Analog Devices Inc./Maxim Integrated MAX709MCSA

Overview

MAX709MCSA from Maxim Integrated is a precision power-supply monitor IC with active-low reset output, designed for +5V/+3.3V/+3V systems. It asserts RESET when VCC falls below 4.40V (±2.5%), holds reset for ≥140ms after VCC recovers, and guarantees valid RESET down to VCC = 1V. Used in microprocessor-based embedded controllers to prevent erratic startup or brownout operation.

For engineers reviewing the MAX709MCSA datasheet, MAX709MCSA pinout, MAX709MCSA application, or MAX709MCSA equivalent, key selection criteria include reset threshold accuracy (4.40V), guaranteed minimum reset timeout (140ms), supply current (65µA), operating temperature range (–40°C to +85°C), and SO-8 package compatibility with legacy 5V/3.3V/3V logic rails.

Technical Context

The MAX709MCSA integrates a precision voltage comparator, internal timing capacitor, and open-drain RESET driver - eliminating external components. Its reset threshold is factory-trimmed to 4.40V with ±2.5% tolerance over –40°C to +85°C, and its 140ms minimum reset timeout is internally generated without external RC networks.

It features immunity to short negative VCC transients (e.g., ≤40µs at 100mV overdrive) and maintains RESET validity down to VCC = 1V. The device operates across full VCC range (1.0V to 5.5V) and supports bidirectional µP reset pins via series resistor buffering per Figure 3 of the datasheet.

Key Specifications

Pinout & Package

MAX709MCSA is supplied in an 8-pin SO (Small Outline) package with 1.27mm pitch, JEDEC MS-012AC compliant footprint, and moisture sensitivity level (MSL) 1. Pin 1 is top-left corner (notch-marked), with pins numbered counterclockwise.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar power-supply monitor applications.

Compared with MAX709MCSA, MAX706RCSA provides lower-threshold supervision ideal for 2.5V/3V logic, while MAX708TESA offers mid-range 3.08V detection optimized for 3.3V rails - both retain identical timing, SO-8 footprint, and industrial temperature rating but differ in threshold voltage and feature set.

Availability

MAX709MCSA is available at Aetrix Electronics and suitable for industrial PLC controllers, medical handheld diagnostics, automotive body control modules, and smart energy meters requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for MAX709MCSA 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 industrial, automotive, communications, and computing applications.

The MAX709 family delivers single-chip power-supply monitoring for microprocessor systems, emphasizing threshold accuracy, guaranteed reset timing, and minimal external component count in space-constrained designs.

FAQ

What is the exact reset threshold voltage for MAX709MCSA?

The MAX709MCSA has a nominal reset threshold voltage of 4.40V, with a guaranteed tolerance of ±2.5% over the full operating temperature range (–40°C to +85°C). This value is factory-trimmed and specified in the Electrical Characteristics table under "RESET Threshold, VTH" for suffix M. The threshold remains stable across VCC from 1.0V to 5.5V, enabling accurate brownout detection in +5V and +3.3V systems. MAX709MCSA's 4.40V point aligns with typical 5V rail dropout margins.

Does MAX709MCSA require external components to operate?

No, MAX709MCSA operates autonomously with no external timing or adjustment components required. Its 140ms reset timeout is generated by an internal capacitor, and the 4.40V threshold is laser-trimmed on-die. A 0.1µF ceramic bypass capacitor on VCC (pin 2) is recommended for transient immunity but is not strictly required for basic functionality. All other pins marked N.C. must remain unconnected. MAX709MCSA thus achieves minimum-component-count supervision in compact layouts.

What is the maximum supply voltage and minimum operating voltage for MAX709MCSA?

MAX709MCSA operates across a VCC range of 1.0V to 5.5V. It guarantees correct RESET state down to VCC = 1V - meaning the output remains valid and actively driven even during deep brownout. Above 5.5V, absolute maximum ratings are exceeded and permanent damage may occur. Below 1.0V, the RESET output transitions to high-impedance (open-circuit), so external pull-down is advised if validity down to 0V is required. This wide range makes MAX709MCSA suitable for both 5V and 3.3V systems.

How does MAX709MCSA handle short negative transients on the VCC line?

MAX709MCSA is specifically designed to ignore short negative-going VCC transients - for example, it tolerates ≤40µs pulses that dip 100mV below the 4.40V reset threshold without asserting RESET. This immunity is achieved through internal filtering and comparator hysteresis, preventing spurious resets in electrically noisy environments like motor drives or automotive subsystems. A 0.1µF bypass capacitor placed close to pin 2 (VCC) further enhances this robustness. MAX709MCSA's transient rejection is documented in Figure 1 of its datasheet.

Is MAX709MCSA pin-compatible with other MAX709 variants such as MAX709LCSA or MAX709RCSA?

Yes, all MAX709 variants including MAX709MCSA, MAX709LCSA, and MAX709RCSA share identical pinout, package (SO-8), electrical interface, and timing specifications - differing only in factory-set reset threshold voltage (4.40V, 4.65V, and 2.63V respectively). No PCB layout change is needed when substituting between these versions. However, system-level validation is required to confirm the selected threshold matches the target supply rail's nominal voltage and tolerance stack-up. MAX709MCSA's 4.40V point is optimized for 5V systems with ±5% regulation.