Analog Devices Inc./Maxim Integrated MAX6845UKD0+T

Overview

MAX6845UKD0+T from Maxim Integrated is an ultra-low-voltage microprocessor supervisory circuit with adjustable reset threshold, active-low open-drain reset output, 0.788V factory-set V_TH (via D suffix), and 150µs timeout period (D0 suffix). It monitors +0.55V to +1.8V supplies in portable systems, asserts reset during brownout or manual trigger, and guarantees valid reset down to V_CC = 0.55V. Used in battery-powered controllers and telecom baseband power rails.

For engineers reviewing the MAX6845UKD0+T datasheet, MAX6845UKD0+T pinout, MAX6845UKD0+T application, or MAX6845UKD0+T equivalent, this page delivers verified functional identity, SOT23-5 terminal mapping, reset timing behavior under V_CC transients, RESET IN threshold calibration method, and validated alternative options for low-voltage µP supervision.

Technical Context

The MAX6845UKD0+T implements a precision comparator referenced to V_CC that triggers reset when the voltage at RESET IN falls below 187.4mV (±2.5% over temperature), enabling externally adjustable monitoring of supplies from 0.9V to 1.5V via resistive divider. Its internal MR input includes a 20kΩ pullup and 150ns glitch rejection.

Reset assertion persists for exactly 150µs after V_CC or RESET IN recovers above threshold and MR deasserts; this fixed timeout eliminates external RC timing components. The open-drain RESET output sinks up to 80µA at V_CC ≥ 0.83V and requires an external pullup to any voltage between 0 and 6V.

Key Specifications

Pinout & Package

Package: 5-pin SOT23-5, surface-mount, lead-free (RoHS-compliant), 1.6mm × 2.9mm footprint.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6845UKD0+T, MAX6843UKD0+T offers simpler drive but less interface flexibility, while TPS3808G01DBVR provides longer timeout and higher supply tolerance but lacks sub-1V operation and threshold adjustability - critical for modern ultra-low-power SoC supervision.

Availability

MAX6845UKD0+T is available at Aetrix Electronics and suitable for portable medical sensors, 5G small cell baseband power, and industrial IoT edge controllers requiring stable component supply with guaranteed long-term availability and RoHS-compliant packaging.

Supply support for MAX6845UKD0+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, with emphasis on high-reliability, low-power solutions.

The MAX6841–MAX6845 family was developed specifically for ultra-low-voltage microprocessor supervision in battery-constrained and space-limited systems, targeting sub-1V core rails in portable and telecom infrastructure equipment.

FAQ

What is the exact reset threshold voltage for MAX6845UKD0+T?

The MAX6845UKD0+T does not have a fixed V_CC threshold - it uses an adjustable RESET IN input with a precise 187.4mV (typ) internal reference referenced to V_CC. The D0 suffix indicates a 150µs timeout period, not a voltage threshold. Users set the effective V_CC trip point via an external resistor divider connected to the RESET IN pin, enabling custom thresholds from 0.9V to 1.5V.

Does MAX6845UKD0+T require an external pullup resistor on the RESET pin?

Yes, MAX6845UKD0+T features an active-low open-drain RESET output and requires an external pullup resistor to function correctly. The pullup can connect to any voltage between 0V and 6V, including a different supply domain than V_CC, enabling level-shifted reset signaling. Typical values range from 10kΩ to 100kΩ depending on bus capacitance and rise-time requirements.

Can MAX6845UKD0+T operate reliably at V_CC = 0.6V?

Yes, MAX6845UKD0+T is fully specified to operate down to V_CC = 0.55V. At 0.6V, it maintains valid reset assertion, RESET IN threshold tracking, and MR input functionality. The open-drain RESET output remains capable of sinking 10µA with VOL ≤ 0.2×V_CC, ensuring clean logic-low signaling even in deep brownout conditions.

How does the manual reset (MR) pin behave during power-up?

The MR pin on MAX6845UKD0+T has an internal 20kΩ pullup to V_CC, so it defaults high when unconnected. During power-up, MR remains inactive unless pulled low externally. If asserted during startup, it forces reset for the full 150µs timeout after release - independent of V_CC level - providing deterministic initialization control regardless of supply ramp rate.

Is MAX6845UKD0+T pin-compatible with other parts in the MAX6841–MAX6845 family?

Yes, all MAX6841–MAX6845 variants share identical 5-pin SOT23-5 pinout and footprint. Pin 1 is RESET, Pin 2 is GND, Pin 3 is RESET IN, Pin 4 is MR, and Pin 5 is V_CC. This allows drop-in substitution between MAX6843UKD0+T, MAX6844UKD0+T, and MAX6845UKD0+T for output-type changes - though system-level validation of reset polarity and drive strength is required.