Analog Devices Inc./Maxim Integrated MAX6855UK38D6+T

Overview

The MAX6855UK38D6+T from Maxim Integrated is a nanopower microprocessor supervisory circuit in a 5-pin SOT23 package, providing voltage monitoring, manual reset input (MR), and fixed-reset timeout functionality. It asserts an active-high push-pull RESET output when VCC drops below 3.800V (±2.5%), MR is pulled low, or during power-up/brownout - with guaranteed reset validity down to VCC = +1.1V and a 600ms minimum timeout period. It targets ultra-low-power portable medical and consumer devices requiring reliable power-on reset and operator-initiated recovery.

For engineers reviewing the MAX6855UK38D6+T datasheet, MAX6855UK38D6+T pinout, MAX6855UK38D6+T application, or MAX6855UK38D6+T equivalent, key selection criteria include its 170nA typical supply current, factory-trimmed 3.800V reset threshold, 600ms reset timeout, active-high push-pull RESET output, and compatibility with battery-powered systems operating down to 1.2V supply.

Technical Context

This device implements a precision bandgap-based voltage monitor with 2.5% threshold accuracy over –40°C to +85°C, coupled to a digital timeout counter that holds RESET asserted for ≥600ms after VCC exceeds VTH and MR deasserts. Its MR input features internal 10kΩ pullup, 1µs minimum pulse width support, and 200ns glitch rejection - enabling direct connection to momentary switches without external debounce.

The active-high push-pull RESET output delivers VOH ≥ 0.8×VCC at ISOURCE = 500µA (VCC ≥ 2.38V) and VOL ≤ 0.3V at ISINK = 1.2mA (VCC ≥ 2.38V), ensuring robust interfacing with µP reset inputs across 1.2V–5.5V supply range. Immunity to short VCC transients (<40µs at 100mV overdrive) prevents spurious resets in noisy environments.

Key Specifications

Pinout & Package

Package: 5-pin SOT23-5, surface-mount, lead-free (RoHS-compliant), 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 TPS3837K33DBVR and MAX6361KA29D3+T, the MAX6855UK38D6+T provides superior battery lifetime (170nA vs. >1µA), eliminates external components via push-pull RESET and internal MR pullup, and matches 3.6V system margins with its 3.800V threshold - making it optimal for next-generation portable medical and consumer designs.

Availability

MAX6855UK38D6+T is available at Aetrix Electronics and suitable for portable medical devices, battery-powered consumer electronics, and industrial handheld terminals requiring stable component supply with long-term lifecycle assurance.

Supply support for MAX6855UK38D6+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) is a semiconductor company specializing in high-performance analog, mixed-signal, and power management ICs for industrial, medical, and communications applications.

The MAX6854–MAX6869 family was designed specifically for nanopower microprocessor supervision in battery-critical applications - delivering ultra-low ICC, precise factory-trimmed thresholds, and robust reset timing without external components.

FAQ

What is the exact reset threshold voltage of the MAX6855UK38D6+T?

The MAX6855UK38D6+T has a factory-trimmed reset threshold voltage of +3.800V, with ±2.5% tolerance over the full operating temperature range (–40°C to +85°C). This value is confirmed in Table 2 (Threshold Suffix Guide) of the datasheet, where suffix "38" corresponds to 3.800V nominal. The MAX6855UK38D6+T uses this threshold to monitor 3.6V nominal supply rails with adequate margin against brownout.

Does the MAX6855UK38D6+T include a watchdog timer function?

No, the MAX6855UK38D6+T does not include a watchdog timer. Per the Selector Guide and Pin Description sections, only MAX6864–MAX6869 variants feature WDI input and watchdog timeout functionality. The MAX6855UK38D6+T belongs to the MAX6854/MAX6855/MAX6856 group, which provides voltage monitoring and manual reset only - confirmed by absence of WDI pin and watchdog-related electrical characteristics in its parameter tables.

What is the function of Pin 1 on the MAX6855UK38D6+T?

Pin 1 of the MAX6855UK38D6+T is the RESET output terminal, configured as an active-high push-pull driver. As documented in the MAX6854/MAX6855/MAX6856 Pin Description table, this pin transitions from low to high when VCC falls below 3.800V or MR is pulled low, and remains high for ≥600ms after VCC exceeds the threshold and MR deasserts - directly driving the µP's active-high reset input without external components.

Can the MAX6855UK38D6+T operate with a 1.2V supply voltage?

Yes, the MAX6855UK38D6+T is fully specified to operate from VCC = 1.2V to 5.5V. Its electrical characteristics table explicitly lists 1.2V as the minimum operating voltage, and the device guarantees RESET validity down to VCC = +1.1V. At 1.2V, supply current remains ultra-low (≤370nA typ), and RESET output meets VOH ≥ 0.8×VCC and VOL ≤ 0.3V specifications - enabling use in single-cell NiMH or low-VDD microcontroller systems.

What does the "D6" suffix in MAX6855UK38D6+T indicate?

The "D6" suffix in MAX6855UK38D6+T specifies the reset timeout period: D6 corresponds to a minimum timeout of 600ms, with typical 900ms and maximum 1200ms values (per Table 4, Reset Timeout Periods). This timeout begins after VCC rises above 3.800V and MR is released, ensuring sufficient hold time for µP clock stabilization and firmware initialization before reset deassertion.