STMicroelectronics MC34063ECN

Overview

MC34063ECN from STMicroelectronics is a monolithic DC-DC converter control circuit designed for step-up, step-down, and voltage-inverting topologies. It integrates a temperature-compensated 1.25 V reference (±2%), comparator, oscillator with timing capacitor control, active current limit, driver, and 1.5 A Darlington output switch. Operates from 3 V to 40 V input, supports up to 100 kHz switching, and delivers stable regulation in industrial power supplies requiring low quiescent current (2.5 mA typ.) and wide ambient range (0–70 °C).

For engineers reviewing the MC34063ECN datasheet, MC34063ECN pinout, MC34063ECN application, or MC34063ECN equivalent, this device is selected for discrete-switching regulator designs where external MOSFET/FET replacement is not required, output current exceeds 1 A, and cost-sensitive, multi-topology flexibility is critical.

Technical Context

The MC34063ECN implements a fixed-frequency, duty-cycle-controlled oscillator whose frequency is set by an external timing capacitor (CT) and internal charge/discharge currents (ICHG = 33 µA typ., IDISCHG = 200 µA typ.). Its current-limit threshold is defined by VIPK(sense) = 300 mV (typ.), enabling precise peak-current mode control independent of input/output conditions.

It features dual-output-stage architecture: a high-current Darlington switch (SWC/SWE pins) with VCE(sat) = 1.3 V at 1 A, and a separate driver output (DRC pin) supporting external transistor configurations. The comparator's inverting input (CII) accepts feedback from resistor-divided output voltage, referenced to the internal 1.25 V bandgap.

Key Specifications

Pinout & Package

MC34063ECN is supplied in an SO-8 surface-mount package (4.8 mm × 6.2 mm body, 1.27 mm pitch), compliant with ECOPACK environmental standards.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MC34063ACN, the ECN variant trades extended temperature rating and tighter reference for lower cost and commercial-grade qualification; versus LM2574N-5.0, it offers full topology versatility and external component optimization at the expense of fixed-output simplicity.

Availability

MC34063ECN is available at Aetrix Electronics and suitable for USB-C adapter design, industrial sensor node power supplies, portable medical devices, and inverting rail generation requiring stable component supply and long-term manufacturability.

Supply support for MC34063ECN 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, specializing in power management, microcontrollers, and analog ICs for industrial, automotive, and consumer markets.

The MC34063 series belongs to ST's legacy DC-DC controller product line, engineered for cost-effective, discrete-based switching power supplies where flexibility, reliability, and wide input range are prioritized over integrated FETs or digital control.

FAQ

What is the minimum input voltage required to start up the MC34063ECN?

The MC34063ECN has a guaranteed start-up voltage of 1.5 V (typ.) - the lowest supply voltage at which the internal oscillator begins oscillating. This enables operation directly from single-cell lithium or alkaline batteries. Startup behavior is verified per datasheet test condition with CT = 1 µF and PIN 5 grounded; actual startup may vary slightly with capacitor ESR and temperature.

Can the MC34063ECN drive an external MOSFET instead of using its internal switch?

Yes - the DRC (pin 8) is an open-collector driver output specifically intended to drive external NPN or PNP transistors. When used with an external switch, the internal Darlington (pins 1/2) is bypassed, allowing higher current, faster switching, or synchronous rectification. Application circuits in Figures 19–23 of the datasheet detail NPN/PNP configurations for step-up, step-down, and inverting topologies.

How does the current limit function interact with the oscillator frequency setting?

The current limit (IPK) and oscillator frequency (fOSC) operate independently: IPK is triggered by voltage across RSC at pin 7 exceeding 300 mV, while fOSC is set solely by CT and internal charge/discharge currents. However, in discontinuous conduction mode, higher fOSC reduces ton, lowering peak inductor current for a given RSC - so frequency selection indirectly affects current limit margin in practical designs.

Is the MC34063ECN RoHS-compliant and lead-free?

Yes - the MC34063ECN is manufactured in ST's ECOPACK2-compliant SO-8 package, meeting RoHS Directive 2011/65/EU and REACH SVHC requirements. Lead-free finish and halogen-free molding compound are confirmed in ST's official package mechanical data (DocID5257 Rev 13, Section 7) and material declarations available on www.st.com.