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

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

1/9January 2003

ST750A

ABSOLUTE MAXIMUM RATINGS

Symbol Parameter² Value Unit

V

V

V

SHDN

V

S,VC

I

LX

I

REF

P

TOT

T

T

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

R

thj-amb

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

DC Input Voltage

CC

Switch Pin Voltage -0.3 to (VCC+ 0.3)

LX

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)

op

Thermal Resistance Junction-ambient (*)

(B series)

160 100 °C/W

-0.3 to 12 V
V
V
V

2A

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

CC

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

for normal operation (ON MODE)

CC

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

CC

pins

ST750A

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ST750A

ELECTRICALCHARACTERISTICS(VCC=5V,IO=0mA,TA=T

MIN

toT

,unless otherwisespecified.)

MAX

Symbol Parameter Test Conditions Min. Typ. Max. Unit

Input Voltage 4 11 V

V

CC

V

Output Voltage VCC=6to11V IO=0 to 450mA 4.75 5 5.25 V

O

∆V
∆V

I

SUPPLY

I

SHDN

V

R

DS(on)

V

∆V

f

Line Regulation VCC= 4 to 11V 0.15 %/V

O

Load Regulatio IO= 0 to 450mA 0.005 %/mA

O

η Power Efficency I

Supply Current ON Mode

V

SHDN Input High Threshold 2 V

IH

SHDN Input Low Threshold 0.25 V

V

IL

=300mA 92 %

O

0.8

OFF Mode, SHDN

=0

0.3

Shutdown Input Leakage
Current

Under Voltage Lockout VCCFalling 2.7 3 V

LOCK

LX On Resistance ILX=500mA 0.5 Ω
LX Leakage Current VCC= 12V VLX=0V 1 µA

I

LX

Reference Voltage TA= 25°C 1.17 1.24 1.31 V

REF

Temperature Reference

REF

Drift
Switching Frequency B series

OSC

Compensation Pin

R

C

Impedance

C series

180
160

50 ppm/°C

200 220

7500 Ω

2.5

100

1 µA

KHz

280

mA

µA

TYPICAL APP LICATION CIRCUIT

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TYPICAL P ERFO RMAN CE CHARACTERISTICS (unless ot herwise spec ified Tj=25°C

ST750A

Figure1 : Ef fice nc y vs Output Current

Figure2 : SupplyCurrentvs Temperature

Figure4 : O scillator Frequency v s Input Voltage

Figure5 : Peak I nduc tor Current vs Output

Current

Figure3 : O s cillator Frequen cy vs Temp erature

Figure6 : O utput Volt age v s Output Current

5/9

ST750A

V

11V,I

300mA

V

11V,I

300mA

Figure7 : Switching Waveforms, Co ntinuous
Conduction

=6Vto

I

=

O

Figure8 : Switching Waveforms, Dis co ntinuous
Conduction

Figure9 : Line Transient

Figure10 : Load Transient

=6Vto

I

6/9

=

O

Plastic DIP-8 MECHANICAL DATA

ST750A

DIM.

MIN. TYP MAX. MIN. TYP. MAX.

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

mm. inch

P001F

7/9

ST750A

SO-8 MECHANICAL DATA

DIM.

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

MIN. TYP MAX. MIN. TYP. MAX.

mm. inch

8

8/9

0016023/C

ST750A

o

rmation furnished is believed to be accurate and reliable. However, STMicroelectronics assumes no responsibility for the

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use. No license is granted by implication or otherwise under any patent or patent rights of STMicroelectronics. Specifications
ntioned in this publication are subject to change without notice. This publication supersedes and replaces all information

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tems without express written approval of STMicroelectronics.

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