ST730A 5V STEP-DOWN, CURRENT-MODE PWM DC-DC CONVERTERS ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ UP TO 450mA LOAD CURRENTS 200kHz HIGH-FREQUENCY CURRENT-MODE PWM 85% TO 96% EFFICIENCIES 33µH OR 100µH PRE-SELECTED INDUCTOR VALUE, NO COMPONENT DESIGN REQUIRED 0.8mA QUIESCENT CURRENT 0.3µA SHUTDOWN SUPPLY CURRENT ADJUSTABLE OUTPUT VOLTAGE OVERCURRENT, SOFT-START AND UNDERVOLTAGE LOCKOUT PROTECTION CYCLE-BY-CYCLE CURRENT LIMITING PACKAGE AVAILABLE: DIP-8 AND SO-8 DESCRIPTION The ST730A is a 5V output CMOS, step-down switching regulator. The ST730A accepts inputs between 5.2V and 11V and delivers 450mA. Typical efficiencies are 85% to 96%. Quiescent supply current is 0.8mA and only 0.3µA in shutdown mode. The output does not exhibit frequency over this specified range. Pulse-width modulation (PWM) current-mode control provides DIP-8 SO-8 precise output regulation and excellent transient responses. Output voltage accuracy is guaranteed to be ±5% over line, load, and temperature varations. Fixed-frequency switching and absence of subharmonic ruipple allows easy filtering of output ripple and noise, as well as the use of small external components. This regulators require only a single inductor value to work in most applications, so no inductor design is necessary. Typical applications are: Cellular phones & radios, portable Instruments, Portable Communications Equipments and Computer Peripherals. SCHEMATIC DIAGRAM January 2003 1/9 ST730A 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 Switching Peak Current ILX 2 A Reference Current 2.5 mA 550 344 mW mW Tstg Continuous Power Dissipation at TA=70°C (DIP-8) (SO-8) Storage Temperature Range -40 to +150 °C Top Operating Junction Temperature Range (C series) (B series) 0 to +70 -40 to +85 °C °C IREF PTOT 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 2/9 TYPE DIP8 SO-8 SO-8 (T&R) ST730AB ST730AC ST730ABN ST730ACN ST730ABD ST730ACD ST730ABD-TR ST730ACD-TR ST730A CONNECTION DIAGRAM (top view) PIN DESCRIPTION Pin N° Symbol 1 SHDN 2 REF 3 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 a capacitor that does not exceed 47nF 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 5V 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 3/9 ST730A ELECTRICAL CHARACTERISTICS (VCC=5V, IO = 0mA, TA = TMIN to TMAX, unless otherwise specified.) Symbol Parameter Test Conditions Min. Typ. Max. 11 V 5 5.25 V VCC Input Voltage VO Output Voltage ∆VO Line Regulation VCC = 5.2 to 11V 0.15 %/V ∆VO Load Regulatio IO = 0 to 450mA 0.005 %/mA η Power Efficency ISUPPLY Supply Current VIH SHDN Input High Threshold VIL SHDN Input Low Threshold ISHDN VLOCK Shutdown Input Leakage Current Under Voltage Lockout RDS(on) LX On Resistance ILX VREF ∆VREF fOSC RC 4 Unit VCC = 6 to 11V IO =300mA 92 0.8 0.3 % 2.5 100 2 VCC Falling 2.7 ILX=500mA 0.5 VCC = 12V Reference Voltage TA = 25°C VLX = 0V V 1 µA 3 1.24 B series C series Compensation Pin Impedance 180 160 200 7500 V Ω µA 1 1.17 mA µA V 0.25 1.31 50 TYPICAL APPLICATION CIRCUIT 4/9 4.75 ON Mode OFF Mode, SHDN=0 LX Leakage Current Temperature Reference Drift Switching Frequency IO =0 to 450mA V ppm/°C 220 280 KHz Ω ST730A TYPICAL PERFORMANCE CHARACTERISTICS (unless otherwise specified Tj = 25°C Figure 1 : Efficency vs Output Current Figure 4 : Oscillator Frequency vs Input Voltage Figure 2 : Supply Current vs Temperature Figure 5 : Peak Inductor Current vs Output Current Figure 3 : Oscillator Frequency vs Temperature Figure 6 : Output Voltage vs Output Current 5/9 ST730A Figure 7 : Switching Waveforms, Continuous Conduction Figure 9 : Line Transient VI=6V to 11V, I O=300mA Figure 8 : Switching Waveforms, Discontinuous Conduction VI=6V to 11V, I O=300mA 6/9 Figure 10 : Load Transient ST730A Plastic DIP-8 MECHANICAL DATA mm. inch DIM. MIN. A TYP 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 7/9 ST730A SO-8 MECHANICAL DATA DIM. mm. MIN. TYP inch MAX. MIN. TYP. MAX. A 1.35 1.75 0.053 0.069 A1 0.10 0.25 0.04 0.010 A2 1.10 1.65 0.043 0.065 B 0.33 0.51 0.013 0.020 C 0.19 0.25 0.007 0.010 D 4.80 5.00 0.189 0.197 E 3.80 4.00 0.150 0.157 e 1.27 0.050 H 5.80 6.20 0.228 0.244 h 0.25 0.50 0.010 0.020 L 0.40 1.27 0.016 0.050 k ddd 8˚ (max.) 0.1 0.04 0016023/C 8/9 ST730A ormation furnished is believed to be accurate and reliable. However, STMicroelectronics assumes no responsibility for the nsequences of use of such information nor for any infringement of patents or other rights of third parties which may result from use. No license is granted by implication or otherwise under any patent or patent rights of STMicroelectronics. Specifications entioned in this publication are subject to change without notice. This publication supersedes and replaces all information eviously supplied. STMicroelectronics products are not authorized for use as critical components in life support devices or stems without express written approval of STMicroelectronics. © The ST logo is a registered trademark of STMicroelectronics © 2003 STMicroelectronics - Printed in Italy - All Rights Reserved STMicroelectronics GROUP OF COMPANIES ustralia - Brazil - Canada - China - Finland - France - Germany - Hong Kong - India - Israel - Italy - Japan - Malaysia - Malta - Morocco Singapore - Spain - Sweden - Switzerland - United Kingdom - United States. © http://www.st.com 9/9