Analog Devices Inc./Maxim Integrated MAX6805US44D3

Overview

MAX6805US44D3 from Maxim Integrated is an open-drain, active-low microprocessor supervisory circuit in a 4-pin SOT143 package, designed to monitor 4.38V power supplies with 100ms minimum reset timeout. It asserts RESET during VCC brownout or manual reset, guarantees correct state down to VCC = 1.0V, and draws only 4–12µA supply current. Used in portable equipment and critical µP power monitoring.

For engineers reviewing the MAX6805US44D3 datasheet, MAX6805US44D3 pinout, MAX6805US44D3 application, or MAX6805US44D3 equivalent, key selection criteria include its 4.38V factory-trimmed reset threshold, open-drain output for bidirectional µP reset pin interfacing (e.g., Motorola 68HC11), guaranteed operation at VCC ≥ 1.0V, and 100ms reset timeout period - all validated across –40°C to +125°C.

Technical Context

The MAX6805US44D3 implements a precision voltage comparator with ±1.8% threshold accuracy at +25°C and ±3% over –40°C to +125°C, rejecting fast VCC transients via built-in immunity circuitry. Its reset assertion logic combines VCC monitoring and debounced manual-reset input (MR), with internal 20kΩ MR pullup.

Reset remains asserted for ≥100ms after VCC rises above 4.38V or MR deasserts. The open-drain RESET output requires an external pullup resistor and supports bidirectional reset interfaces, unlike push/pull variants (MAX6803/MAX6804).

Key Specifications

Pinout & Package

Package: 4-pin SOT143 (U4-1 outline, land pattern 90-0183), surface-mount, lead-free compatible (replace "-T" with "+T" for RoHS-compliant ordering).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar µP reset supervision applications.

Compared with MAX6805US44D3, MAX6315US44D3 offers push/pull drive but loses bidirectional interface capability, while TPS3808G33DBVR provides longer timeout and tighter threshold tolerance but sacrifices MR functionality and physical compatibility.

Availability

MAX6805US44D3 is available at Aetrix Electronics and suitable for portable/battery-powered equipment, critical µP/µC power monitoring, and intelligent instruments 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 designs high-performance analog and mixed-signal semiconductor solutions for industrial, communications, computing, and consumer applications.

The MAX680x family delivers ultra-low-power, factory-trimmed µP supervisory circuits with manual reset, targeting space-constrained and battery-sensitive systems requiring precise voltage monitoring and robust reset timing.

FAQ

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

The MAX6805US44D3 has a factory-trimmed reset threshold of 4.38V, specified with ±1.8% accuracy at +25°C and ±3% over the full –40°C to +125°C operating temperature range. This value is confirmed in Table 1 of the official datasheet and corresponds to suffix "44" in the part number. The threshold is laser-trimmed during production and requires no external components for calibration.

Does MAX6805US44D3 support manual reset functionality?

Yes, MAX6805US44D3 includes a debounced manual-reset input (MR) that asserts the open-drain RESET output when pulled low. The MR pin features an internal 20kΩ pullup resistor, allowing direct connection of a momentary switch to ground without external components. MR pulse width must exceed 1µs, and glitch immunity is rated at 50ns - enabling reliable operator-initiated reset in field-deployed equipment.

What is the minimum supply voltage required for MAX6805US44D3 to guarantee correct reset output state?

MAX6805US44D3 guarantees correct RESET/RESET output state down to VCC = 1.0V at –40°C to +125°C, and down to 1.2V across the full temperature range. This is distinct from the MAX6803/MAX6804 variants (guaranteed to 0.7V) and reflects the open-drain architecture's lower operating floor. Below 1.0V, sinking capability degrades and RESET may drift non-active due to pullup dominance.

What package type and footprint does MAX6805US44D3 use?

MAX6805US44D3 is supplied in a 4-pin SOT143 package (outline U4-1, land pattern 90-0183), with pin 1 = GND, pin 2 = RESET (open-drain), pin 3 = MR, and pin 4 = VCC. It is available in both leaded and lead-free versions; specify "+T" instead of "-T" for RoHS-compliant ordering. Tape-and-reel packaging is standard, with minimum order quantity of 2500 pieces for standard versions.

How does the open-drain output of MAX6805US44D3 differ from push/pull alternatives like MAX6804US44D3-T?

The open-drain RESET output of MAX6805US44D3 requires an external pullup resistor and enables wired-OR configurations and direct interfacing with bidirectional µP reset pins (e.g., Motorola 68HC11), whereas MAX6804US44D3-T uses a push/pull output that drives high/low actively without external components. This makes MAX6805US44D3 suitable for multi-source reset buses but necessitates careful pullup selection to meet VOL < 0.4V at ISINK = 3.2mA.