Analog Devices Inc./Maxim Integrated MAX709LCSA

Overview

MAX709LCSA from Maxim Integrated is a precision power-supply monitor IC with active-low reset output, designed for +5V systems requiring 4.65V reset threshold, 140ms minimum reset timeout, and guaranteed operation down to VCC = 1V. It eliminates external components in microprocessor supervisory circuits for embedded controllers, industrial PLCs, and telecom line cards.

For engineers reviewing the MAX709LCSA datasheet, MAX709LCSA pinout, MAX709LCSA application, or MAX709LCSA equivalent, key selection criteria include reset threshold accuracy (±150mV), temperature-stable delay timing, immunity to sub-40µs negative VCC transients, and compatibility with 8-pin SO package layouts.

Technical Context

The MAX709LCSA integrates a precision voltage comparator with hysteresis, internal timing capacitor, and open-drain RESET driver. Its reset assertion is triggered when VCC drops below 4.65V (nominal), with ±150mV tolerance over temperature and supply variation.

It delivers a guaranteed 140ms minimum reset pulse width after VCC rises above threshold, with no external timing components required. The device draws only 65µA typical supply current and remains functional down to VCC = 1V, ensuring deterministic reset state during brownout recovery.

Key Specifications

Pinout & Package

MAX709LCSA is housed in an 8-pin SO (Small Outline) package with 1.27mm pitch, JEDEC MS-012AC compliant footprint, and exposed pad not connected internally.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX706PESA and TPS3808G33DBVR, the MAX709LCSA provides minimal-feature, high-reliability reset supervision optimized for cost-sensitive +5V systems - avoiding unnecessary complexity while delivering precise 4.65V detection and deterministic 140ms timing without external components.

Availability

MAX709LCSA is available at Aetrix Electronics and suitable for industrial PLC controllers, telecom line cards, and embedded medical devices requiring stable component supply and long-term lifecycle support.

Supply support for MAX709LCSA 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) is a semiconductor company specializing in high-performance analog, mixed-signal, and power-management ICs for industrial, communications, and computing markets.

The MAX709 family was engineered specifically for microprocessor supervisory functions in cost-constrained, space-limited embedded systems - delivering precision reset generation with zero external components across multiple voltage rails.

FAQ

What is the exact reset threshold voltage of the MAX709LCSA?

The MAX709LCSA has a nominal reset threshold of 4.65V, with a guaranteed range of 4.50V to 4.75V over the full operating temperature range (-40°C to +85°C). This specification ensures reliable detection of +5V supply faults while accommodating manufacturing tolerances and thermal drift - critical for preventing premature µP release during power recovery. The MAX709LCSA threshold is factory-trimmed and does not require external calibration.

Does the MAX709LCSA require external capacitors or resistors to operate?

No, the MAX709LCSA operates autonomously with no external timing or biasing components. Its internal oscillator and comparator eliminate the need for RC networks typically used in discrete reset circuits. A 0.1µF ceramic bypass capacitor is recommended at the VCC pin for noise suppression, but this is a standard decoupling practice - not a functional requirement for basic reset operation. The MAX709LCSA achieves full functionality with only VCC, GND, and RESET connections.

Can the MAX709LCSA drive a microprocessor reset pin directly?

Yes, the MAX709LCSA RESET pin is an open-drain output rated for 20mA sink current, making it compatible with standard CMOS and TTL reset inputs. It requires only an external pull-up resistor (typically 10kΩ to VCC) to generate a clean active-low signal. For µPs with bidirectional reset pins (e.g., Motorola 68HC11), a 4.7kΩ series resistor between MAX709LCSA RESET and the µP pin prevents contention - as documented in Maxim's application note for the MAX709LCSA.

What is the minimum VCC voltage at which the MAX709LCSA guarantees correct RESET state?

The MAX709LCSA guarantees correct RESET output state down to VCC = 1.0V. Below this voltage, the RESET output transitions to a high-impedance state rather than floating unpredictably. This behavior ensures deterministic system behavior during deep brownout - unlike many competitors that lose reset assertion below 2V. For applications requiring RESET validity down to 0V, a 100kΩ pull-down resistor on the RESET line is recommended, as specified in the MAX709LCSA datasheet.

How does the MAX709LCSA handle short negative transients on the VCC line?

The MAX709LCSA is specifically designed to ignore short negative-going VCC transients: it will not assert reset for glitches ≤40µs duration when the transient magnitude is ≤100mV below the 4.65V threshold. This immunity is achieved through internal filtering and comparator hysteresis, enabling reliable operation in electrically noisy environments such as motor drives or switch-mode power supplies. The MAX709LCSA's transient rejection is characterized and guaranteed across temperature, unlike generic supervisors relying on external RC filtering.