Analog Devices Inc./Maxim Integrated MAX6805US44D3+

Overview

MAX6805US44D3+ from Maxim Integrated is an open-drain, active-low microprocessor supervisory circuit designed to monitor 4.38V power supplies in embedded systems. It asserts reset when VCC falls below 4.38V (±3% over temperature) or upon manual reset activation, with a guaranteed minimum 100ms timeout period and valid operation down to VCC = 1.0V. Used in automotive and industrial controllers for reliable brownout detection and system initialization.

For engineers reviewing the MAX6805US44D3+ datasheet, MAX6805US44D3+ pinout, MAX6805US44D3+ application, or MAX6805US44D3+ equivalent, key selection criteria include its factory-trimmed 4.38V threshold, 100ms reset timeout, open-drain output architecture, and SOT143 package compatibility with bidirectional µP reset pins.

Technical Context

The MAX6805US44D3+ implements a precision bandgap-based voltage comparator with factory-trimmed 4.38V reset threshold (±3% over -40°C to +125°C), immune to fast VCC transients up to 30µs at 100mV overdrive. Its internal MR pullup resistor (12–30kΩ) enables direct connection of a momentary switch to GND without external debounce circuitry.

As an open-drain RESET output device, it requires an external pullup resistor and interfaces natively with µPs having bidirectional reset pins (e.g., Motorola 68HC11). Unlike push/pull variants, it does not guarantee RESET validity down to VCC = 0 due to reduced sink capability below 1.0V.

Key Specifications

Pinout & Package

MAX6805US44D3+ is housed in a 4-pin SOT143 package (1.3mm × 2.1mm × 0.95mm), optimized for space-constrained PCB layouts. The package is lead-free (RoHS-compliant) and tape-and-reel supplied.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6804US44D3+, the MAX6805US44D3+ saves board space by eliminating the need for a pullup resistor in wired-OR configurations but sacrifices VCC = 0 reset validity. Against MAX6315US44D3+, it offers superior thermal robustness and lower power consumption at the expense of slightly higher unit cost.

Availability

MAX6805US44D3+ is available at Aetrix Electronics and suitable for automotive engine control units, industrial PLC I/O modules, and portable medical diagnostic devices requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for MAX6805US44D3+ 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 connectivity applications in industrial, automotive, and computing markets.

The MAX680x family delivers low-power, factory-trimmed supervisory circuits targeting space- and power-constrained µP systems requiring reliable reset generation with minimal external components.

FAQ

What is the factory-trimmed reset threshold voltage for MAX6805US44D3+?

The MAX6805US44D3+ has a factory-trimmed reset threshold of 4.38V, with a tolerance of ±3% over the full operating temperature range of -40°C to +125°C. This value is confirmed in Table 1 of the datasheet and corresponds to the "44" suffix in the part number. The threshold is set using laser trimming during production to ensure accuracy without external calibration components.

Does MAX6805US44D3+ support operation down to 0V VCC?

No, MAX6805US44D3+ is guaranteed to maintain correct reset state only down to VCC = 1.0V. Below this voltage, its open-drain output cannot reliably sink current, causing RESET to drift non-active due to the external pullup resistor. For VCC = 0 operation, consider MAX6804US44D3+ (guaranteed to 0.7V) or MAX6803US44D3+ (push/pull, guaranteed to 0.7V).

What is the minimum reset timeout period for MAX6805US44D3+?

The MAX6805US44D3+ has a minimum reset timeout period of 100ms, as indicated by the "D3" suffix in the part number. This is a factory-programmed, temperature-stable delay that ensures the reset signal remains asserted long enough for microprocessor initialization, clock stabilization, and peripheral readiness before release.

Can MAX6805US44D3+ interface directly with a Motorola 68HC11 microcontroller?

Yes, MAX6805US44D3+ is explicitly designed for direct interface with µPs having bidirectional reset pins like the Motorola 68HC11. Its open-drain RESET output connects to the µP's reset pin through a single external pullup resistor, enabling either device to assert reset - a configuration validated in Figure 1 of the MAX6805US44D3+ datasheet.

What package type and dimensions does MAX6805US44D3+ use?

MAX6805US44D3+ uses a 4-pin SOT143 package measuring 1.3mm × 2.1mm × 0.95mm with standard lead spacing. It is RoHS-compliant and supplied in tape-and-reel format. The top-mark "KACW" identifies this specific variant, and the package outline conforms to JEDEC MO-178AA standards per Maxim's package documentation.