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ST730A
5V STEP-DOWN, CURRENT-MODE PWM DC-DC CONVERTERS
s s
s s
s s s s
s s
UP TO 450mA LOAD CURRENTS 200kHz HIGH-FREQUENCY CURRENT-MODE PWM 85% TO 96% EFFICIENCIES 33H OR 100H PRE-SELECTED INDUCTOR VALUE, NO COMPONENT DESIGN REQUIRED 0.8mA QUIESCENT CURRENT 0.3A 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
DIP-8
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 0.3A in shutdown mode. The output does not exhibit frequency over this specified range. Pulse-width modulation (PWM) current-mode control provides SCHEMATIC DIAGRAM
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.
January 2003
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ST730A
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 (C series) (B 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 ST730AB ST730AC DIP8 ST730ABN ST730ACN SO-8 ST730ABD ST730ACD SO-8 (T&R) ST730ABD-TR ST730ACD-TR
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ST730A
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 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 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
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ST730A
ELECTRICAL CHARACTERISTICS (VCC=5V, IO = 0mA, TA = TMIN to TMAX, unless otherwise specified.)
Symbol VCC VO VO VO Parameter Input Voltage Output Voltage Line Regulation Load Regulatio Power Efficency VCC = 6 to 11V VCC = 5.2 to 11V IO = 0 to 450mA IO =300mA ON Mode OFF Mode, SHDN=0 2 0.25 1 VCC Falling ILX=500mA VCC = 12V TA = 25C VLX = 0V 1.17 2.7 0.5 1 1.24 50 B series C series 180 160 200 7500 220 280 1.31 3 IO =0 to 450mA Test Conditions Min. 4 4.75 5 0.15 0.005 92 0.8 0.3 2.5 100 Typ. Max. 11 5.25 Unit V V %/V %/mA % mA A V V A V A V ppm/C KHz
ISUPPLY Supply Current VIH VIL ISHDN VLOCK ILX VREF VREF fOSC RC SHDN Input High Threshold SHDN Input Low Threshold Shutdown Input Leakage Current Under Voltage Lockout LX Leakage Current Reference Voltage Temperature Reference Drift Switching Frequency Compensation Pin Impedance
RDS(on) LX On Resistance
TYPICAL APPLICATION CIRCUIT
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ST730A
TYPICAL PERFORMANCE CHARACTERISTICS (unless otherwise specified Tj = 25C 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
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ST730A
Figure 7 : Switching Waveforms, Continuous Conduction Figure 9 : Line Transient
VI=6V to 11V, I O=300mA
Figure 8 : Switching Waveforms, Discontinuous Conduction
Figure 10 : Load Transient
VI=6V to 11V, I O=300mA
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ST730A
Plastic DIP-8 MECHANICAL DATA
mm. 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 TYP 3.3 0.028 0.055 0.036 0.020 0.020 0.386 0.065 0.041 MAX. MIN. TYP. 0.130 MAX. inch
P001F
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ST730A
SO-8 MECHANICAL DATA
DIM. A A1 A2 B C D E e H h L k ddd 0.1 5.80 0.25 0.40 mm. MIN. 1.35 0.10 1.10 0.33 0.19 4.80 3.80 1.27 6.20 0.50 1.27 8 (max.) 0.04 0.228 0.010 0.016 TYP MAX. 1.75 0.25 1.65 0.51 0.25 5.00 4.00 MIN. 0.053 0.04 0.043 0.013 0.007 0.189 0.150 0.050 0.244 0.020 0.050 inch TYP. MAX. 0.069 0.010 0.065 0.020 0.010 0.197 0.157
0016023/C
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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. (c) The ST logo is a registered trademark of STMicroelectronics (c) 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. (c) http://www.st.com
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