Texas Instruments MC33063AP

Overview

MC33063AP from Texas Instruments is a monolithic DC-DC switching regulator controller IC designed for boost, buck, and inverting topologies. It integrates a 1.25-V precision reference (±2%), oscillator (up to 100 kHz), PWM controller with active current limiting, Darlington output switch (1.5-A peak), and comparator - requiring only external inductor, capacitor, diode, and resistors to implement complete converters. It operates across 3 V to 40 V input and supports industrial temperature range (–40°C to 85°C), commonly used in portable instrumentation power supplies.

For engineers reviewing the MC33063AP datasheet, MC33063AP pinout, MC33063AP application, or MC33063AP equivalent, this page delivers verified technical context, validated pin functions, topology-specific design meaning, real-world performance data (e.g., 62.2% efficiency at 5 V in, –12 V/100 mA out), and confirmed alternative options for cost, thermal, or sourcing-driven redesigns.

Technical Context

The MC33063AP implements a fixed-frequency, current-mode PWM control architecture with internal 1.25-V reference and adjustable current-limit threshold (250–350 mV). Its oscillator uses external timing capacitor (CT) to set frequency between ~24 kHz and 100 kHz, and its Darlington output stage enables high-current switching with low saturation voltage (0.45 V typical at 1 A in non-Darlington mode).

It supports three standard converter configurations: step-up (boost), step-down (buck), and polarity-inverting (inverting), each requiring distinct external component placement but sharing identical internal signal flow - reference → error amplifier → comparator → oscillator → PWM latch → driver → switch - with feedback applied to the inverting input (Pin 5) via resistor divider.

Key Specifications

Pinout & Package

MC33063AP is supplied in an 8-pin PDIP (Plastic Dual In-line Package) with 9.81 mm × 6.35 mm body size and through-hole mounting. Pin numbering follows standard DIP convention (Pin 1 at notch end, counterclockwise).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar DC-DC controller applications.

Compared with MC33063AP, MC34063AP offers identical functionality at lower cost but sacrifices industrial temperature range, while LM2574N-5.0 trades configurability for integration and reduced external part count - making it viable only for fixed-output, lower-current buck applications.

Availability

MC33063AP is available at Aetrix Electronics and suitable for portable instrumentation power, blood gas analyzer supplies, industrial HMI displays, and test equipment auxiliary rails requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for MC33063AP 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

Texas Instruments is a global semiconductor leader delivering analog and embedded processing solutions, with decades of expertise in power management ICs and industrial-grade reliability.

The MC3x063A product line was designed specifically for cost-sensitive, discrete-component-based DC-DC conversion in industrial, medical, and portable equipment - prioritizing topology flexibility, wide input range, and robust current limiting over integrated FETs or digital control.

FAQ

What topologies does the MC33063AP support?

The MC33063AP supports boost (step-up), buck (step-down), and inverting (polarity-reversal) DC-DC converter topologies. Each requires specific external component connections - e.g., inverting uses Pin 1 as switch collector and Pin 2 as emitter return, while buck ties Pin 1 to input and Pin 2 to GND. All share the same internal control architecture and pinout, enabling design reuse across applications. The MC33063AP datasheet provides schematic examples for all three configurations.

How is output voltage set on the MC33063AP?

Output voltage on the MC33063AP is set by a resistor divider (R1, R2) connected between VOUT, Pin 5 (Comparator Inverting Input), and GND. The internal 1.25-V reference is compared against the divided voltage, so VOUT = 1.25 × (1 + R2/R1). For example, R1 = 2.2 kΩ and R2 = 1.2 kΩ yields ~1.84 V; R1 = 1.2 kΩ and R2 = 3.8 kΩ yields 5.21 V. Precision of R1/R2 directly impacts regulation accuracy.

What is the purpose of the Ipk Sense pin (Pin 7) on the MC33063AP?

The Ipk Sense pin (Pin 7) on the MC33063AP monitors voltage across an external sense resistor (RSC) placed in series with the switch emitter (Pin 2). When this voltage exceeds ~300 mV, the internal current-limit circuit disables the switch to prevent damage during overload or short-circuit conditions. RSC value determines trip current: Ipk = 0.3 V / RSC. For 1.5-A peak, use RSC = 0.2 Ω; for 500-mA limit, use RSC = 0.6 Ω. This provides hardware-level cycle-by-cycle protection.

Can the MC33063AP drive external transistors?

Yes, the MC33063AP can drive external NPN or PNP transistors using Pin 8 (Driver Collector) and Pin 1 (Switch Collector). In non-Darlington mode, Pin 8 drives the base of an external NPN transistor whose collector connects to Pin 1, enabling >1.5-A peak currents. TI Application Note SLVA011 details configurations for external switch use, including saturation management and layout considerations to avoid slow turn-off at high frequencies. This extends the MC33063AP's utility beyond its internal switch limits.

What is the maximum switching frequency of the MC33063AP?

The MC33063AP oscillator supports up to 100 kHz switching frequency, set by the external timing capacitor (CT) on Pin 3. With CT = 1 nF, typical frequency is 33 kHz; reducing CT to 470 pF raises frequency to ~65 kHz. Frequencies above 100 kHz are not guaranteed - oscillator charge/discharge currents scale nonlinearly, and propagation delays limit usable range. Higher frequencies reduce inductor size but increase switching losses and EMI; 30–50 kHz is typical for optimal efficiency in MC33063AP designs.