Datasheet ST735CN, ST735CD, ST735CD-TR Datasheet (SGS Thomson Microelectronics)

-5V INVERTING, NEGATIVE OUTPUT

CURRENT-MODE PWM REGULATOR

■ CONVERTS +4.0V TO + 6.2V INPUT TO -5V

OUTPUT

■ 1W GUARANTEEDOUTPUT POWER

■ 75% TYPICAL EFFICIENCY

■ 0.8mA QUIESCENT CURRENT

■ 10µA SHUTDOWN MODE

■ 160KHZ FIXED FREQUENCY OSCILLATOR

■ CURRENT MODE PWM CONVERTER

■ LOW NOISE AND JITTER

■ SOFT START

■ SIMPLE APPLICATION CIRCUIT

■ UNDERVOLTAGE LOCKOUT

DESCRIPTION

The ST735 is a Bi-CMOS, inverting s w itch mode
DC-DC regulator with internal Power MOSFE T's
that generates a fixed -5V output voltage from a
4V to 6.2V input voltage; is guaranteed an output
current of 200mA for inputs great er than 4.5V . The
quiescent current for this device is typically of

0.8mA and, in shutdown mode it is reduced to
10µA.

ST735

DIP-8 SO-8

These power-conserving features, along with hi gh
efficiency and applications circuits, t hat lend itself
to minaturization, make the ST735 excellent in a
broad range of on-card, HDD and portable
equipment applications. The ST735 employ a
high performance current mode puls e with
modulation (PWM) control scheme to provide tight
output voltage regulat ion and low noise. T he
fixed frequency oscillator is factory trimmed to
160KHz, allowing for easy noise filtering. T he
regulator in production is tested to guarantee an
output accuracy within ±5% over all specified
conditions.

SCHEMATIC DIAGRAM

1/9August 2002

ST735

ABSOLUTE MAXIMUM RATINGS

Symbol Parameter Value Unit

V

SHDN

V
V

V

OUT

I

LX

P
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 DIP-8 SO-8 Unit

R

thj-case

DC Input Voltage (VINto GND)

IN

Shutdown Voltage (SHDN to GND) -0.3 to V
Switch Voltage (Lx to VIN)

LX

Feedback Voltage (V

FB

Output Voltage (V

OUT

to GND)

OUT

to GND)
Other Input Voltage (SS, CC to GND) -0.3 to V
Peack Switch Current
Power Dissipation at Tj= 70°C DIP-8 725

tot

Storage Temperature Range

stg

Operating Junction Temperature Range

op

Thermal Resistance Junction-case

SO-8 470

2 8 °C/W

-0.3 to +7 V
+0.3

+

V

-12.5 to +0.3 V

-11to+0.3 V

-11to+0.3 V
+0.3

+

V

2A

mW

-55 to +150 °C

-40 to +125 °C

CONNECTION DIAGRAM (t op v iew)

PIN DESCRIPTION

Pin N° Symbol Name and Function

1 SHDN SHUT-DOWN Control (VCC=ON GND=Shutdown
2V

REF

3 SS Soft Start
4 CC Compensation Input
5V

OUT

6 GND Ground
7 LX Switch Output
8V

IN

Reference Output Voltage

Negative Output Voltage

Positive Supply - Voltage Input

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ORDERING CODES

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

ST735 ST735CN ST735CD ST735CD-TR

TYPICAL APPLICATION CIRCUIT

ST735

NOTE:

1) All capacitors are X7R ceramic

2) C

can be omitted if are used higher values for the input and output capacitors C2=47µF, C1=100pF.

5

3/9

ST735

ELECTRICAL CHARACTERISTICS (Refer to test circuit, VIN=5V,CIN=4.7µF, C

T

= -40 to 125°C, unless otherwise specified. Typical value are referred at T

amb

=10µF, L = 10µH,

OUT

= 25°C)

amb

Symbol Parameter Test Conditions Min. Typ. Max. Unit

V

V

I

I

SUPPLY

I

STANDBY

V

∆V
∆V

V
∆V
R

DSON

I

LEAK

V

f

R

Note1 : Tested at I

Input Voltage 4 6.2 V

IN

Output Voltage VIN= 4.5V to 6.2V I

OUT

T

amb

V

IN

T

amb

OUT

Output Current

V
V

T
V

IN
IN

amb

IN

= -40 to 125°C

= 4.0V to 6.2V I

= -40 to 125°C

= 4.5V to 6.2V T
= 4.5V to 6.2V I

= -40 to 125°C

= 4.0V V

OUT

= 0 to 200mA

OUT

= 0 to 175mA

OUT

= 0 to 125°C

amb

= 0 to 175mA

OUT

-5.25 -5 -4.75 V

-5.25 -5 -4.75 V

200 275 mA
175 mA

= -5V 175 mA
Supply Current Includes Switch Current 0.8 1.6 mA
Standby Current V
Short Circuit Current 1.5 A

I

SC

Undervoltage Lock-out 3.5 4 V

LO

Line Regulation VIN= 4.0V to 6.2V 0.1 %/V

OUT

Load Regulation I

OUT

Reference Voltage

REF

Reference Drift

REF

=0V 1 10 µA

SHDN

= 0 to 200mA 0.003 %/mA

OUT

T

=25°C (Note 1)

amb

T

= -40 to 125°C

amb

1.247 V
50 ppm/°C

LX ON Voltage 0.5 Ω
LX Leakage Current VDS= 10V 1 µA
Shutdown Pin Current 1 µA

I

SH

Shutdown Input Low

V

IL

Threshold
Shutdown Input High

IH

Threshold
Maximum Oscillator

OSC

Frequency

ν Efficency I

Compensation Pin

CC

Impedance on CC Pin

=0mA

VREF

= 100mA 72 %

OUT

2V

160 KHz

7.5 KΩ

0.25 V

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ST735

TYPICAL CHARACTERISTICS

(Referredtotypicalapplicationcircuit,T

Figure1 : Output Voltage vs Temperature

Figure2 : Reference Voltage vs Temperatu re

=25°C unless otherwise specified)

amb

Figure4 : EfficencyvsTemperature

Figure5 : Efficency vs Ouput Current

Figure3 : Oscillator Frequency vs Temperature

Figure6 : Supply Currentvs Temperature

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ST735

Figure7 : Supply Current vs Input Voltage

Figure8 : Shutdown Threshold vs Temp eratu re

Figure10 : Switch Current Limit vs Soft Start

Voltage

Figure11 : LX On Resistance vs Temperature

Figure9 : Peak Inductor Current vs Output

Current

6/9

Figure12 : LX On Resistance vs Input Voltage

Plastic DIP-8 MECHANICAL DATA

ST735

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

ST735

SO-8 MECHANICAL DATA

DIM.

A 1.75 0.068

a1 0.1 0.25 0.003 0.009
a2 1.65 0.064
a3 0.65 0.85 0.025 0.033

b 0.35 0.48 0.013 0.018

b1 0.19 0.25 0.007 0.010

C 0.25 0.5 0.010 0.019

c1 45˚ (typ.)

D 4.8 5.0 0.189 0.196

E 5.8 6.2 0. 228 0.244
e 1.27 0.050

e3 3.81 0.150

F 3.8 4.0 0.149 0.157
L 0.4 1. 27 0. 015 0.050

M 0.6 0. 023

S

MIN. TYP MAX. MIN. TYP. MAX.

mm. inch

˚ (max.)

8

8/9

0016023

ST735

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