Analog Devices Inc./Maxim Integrated MAX6855UK19D3+T

Overview

The MAX6855UK19D3+T from Maxim Integrated is a nanopower microprocessor supervisory circuit in a 5-pin SOT23 package, featuring ultra-low 170nA typical supply current, a factory-trimmed 1.9V reset threshold (±2.5%), and a 150ms minimum reset timeout period. It provides active-low push-pull reset output, manual reset input (MR), and operates across –40°C to +85°C for reliable power-up/brownout monitoring in battery-powered medical and portable electronics.

For engineers reviewing the MAX6855UK19D3+T datasheet, MAX6855UK19D3+T pinout, MAX6855UK19D3+T application, or MAX6855UK19D3+T equivalent, this device serves as a low-quiescent-current voltage monitor with deterministic reset timing, MR-triggered recovery, and guaranteed reset validity down to VCC = +1.1V - critical for glucose monitors, patient monitors, and ultra-low-power embedded systems.

Technical Context

The MAX6855UK19D3+T integrates a precision voltage comparator with hysteresis (0.5% of VTH), a monolithic reset timeout generator, and an internal 10kΩ MR pullup. Its reset assertion is triggered by VCC falling below 1.9V, MR logic-low assertion, or (in watchdog variants) WDI timeout - but MAX6855 lacks WDI functionality per Selector Guide and Pin Description tables.

This variant delivers active-high push-pull RESET output (confirmed in MAX6855-specific Pin Description), enabling direct interface to µP reset inputs without external pullups. It guarantees valid reset signaling even as VCC decays to 1.1V, and exhibits immunity to VCC transients ≤40µs at 100mV overdrive - essential for noisy battery-supplied environments.

Key Specifications

Pinout & Package

Package: 5-pin SOT23-5 (lead-free, +T suffix), footprint-compatible with industry-standard 5-lead SC-70/SOT-23 packages.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TPS3837K33DBVR and MAX6361KA19D3+T, the MAX6855UK19D3+T uniquely delivers sub-200nA supply current at 1.9V threshold with active-high push-pull output - making it optimal for long-life, low-voltage, MR-dependent portable medical instruments where minimal BOM and guaranteed low-VCC reset validity are mandatory.

Availability

MAX6855UK19D3+T is available at Aetrix Electronics and suitable for glucose monitors, patient monitors, and MP3 players requiring stable component supply across extended production lifecycles and temperature ranges.

Supply support for MAX6855UK19D3+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 communications markets.

The MAX6854–MAX6869 family targets ultra-low-power microprocessor supervision in battery-constrained devices, emphasizing nanoscale current consumption, rail-to-rail voltage monitoring, and robust reset timing without external components.

FAQ

What is the exact reset threshold voltage of the MAX6855UK19D3+T?

The MAX6855UK19D3+T has a factory-trimmed reset threshold of 1.9V with ±2.5% tolerance over –40°C to +85°C, as defined by the "19" suffix in the ordering code and confirmed in Table 2 (Threshold Suffix Guide). This value is laser-trimmed during production and does not require external calibration. The MAX6855UK19D3+T maintains this accuracy across its full operating temperature range and supply voltage window (1.2V–5.5V).

Does the MAX6855UK19D3+T include a watchdog timer function?

No, the MAX6855UK19D3+T does not include a watchdog timer. Per the Selector Guide and Pin Description sections, only MAX6864–MAX6869 variants feature WDI input; MAX6855 is explicitly listed without WDI or watchdog capability. The MAX6855UK19D3+T provides voltage monitoring and manual reset only - confirming its role as a dedicated, low-complexity supervisory IC for applications where software execution monitoring is handled externally.

What is the function of Pin 4 on the MAX6855UK19D3+T?

Pin 4 on the MAX6855UK19D3+T is a second ground (GND) terminal, electrically connected to Pin 2 internally. Its inclusion improves noise immunity and thermal dissipation in high-density PCB layouts. Unlike variants with I.C., CT, or WDI pins, the MAX6855UK19D3+T uses both Pin 2 and Pin 4 exclusively for grounding - a design choice that enhances stability in battery-powered medical instrumentation where EMI resilience is critical.

Can the MAX6855UK19D3+T drive a microprocessor reset pin directly?

Yes, the MAX6855UK19D3+T features an active-high push-pull RESET output (Pin 1) that drives directly to VCC or GND without external components. It sources ≥200µA at 0.8×VCC and sinks ≥1.2mA at 0.3V, meeting standard µP reset input requirements. This eliminates the need for pullup resistors or level shifters - a key advantage confirmed in the MAX6855-specific Pin Description and Electrical Characteristics table for VOH/VOL.

What does the "D3" suffix indicate in MAX6855UK19D3+T?

The "D3" suffix in MAX6855UK19D3+T specifies a 150ms minimum reset timeout period, per Table 4 (Reset Timeout Periods). This value defines the guaranteed duration RESET remains asserted after VCC rises above 1.9V or MR deasserts. The D3 option ensures sufficient time for slow-starting regulators and µP internal initialization - a fixed, non-adjustable timing parameter laser-trimmed during manufacturing and validated across temperature.