Analog Devices Inc./Maxim Integrated MAX6348UR45+

Overview

MAX6348UR45+ from Maxim Integrated is an ultra-low-power open-drain microprocessor supervisory circuit designed to monitor 4.5V power supplies and assert a reset signal during brownout, power-up, or power-down events. It features a factory-trimmed 4.5V reset threshold (±1.5% at +25°C), 100ms minimum reset timeout, 1µA max supply current, and operation down to 1V VCC - making it suitable for battery-powered portable systems requiring reliable power-on reset functionality.

For engineers reviewing the MAX6348UR45+ datasheet, MAX6348UR45+ pinout, MAX6348UR45+ application, or MAX6348UR45+ equivalent, key selection criteria include its open-drain active-low RESET output, SC70-3 package compatibility, immunity to fast VCC transients (<200µs at 100mV overdrive), and direct interface capability with bidirectional µP reset pins such as those on Motorola 68HC11-family controllers.

Technical Context

The MAX6348UR45+ implements a precision bandgap-based voltage comparator with hysteresis (9.5mV typical) to detect when VCC falls below its 4.5V threshold. Its internal timing circuit ensures a guaranteed minimum 100ms reset pulse width after VCC rises above threshold, independent of supply ramp rate.

Designed for single-supply operation from 1V to 5.5V, the device uses no external components and rejects transients up to 100µs in duration when VCC dips 100mV below threshold - verified across -40°C to +85°C. The open-drain RESET output supports flexible pull-up configurations and bidirectional reset arbitration in embedded µP systems.

Key Specifications

Pinout & Package

MAX6348UR45+ is housed in a 3-pin SC70 package (2.0mm × 2.1mm × 0.9mm), pin-compatible with SOT23-3 and footprint-compatible with MAX803/MAX809/MAX810 series. The SC70 package supports high-density PCB layouts and automated assembly.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX809TR45+T, MAX6348UR45+ offers superior transient immunity and lower ICC, while TPS3808G33DBVR provides configurability at the cost of higher current and larger package - making MAX6348UR45+ optimal for space-constrained, ultra-low-power, fixed-threshold applications.

Availability

MAX6348UR45+ is available at Aetrix Electronics and suitable for portable medical sensors, automotive body control modules, industrial PLC I/O submodules, smart energy meters, and other applications requiring stable component supply with guaranteed long-term availability and traceable sourcing.

Supply support for MAX6348UR45+ 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 industrial, automotive, communications, and consumer applications.

The MAX63xx family delivers ultra-low-power, pin-compatible µP reset supervisors optimized for battery-operated and space-constrained embedded systems where reliability, small size, and minimal quiescent current are critical.

FAQ

What is the exact reset threshold voltage of MAX6348UR45+ and how tightly is it specified?

The MAX6348UR45+ has a factory-trimmed reset threshold of 4.5V, with ±1.5% tolerance at +25°C and ±2.5% over the full -40°C to +85°C operating range. This specification is guaranteed by production testing and documented in the Electrical Characteristics table of the official datasheet. The 4.5V threshold is confirmed by the "R45" suffix in the part number and validated across all units shipped.

Does MAX6348UR45+ require any external components to function?

No, MAX6348UR45+ operates autonomously with no external components required. Its internal voltage reference, comparator, and timing circuit eliminate the need for resistors, capacitors, or trimming. Only an external pull-up resistor on the open-drain RESET pin is necessary for proper logic-level definition - a standard requirement for all open-drain outputs, not a design limitation of the MAX6348UR45+ itself.

Can MAX6348UR45+ be used with microcontrollers that have bidirectional reset pins?

Yes, MAX6348UR45+ is explicitly designed for this use case. Its open-drain RESET output allows direct connection to bidirectional µP reset pins (e.g., Motorola 68HC11) using a single external pull-up resistor. Either the MAX6348UR45+ or the µP can assert reset on the shared line - a capability confirmed in the Applications Information section of the datasheet and validated in Figure 1.

What is the minimum VCC voltage at which MAX6348UR45+ continues to assert reset reliably?

MAX6348UR45+ guarantees correct reset assertion down to VCC = 1.0V, as stated in the General Description and Absolute Maximum Ratings sections. This means that even during severe brownout conditions where the supply sags to 1V, the device maintains a valid low-state RESET output - a critical feature for fail-safe operation in portable and automotive systems.

How does MAX6348UR45+ handle fast voltage transients on the VCC line?

MAX6348UR45+ rejects negative-going VCC transients up to 200µs in duration when the overdrive (VTH – VCC) is 100mV, as shown in the Typical Operating Characteristics graph "Maximum Transient Duration vs. Reset Threshold Overdrive". This immunity is built into the comparator design and tested across temperature, preventing false resets caused by switching noise or load-dump events without requiring external filtering.