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 operation down to VCC = 1V. It eliminates external components in microprocessor supervisory circuits and supports SO-8 packaging for space-constrained embedded designs.

For engineers reviewing the MAX709LCSA+ datasheet, MAX709LCSA+ pinout, MAX709LCSA+ application, or MAX709LCSA+ equivalent, key selection criteria include reset threshold accuracy (±150mV), guaranteed reset assertion at low VCC, immunity to short VCC transients (<40µs at 100mV overdrive), and compatibility with 0°C to +70°C industrial temperature range.

Technical Context

The MAX709LCSA+ integrates a precision voltage comparator with hysteresis and an internal timer to generate a clean, glitch-immune reset signal during power-up, brownout, and power-down events. Its reset threshold is factory-trimmed to 4.65V (L-suffix) with ±150mV tolerance over temperature.

It features open-drain RESET output capable of sinking 1.2mA at VCC ≥ reset threshold min, operates with supply current as low as 65µA (typical), and maintains valid reset state down to VCC = 1V - ensuring reliable µP hold-off even during deep undervoltage conditions.

Key Specifications

Pinout & Package

MAX709LCSA+ uses an 8-pin SO (SOIC) package with exposed pad not connected internally. Pin 1 is top-left corner (notch-marked), pin numbering counterclockwise.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX706PESA+, MAX709LCSA+ trades extended temperature rating for lower cost in commercial-grade applications; versus TPS3808G33DBVR, it provides precise +5V compatibility and lower supply current but lacks adjustable timeout or watchdog capability.

Availability

MAX709LCSA+ is available at Aetrix Electronics and suitable for industrial PLC controllers, medical diagnostic devices, automotive infotainment head units, and point-of-sale terminals requiring stable component supply and long-term production continuity.

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 fabless 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 cost-sensitive, space-constrained microprocessor supervisory applications in commercial and industrial equipment requiring precise, low-component-count power monitoring.

FAQ

What is the exact reset threshold voltage for MAX709LCSA+?

The MAX709LCSA+ has a nominal reset threshold voltage of 4.65V, with a guaranteed tolerance of ±150mV over the full operating temperature range (0°C to +70°C). This value is factory-trimmed and specified in the Electrical Characteristics table under "RESET Threshold, VTH" for suffix L. The threshold remains stable across temperature, with normalized variation within ±0.5% from -40°C to +85°C.

Does MAX709LCSA+ require external components to function?

No, the MAX709LCSA+ requires no external resistors, capacitors, or trimming components to perform its core power-supply monitoring function. A 0.1µF ceramic bypass capacitor on VCC (pin 2) is recommended for noise immunity but is not strictly required for basic operation. The internal voltage reference, comparator, and timer are fully integrated, enabling single-chip reset generation in +5V systems.

Can MAX709LCSA+ operate reliably when VCC drops below 2V?

Yes, the MAX709LCSA+ guarantees correct RESET output state down to VCC = 1V. Below 1V, the RESET output becomes high-impedance (open-circuit), but this behavior is explicitly characterized and safe for most µP interfaces. For applications requiring RESET validity down to 0V, a 100kΩ pull-down resistor on the RESET line is recommended - a design detail confirmed in the Applications Information section of the MAX709LCSA+ datasheet.

What is the maximum allowable negative VCC transient duration that will not trigger a reset on MAX709LCSA+?

For the MAX709LCSA+, a negative VCC transient of up to 40µs duration will not cause a spurious reset if its magnitude is ≤100mV below the 4.65V reset threshold. This immunity is verified in Figure 1 of the MAX709LCSA+ datasheet and applies at TA = +25°C. Transients exceeding this duration or amplitude will assert RESET, ensuring robust brownout response while rejecting common power-rail noise.

Is MAX709LCSA+ pin-compatible with other MAX709 variants like MAX709MCSA+?

Yes, all MAX709 variants including MAX709LCSA+, MAX709MCSA+, and MAX709RCSA+ share identical 8-pin SO packaging and pinout. The only functional difference is the factory-set reset threshold voltage (4.65V for L, 4.40V for M, 2.63V for R). No PCB layout change is needed when substituting between these variants - only the reset threshold specification changes, making them direct replacements in the same footprint.