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| ST763A SERIES 3.3V STEP DOWN CURRENT MODE PWM DC-DC CONVERTERS s s s s s s s s s OUTPUT VOLTAGE 3.3V SUPPLY VOLTAGE RANGE FROM 3.3V TO 11V GUARANTEED OUTPUT CURRENT: 500mA TYPICAL OPERATION FREQUENCY: 200KHz VERY LOW QUIESCENT CURRENT: 0.6mA ON MODE 0.2A OFF MODE SWITCH ON/OFF CONTROL TYPICAL EFFICENCY: 90% OPERATING TEMPERATURE RANGE: -40C TO 85C AVAILABLE IN SO-8 AND DIP-8 PACKAGES DIP-8 SO-8 DESCRIPTION The ST763A is a step-down switching regulator . It operates from 3.3V to 11V giving a fixed 3.3V output voltage, delivering up to 500mA. The mainly features are typical efficiency of 90%, quiescent current of 0.6mA, and only 0.2A in shut-down. The PWM current mode control provides precise output regulation and very good transient response. Output voltage accuracy is guaranteed to be 5% over line, load and temperature variations. A minimum number of external components is used and the fixed frequency switching allows easy filtering of output ripple and noise. Other features of this ddevice are cycle-by-clicle current limiting, overcurrent limiting, under voltage lockout and programmable soft-start protection. A 22H inductor works in most applications, so no sophisticated design is necessary. Package available are SO-8 and DIP-8. Typical application are in 5V to 3.3V converters, cellular phones, portable instruments, hand-held computers, and peripherals. SCHEMATIC DIAGRAM November 2000 1/10 ST763A SERIES ABSOLUTE MAXIMUM RATINGS Symbol VCC VLX VSHDN VS,VC ILX IREF PTOT Tstg Top DC Input Voltage Switch Pin Voltage Shutdown Voltage (SHDN) Soft Start (SS) and Compensation Capacitor (CC) Pins Voltage Switching Peak Current Reference Current Continuous Power Dissipation at TA=70C (DIP-8) (SO-8) Storage Temperature Range Operating Junction Temperature Range (AC series) (AB series) Parameter Value -0.3 to 12 -0.3 to (VCC + 0.3) -0.3 to (VCC + 0.3) -0.3 to (VCC + 0.3) 2 2.5 550 344 -40 to +150 0 to +70 -40 to +85 Unit V V V V A mA mW mW C C C Absolute Maximum Ratings are those values beyond which damage to the device may occur. Functional operation under these condition is not implied. THERMAL DATA Symbol Rthj-amb Parameter Thermal Resistance Junction-ambient (*) SO-8 160 DIP-8 100 Unit C/W (*) This value depends from thermal design of PCB on which the device is mounted. ORDERING CODES TYPE ST763AB ST763AC DIP8 ST763ABN ST763ACN SO-8 ST763ABD ST763ACD SO-8 (T&R) ST763ABDTR ST763ACDTR 2/10 ST763A SERIES CONNECTION DIAGRAM (top view) PIN DESCRIPTION Pin N 1 2 3 4 5 6 7 8 Symbol SHDN REF SS CC OUT GND LX VCC Name and Function Shutdown control (active low): If connected to GND the IC is in shutdown. Connect to VCC for normal operation (ON MODE) Reference Output Voltage:(1.25V): Bypass to GND with 47nF capacitor Soft Start: a capacitor between SS and GND provides soft-start and short-circuit protections. Compensation Capacitor Input: externally compensates the outer (voltage) feedback loop. Connect to OUT with 330pF capacitor Output Voltage Sense Input: provides regulation of feedback sensing. Connect to 3.3V output. Ground Switch Output. Drain of internal P-Channel Power MOSFET Supply Voltage Input. Bypass to GND with 1F ceramic capacitance and large value electrolytic capacitor in parallel. The 1F capacitor must be as close as possible to the GND and VCC pins 3/10 ST763A SERIES ELECTRICAL CHARACTERISTICS (V CC=5V, IO = 0mA, TA = T MIN to TMAX, unless otherwise specified.) Symbol VCC VO VO VO Parameter Input Voltage Output Voltage Line Regulation Load Regulatio Power Efficency IO = 1 to 500mA IO =300mA IO =100mA ON Mode (Including Switch Current) OFF Mode VIH VIL ISHDN VLOCK ILEAK VREF VREF fOSC RC SHDN Input High Threshold SHDN Input Low Threshold Shutdown Input Leakage Current Under Voltage Lockout LX Leakage Current Reference Voltage Temeperature Reference Drift Switching Frequency Compensation Pin Impedance 2 0.25 1 VCC Falling ILX=500mA VCC = 12V TA = 25C TA = TMIN to TMAX 159 VLX = 0V 1.18 2.7 1 10 1.25 50 200 7500 212.5 1.32 3 VCC = 4 to 11V IO =0 to 300mA VCC = 4.75 to 11V IO =0 to 500mA Test Conditions Min. 3.3 3.135 3.135 3.3 3.3 0.13 0.005 88 90 0.6 0.2 2.5 100 Typ. Max. 11 3.465 3.465 Unit V V V %/V %/mA % % mA A V V A V nA V ppm/C KHz ISUPPLY Supply Current RDS(on) LX On Resistance TYPICAL APPLICATION CIRCUIT SHDN REF 0.047 F Vin Vcc + 22 H 100 F 1 F Lx STPS330U SS 1500 pF GND OUT Vout CC + 470 pF 220 F 4/10 ST763A SERIES TYPICAL PERFORMANCE CHARACTERISTICS (unless otherwise specified Tj = 25C Figure 1 : Output Voltage vs Temperature Figure 4 : Efficency vs Temperature Figure 2 : Output Voltage vs Input Voltage Figure 5 : Efficency vs Output Current Figure 3 : Reference Voltage vs Temperature Figure 6 : LX Leakage Current vs Temperature 5/10 ST763A SERIES Figure 7 : LX ON Resistance vs Temperature Figure 10 : Oscillator Frequency vs Temperature Figure 8 : Shutdown Input Threshold vs Temperature Figure 11 : Oscillator Frequency vs Input Voltage Figure 9 : Shutdown Input Leakage Current vs Temperature Figure 12 : Switching Waveforms, Continuous Conduction VI=6V, IO=250mA 6/10 ST763A SERIES Figure 13 : Switching Waveforms, Discontinuous Conduction Figure 15 : Load Transient VI=6V, IO=75mA VI=5V, IO=0 to 500mA Figure 14 : Line Transient iO=350mA 7/10 ST763A SERIES Plastic DIP-8 MECHANICAL DATA DIM. MIN. A a1 B B1 b b1 D E e e3 e4 F I L Z 0.44 3.3 1.6 0.017 8.8 2.54 7.62 7.62 7.1 4.8 0.130 0.063 0.38 0.7 1.39 0.91 0.5 0.5 9.8 0.346 0.100 0.300 0.300 0.280 0.189 0.015 1.65 1.04 mm TYP. 3.3 0.028 0.055 0.036 0.020 0.020 0.386 0.065 0.041 MAX. MIN. inch TYP. 0.130 MAX. P001F 8/10 ST763A SERIES SO-8 MECHANICAL DATA DIM. MIN. A a1 a2 a3 b b1 C c1 D E e e3 F L M S 3.8 0.4 4.8 5.8 1.27 3.81 4.0 1.27 0.6 8 (max.) 0.14 0.015 5.0 6.2 0.65 0.35 0.19 0.25 0.1 mm TYP. MAX. 1.75 0.25 1.65 0.85 0.48 0.25 0.5 45 (typ.) 0.188 0.228 0.050 0.150 0.157 0.050 0.023 0.196 0.244 0.025 0.013 0.007 0.010 0.003 MIN. inch TYP. MAX. 0.068 0.009 0.064 0.033 0.018 0.010 0.019 0016023 9/10 ST763A SERIES Information furnished is believed to be accurate and reliable. However, STMicroelectronics assumes no responsibility for the consequences of use of such information nor for any infringement 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 STMicroelectronics. Specifications mentioned in this publication are subject to change without notice. This publication supersedes and replaces all information previously supplied. STMicroelectronics products are not authorized for use as critical components in life support devices or systems without express written approval of STMicroelectronics. (c) The ST logo is a registered trademark of STMicroelectronics (c) 2000 STMicroelectronics - Printed in Italy - All Rights Reserved STMicroelectronics GROUP OF COMPANIES Australia - Brazil - China - Finland - France - Germany - Hong Kong - India - Italy - Japan - Malaysia - Malta - Morocco Singapore - Spain - Sweden - Switzerland - United Kingdom (c) http://www.st.com 10/10 |
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