Analog Devices Inc./Maxim Integrated MAX630CSA+

Overview

MAX630CSA+ from Maxim Integrated is a CMOS micropower step-up switching regulator IC integrating a 1.31V bandgap reference, oscillator, voltage comparator, and 375mA N-channel output MOSFET in an 8-pin SO package. It operates from 2.0V to 16.5V input, delivers up to 5W output, achieves ±1.5% output voltage accuracy, and supports low-battery detection for battery-powered DC-DC converters.

For engineers reviewing the MAX630CSA+ datasheet, MAX630CSA+ pinout, MAX630CSA+ application, or MAX630CSA+ equivalent, key selection criteria include its 70µA typical operating current, 1µA max shutdown current, 4Ω LX on-resistance, 40kHz typical switching frequency (set by external CX capacitor), and compatibility with RC4191/2/3 bipolar regulators in footprint-constrained portable power designs.

Technical Context

The MAX630CSA+ implements pulse-frequency modulation (PFM) with a constant-frequency oscillator-switching the LX output only when output voltage falls below the 1.31V reference threshold. Its internal N-channel MOSFET (525mA peak, 4Ω on-resistance) drives external inductors in boost topology, while the LBR/VFB comparator loop enables precise output regulation without external op-amps.

It features dual monitoring functions: VFB regulates output via resistive divider feedback, and LBR triggers open-drain LBD output when input drops below ~1.31V. Shutdown via IC pin reduces quiescent current to ≤1µA, and bootstrapped +VS operation (tied to boosted output) lowers LX R_ON for improved efficiency at higher voltages.

Key Specifications

Pinout & Package

MAX630CSA+ is housed in an 8-pin SO (Small Outline) package, 3.9mm × 4.9mm body, 1.27mm pitch, JEDEC MS-012AC compliant. Thermal performance: 441mW max power dissipation at +50°C, derating 5.88mW/°C above.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar step-up switching regulator applications.

Compared with MAX630CSA+, MAX631CSA+ simplifies design for fixed 5V outputs but sacrifices adjustability, while TPS61040DRVR offers higher frequency and input voltage tolerance at the cost of increased external component count and complexity.

Availability

MAX630CSA+ is available at Aetrix Electronics and suitable for portable instrumentation, battery-backed memory modules, and uninterruptible logic supplies requiring stable component supply across extended production lifecycles.

Supply support for MAX630CSA+ 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, automotive, and communications markets.

The MAX630CSA+ belongs to Maxim's micropower DC-DC converter product line, designed specifically for ultra-low-quiescent-current boost regulation in battery-critical portable and backup power applications.

FAQ

What is the maximum output power achievable with the MAX630CSA+?

The MAX630CSA+ supports up to 5W output power in optimized boost configurations. This is achieved using a 470µH inductor, 47pF CX capacitor, and appropriate Schottky catch diode. Peak LX current is rated at 525mA, and efficiency reaches 85% under typical conditions. Actual output power depends on input voltage, inductor DCR, diode forward voltage, and PCB thermal design - full 5W requires careful thermal management and low-loss external components.

Can the MAX630CSA+ operate from a single 1.5V alkaline cell?

No, the MAX630CSA+ has a minimum operating voltage of 2.0V per its Absolute Maximum Ratings and Electrical Characteristics tables. Startup requires ≥1.9V, and stable regulation begins at ≥2.2V. For 1.5V battery operation, consider the MAX631 or MAX660 families, which support lower startup thresholds. Using MAX630CSA+ below 2.0V risks erratic behavior, failure to regulate, or undefined shutdown state.

How does the low-battery detector (LBD) function in the MAX630CSA+?

The MAX630CSA+ LBD circuit compares the voltage on pin 1 (LBR) to its internal 1.31V reference. When LBR falls below this threshold, the open-drain LBD output (pin 8) sinks up to 600µA. An external pullup resistor converts this to an active-low warning signal. The detector operates independently of regulation - it functions even during shutdown - making it ideal for preemptive battery cutoff or power-fail indication in safety-critical systems.

Is the MAX630CSA+ pin-compatible with the RC4191/2/3 series?

Yes, the MAX630CSA+ is explicitly designed as a pin-compatible replacement for Raytheon's RC4191, RC4192, and RC4193 bipolar DC-DC controllers. Pin assignments, package outline, and functional mapping match exactly - allowing direct substitution without PCB modification. This enables significant efficiency gains (85% vs. ~65%) and extended low-voltage operation (down to 2.0V vs. ~3.5V) while reusing existing layouts.

What is the recommended inductor value for a +3V to +5V boost converter using MAX630CSA+?

For +3V to +5V conversion at ~40mA output, a 470µH molded inductor (e.g., Dale IHA-104) is recommended, matching the typical operating circuit in the datasheet. This value balances peak current (within 525mA limit), output ripple, and physical size. Lower inductance (e.g., 220µH) increases available output current but raises ripple and ESR losses; higher values reduce peak current but may limit power delivery. Inductor saturation current must exceed 525mA, and DCR should be ≤1Ω for optimal efficiency.