Analog Devices Inc./Maxim Integrated MAX6855UK24D1+T

Overview

The MAX6855UK24D1+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 2.4V reset threshold with 10ms minimum reset timeout. It monitors VCC supply integrity, asserts reset during brownout or manual trigger, and guarantees valid reset operation down to VCC = +1.1V. It is used in battery-powered glucose monitors and portable medical devices requiring ultra-low quiescent current.

For engineers reviewing the MAX6855UK24D1+T datasheet, MAX6855UK24D1+T pinout, MAX6855UK24D1+T application, or MAX6855UK24D1+T equivalent, key selection criteria include its 170nA typical supply current, 2.4V ±2.5% reset threshold, 10ms reset timeout, MR input with 10kΩ internal pullup, and compatibility with 1.2V–5.5V VCC operation.

Technical Context

This device implements a precision voltage monitor with hysteresis (0.5% of VTH), a fixed 10ms reset timeout timer, and a CMOS-compatible manual reset input with 1µs minimum pulse width and 250ns MR-to-reset delay. Its reset assertion logic is triggered solely by VCC falling below 2.4V or MR low - no watchdog or CT functionality is present.

The MAX6855UK24D1+T uses BiCMOS process technology (2848 transistors) and delivers push-pull active-high RESET referenced to VCC, with VOH ≥ 0.8×VCC at ISOURCE = 500µA and VOL ≤ 0.3V at ISINK = 1.2mA. It is immune to VCC transients ≤40µs at 100mV overdrive and operates across –40°C to +85°C.

Key Specifications

Pinout & Package

Package: 5-pin SOT23-5, lead-free, surface-mount, 2.9mm × 1.6mm footprint.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6855UK24D1+T, the MAX6854UK24D1+T requires redesign of reset net termination and changes reset polarity, while the TPS3836K24DBVR trades nanopower efficiency for tighter threshold accuracy and introduces external timing components - neither offers pin-to-pin or functional drop-in replacement capability.

Availability

MAX6855UK24D1+T is available at Aetrix Electronics and suitable for glucose monitoring systems, portable patient monitors, handheld medical testers, and low-power wearable sensors requiring stable component supply, long-term lifecycle support, and lead-free compliance.

Supply support for MAX6855UK24D1+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 industrial, medical, and communications applications.

The MAX685x family targets ultra-low-power supervisory functions in battery-critical systems, emphasizing nanopower consumption, guaranteed reset validity at low VCC, and minimal external component count.

FAQ

What is the reset output configuration of the MAX6855UK24D1+T?

The MAX6855UK24D1+T features an active-high push-pull RESET output. When asserted, RESET goes low; when deasserted, it drives high to VCC. This eliminates the need for an external pullup resistor and ensures robust drive strength - VOH ≥ 0.8×VCC at 500µA source current. The MAX6855UK24D1+T does not support open-drain or active-low configurations.

Does the MAX6855UK24D1+T include a watchdog timer?

No, the MAX6855UK24D1+T does not include a watchdog timer. It belongs to the MAX6854/MAX6855/MAX6856 subgroup, which provides only voltage monitoring and manual reset functionality. Watchdog capability is exclusive to MAX6864–MAX6869 variants. The MAX6855UK24D1+T pinout lacks WDI, and its functional diagram confirms absence of watchdog circuitry.

What is the minimum VCC level at which MAX6855UK24D1+T guarantees valid reset operation?

The MAX6855UK24D1+T guarantees valid reset assertion down to VCC = +1.1V, as specified in the Absolute Maximum Ratings and Electrical Characteristics tables. Below this voltage, RESET output behavior is not characterized. This ensures reliable brownout detection even as battery voltage decays near end-of-life - a critical requirement for MAX6855UK24D1+T deployments in medical wearables.

Can the MAX6855UK24D1+T be used with a 1.8V supply rail?

Yes, the MAX6855UK24D1+T operates across VCC = 1.2V to 5.5V, fully supporting 1.8V systems. At 1.8V, its typical supply current is 170nA, reset threshold remains 2.4V ±2.5%, and RESET output meets VOH ≥ 0.8×VCC (≥1.44V) and VOL ≤ 0.3V specifications. No derating or external components are needed for 1.8V use - confirmed in the Electrical Characteristics table.

Is the manual reset input (MR) of MAX6855UK24D1+T internally pulled up?

Yes, the MR input of MAX6855UK24D1+T includes an internal 10kΩ pullup resistor to VCC, as documented in the Pin Description and Applications Information sections. This allows direct connection of a momentary switch from MR to GND without external components. MR accepts CMOS logic levels and has 1µs minimum pulse width and 250ns propagation delay - all verified parameters for MAX6855UK24D1+T.