Analog Devices Inc./Maxim Integrated MAX603CSA

Overview

The MAX603CSA from Maxim Integrated is a 5V fixed-output, low-dropout linear regulator with P-channel MOSFET pass transistor, delivering up to 500mA output current, 320mV dropout at 5V/500mA, and 15μA typical quiescent current. It operates from 2.7V to 11.5V input and features shutdown mode (2μA), reverse-current protection, and thermal overload protection - ideal for battery-powered instrumentation and portable 5V systems.

For engineers reviewing the MAX603CSA datasheet, MAX603CSA pinout, MAX603CSA application, or MAX603CSA equivalent, key selection considerations include dropout performance under load, ultra-low IQ across temperature, dual-mode (fixed/adjustable) configuration via SET pin, and SO-8 package thermal management with four GND pins acting as heatsinks.

Technical Context

The MAX603CSA uses an internal 1.20V bandgap reference and error amplifier to regulate output voltage by controlling a 500mA P-channel MOSFET pass transistor. Its Dual Mode™ operation selects between internal fixed feedback (5V) or external resistor divider (1.25V–11V) based on SET pin voltage (<80mV for fixed mode).

Reverse-current protection activates when VIN falls 6–20mV below VOUT, switching substrate bias to limit reverse leakage to ≤10μA. Foldback current limiting provides 350mA short-circuit protection below 0.8V output and 1.2A current limit above 0.8V with sufficient VIN–VOUT margin.

Key Specifications

Pinout & Package

MAX603CSA is housed in an 8-pin SOIC (SO-8) package with 1.8W power dissipation capability at +70°C ambient. Four dedicated GND pins (2,3,6,7) serve dual roles: electrical ground reference and thermal conduction paths - requiring connection to large copper pads or planes for reliable high-current operation.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LT1761ES5-5#TRMPBF and TPS76350DBVR, the MAX603CSA delivers 3.3× higher output current, 5.7× lower quiescent current, integrated reverse-current protection, and Dual Mode™ flexibility - making it uniquely suited for thermally demanding, battery-backed 500mA 5V applications.

Availability

MAX603CSA is available at Aetrix Electronics and suitable for battery-powered instruments, portable microcontroller systems, and solar-powered remote sensors requiring stable component supply, consistent parametric performance, and long-term manufacturing continuity.

Supply support for MAX603CSA 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 precision analog, mixed-signal, and power management ICs for industrial, medical, and communications applications.

The MAX603CSA belongs to Maxim's low-dropout linear regulator product line, designed specifically for energy-constrained, battery-operated systems requiring ultra-low quiescent current, robust thermal behavior, and flexible output configuration.

FAQ

What is the maximum continuous output current of the MAX603CSA?

The MAX603CSA delivers up to 500mA continuous output current when operated within its thermal limits and input-output differential constraints. At 5V output and 11.5V input, power dissipation limits current to ~150mA unless PCB thermal design meets SO-8 1.8W specification. Derating applies above +70°C ambient per the 23.6mW/°C thermal coefficient.

How does the MAX603CSA achieve such low quiescent current?

The MAX603CSA achieves 15μA typical quiescent current by using a P-channel MOSFET pass transistor that requires no gate/base drive current - unlike bipolar PNP-based regulators. This architecture eliminates load-dependent base current losses, maintaining ultra-low IQ across all output loads and input voltages from 2.7V to 11.5V.

Can the MAX603CSA be used in adjustable-output configurations?

Yes, the MAX603CSA supports adjustable output from 1.25V to 11V using external resistors connected to the SET pin. When SET is grounded, it defaults to 5V fixed output. The SET pin senses 1.20V reference, enabling precise output setting via R1/R2 divider while drawing <±10nA bias current - preserving accuracy and efficiency.

What thermal design practices are required for full 500mA operation of the MAX603CSA?

Full 500mA operation of the MAX603CSA requires all four GND pins (2,3,6,7) to be soldered to a large copper ground plane or thermal pad per Maxim's layout guidelines. The SO-8 package has θ_JB = 42°C/W; insufficient copper area causes thermal shutdown. Figure 4 in the datasheet specifies minimum pad sizes - e.g., ≥1.3 cm² for +125°C junction at +25°C ambient.

Does the MAX603CSA provide protection against reverse current flow?

Yes, the MAX603CSA includes reverse-current protection that activates when VIN falls 6–20mV below VOUT. It switches internal substrate bias to the more positive node (IN or OUT), turning off the pass transistor and limiting reverse leakage to ≤10μA. This enables safe use with backup batteries or supercapacitors without external blocking diodes.