ST763A SERIES 3.3V STEP DOWN CURRENT MODE PWM DC-DC CONVERTERS ■ ■ ■ ■ ■ ■ ■ ■ ■ 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 0.2µA OFF MODE SWITCH ON/OFF CONTROL TYPICAL EFFICENCY: 90% OPERATING TEMPERATURE RANGE: -40°C TO 85°C AVAILABLE IN SO-8 AND DIP-8 PACKAGES 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 0.2µA 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 DIP-8 SO-8 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 22µH 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 Parameter² Value Unit VCC DC Input Voltage -0.3 to 12 V VLX Switch Pin Voltage -0.3 to (VCC + 0.3) V VSHDN Shutdown Voltage (SHDN) -0.3 to (VCC + 0.3) V VS,VC Soft Start (SS) and Compensation Capacitor (CC) Pins Voltage -0.3 to (VCC + 0.3) V 2 A ILX Switching Peak Current IREF PTOT Tstg Reference Current 2.5 mA Continuous Power Dissipation at TA=70°C (DIP-8) (SO-8) Storage Temperature Range 550 344 mW mW -40 to +150 °C 0 to +70 -40 to +85 °C °C Operating Junction Temperature Range (AC series) Top (AB series) 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 DIP-8 Unit 160 100 °C/W (*) This value depends from thermal design of PCB on which the device is mounted. ORDERING CODES 2/10 TYPE DIP8 SO-8 SO-8 (T&R) ST763AB ST763AC ST763ABN ST763ACN ST763ABD ST763ACD ST763ABDTR ST763ACDTR ST763A SERIES CONNECTION DIAGRAM (top view) PIN DESCRIPTION Pin N° Symbol 1 SHDN 2 3 REF SS 4 CC 5 OUT 6 7 8 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 1µF ceramic capacitance and large value electrolytic capacitor in parallel. The 1µF 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 Parameter Test Conditions VCC Input Voltage VO Output Voltage ∆VO Line Regulation ∆VO Load Regulatio IO = 1 to 500mA η Power Efficency Min. 3.135 3.135 SHDN Input High Threshold VIL SHDN Input Low Threshold Shutdown Input Leakage Current Under Voltage Lockout RDS(on) LX On Resistance V V %/V IO =300mA IO =100mA 88 90 % % ON Mode (Including Switch Current) 0.6 0.2 2.7 ILX=500mA Reference Voltage TA = 25°C Temeperature Reference Drift Switching Frequency TA = TMIN to TMAX VLX = 0V 1.18 Compensation Pin Impedance 1.25 200 + 100 µF 22 µH 1 µF Lx 0.047 µF STPS330U OUT 1500 pF Vout + 470 pF 3 V Ω Vin CC µA nA Vcc GND 1 1 TYPICAL APPLICATION CIRCUIT SS V 10 7500 REF 0.25 1.32 50 159 SHDN 220 µF mA µA V VCC Falling VREF 4/10 2.5 100 2 VCC = 12V RC V 3.465 3.465 %/mA LX Leakage Current fOSC 11 3.3 3.3 0.13 ILEAK ∆VREF Unit 0.005 OFF Mode VIH VLOCK Max. 3.3 VCC = 4 to 11V IO =0 to 300mA VCC = 4.75 to 11V IO =0 to 500mA ISUPPLY Supply Current ISHDN Typ. V ppm/°C 212.5 KHz Ω ST763A SERIES TYPICAL PERFORMANCE CHARACTERISTICS (unless otherwise specified Tj = 25°C 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 mm DIM. MIN. A TYP. inch MAX. MIN. 3.3 TYP. MAX. 0.130 a1 0.7 B 1.39 1.65 0.055 0.065 B1 0.91 1.04 0.036 0.041 b b1 0.028 0.5 0.38 0.020 0.5 D 0.015 0.020 9.8 0.386 E 8.8 0.346 e 2.54 0.100 e3 7.62 0.300 e4 7.62 0.300 F 7.1 0.280 I 4.8 0.189 L Z 3.3 0.44 0.130 1.6 0.017 0.063 P001F 8/10 ST763A SERIES SO-8 MECHANICAL DATA mm DIM. MIN. TYP. A a1 inch MAX. MIN. TYP. 1.75 0.1 0.068 0.25 a2 MAX. 0.003 0.009 1.65 0.064 a3 0.65 0.85 0.025 0.033 b 0.35 0.48 0.013 0.018 b1 0.19 0.25 0.007 0.010 C 0.25 0.5 0.010 0.019 c1 45 (typ.) D 4.8 5.0 0.188 0.196 E 5.8 6.2 0.228 0.244 e 1.27 e3 0.050 3.81 0.150 F 3.8 4.0 0.14 0.157 L 0.4 1.27 0.015 0.050 M S 0.6 0.023 8 (max.) 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. © The ST logo is a registered trademark of STMicroelectronics © 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 © http://www.st.com 10/10