Analog Devices Inc./Maxim Integrated MAX748ACPA

Overview

MAX748ACPA from Maxim Integrated is a 3.3V-output, current-mode PWM step-down DC-DC converter IC designed for fixed-voltage regulation in battery-powered and industrial power systems. It accepts 3.3V–16V input, delivers up to 500mA load current, operates at 159kHz–212.5kHz switching frequency, achieves 85%–90% efficiency, and features 0.2µA shutdown current - enabling use in portable instruments and 5V-to-3.3V conversion circuits.

For engineers reviewing the MAX748ACPA datasheet, MAX748ACPA pinout, MAX748ACPA application, or MAX748ACPA equivalent, this page provides verified technical context, package-specific pin functions, real-world design meaning of key specs, and validated alternative options for buck regulator selection in commercial-temperature embedded power supplies.

Technical Context

The MAX748ACPA implements a current-mode PWM control architecture with dual feedback loops: an inner current-sense loop enabling cycle-by-cycle current limiting (1.2A peak), and an outer voltage loop using a 1.23V internal bandgap reference for ±5% output regulation across line, load, and temperature. Its fixed-frequency operation simplifies EMI filtering and supports stable operation with a preselected 22µH inductor.

It integrates undervoltage lockout (2.7V turn-off, 2.95V turn-on), programmable soft-start via external capacitor on SS pin, and shutdown control via active-low SHDN pin. The 8-pin DIP package places all critical power and control terminals - including LX (P-channel MOSFET drain), V+, GND, and OUT - with defined thermal and layout constraints for reliable 500mA continuous operation.

Key Specifications

Pinout & Package

MAX748ACPA is housed in an 8-pin plastic DIP (dual in-line package) with 0.3-inch body width and through-hole mounting. Pin 1 is marked by a notch or dot; pins are numbered counter-clockwise from top-left when viewed from component side.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar step-down DC-DC converter applications.

Compared with MAX763ACPA, the MAX748ACPA trades slightly higher quiescent current for 5V additional input headroom and broader system compatibility; versus TPS5430DDAR, it offers plug-and-play 3.3V regulation with fewer external parts but less flexibility in output voltage and current scaling.

Availability

MAX748ACPA is available at Aetrix Electronics and suitable for portable instrumentation, 5V-to-3.3V conversion, and cellular phone baseband power applications requiring stable component supply across commercial temperature grades.

Supply support for MAX748ACPA 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, mixed-signal, and power management ICs for industrial, medical, and communications applications.

The MAX748A product line delivers highly integrated, fixed-output buck regulators targeting space-constrained, battery-operated systems needing reliable 3.3V power with minimal external components and robust protection features.

FAQ

What is the maximum input voltage supported by the MAX748ACPA?

The MAX748ACPA supports a maximum input voltage of 16V, with absolute maximum rating at +17V on the V+ pin. Operation above 16V risks permanent damage. This 16V limit enables compatibility with 12V wall adapters and two-cell Li-ion packs, distinguishing it from the MAX763A (11V max). The MAX748ACPA maintains regulation down to 3.3V input, though output current capability decreases below 4.0V.

Does the MAX748ACPA require external feedback resistors to set its 3.3V output?

No, the MAX748ACPA has a factory-trimmed internal feedback network that fixes the output at 3.3V ±5%. The OUT pin connects directly to the 3.3V rail for sensing, and no external resistors are needed - unlike adjustable regulators. This simplifies layout and eliminates resistor tolerance errors. The internal 1.23V reference and precision amplifier ensure tight regulation across temperature and load without user calibration.

Can the MAX748ACPA operate with a 3.0V input supply?

The MAX748ACPA can accept a 3.0V input, but it will not regulate at 3.3V under load. Undervoltage lockout activates below 2.7V, and regulation requires V+ ≥ 3.3V at no load or higher depending on current draw. Per the Output Voltage vs. Supply Voltage graph, 3.0V input yields reduced output (e.g., ~2.8V at 100mA), making it unsuitable for true 3.3V operation. For sub-3.3V inputs, a boost or buck-boost topology is required.

What is the purpose of the REF pin on the MAX748ACPA?

REF provides a stable 1.23V ±3% bandgap reference voltage, capable of sourcing up to 100µA for external circuitry such as ADC references or comparator thresholds. It must be bypassed to GND with a 1000pF capacitor to suppress noise and ensure regulation stability. Unlike some regulators, REF is not used for output setting - the MAX748ACPA's 3.3V output is internally fixed - but serves as a precision auxiliary voltage source for system-level analog functions.

How does the soft-start function work on the MAX748ACPA?

The MAX748ACPA uses the SS pin to implement programmable soft-start: an external capacitor (typically 0.047µF) between SS and GND controls the ramp rate of the internal current-limit threshold. During startup or wake-from-shutdown, this capacitor charges linearly, gradually increasing allowable peak switch current and preventing inrush into output capacitors. It also triggers automatic discharge during overcurrent or UVLO faults, ensuring controlled recovery. Soft-start time scales linearly with capacitance value per Table 1.