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, 3.08V factory-fixed threshold) and RESET IN2 (adjustable down to 625mV), asserts RESET1 (push-pull) and RESET2 (open-drain) in controlled order, and guarantees valid reset operation down to VCC = 1.0V. Used in servers and industrial controllers requiring precise power-up sequencing.

For engineers reviewing the MAX6392KA31+ datasheet, MAX6392KA31+ pinout, MAX6392KA31+ application, or MAX6392KA31+ equivalent, this page delivers verified timing behavior, manual reset interaction, CSRT capacitor-adjustable timeout, and SOT23-8 package integration details critical for reliable system initialization and brownout recovery.

Technical Context

The MAX6392KA31+ implements two independent voltage monitoring paths: a fixed-threshold comparator for VCC (3.08V ±75mV) and a high-impedance 625mV reference comparator for RESET IN2. RESET1 deasserts 140ms (min) after VCC exceeds its threshold, while RESET2 deasserts either 140ms (min) after both VCC and RESET IN2 exceed thresholds-or after a user-adjustable delay set by an external capacitor on CSRT.

Its internal 47kΩ MR pullup and push-pull RESET1 output eliminate external components for manual reset assertion and primary reset drive. The device maintains guaranteed reset validity at VCC ≥ 1.0V and rejects transients ≤100ns (glitch immunity), ensuring robust operation during noisy power transitions.

Key Specifications

Pinout & Package

MAX6392KA31+ is housed in an 8-pin SOT23 package (3.0mm × 1.7mm × 1.3mm height), optimized for space-constrained PCB layouts and compatible with standard reflow processes.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6392KA29+ and TPS3808G33DBVR, the MAX6392KA31+ uniquely delivers factory-trimmed 3.08V VCC supervision paired with fully configurable secondary rail monitoring and guaranteed reset sequencing-making it irreplaceable in multi-voltage systems requiring deterministic power-up order.

Availability

MAX6392KA31+ is available at Aetrix Electronics and suitable for industrial PLC controllers, servers/workstations, and medical diagnostic equipment requiring stable component supply, long-term lifecycle support, and guaranteed reset timing accuracy across temperature extremes.

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 MAX6391/MAX6392 product line delivers integrated dual-supply supervision with sequenced reset outputs-specifically engineered to replace discrete reset solutions in multi-rail embedded systems where reliability and board space are critical.

FAQ

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

The MAX6392KA31+ has a factory-trimmed VCC reset threshold of 3.08V (minimum 3.00V, maximum 3.15V). This value is laser-trimmed during production and applies across the full -40°C to +85°C operating temperature range. The threshold is designed specifically for reliable supervision of nominal 3.3V power rails, providing adequate hysteresis against noise and transient dips without false triggering.

How does the manual reset (MR) input affect both reset outputs in MAX6392KA31+?

When the MR pin of MAX6392KA31+ is pulled low, it immediately asserts both RESET1 (push-pull) and RESET2 (open-drain) active-low outputs. RESET1 remains asserted for its fixed 140ms timeout after MR returns high, while RESET2 remains asserted for its configured timeout (140ms min or capacitor-adjusted) after MR goes high. The MR-to-RESET1 delay is 10µs max, and MR-to-RESET2 delay is 100ns max-ensuring synchronized, low-skew reset initiation.

Can MAX6392KA31+ monitor a 1.2V supply as the secondary voltage?

Yes, MAX6392KA31+ can monitor a 1.2V supply using the RESET IN2 pin with an external resistor divider. Since the internal reference is 625mV, a simple two-resistor network (e.g., R3 = 920kΩ, R4 = 500kΩ) scales 1.2V down to 625mV at RESET IN2. The device's high-impedance input draws only 50nA, minimizing divider current and power loss-making it suitable for battery-powered or low-quiescent-current applications.

What is the purpose of the CSRT pin on MAX6392KA31+, and how is it configured?

The CSRT pin on MAX6392KA31+ configures the RESET2 timeout period. Connecting CSRT to VCC selects a fixed 140ms (minimum) delay. Connecting CSRT to an external capacitor (e.g., 1500pF to GND) enables user-adjustable timeout-calculated as tRP2 ≈ 2.08 × 10⁶ × CCSRT seconds. For example, a 1500pF capacitor yields ~3.1ms. This flexibility allows precise tuning of RESET2 deassertion relative to RESET1, critical for complex multi-rail sequencing.

Does MAX6392KA31+ remain functional when VCC drops below 2.0V?

Yes, MAX6392KA31+ guarantees valid reset operation down to VCC = 1.0V. Its internal comparators and logic continue functioning, and both RESET1 and RESET2 outputs remain asserted as long as VCC or RESET IN2 fall below their respective thresholds-even at VCC = 1.0V. This ensures robust brownout detection in low-voltage systems such as 1.2V or 1.8V domains, where many supervisors cease operation above 1.5V.