK26D3+T from Maxim Integrated is a nanopower microprocessor supervisory circuit in a 5-pin SOT23 package, featuring active-high push-pull reset output, manual reset input (MR), and factory-trimmed 2.625V reset threshold (suffix "26"). It delivers ultra-low 170nA typical supply current, guarantees valid reset down to VCC = +1.1V, and provides 150ms minimum reset timeout (suffix "D3"). It is used in battery-powered medical monitors and portable electronics to ensure reliable power-on reset and brownout protection.

For engineers reviewing the MAX6855UK26D3+T datasheet, MAX6855UK26D3+T pinout, MAX6855UK26D3+T application, or MAX6855UK26D3+T equivalent, key selection criteria include its active-high push-pull RESET logic, 2.625V threshold accuracy (±2.5%), 150ms timeout tolerance (150–300ms), MR input with 10kΩ internal pullup, and guaranteed operation across –40°C to +85°C.

Technical Context

This device integrates voltage monitoring, manual reset assertion, and reset timing control-without watchdog or CT functionality-into a single BiCMOS IC. Its reset assertion is triggered solely by VCC falling below 2.625V or MR being pulled low, and deassertion occurs only after VCC rises above threshold and the 150ms timeout elapses.

The active-high push-pull RESET output is referenced to VCC and sources ≥0.8×VCC at 200µA (VCC ≥ 1.71V); it remains valid down to VCC = 1.1V. Immunity to short VCC transients (<40µs for 100mV overdrive) and no external components required are core design attributes.

Key Specifications

Pinout & Package

Package: 5-pin SOT23-5, lead-free, surface-mount, footprint compatible with industry-standard 5-lead SOT23.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TPS3837K26DBVR and MAX6315US26D3+, the MAX6855UK26D3+T uniquely balances ultra-low 170nA ICC with factory-trimmed 2.625V threshold and integrated MR pullup-making it optimal for long-life, space-constrained, battery-powered medical and portable devices where every nanoamp counts.

Availability

MAX6855UK26D3+T is available at Aetrix Electronics and suitable for glucose monitors, patient vital sign loggers, industrial handheld scanners, and smart asset trackers requiring stable component supply across extended temperature ranges and multi-year battery life.

Supply support for MAX6855UK26D3+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 MAX685x family delivers nanopower supervisory functions for battery-critical systems-emphasizing ultra-low ICC, guaranteed reset validity at low VCC, and factory-trimmed thresholds to eliminate calibration overhead.

FAQ

What is the exact reset threshold voltage of the MAX6855UK26D3+T?

The MAX6855UK26D3+T has a factory-trimmed reset threshold of 2.625V, with guaranteed tolerance of ±2.5% over –40°C to +85°C. This value is confirmed by the "26" suffix in the part number per Maxim's Threshold Suffix Guide (Table 2), and is measured under standard conditions with VCC ≥ 1.2V. The MAX6855UK26D3+T asserts reset when VCC falls below this threshold and holds it for the full 150ms timeout after VCC recovers.

Does the MAX6855UK26D3+T include a watchdog timer function?

No, the MAX6855UK26D3+T does not include a watchdog timer. Per the Selector Guide and Pin Description tables, only MAX6864–MAX6869 variants feature WDI input; the MAX6855UK26D3+T belongs to the MAX6854/MAX6855/MAX6856 group, which provides voltage monitoring and manual reset only. Its functional block diagram confirms absence of watchdog circuitry, and the datasheet explicitly lists WDI as "not applicable" for this variant.

What is the reset output configuration of the MAX6855UK26D3+T?

The MAX6855UK26D3+T features an active-high push-pull reset output (RESET), as indicated by its position in the Selector Guide and Pin Description table. Unlike open-drain or active-low variants, this output drives high (≥0.8×VCC) when asserted and low (≤0.3V) when deasserted-eliminating need for external pullup resistors and enabling direct connection to µP reset pins requiring active-high logic.

How is the 150ms reset timeout period implemented in the MAX6855UK26D3+T?

The 150ms minimum reset timeout in the MAX6855UK26D3+T is fixed and factory-programmed, corresponding to the "D3" suffix per Table 4. It is generated by an internal RC oscillator and timer circuit, with typical value 225ms and maximum 300ms across temperature and voltage. The timeout begins when VCC rises above 2.625V and MR is deasserted, and the RESET output remains high until completion-ensuring µP initialization completes before release.

Is the MR input of the MAX6855UK26D3+T internally pulled up, and what is its value?

Yes, the MR input of the MAX6855UK26D3+T includes an internal 10kΩ pullup resistor to VCC, as documented in the Pin Description table and Applications Information section. This allows direct connection of a momentary switch from MR to GND for manual reset, with no external components required. The MR pin accepts CMOS logic levels and has 200ns glitch rejection, making it robust against contact bounce and EMI in portable equipment.