Analog Devices Inc./Maxim Integrated MAX6865UK34D3S+T

Overview

The MAX6865UK34D3S+T from Maxim Integrated is a nanopower microprocessor supervisory circuit in 5-pin SOT23 package, integrating voltage monitoring (3.315V factory-trimmed reset threshold), manual reset input (MR), and watchdog timer (209s typical timeout). It asserts an active-high push-pull RESET output during VCC brownout, MR assertion, or watchdog timeout, with guaranteed reset validity down to VCC = +1.1V. It targets ultra-low-power portable medical and consumer devices requiring reliable power-on reset and firmware crash recovery.

For engineers reviewing the MAX6865UK34D3S+T datasheet, MAX6865UK34D3S+T pinout, MAX6865UK34D3S+T application, or MAX6865UK34D3S+T equivalent, key selection criteria include its 170nA typical supply current, 3.315V ±2.5% reset threshold, 300ms minimum reset timeout, 209s watchdog period, and compatibility with 1.2V–5.5V VCC operation in battery-constrained systems.

Technical Context

This device implements a precision bandgap-based voltage monitor with 2.5% threshold tolerance and hysteresis of 0.5% VTH, coupled with a digital watchdog timer that clears on any WDI edge and expires if WDI remains static beyond 209s (typ). The internal MR pullup is fixed at 10kΩ, and reset deassertion follows a deterministic timeout after VCC exceeds VTH and MR deasserts.

The push-pull active-high 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 logic-level compatibility with modern µPs. Immunity to VCC transients <40µs at 100mV overdrive enables stable operation in noisy power environments.

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 MAX6864UK34D3S+T and TPS3837K33DBVR, the MAX6865UK34D3S+T uniquely combines ultra-low 170nA supply current, active-high push-pull RESET, and 209s watchdog in a single 5-pin SOT23 - enabling longer runtime and simpler integration in next-generation portable medical and wearable electronics.

Availability

MAX6865UK34D3S+T is available at Aetrix Electronics and suitable for glucose monitors, patient monitoring devices, and smart wearables requiring stable component supply with guaranteed long-term lifecycle support.

Supply support for MAX6865UK34D3S+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, mixed-signal, and power management ICs for demanding industrial, medical, and communications applications.

The MAX6854–MAX6869 family was engineered specifically for ultra-low-power microprocessor supervision in battery-operated medical and portable electronics, emphasizing nanoscale current consumption and robust reset timing integrity.

FAQ

What is the exact reset threshold voltage of the MAX6865UK34D3S+T?

The MAX6865UK34D3S+T has a factory-trimmed reset threshold of 3.315V, with ±2.5% tolerance over temperature (-40°C to +85°C). This value is confirmed in Table 2 (Threshold Suffix Guide) of the datasheet, where suffix "34" corresponds to 3.315V nominal. The MAX6865UK34D3S+T maintains this accuracy without external calibration components.

Does the MAX6865UK34D3S+T support active-high or active-low reset output?

The MAX6865UK34D3S+T provides an active-high push-pull RESET output, as specified in its pin description and Selector Guide. Pin 1 outputs high during normal operation and transitions low only during reset assertion - unlike the MAX6864UK34D3S+T variant, which offers active-low. This eliminates the need for external inverters or pullup resistors in active-high µP interfaces.

What is the watchdog timeout period for the MAX6865UK34D3S+T?

The MAX6865UK34D3S+T features a watchdog timeout period of 209s (typical), corresponding to the "L" suffix in its ordering code. This is verified in Table 3 (Watchdog Timeout) and applies across the full operating temperature range. The timer clears on any WDI edge and expires only if WDI remains static beyond this interval, providing reliable firmware crash detection in long-cycle applications.

Can the MAX6865UK34D3S+T operate down to 1.2V supply voltage?

Yes, the MAX6865UK34D3S+T is fully specified to operate from VCC = 1.2V to 5.5V, as stated in the Absolute Maximum Ratings and Electrical Characteristics tables. Its 170nA typical supply current and guaranteed reset validity down to VCC = +1.1V make it suitable for single-cell alkaline or lithium primary batteries, where voltage can decay below 1.5V during end-of-life.

Is an external pullup resistor required for the MR pin on the MAX6865UK34D3S+T?

No, the MR pin on the MAX6865UK34D3S+T includes an internal 10kΩ pullup resistor to VCC, as documented in the Pin Description section. This allows direct connection of a momentary switch from MR to GND without external components. Leaving MR unconnected or tying it to VCC disables manual reset functionality safely.