Document
a
FEATURES Wide Input Voltage Range: 3.6 V to 30 V Adjustable and Fixed (3.3 V, 5 V) Output Options Integrated 1 A Power Switch Uses Small Surface-Mount Components Cycle-By-Cycle Current Limiting Peak Input Voltage (100 ms): 60 V Thermally Enhanced 8-Lead SOIC Package Configurable as a Buck, Buck-Boost and SEPIC Regulator APPLICATIONS Industrial Power Systems PC Peripheral Power Systems Preregulator for Linear Regulators Distributed Power Systems Automotive Systems Battery Chargers
200 kHz, 1 A High-Voltage Step-Down Switching Regulator ADP3050
FUNCTIONAL BLOCK DIAGRAM
BIAS IN CURRENT SENSE AMPLIFIER
SD GND
2.5V REGULATOR
FREQUENCY AND CURRENT LIMIT FOLDBACK
CURRENT LIMIT
+
200kHz OSCILLATOR BOOST CMP S R gm Q DRIVER SWITCH
FB
1.2V
ADP3050
COMP
GENERAL DESCRIPTION
The ADP3050 is a current-mode monolithic buck (step-down) PWM switching regulator that contains a high current 1 A power switch and all control, logic, and protection functions. It uses a unique compensation scheme that allows the use of any type of output capacitor (tantalum, ceramic, electrolytic, OS-CON). Unlike some buck regulators, the design is not restricted to using a specific type of output capacitor or ESR value. A special boosted drive stage is used to saturate the NPN power switch, providing a system efficiency higher than conventional bipolar buck switchers. Further efficiency improvements are obtained by using the low voltage regulated output to provide the device's internal operating current. A high switching frequency allows the use of small external surface-mount components. A wide variety of standard off-the-shelf devices can be used, providing a great deal of design flexibility. A complete regulator design requires only a few external components.
The ADP3050 includes a shutdown input that places the device in a low-power mode, reducing the total supply current to under 20 µA. Internal protection features include thermal shutdown circuitry and a cycle-by-cycle current-limit for the power switch to provide complete device protection under fault conditions. The ADP3050 provides excellent line and load regulation, maintaining typically less than ± 3% output voltage accuracy over temperature and under all input voltage and output current conditions. The ADP3050 is specified over the industrial temperature range of –40°C to +85°C and is available in a thermally enhanced 8-lead SOIC package.
REV. 0
Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other rights of third parties which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of Analog Devices. One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. Tel: 781/329-4700 World Wide Web Site: http://www.analog.com Fax: 781/326-8703 © Analog Devices, Inc., 2000
ADP3050–SPECIFICATIONS (V
Parameter FEEDBAC.