Analog Devices Inc./Maxim Integrated MAX6358SYUT+T

Overview

The MAX6358SYUT+T from Maxim Integrated is a dual-voltage microprocessor supervisory circuit with active-low open-drain reset output, 2.93V VCC1 threshold, 2.19V VCC2 threshold, integrated watchdog timer (46.4s startup / 2.9s normal timeout), and guaranteed RESET validity down to VCC1 ≥ 1.0V or VCC2 ≥ 1.0V. It monitors two independent supply rails in multivoltage embedded systems requiring robust power-fail detection and processor activity supervision.

For engineers reviewing the MAX6358SYUT+T datasheet, MAX6358SYUT+T pinout, MAX6358SYUT+T application, or MAX6358SYUT+T equivalent, this device serves as a precision dual-supply monitor with watchdog functionality for industrial controllers, portable instrumentation, and battery-powered systems where supply sequencing and firmware hang detection are critical.

Technical Context

The MAX6358SYUT+T implements a dual-threshold comparator architecture monitoring VCC1 and VCC2 independently: reset asserts if either supply drops below its factory-set threshold (2.93V ±1.5% for VCC1, 2.19V ±1.5% for VCC2). Its watchdog timer features two distinct timeout modes - a 46.4s startup period after power-up or manual reset, followed by a 2.9s normal timeout requiring periodic WDI transitions.

Reset assertion is guaranteed while either VCC1 or VCC2 remains ≥1.0V, enabling valid reset signaling during brownout conditions. The open-drain RST output supports flexible pull-up configurations and interfaces directly with µP reset inputs requiring external pull-up, with VOL ≤ 0.3V at ISINK = 50µA over full temperature range.

Key Specifications

Pinout & Package

MAX6358SYUT+T is housed in a 6-pin SOT23 package (U6-1 outline) with 0.95mm pitch, 2.9mm × 1.6mm body, and exposed pad option not applicable. Pin 1 is RST (open-drain), Pin 2 is GND, Pin 3 is MR (manual reset input), Pin 4 is VCC2, Pin 5 is WDI (watchdog input), and Pin 6 is VCC1.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar dual-voltage supervisory applications.

Compared with MAX6358SYUT+T, MAX6359SYUT+T simplifies BOM by eliminating the pull-up resistor but sacrifices interface flexibility, while TPS3808G33DBVR reduces cost and improves threshold accuracy at the expense of dual-supply capability and system-level fault coverage.

Availability

MAX6358SYUT+T is available at Aetrix Electronics and suitable for industrial PLC controllers, battery-powered data loggers, medical point-of-care devices, and automotive body control modules requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for MAX6358SYUT+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 high-performance analog and mixed-signal ICs for industrial, communications, computing, and consumer applications.

The MAX6351–MAX6360 family delivers dual- and triple-voltage µP supervisors with integrated watchdog timers, targeting multirail embedded systems needing reliable power sequencing, brownout protection, and firmware supervision.

FAQ

What is the exact reset threshold voltage for VCC1 and VCC2 on the MAX6358SYUT+T?

The MAX6358SYUT+T has a factory-set VCC1 threshold of 2.93V ±1.5% and VCC2 threshold of 2.19V ±1.5%, both specified at +25°C and guaranteed over -40°C to +85°C. These values correspond to the "SY" suffix in the Voltage Threshold Levels table and are laser-trimmed during production for precision monitoring of 3.0V and 2.2V rails.

Does the MAX6358SYUT+T require an external pull-up resistor on the RST pin?

Yes, the MAX6358SYUT+T features an open-drain RST output (Pin 1), which requires an external pull-up resistor to a valid supply rail (typically VCC1 or system 3.3V). The datasheet confirms no internal pull-up exists, and proper reset assertion depends on selecting a resistor value that ensures VOL ≤ 0.3V at 50µA sink current across temperature.

How does the watchdog timer on the MAX6358SYUT+T operate during power-up?

The MAX6358SYUT+T watchdog initiates a 46.4s startup timeout period immediately after power-on reset, manual reset, or watchdog-induced reset. This extended window allows complex firmware initialization before transitioning to the 2.9s normal timeout mode, which begins either after 46.4s elapses or upon the first valid WDI edge detected prior to timeout completion.

Can the MAX6358SYUT+T maintain valid reset output if one supply drops to 0V?

No - the MAX6358SYUT+T guarantees RESET validity only while at least one supply (VCC1 ≥ 1.0V or VCC2 ≥ 1.0V) remains active. If both VCC1 and VCC2 fall below 1.0V simultaneously, the internal circuitry loses bias, and RST state becomes undefined. For true 0V reset assurance, external circuitry (e.g., Figure 4 in the datasheet) is required, though it's incompatible with open-drain outputs like MAX6358SYUT+T's RST.

What is the maximum allowable voltage on the WDI pin of the MAX6358SYUT+T?

The WDI pin (Pin 5) of the MAX6358SYUT+T accepts input voltages from -0.3V to (VCC1 + 0.3V), per Absolute Maximum Ratings. With VCC1 up to 5.5V, the absolute maximum is +5.8V. However, functional operation requires VIH ≥ 0.65 × VCC1 and VIL ≤ 0.3 × VCC1, meaning logic-high levels scale with VCC1 and must stay within these ratios to ensure reliable watchdog clearing.