Analog Devices Inc./Maxim Integrated MAX689CSA

Overview

The MAX689CSA from Maxim Integrated is a 3.0V fixed-output, high-accuracy low-dropout linear regulator that uses an external PNP pass transistor to deliver up to 1A output current with dropout as low as 40mV at 200mA. It features active-low shutdown control (SHDN), power-fail monitoring (PFO), and operates from 2.7V to 11.0V input. It is designed for battery-powered portable instruments requiring precise voltage regulation and low-quiescent-current shutdown.

For engineers reviewing the MAX689CSA datasheet, MAX689CSA pinout, MAX689CSA application, or MAX689CSA equivalent, this page delivers verified technical context, real-world design meaning of key specs, validated pin functions, confirmed alternatives, and supply-chain support details specific to the MAX689CSA in 8-pin SO package.

Technical Context

The MAX689CSA implements precision regulation via an internal bandgap reference and error amplifier driving the base of an external PNP transistor. Its SHDN input enables three-level operation-on (>1.25V), standby (<1.2V, <25µA I_IN), and full shutdown (<0.2V, <1µA I_IN)-with ±2% threshold accuracy and 70mV hysteresis to prevent chatter. The PFO output is open-drain and trips when V_OUT falls 170mV below nominal (2.83V at 3.0V output).

Base current limiting is achieved via a resistor (R_B) between BASE and BLIM pins, enforcing I_BASE ≤ 0.1V/(R_B + 5Ω); this controls output current without adding collector-side sensing or increasing dropout. Compensation is handled externally via a 10nF capacitor on CC–GND, ensuring stability across load and temperature.

Key Specifications

Pinout & Package

MAX689CSA is housed in an 8-pin SO (Small Outline) package, 3.9mm × 4.9mm body, 1.27mm pitch, RoHS-compliant, rated for 0°C to +70°C operation.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar low-dropout linear regulator applications.

Compared with LT1528CS8#PBF and TPS76330DBVR, the MAX689CSA uniquely combines 3.0V output, external PNP flexibility for >1A loads, precise SHDN thresholds, and PFO monitoring - making it optimal for battery-powered systems requiring both high current and intelligent power management.

Availability

MAX689CSA is available at Aetrix Electronics and suitable for portable instruments, battery-powered devices, memory backup supplies, and portable telephones requiring stable component supply across industrial temperature ranges and long production lifecycles.

Supply support for MAX689CSA 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 U.S.-based semiconductor company specializing in high-performance analog, mixed-signal, and power-management ICs for industrial, communications, and consumer applications.

The MAX687/MAX688/MAX689 family was designed specifically for high-accuracy, low-dropout regulation in battery-critical portable systems - emphasizing programmable current limiting, intelligent shutdown, and robust power-fail detection without sacrificing efficiency.

FAQ

What is the output voltage tolerance of the MAX689CSA?

The MAX689CSA has a fixed 3.0V output with guaranteed accuracy of ±2% over temperature (0°C to +70°C) and load conditions. This means the output remains within 2.9V to 3.1V under all specified operating conditions, ensuring reliable operation for 3.0V logic and memory interfaces. The MAX689CSA's tight tolerance eliminates the need for post-regulation trimming in most applications.

Does the MAX689CSA include an integrated pass transistor?

No, the MAX689CSA does not include an integrated pass transistor. It is a controller IC that drives an external PNP transistor (e.g., FZT749 or 2N2907A) to deliver regulated 3.0V output. This architecture enables scalable current handling (up to 1A+), minimal dropout voltage determined by the PNP's V_CE(SAT), and thermal separation between control IC and power device - a key advantage of the MAX689CSA over monolithic LDOs.

How does the SHDN pin function on the MAX689CSA?

The SHDN pin on the MAX689CSA is an active-low, three-level control input: device is fully on when V_SHDN > 1.25V, enters low-current standby (<25µA I_IN) when V_SHDN < 1.2V, and achieves full shutdown (<1µA I_IN) when V_SHDN < 0.2V. The ±2% threshold accuracy and 70mV hysteresis ensure clean transitions. This behavior is intrinsic to the MAX689CSA and differs from the MAX687's latched ON pin.

What is the purpose of the BLIM and BASE pins on the MAX689CSA?

The BASE pin on the MAX689CSA sources ≥10mA to drive the base of the external PNP transistor, while the BLIM pin enables programmable base-current limiting via a resistor (R_B) connected between BASE and BLIM. This limits I_BASE ≤ 0.1V/(R_B + 5Ω), which directly controls maximum output current and prevents excessive quiescent current during dropout - a defining functional feature of the MAX689CSA.

Can the MAX689CSA be used with a 2.5V input supply?

No, the MAX689CSA cannot regulate with a 2.5V input because its minimum input voltage is 2.7V per Absolute Maximum Ratings and Electrical Characteristics tables. At 3.0V output, even the lowest specified dropout (40mV at 200mA) requires VIN ≥ 3.04V. Using 2.5V input would place the MAX689CSA outside its operational range and result in unregulated output - this limitation is explicitly defined for the MAX689CSA and applies regardless of load or external transistor choice.