Analog Devices Inc./Maxim Integrated MAX6392KA31

Overview

MAX6392KA31 from Maxim Integrated is a dual-voltage microprocessor supervisory circuit with sequenced active-low reset outputs for multi-rail systems. It monitors VCC (master supply) at 3.08V threshold and RESET IN2 (adjustable secondary supply) down to 625mV, provides fixed 140ms min timeout for RESET1 and fixed or capacitor-adjustable timeout for RESET2, and includes an active-low manual reset input (MR). It is used in industrial controllers and multivoltage servers requiring controlled power-up sequencing.

For engineers reviewing the MAX6392KA31 datasheet, MAX6392KA31 pinout, MAX6392KA31 application, or MAX6392KA31 equivalent, this device supports precise dual-supply monitoring with guaranteed reset validity down to VCC = 1V, push-pull RESET1 + open-drain RESET2 outputs, and immunity to short negative VCC transients - critical for reliable µP initialization in brownout-prone environments.

Technical Context

The MAX6392KA31 implements two independent voltage comparators: one for VCC (factory-set 3.08V threshold), another for RESET IN2 (625mV internal reference, adjustable via external resistor divider). RESET1 is push-pull, asserted when VCC < 3.08V, and deasserts ≥140ms after VCC exceeds threshold.

RESET2 is open-drain and asserts if either VCC < 3.08V or RESET IN2 < 625mV; it deasserts ≥140ms (or user-adjusted time via CSRT capacitor) after both conditions are satisfied, and always deasserts after RESET1 on power-up and asserts before RESET1 on power-down. MR input forces both resets low with 50µs minimum pulse width and 100ns glitch rejection.

Key Specifications

Pinout & Package

MAX6392KA31 is housed in an 8-pin SOT23 package (3.00mm × 1.75mm × 1.30mm body, 0.65mm pitch), specified for -40°C to +85°C operation.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6391KA31, MAX6392KA31 adds MR functionality and push-pull RESET1 - simplifying layout and enabling field-service reset. Versus TPS3808G33, MAX6392KA31 provides true dual-supply monitoring and configurable sequencing, making it essential for multivoltage systems where timing coordination between rails is mandatory.

Availability

MAX6392KA31 is available at Aetrix Electronics and suitable for industrial controllers, server power management, and medical diagnostic equipment requiring stable component supply and long-term lifecycle assurance.

Supply support for MAX6392KA31 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, computing, and communications applications.

The MAX6392KA31 belongs to Maxim's µP supervisory product line, engineered specifically for reliable power sequencing and voltage monitoring in multirail embedded systems where deterministic reset timing and dual-supply coordination are critical.

FAQ

What is the factory-set VCC reset threshold voltage for MAX6392KA31?

The MAX6392KA31 has a factory-set VCC reset threshold of 3.08V (minimum 3.00V, maximum 3.15V across temperature). This value is laser-trimmed during production and applies specifically to the "KA31" suffix variant. The threshold ensures robust detection of brownout on standard 3.3V rails while maintaining margin against noise. All timing and assertion behavior of RESET1 and RESET2 is referenced to this precise threshold.

How does the CSRT pin configure RESET2 timeout behavior in MAX6392KA31?

In MAX6392KA31, the CSRT pin determines whether RESET2 uses a fixed or adjustable timeout. When CSRT is tied to VCC, RESET2 deasserts after a guaranteed minimum 140ms delay. When CSRT is connected to a capacitor-to-ground, the internal 600nA current source ramps voltage across the capacitor; RESET2 deasserts when that voltage reaches 1.25V, yielding tRP2 ≈ 2.08×10⁶ × CCSRT seconds. This allows precise tuning from ~1ms to >1s without external components.

Can MAX6392KA31 monitor a 1.2V supply as the secondary voltage (RESET IN2)?

Yes - MAX6392KA31 can monitor a 1.2V supply via RESET IN2 using an external resistor divider. Since the internal reference is 625mV, a divider with R3/R4 ratio of ~0.92 (e.g., R4 = 500kΩ, R3 = 460kΩ) sets VRST = 1.2V. The high-impedance input draws only 50nA, minimizing divider current. This enables supervision of low-voltage cores (e.g., 1.2V FPGA banks) while maintaining full reset sequencing control with the 3.08V VCC threshold.

What is the function of the R2 pin on MAX6392KA31, and how should it be used?

The R2 pin on MAX6392KA31 is an internal 47kΩ pullup resistor connected to the open-drain RESET2 output. To set RESET2's high-level voltage (VOH) independently of VCC - for example, to 3.3V in a 5V system - tie R2 to the desired VOH rail. Leaving R2 unconnected disables the pullup, requiring an external resistor. This feature eliminates discrete pullups and enables mixed-voltage interfacing, such as driving a 3.3V FPGA from a 5V-supplied MAX6392KA31.

Does MAX6392KA31 guarantee reset assertion when VCC drops to 1.0V?

Yes - MAX6392KA31 guarantees valid reset assertion down to VCC = 1.0V across the full -40°C to +85°C temperature range. This is explicitly specified in the Electrical Characteristics table under "Reset Pullup Resistance" and "RESET_ Output Voltage Low" conditions. The internal comparators and logic remain functional at this level, ensuring µP reset remains active even during severe brownout or battery-depletion scenarios where other supervisors may fail.