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ST750A Dataheets PDF



Part Number ST750A
Manufacturers ST Microelectronics
Logo ST Microelectronics
Description ADJUSTABLE STEP-DOWN / CURRENT-MODE PWM DC-DC CONVERTERS
Datasheet ST750A DatasheetST750A Datasheet (PDF)

ST750A ADJUSTABLE 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 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 DIP-8 SO-8 DESCRIPTION The ST750A is an.

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ST750A ADJUSTABLE 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 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 DIP-8 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 SCHEMATIC DIAGRAM 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. January 2003 1/9 ST750A 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=70°C (DIP-8) (SO-8) Storage Temperature Range Operating Junction Temperature Range (C series) (B series) Parameter² 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 ST750AB ST750AC DIP8 ST750ABN ST750ACN SO-8 ST750ABD ST750ACD SO-8 (T&R) ST750ABD-TR ST750ACD-TR 2/9 ST750A CONNECTION DIAGRAM (top view) PIN DESCRIPTION Pin N° 1 2 3 4 5 6 7 8 Symbol SHDN REF SS CC IC 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 Internal Connection: make no external connection to this pin 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 ST750A ELECTRICAL CHARACTERISTICS (VCC=5V, IO = 0mA, TA = TMIN to TMAX, unless otherwise specified.) Symbol VCC VO ∆VO ∆VO η Parameter Input Voltage Output Voltage Line Regulation Load Regulatio Power Efficency VCC = 6 to 11V VCC = 4 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 = 25°C 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 µA V V µA V Ω µA V ppm/°C KHz Ω 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 4/9 ST750A 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 ST750A 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 6/9 ST750A 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.


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