ADP3050

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. R EV. 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 FEEDBACK Feedback Voltage ADP3050 ADP3050-3.3 ADP3050-5 Line Regulation Load Regulation Symbol VFB 1 IN = 10 V, TA = –40 C to +85 C, unless otherwise noted) Min Typ Max Unit Conditions Over Line and Temperature 1.16 3.20 4.85 VIN = 10 V to 30 V, no load ILOAD = 100 mA to 1 A, ADP3050AR Only ADP3050AR-3.3, ADP3050AR-5 ADP3050AR Only 1.20 3.30 5.00 0.005 +0.1 +0.1 0.65 1250 300 1.24 3.40 5.15 V V V %/V %/A %/A µA µMho V/V µA µA µA –1.0 –0.5 Input Bias Current ERROR AMPLIFIER Transconductance2 Voltage Gain2 Output Current ADP3050 ADP3050-3.3 ADP3050-5 OSCILLATOR Oscillator Frequency3 Minimum Duty Cycle Maximum Duty Cycle SWITCH Average Output Current Limit4 ADP3050 ADP3050-3.3 ADP3050-5 Peak Switch Current Limit5 Saturation Voltage Leakage Current SHUTDOWN Input Voltage Low Input Voltage High SUPPLY Minimum Input Voltage6 Minimum BIAS Voltage Minimum BOOST Voltage IN Supply Current Normal Mode Shutdown Mode BIAS Supply Current BOOST Supply Current IFB gm AVOL +1.0 +0.5 2 COMP = 1.0 V, FB = 1.1 V to 1.3 V COMP = 1.0 V, FB = 3.0 V to 3.6 V COMP = 1.0 V, FB = 4.5 V to 5.5 V fOSC DMIN DMAX ICL(AVG) BOOST = 15 V, FB = 1.1 V BOOST = 15 V, FB = 3.0 V BOOST = 15 V, FB = 4.5 V ICL(PEAK) BOOST = 15 V, ILOAD = 1 A 1.0 1.0 1.0 1.5 170 ± 115 ± 120 ± 135 200 10 90 240 kHz % % 1.25 1.25 1.25 1.7 0.65 50 1.5 1.5 1.5 2.1 0.95 A A A A V nA V V V V V mA µA mA mA mA 0.4 2.0 VIN VBIAS VBOOST IQ IBIAS IBOOST BIAS = 5.0 V SD = 0 V, VIN ≤ 30 V BIAS = 5.0 V BOOST = 15 V, ISW = 0.5 A BOOST = 15 V, ISW = 1.0 A 0.7 15 4.0 18 20 3.6 3.0 3.0 1.5 40 6.0 40 NOTES 1 All limits at temperature extremes are guaranteed via correlation using standard Statistical Quality Control (SQC). 2 Transconductance and voltage gain measurements refer to the internal amplifier without the voltage divider. To calculate the transconductance and gain of the fixed voltage parts, divide the values shown by FB/1.20. 3 The switching frequency is reduced when the feedback pin is lower than 0.8 FB. 4 See Figure 22 for test circuit. 5 Switch current limit is measured with no diode, no inductor, and no output capacitor. 6 Minimum input voltage is not measured directly, but is guaranteed by other tests. The actual minimum input voltage needed to keep the output in regulation will depend on output voltage and load current. Specifications subject to change without notice. – 2– REV. 0 ADP3050 ABSOLUTE MAXIMUM RATINGS * PIN FUNCTION DESCRIPTION IN Voltage Steady State . . . . . . . . . . . . . . . . . . . . . . . . –0.3 V to +30 V Peak (