Analog Devices Inc./Maxim Integrated MAX6866UK38D3S+T

Overview

MAX6866UK38D3S+T from Maxim Integrated is a nanopower microprocessor supervisory circuit in 5-pin SOT23 package, featuring ultra-low 170nA typical supply current, factory-trimmed 3.800V reset threshold (±2.5%), 300ms minimum reset timeout, and integrated watchdog timer with 3.3s typical timeout. It monitors VCC, responds to manual reset (MR), and asserts active-low open-drain RESET during brownout, power-up, or watchdog expiry - used in glucose monitors and portable medical devices.

For engineers reviewing the MAX6866UK38D3S+T datasheet, MAX6866UK38D3S+T pinout, MAX6866UK38D3S+T application, or MAX6866UK38D3S+T equivalent, this page delivers verified electrical specs, validated pin functions, confirmed watchdog timing behavior, and real-world design constraints including VCC = 1.1V reset validity and immunity to ≤40µs VCC transients.

Technical Context

The MAX6866UK38D3S+T implements a dual-trigger reset architecture: one path responds to VCC falling below 3.800V (with 0.5% hysteresis), another activates on MR assertion or WDI timeout. Its watchdog timer clears on any WDI edge (≥150ns pulse width) and expires after 3.3s (typ) if no transition occurs - independent of VCC level as long as VCC ≥ 1.2V.

Reset assertion persists for ≥300ms after VCC rises above threshold and MR deasserts; the open-drain RESET output requires external pullup and sinks up to 1.2mA at VCC ≥ 2.38V while maintaining VOL ≤ 0.3V. The device guarantees valid reset operation down to VCC = 1.1V and rejects VCC glitches < 40µs at 100mV overdrive.

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 MAX6361KA29D3+T, the MAX6866UK38D3S+T uniquely integrates both precise 3.800V supervision and a 3.3s watchdog in nanopower envelope - enabling single-chip safety-critical restart in battery-constrained medical wearables without external timing components.

Availability

MAX6866UK38D3S+T is available at Aetrix Electronics and suitable for glucose monitoring systems, portable patient monitors, industrial handheld scanners, and smart wearable health trackers requiring stable component supply across extended production lifecycles.

Supply support for MAX6866UK38D3S+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 delivers nanopower supervisory functions - specifically engineered for battery-operated medical and portable electronics where sub-µA quiescent current and guaranteed low-VCC reset validity are mandatory.

FAQ

What is the exact reset threshold voltage of MAX6866UK38D3S+T?

The MAX6866UK38D3S+T has a factory-trimmed reset threshold of 3.800V, with guaranteed tolerance of ±2.5% over -40°C to +85°C. This value is confirmed in Table 2 (Threshold Suffix Guide) where suffix "38" corresponds to 3.800V nominal, and in Electrical Characteristics where VTH = VTH ±2.5%. The device asserts RESET when VCC falls below this threshold and holds it for ≥300ms after VCC rises above it.

Does MAX6866UK38D3S+T include a watchdog timer, and what is its timeout?

Yes, MAX6866UK38D3S+T includes an integrated watchdog timer with 3.3s typical timeout (S suffix), specified as 1.5s min to 7.75s max. The timer clears on any rising or falling edge at WDI (≥150ns wide) and expires only if WDI remains static longer than the timeout period - triggering a full reset cycle. This behavior is documented in Table 3 (Watchdog Timeout) and the Watchdog Input section of the datasheet.

What is the function of Pin 1 (RESET) on MAX6866UK38D3S+T?

Pin 1 of MAX6866UK38D3S+T is the active-low open-drain RESET output. It pulls low during VCC brownout, MR assertion, or watchdog timeout, and remains low for ≥300ms after fault clearance. As an open-drain output, it requires an external pullup resistor to a compatible voltage rail (≤5.5V). Its VOL is guaranteed ≤0.3V at ISINK = 1.2mA when VCC ≥ 2.38V - per Electrical Characteristics and Pin Description sections.

Can MAX6866UK38D3S+T operate reliably at VCC = 1.2V?

Yes, MAX6866UK38D3S+T operates reliably at VCC = 1.2V: its Absolute Maximum Ratings specify VCC = 1.2V to 5.5V, and Electrical Characteristics guarantee RESET assertion validity down to VCC = 1.1V. At 1.2V, supply current is 190nA (typ), reset threshold remains 3.800V ±2.5%, and WDI edge detection continues functioning - all confirmed in the datasheet's operating conditions and parameter tables.

What does the "D3S" suffix in MAX6866UK38D3S+T indicate?

The "D3" in MAX6866UK38D3S+T selects the 300ms minimum reset timeout period (per Table 4), and "S" selects the 3.3s typical watchdog timeout (per Table 3). Together with "38" (3.800V threshold) and "+T" (lead-free SOT23-5), the full suffix encodes all key functional parameters - eliminating need for external configuration resistors or timing capacitors in the MAX6866UK38D3S+T design.