Analog Devices Inc./Maxim Integrated MAX6385XS43D7-T

Overview

MAX6385XS43D7-T from Maxim Integrated is a low-power microprocessor supervisory circuit with active-high push-pull reset output, factory-set 4.30V reset threshold (±2.5% over –40°C to +125°C), 1200ms VCC reset timeout, and debounced manual reset input. It monitors single-supply rails in battery-powered controllers and portable instrumentation where reliable power-on reset and brownout protection are critical.

For engineers reviewing the MAX6385XS43D7-T datasheet, MAX6385XS43D7-T pinout, MAX6385XS43D7-T application, or MAX6385XS43D7-T equivalent, key selection factors include its 4-pin SC70 package, 3μA supply current at 1.8V, guaranteed reset validity down to VCC = 1V, and compatibility with systems requiring precise 4.3V threshold detection and long-duration reset assertion during power recovery.

Technical Context

The MAX6385XS43D7-T implements a precision bandgap-based voltage comparator for VCC monitoring and an internal monostable timer for fixed 1200ms reset timeout after VCC exceeds 4.30V. Its MR input features a 63kΩ internal pullup resistor and guarantees reset assertion for ≥150ms after MR release.

It operates across –40°C to +125°C with ±2.5% reset threshold accuracy and supports valid reset output state down to VCC = 1V. The active-high push-pull RESET output drives high during reset and sinks ≤0.3V at 1.2mA when asserted, eliminating need for external pullup.

Key Specifications

Pinout & Package

MAX6385XS43D7-T uses a 4-pin SC70 package (outline 21-0098, land pattern 90-0187) with 0.65mm pitch and exposed pad not connected internally.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6385LT43D7-T, the MAX6385XS43D7-T saves 0.64mm² board area in ultra-compact wearables; versus TPS3808G33DBVR, it delivers 4.3V threshold accuracy critical for 5V-tolerant I/O domains and supports hardware-initiated recovery via MR.

Availability

MAX6385XS43D7-T is available at Aetrix Electronics and suitable for portable medical sensors, industrial PLC I/O modules, automotive body control units, and smart home hub power management requiring stable component supply across extended temperature ranges.

Supply support for MAX6385XS43D7-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 precision analog and mixed-signal ICs for power, sensing, and connectivity applications.

The MAX638x family targets low-power microprocessor supervision in space- and energy-constrained systems, emphasizing factory-trimmed accuracy, ultra-low ICC, and robust reset timing across automotive and industrial temperature ranges.

FAQ

What is the exact reset threshold voltage of MAX6385XS43D7-T and how stable is it over temperature?

The MAX6385XS43D7-T has a factory-set nominal reset threshold of 4.30V, with guaranteed tolerance of ±2.5% over the full operating range of –40°C to +125°C. This stability is achieved through laser-trimmed bandgap references and matched transistor ratios in the BiCMOS process. At +25°C, the threshold is typically 4.30V ±1.5%, and the tempco is specified at 60ppm/°C - meaning drift is under 12mV across the entire temperature span. This precision eliminates need for external calibration in 4.3V rail monitoring.

Does MAX6385XS43D7-T require an external pullup resistor on the RESET pin?

No, MAX6385XS43D7-T does not require an external pullup resistor on the RESET pin because it features an active-high push-pull output configuration. When reset is asserted, the output drives high (VOH ≥ 0.8×VCC); when deasserted, it actively pulls low (VOL ≤ 0.3V at 1.2mA). This eliminates reliance on external components for logic-level definition and improves noise immunity compared to open-drain alternatives. The push-pull structure also ensures fast rise/fall times (<200ns) critical for modern high-speed processors.

What is the function and electrical behavior of the MR pin on MAX6385XS43D7-T?

The MR (Manual Reset) pin on MAX6385XS43D7-T is an active-low input that forces reset assertion when pulled below 0.3×VCC. It includes a 63kΩ internal pullup resistor to VCC, allowing direct connection of a normally-open momentary switch to GND without external components. MR has 100ns glitch rejection and guarantees reset assertion for ≥150ms after MR is released. The input leakage is ±1μA, and it accepts TTL/CMOS logic levels. This makes MAX6385XS43D7-T ideal for field-serviceable devices requiring hardware-initiated firmware recovery.

Can MAX6385XS43D7-T operate reliably at VCC = 1.2V, and what happens to the RESET output below 1.8V?

Yes, MAX6385XS43D7-T is fully specified to operate down to VCC = 1.0V, and its RESET output state is guaranteed valid at all supply voltages ≥1.0V. Below 1.8V, the VOH specification degrades to 0.8×VCC (e.g., 0.96V at 1.2V), and VOL remains ≤0.3V at 80μA sink current. The internal comparator continues functioning accurately, and the 1200ms timeout timer remains active. This capability ensures safe reset hold during deep brownout conditions common in battery-powered systems approaching end-of-life.

Is MAX6385XS43D7-T pin-compatible with legacy Maxim reset ICs like MAX809 or MAX6326?

MAX6385XS43D7-T is not pin-compatible with MAX809 or MAX6326 due to differing pin counts and functions: MAX809 uses 3-pin SOT23, while MAX6385XS43D7-T uses 4-pin SC70 with dedicated MR and RESET pins. However, it is functionally compatible and listed as pin-compatible with MAX6346/MAX6347/MAX6348 in the datasheet - all share the same 4-pin SC70 pinout (VCC, RESET, MR, GND) and active-high push-pull output. For drop-in replacement, verify matching reset threshold (4.3V) and timeout (1200ms) suffixes in the part number.