SGS Thomson Microelectronics ST750ACN, ST750ACD-TR, ST750ACD, ST750ABN, ST750ABD-TR Datasheet

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CURRENT-MODE PWM DC-DC CONVERTERS

■ UP TO 450mA LOAD CURRENTS

■ 200kHz HIGH-FREQUENCY

CURRENT-MODE PWM

■ 85% TO 96% EFFICIENCIES

■ 33µHOR100µH 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 1 1V 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 th is specified range. Pulse-width modulation (PWM) current-mode control provides

ST750A

ADJUSTABLE STEP-DOWN,

DIP-8 SO-8

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 absenc e of subharmonic ruipple allows easy filtering of output ripple and noise, as well as the use of smal l external components. This regul ators requi re o nly a s ingle inductor value to work in most applications, so no inductor design is necessary. Typical applications are: Cellular phones & radios, portable Instruments, Porta ble Communications Equipments and Computer Peripherals.

SCHEMATIC DIAGRAM

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ST750A

ABSOLUTE MAXIMUM RATINGS

Symbol Parameter² Value Unit

SHDN

S,VC

REF

TOT

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 Parameter SO-8 DIP-8 Unit

thj-amb

(*) This value depends from thermal design of PCB on which the device is mounted.

DC Input Voltage

Switch Pin Voltage -0.3 to (VCC+ 0.3)

Shutdown Voltage (SHDN) -0.3 to (VCC+ 0.3) Soft Start (SS) and Compensation Capacitor (CC) Pins Voltage -0.3 to (VCC+ 0.3) Switching Peak Current Reference Current Continuous Power Dissipation at TA=70°C (DIP-8)

(SO-8)

Storage Temperature Range

stg

Operating Junction Temperature Range (C series)

Thermal Resistance Junction-ambient (*)

(B series)

160 100 °C/W

-0.3 to 12 V V V V

2.5 mA

550 344

mW mW

-40 to +150 °C 0to+70

-40 to +85

°C °C

ORDERING CODES

TYPE DIP8 SO-8 SO-8 (T&R)

ST750AB ST750ABN ST750ABD ST750ABD-TR ST750AC ST750ACN ST750ACD ST750ACD-TR

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CONNECTION DIAGRAM (top view)

PIN DESCRIPTION

Pin N° Symbol Name and Function

1 SHDN

2 REF Reference Output Voltage: (1.25V): Bypass to GND with a capacitor that does not

3 SS Soft Start: a capacitor between SS and GND provides soft-start and short-circuit

4 CC Compensation Capacitor Input: externally compensates the outer (voltage)

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 8V

Shutdown control (active low): If connected to GND the IC is in shutdown. Connect to V

for normal operation (ON MODE)

exceed 47nF

protections.

feedback loop. Connect to OUT with 330pF capacitor

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 V

pins

ST750A

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