Analog Devices Inc./Maxim Integrated MAX6855UK40D5+T

Overview

MAX6855UK40D5+T from Maxim Integrated is a nanopower microprocessor supervisory circuit in 5-pin SOT23 package, featuring active-high push-pull reset output, 4.000V factory-trimmed reset threshold (±2.5%), 300ms minimum reset timeout, manual reset input (MR), and ultra-low 170nA typical supply current. It monitors VCC in battery-powered systems to assert reset during power-up, brownout, or manual trigger events.

For engineers reviewing the MAX6855UK40D5+T datasheet, MAX6855UK40D5+T pinout, MAX6855UK40D5+T application, or MAX6855UK40D5+T equivalent, this device serves as a low-power voltage monitor with deterministic reset timing for portable medical and consumer electronics where supply stability and energy efficiency are critical.

Technical Context

The MAX6855UK40D5+T implements a precision bandgap-based voltage reference and comparator to detect VCC falling below 4.000V (±2.5%), with guaranteed reset validity down to VCC = +1.1V. Its internal timer enforces a fixed 300ms minimum reset assertion period after VCC recovery and MR deassertion.

It features an internally pulled-up MR input (10kΩ to VCC), glitch rejection of 200ns, and MR-to-reset delay of 250ns. Unlike watchdog-equipped variants, MAX6855UK40D5+T omits WDI and CT pins-confirmed by its pin configuration and Selector Guide entry-making it a dedicated voltage-monitoring reset IC without watchdog or timeout-select functionality.

Key Specifications

Pinout & Package

Package: 5-pin SOT23-5, 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 TPS3836K33DBVR and MAX6315US31D3+T, MAX6855UK40D5+T uniquely delivers 4.000V threshold accuracy, 300ms timeout, and 170nA supply current in one SOT23-5 device-making it optimal for long-life 4V-rail applications like clinical diagnostics equipment.

Availability

MAX6855UK40D5+T is available at Aetrix Electronics and suitable for portable glucose monitors, medical patient monitors, MP3 players, and PDA power management systems requiring stable component supply across extended production lifecycles.

Supply support for MAX6855UK40D5+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 power, sensing, and interface applications in industrial, medical, and consumer markets.

The MAX6854–MAX6869 family delivers nanopower supervisory functions targeting battery-critical portable electronics-specifically engineered to replace discrete reset solutions with integrated, low-quiescent-current voltage monitoring and reset generation.

FAQ

What is the exact reset threshold voltage of MAX6855UK40D5+T?

The MAX6855UK40D5+T has a factory-trimmed reset threshold of 4.000V with ±2.5% tolerance over -40°C to +85°C. This value is confirmed in Table 2 (Threshold Suffix Guide) where suffix "40" corresponds to 4.000V nominal, and Electrical Characteristics specify VTH = VTH ±2.5% at TA = -40°C to +85°C. The MAX6855UK40D5+T uses this exact threshold for reliable detection of 4V rail brownout conditions.

Does MAX6855UK40D5+T include a watchdog timer function?

No, MAX6855UK40D5+T does not include a watchdog timer. Per the Selector Guide and Pin Configurations, MAX6855UK40D5+T belongs to the MAX6854/MAX6855/MAX6856 group, which lacks WDI pin and watchdog circuitry. Only MAX6864–MAX6869 variants integrate watchdog functionality. The MAX6855UK40D5+T is a dedicated voltage-monitoring supervisory IC with manual reset only.

What is the reset output type and drive capability of MAX6855UK40D5+T?

MAX6855UK40D5+T features an active-high push-pull reset output (RESET pin 1). As specified in Electrical Characteristics, VOH ≥ 0.8 × VCC at ISOURCE = 200µA (VCC ≥ 1.71V) and VOL ≤ 0.3V at ISINK = 1.2mA (VCC ≥ 2.38V). This eliminates need for external pullup resistors and ensures robust logic-level compatibility with modern µPs. The MAX6855UK40D5+T output is fully specified across its 1.2V–5.5V operating range.

How does the manual reset (MR) input behave on MAX6855UK40D5+T?

The MR input on MAX6855UK40D5+T is active-low with internal 10kΩ pullup to VCC. Driving MR low asserts reset immediately; reset remains asserted for the full 300ms timeout after MR returns high. MR accepts CMOS logic levels, rejects <200ns glitches, and exhibits 250ns MR-to-reset delay. Leaving MR unconnected defaults to VCC via internal pullup-no external components needed. This behavior is documented in the MAX6855UK40D5+T Pin Description and Electrical Characteristics tables.

Is MAX6855UK40D5+T pin-compatible with other supervisory ICs?

Yes, MAX6855UK40D5+T is pin-compatible with Texas Instruments' TPS3836/TPS3837/TPS3838 family per the datasheet Features section. All share identical 5-pin SOT23-5 pinout: Pin 1 = RESET, Pins 2&4 = GND, Pin 3 = MR, Pin 5 = VCC. This allows direct substitution in existing layouts, though threshold voltage (4.000V vs. TPS3836K33's 3.08V) and timeout (300ms vs. 200ms) differ-requiring validation in target application. The MAX6855UK40D5+T maintains mechanical and electrical interoperability at the board level.