ST750A STMICROELECTRONICS | Alldatasheet
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Technical content
■ UP TO 450mA LOAD CURRENTS ■ 200kHz HIGH-FREQUENCY CURRENT-MODE PWM ■ 85% TO 96% EFFICIENCIES ■ 33µHO R1 0 0µH 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 ST750A is an adjustable output CMOS, step-down switching regulator. The ST750A accepts inputs between 4V 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 precise output regulation and excellent transient responses. Output voltage accuracy is guaranteed to be ±4.5% plus feedback resistor tolerance 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. ST750A ADJUSTABLE STEP-DOWN, CURRENT-MODE PWM DC-DC CONVERTERS SCHEMATIC DIAGRAM DIP-8 SO-8
Absolute Maximum Ratings are those values beyond which damage to the device may occur. Functional operation under these condition is not implied. THERMAL DATA (*) This value depends from thermal design of PCB on which the device is mounted. ORDERING CODES Symbol Parameter² Value Unit VCC DC Input Voltage -0.3 to 12 V VLX Switch Pin Voltage -0.3 to (V CC + 0.3) V VSHDN Shutdown Voltage (SHDN) -0.3 to (V CC + 0.3) V V S,VC Soft Start (SS) and Compensation Capacitor (CC) Pins Voltage -0.3 to (VCC + 0.3) V ILX Switching Peak Current 2A IREF Reference Current 2.5 mA PTOT Continuous Power Dissipation at TA=70°C (DIP-8) (SO-8) 550 344 mW mW Tstg Storage Temperature Range -40 to +150 °C Top Operating Junction Temperature Range (C series) (B series) 0t o+ 7 0 -40 to +85 Symbol Parameter SO-8 DIP-8 Unit Rthj-amb Thermal Resistance Junction-ambient (*) 160 100 °C/W TYPE DIP8 SO-8 SO-8 (T&R) ST750AB ST750ABN ST750ABD ST750ABD-TR ST750AC ST750ACN ST750ACD ST750ACD-TR
CONNECTION DIAGRAM (top view) PIN DESCRIPTION Pin N° Symbol Name and Function 1 SHDN Shutdown control (active low): If connected to GND the IC is in shutdown. Connect to VCC for normal operation (ON MODE) 2 REF Reference Output Voltage: (1.25V): Bypass to GND with a capacitor that does not exceed 47nF
3 SS Soft Start: a capacitor between SS and GND provides soft-start and short-circuit
protections.
4 CC Compensation Capacitor Input: externally compensates the outer (voltage)
feedback loop. Connect to OUT with 330pF capacitor
5 IC Internal Connection: make no external connection to this pin
6 GND Ground
7 LX Switch Output. Drain of internal P-Channel Power MOSFET CC 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
ELECTRICAL CHARACTERISTICS (VCC =5V, IO =0 m A ,TA =T MIN to TMAX , unless otherwise specified.) TYPICAL APPLICATION CIRCUIT Symbol Parameter Test Conditions Min. Typ. Max. Unit VCC Input Voltage 4 11 V VO Output Voltage V CC =6t o1 1 V I O =0 to 450mA 4.75 5 5.25 V ΔV O Line Regulation V CC = 4 to 11V 0.15 %/V ΔV O Load Regulatio I O = 0 to 450mA 0.005 %/mA η Power Efficency I O =300mA 92 % ISUPPLY Supply Current ON Mode OFF Mode, SHDN =0 0.8 0.3 2.5 100 mA µA VIH SHDN Input High Threshold 2 V VIL SHDN Input Low Threshold 0.25 V ISHDN Shutdown Input Leakage Current 1 µA VLOCK Under Voltage Lockout V CC Falling 2.7 3 V R DS(on) LX On Resistance I LX=500mA 0.5 Ω ILX LX Leakage Current V CC = 12V V LX =0 V 1 µA VREF Reference Voltage T A = 25°C 1.17 1.24 1.31 V Δ VREF Temperature Reference Drift 50 ppm/°C fOSC Switching Frequency B series C series 180 160 200 220 280 KHz R C Compensation Pin Impedance 7500 Ω
DIM. mm. inch A 3.3 0.130 a1 0.7 0.028 B 1.39 1.65 0.055 0.065 B1 0.91 1.04 0.036 0.041 b 0.5 0.020 b1 0.38 0.5 0.015 0.020 D 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 3.3 0.130 Z 0.44 1.6 0.017 0.063 Plastic DIP-8 MECHANICAL DATA P001F
DIM. mm. inch 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 ˚ (max.) ddd 0.1 0.04 SO-8 MECHANICAL DATA 0016023/C
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