Analog Devices Inc./Maxim Integrated MAX6349WPUT

Overview

The MAX6349WPUT from Maxim Integrated is a 150mA, low-dropout linear voltage regulator with integrated microprocessor reset circuit, preset for +1.8V output and -5% reset threshold (W suffix), housed in SOT23-6 package. It delivers ultra-low 25µA quiescent current, 180mV dropout at 100mA, and features open-drain active-low RESET output - optimized for battery-powered handheld instruments and USB devices.

For engineers reviewing the MAX6349WPUT datasheet, MAX6349WPUT pinout, MAX6349WPUT application, or MAX6349WPUT equivalent, key selection criteria include its fixed +1.8V output, -5% reset tolerance, manual reset input (MR), thermal/short-circuit protection, and compatibility with 1µF ceramic output capacitors.

Technical Context

The MAX6349WPUT integrates a P-channel MOSFET LDO regulator core with a precision bandgap reference shared by both regulation and reset functions. Its SET pin enables dual-mode operation: grounded for fixed +1.8V output (W variant), or connected to an external resistor divider for adjustable outputs from 1.23V to 5.0V.

The internal reset supervisor monitors VOUT against a -5% threshold (1.71V nominal for +1.8V output), asserts RESET for ≥100ms after recovery, and responds to MR input pulses as short as 1µs. MR includes a 20kΩ internal pullup to OUT and supports TTL/CMOS logic levels without external debounce.

Key Specifications

Pinout & Package

Package: SOT23-6 - compact 2.9mm × 1.6mm surface-mount package with exposed pad for thermal dissipation; GND pin serves dual role as electrical ground and heatsink.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar low-dropout regulator with integrated reset applications.

Compared with MAX6329WPUT, the MAX6349WPUT provides manual reset functionality essential for field-serviceable portable devices, while TPS76318QDBVRQ1 offers automotive qualification at the cost of higher quiescent current and no reverse leakage protection - making MAX6349WPUT optimal for consumer-grade battery-powered equipment requiring robust, low-power supervision.

Availability

MAX6349WPUT is available at Aetrix Electronics and suitable for hand-held instruments, USB devices, electronic planners, and palm top computers requiring stable component supply with guaranteed long-term availability.

Supply support for MAX6349WPUT 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 portable applications.

The MAX6329/MAX6349 product line targets battery-constrained systems needing highly integrated, ultra-low-power voltage regulation and reliable power-on/brownout reset - specifically engineered for space- and energy-sensitive portable electronics.

FAQ

What output voltage does the MAX6349WPUT deliver, and how is it set?

The MAX6349WPUT delivers a fixed +1.8V output with ±3.0% accuracy over temperature and load. This is achieved by grounding the SET pin - the 'W' suffix in the part number explicitly denotes the +1.8V/-5% variant. No external resistors are required for this configuration, simplifying design and reducing BOM count. The internal feedback network uses a 1.23V reference to generate the precise 1.8V output.

Does the MAX6349WPUT support manual reset, and how is it implemented?

Yes, the MAX6349WPUT includes a dedicated MR (manual reset) input on pin 3. A logic-low pulse ≥1µs on MR forces the open-drain RESET output low for the full reset timeout period (≥100ms), even if VOUT remains within specification. MR has a 20kΩ internal pullup to OUT, allowing direct connection to a momentary switch (GND) without external components. This feature is absent in the MAX6329 series, which uses SHDN instead.

What is the minimum output capacitor required for stable operation of the MAX6349WPUT?

The MAX6349WPUT requires a minimum 1µF ceramic (X7R or X5R) or tantalum output capacitor for stable operation across the full temperature range and up to 150mA load. This low capacitance requirement reduces board area and cost versus legacy regulators. For improved noise suppression and transient response, a 10µF capacitor is recommended. Avoid Z5U/Y5V dielectrics below -10°C unless capacitance is increased to ≥2.2µF.

How does the MAX6349WPUT protect against reverse current flow from output to input?

The MAX6349WPUT incorporates internal reverse leakage protection that actively disables the pass transistor and parasitic paths when VOUT exceeds VIN. This results in zero reverse leakage current - verified at <0.01µA - enabling safe use in systems with backup batteries or auxiliary supplies without external blocking diodes. This feature preserves backup power integrity and eliminates associated voltage drop and thermal losses.

What thermal protection mechanisms are built into the MAX6349WPUT?

The MAX6349WPUT includes thermal shutdown protection that disables the pass transistor when junction temperature exceeds +160°C. After shutdown, the device remains off until the junction cools by 20°C (hysteresis), then resumes regulation. This pulsed operation prevents permanent damage during continuous overload or inadequate PCB thermal design. The GND pin serves as the primary thermal path, requiring connection to a large copper area or ground plane for effective heat dissipation.