Analog Devices Inc./Maxim Integrated MAX6868UK29D3S

Overview

MAX6868UK29D3S from Maxim Integrated is a nanopower microprocessor supervisory circuit in 5-pin SOT23 package, featuring ultra-low 170nA typical supply current, factory-trimmed 2.925V reset threshold (suffix '29'), 150ms minimum reset timeout (suffix 'D3'), and watchdog timer with 209s typical timeout (suffix 'S'). It monitors VCC, responds to manual reset (MR), and triggers reset on watchdog expiration - designed for battery-powered medical and portable electronics requiring guaranteed reset validity down to VCC = +1.1V.

For engineers reviewing the MAX6868UK29D3S datasheet, MAX6868UK29D3S pinout, MAX6868UK29D3S application, or MAX6868UK29D3S equivalent, key selection criteria include its 2.925V threshold accuracy (±2.5%), 150–300ms reset timeout range, 209s watchdog period, push-pull active-high RESET output, and immunity to sub-40µs VCC transients at 100mV overdrive - all critical for low-power brownout recovery and firmware crash detection.

Technical Context

The MAX6868UK29D3S integrates voltage monitoring, manual reset input (MR), and watchdog timer (WDI) in a single BiCMOS IC. Its reset assertion logic combines three independent triggers: VCC falling below 2.925V, MR pulled low, or WDI inactivity exceeding 209s (typ). Reset remains asserted for ≥150ms after VCC rises above threshold and MR deasserts, or after watchdog expiry.

It uses an internal 10kΩ pull-up on MR and accepts CMOS-compatible WDI edges as short as 150ns. The push-pull active-high RESET output is referenced to VCC and guarantees VOH ≥ 0.8×VCC (ISOURCE = 500µA) and VOL ≤ 0.3V (ISINK = 1.2mA), ensuring robust interfacing with µP reset inputs across 1.2V–5.5V supply range.

Key Specifications

Pinout & Package

Package: 5-pin SOT23-5, surface-mount, lead-free compatible (order with '+T' suffix).

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6864UK29D3S, MAX6868UK29D3S offers active-high RESET eliminating level-shifting needs; versus TPS3838K29, it adds critical watchdog functionality and cuts supply current by 90%, making it superior for autonomous medical and portable systems requiring long-term reliability.

Availability

MAX6868UK29D3S is available at Aetrix Electronics and suitable for glucose monitors, patient vital sign recorders, industrial handheld scanners, and smart wearable health trackers requiring stable component supply across extended production lifecycles.

Supply support for MAX6868UK29D3S 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 supervision with integrated watchdog for battery-critical embedded systems - engineered specifically for portable medical devices and ultra-low-power IoT endpoints where runtime and fault resilience are non-negotiable.

FAQ

What is the exact reset threshold voltage of MAX6868UK29D3S?

The MAX6868UK29D3S has a factory-trimmed reset threshold of 2.925V, with ±2.5% tolerance over -40°C to +85°C. This value is defined by the '29' suffix in the part number and is verified per Table 2 (Threshold Suffix Guide) in the datasheet. The threshold remains stable across temperature, with normalized variation <±0.5% from -40°C to +85°C.

Does MAX6868UK29D3S require external components for basic operation?

No, MAX6868UK29D3S operates autonomously with no external components required. It includes an internal 10kΩ pull-up on MR, precision voltage reference, and timing circuitry. Only a 0.1µF bypass capacitor on VCC is recommended for noise immunity - no external resistors, capacitors, or pull-ups are needed for RESET, MR, or WDI functionality.

How does the watchdog timer in MAX6868UK29D3S respond to software faults?

The MAX6868UK29D3S watchdog timer expires if WDI remains static (high or low) for >209s (typ). Each rising or falling edge on WDI clears the timer. During reset assertion, the watchdog is disabled; it resumes counting only after RESET deasserts. This ensures reliable detection of firmware hangs without false triggers from transient noise.

What is the minimum VCC voltage at which MAX6868UK29D3S guarantees valid RESET output?

MAX6868UK29D3S guarantees valid RESET output down to VCC = +1.1V, as specified in the Electrical Characteristics table. Below this voltage, RESET may become indeterminate. This feature ensures deterministic µP reset behavior during deep brownout conditions common in battery-powered medical devices nearing end-of-life.

Can MAX6868UK29D3S be used with a 1.8V microcontroller supply?

Yes, MAX6868UK29D3S supports VCC from 1.2V to 5.5V and is fully specified at 1.8V. At VCC = 1.8V, its supply current is 170nA (typ), RESET VOH ≥ 1.44V (0.8×VCC) with 200µA source, and VOL ≤ 0.3V with 500µA sink - all compatible with standard 1.8V CMOS I/O thresholds and µP reset input requirements.