STMicroelectronics MC34063ACD

Overview

MC34063ACD from STMicroelectronics is a monolithic DC-DC converter control circuit in SO-8 package, featuring 2% reference accuracy, 1.5 A output switch current, and operation from 3 V to 40 V input. It supports step-up, step-down, and voltage-inverting topologies with up to 100 kHz switching frequency, commonly used in industrial power supplies and battery-powered instrumentation.

For engineers reviewing the MC34063ACD datasheet, MC34063ACD pinout, MC34063ACD application, or MC34063ACD equivalent, key selection criteria include internal Darlington switch saturation voltage (1.3 V typ.), current-limit sense threshold (300 mV), oscillator timing capacitor dependency, and thermal resistance (160 °C/W for SO-8).

Technical Context

The device integrates a temperature-compensated 1.25 V reference, comparator, duty-cycle-controlled oscillator with active current limiting, driver stage, and high-current Darlington output switch. Its oscillator frequency is set by an external timing capacitor (CT) and scales linearly with charge/discharge current ratio (IDISCHG/ICHG = 6.2 typ.).

Current limiting is implemented via IPK sense pin (Pin 7), comparing external resistor voltage against a 300 mV threshold. The output switch operates in either Darlington (low VCE(sat) at high current) or common-emitter mode, with forced β ≥10 recommended when external transistors are used.

Key Specifications

Pinout & Package

MC34063ACD is housed in an SO-8 surface-mount package (ECOPACK® compliant), with 1.27 mm pitch, 4.8 × 6.2 mm body, and thermal resistance RthJA = 160 °C/W.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM2574N-5.0 and TPS61040DRVR, MC34063ACD offers unique multi-topology flexibility and 40 V input tolerance at the cost of lower switching frequency and external component count - making it optimal for cost-sensitive, wide-input, non-standard voltage conversion where programmability matters more than peak efficiency.

Availability

MC34063ACD is available at Aetrix Electronics and suitable for industrial power supplies, battery-powered instrumentation, automotive lighting controllers, and point-of-sale terminal power systems requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for MC34063ACD 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

STMicroelectronics is a global semiconductor leader headquartered in Geneva, Switzerland, designing and manufacturing analog, microcontroller, power, and sensor solutions for industrial, automotive, and consumer markets.

MC34063ACD belongs to ST's legacy analog power management portfolio, engineered for robust, low-cost DC-DC conversion in applications where reliability, wide input range, and topology flexibility outweigh ultra-high efficiency or integration density requirements.

FAQ

What is the maximum input voltage for MC34063ACD?

The absolute maximum input voltage (VCC) is 50 V, but continuous operation is rated up to 40 V per datasheet specifications. Exceeding 40 V risks exceeding power dissipation limits and thermal stress, especially in SO-8 package with RthJA = 160 °C/W. For 48 V systems, derating or heatsinking is mandatory.

Can MC34063ACD be used in synchronous rectification designs?

No - MC34063ACD lacks gate-drive outputs compatible with synchronous MOSFETs. Its DRC pin is an open-collector NPN driver intended for bipolar transistors, and SWC/SWE pins are Darlington-based with inherent 1.3 V saturation drop. External MOSFET drivers require separate logic-level control signals not provided by this IC.

How does the IPK current limit function during startup?

IPK sensing is active immediately after VCC exceeds 2.1 V start-up threshold. During soft-start or light-load conditions, the internal oscillator begins cycling and the current limit responds within one switching cycle. No external delay or blanking is needed - the 300 mV threshold triggers immediate duty-cycle reduction if sensed voltage exceeds the limit.

Is the 2% reference accuracy maintained over temperature?

Yes - the 1.25 V reference has ±2% initial tolerance and exhibits ±10 mV line regulation (over 3–40 V VCC) and ±0.04 V typical drift from 0°C to 70°C (AC series). Full datasheet plots show <±15 mV total deviation across operating ambient range, supporting stable regulation in unheated enclosures.