ST1S03 [STMICROELECTRONICS]

1.5A, 1.5 MHZ ADJUSTABLE, STEP-DOWN SWITCHING REGULATOR IN DFN6; 1.5A ， 1.5MHz的可调，在DFN6降压型开关稳压器


型号：	ST1S03
厂家：	ST
描述：	1.5A, 1.5 MHZ ADJUSTABLE, STEP-DOWN SWITCHING REGULATOR IN DFN6 1.5A ， 1.5MHz的可调，在DFN6降压型开关稳压器稳压器开关
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中文：	中文翻译
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ST1S03

1.5A, 1.5 MHZ ADJUSTABLE,

STEP-DOWN SWITCHING REGULATOR IN DFN6

STEP-DOWN CURRENT MODE PWM

(1.5MHz) DC-DC CONVERTER

2% DC OUTPUT VOLTAGE TOLERANCE

INTERNAL SOFT START FOR START-UP

CURRENT LIMITIATION AND POWER ON

DELAY OF 50-100µs

TYPICAL EFFICIENCY: > 70% OVER ALL

OPERATING CONDITIONS

DFN6 (3x3)

1.5A OUTPUT CURRENT CAPABILITY

NOT SWITCHING QUIESCENT CURRENT:

MAX 2.5mA OVER TEMPERATURE RANGE

SWITCH V : MAX 350mV @ISW=750mA

USES TINY CAPACITORS AND INDUCTORS

AVAILABLE IN DFN 3x3 EXPOSED PAD

switching frequency (1.5MHz) allows the use of

tiny surface-mount components: as well as the

resistor divider to set the output voltage value,

only an inductor, a schottky diode and two

capacitors are required. Besides, a low output

ripple is guaranteed by the current mode PWM

topology and by the use of low E.S.R. SMD

ceramic capacitors. The device is thermal

protected and current limited to prevent damages

due to accidental short circuit. The ST1S03 is

available in DFN6 package.

DESCRIPTION

The ST1S03 is a step down DC-DC converter

optimized for powering low-voltage digital core in

HDD applications and, generally, to replace the

high current linear solution when the power

dissipation may cause an high heating of the

application environment. It provides up to 1.5A

over an input voltage range of 3V to 16V. An high

Figure 1: Schematic Diagram

Rev. 3

1/11

March 2005

ST1S03

Table 1: Order Codes

SYMBOL

DFN6

(Tape & Reel)

ST1S03

ST1S03PM

ST1S03RPM

Figure 2: Pin Connection (top through view)

Table 2: Pin Description

PIN N°

Symbol

Name and Function

Voltage of Feedback

Sistem Ground

GND

Output of the internal Power Swithch

Power Supply for the MOSFET Switch

IN_SW

Power Supply for the Analog Circuit

Not Connected

IN_A

N.C.

Table 3: Absolute Maximum Ratings

Symbol

Parameter

Value

Unit

Positive Power Supply Voltage

-0.3 to 16

I_SW

SWITCH Max Voltage of output pin

Voltage

-0.3 to 16

Feedback Voltage

2.5

±1

°C

Common mode input voltage

Max Junction Temperature

Storage Temperature Range

VFB

150

-25 to 150

300

STG

Lead Temperature (Soldering) 10 Sec.

LEAD

Absolute Maximum Ratings are those beyond which damage to the device may occur. Functional operation under these condition is not im-

plied.

Table 4: Thermal Data

Symbol

Parameter

Thermal Resistance Junction-case

Thermal Resistance Junction-ambient

DFN6

Unit

°C/W

THJ-C

THJ-A

2/11

ST1S03

Table 5: Electrical Characteristics (V

= V

= 5V, C = 4.7µF, C = 22µF, L1 = 3.3µH, T = 0 to

IN_A I O J

IN_SW

125°C, unless otherwise specified. Typical values are referred to 25°C)

Symbol

Parameter

Test Conditions

Min.

Typ.

Max.

Unit

Feedback Voltage

Feedback PSRR

784

800

-60

816

PSRR

1Hz < Frequency V

Pin Bias Current

600

2.5

Bandwidth of Error Amplifier Closed Loop

300

KHz

Quiescent Current

No Switching

Output Current

=3V to 16V

= 3V to 16V

1.5

OUT

Minimum Output Current

Reference Line Regulation

MIN

∆V

0.032

0.06 %V

OUT

/∆V

Reference Load Regulation

= 10mA to 1.2A

0.0014 0.003 %V

OUT

∆I

/mA

OUT

PWM f

PWM Switching Frequency

(1)

= 0.8V, T =25°C

1.2

1.5

1.8

MHz

Maximum Duty Cycle

MAX

Switching Current Limitation

1.65

SWL

Switch V

= 750 mA

200

350

Efficiency

I_OUT=10mA to 1.2A

Thermal Shut Down (1)

130

150

°C

SHDN

Thermal Shut Down

Hysteresis (1)

HYS

∆V

∆I

Load Transient Response

(1)

= 100mA to 700mA

-5

OUT

t = t ≥ 100ns, T = 25°C

∆V

∆I

Short Circuit Removal

Response (1)

= 10mA to short, T = 25°C

OUT

@I = short

NOTE 1: Guaranteed by design, not tested in production.

3/11

ST1S03

APPLICATION NOTES

The ST1S03 is an adjustable current mode PWM

step-down DC/DC converter with internal 1.5A

power switch, packaged in a 6-lead DFN 3x3.

resistor divider. The desired value is given by the

following equation:

= V [1+R1/R2]

OUT

To make the device working, only other four

external components are required: a Schottky

diode, an inductor and two capacitors. The chosen

inductor must be able to not saturate at the peak

current level. Besides, its value can be selected

keeping in account that a large inductor value

increases the efficiency at low output current and

reduces output voltage ripple, while a smaller

inductor can be chosen when it is important to

reduce the package size and the total cost of the

application. Finally, the ST1S03 has been

designed to work properly with X5R or X7R SMD

ceramic capacitors both at the input and at the

output. this kind of capacitors, thanks to their very

low series resistance (ESR), minimize the output

voltage ripple. Other low ESR capacitors can be

used according to the need of the application

without invalidating the right functioning of the

device. Due to the high switching frequency and

peak current, it is important to optimize the

application environment reducing the length of the

PCB traces and placing all the external

component near the device.

It’s a complete 1.5A switching regulator with its

internal compensation eliminating additional

component.

The constant frequency, current mode, PWM

architecture and stable operation with ceramic

capacitors results in low, predictable output ripple.

However, in order to keep the output regulated,

the devices goes in pulse skipping mode when a

very light load is required.

To clamp the error amplifier reference voltage a

Soft Start control block generating a voltage ramp,

has been implemented. Besides an On-Chip

Power on Reset of 50 = 100µs ensure the proper

operation when switching on the power supply.

Other circuits fitted to the device protection are the

Thermal Shut down block which turn off the

regulator when the junction temperature exceeds

150°C typically and the Cycle-by-cycle Current

Limiting that provides protection against shorted

outputs.

Being the ST1S03 an adjustable regulator, the

output voltage is determined by an external

Figure 3: Application Circuit

4/11

ST1S03

TYPICAL CHARACTERISTICS (C = 4.7µF, C = 22µF, L1 = 3.3µH, unless otherwise specified)

Figure 4: Load Voltage Feedback vs

Figure 7: Line Voltage Feedback vs Temperature

Temperature

Figure 5: Voltage Feedback vs Temperature

Figure 8: Voltage Feedback vs Output Current

Figure 6: Line Output Voltage Regulation vs

Figure 9: PWM Switching Frequency vs

Temperature

5/11

ST1S03

Figure 10: Quiescent Current vs Temperature

Figure 13: Efficiency vs Temperature

Figure 14: Efficiency vs Output Current

Figure 15: Switch VDS vs Temperature

Figure 11: Quiescent Current vs Input Voltage

Figure 12: Minimum Operating Voltage vs Output

Voltage

6/11

ST1S03

Figure 16: Switch RDS-ON vs Temperature

Figure 19: Load Transient Response

=5V, I =200mA to 1.2A, C =4.7µF, C =22µF, L=3.3µH,

O I O

=38µs, T =25°C

Figure 17: Switch Current Limitation vs

Figure 20: Start-Up Transient

Temperature

= 5V, T = 25°C

Figure 18: Load Transient Response

Figure 21: Start-Up Transient

=5V, I =100mA to 780mA, C =4.7µF, C =22µF, L=3.3µH,

= 5V, T = 25°C

CC J

=38µs, T =25°C

7/11

ST1S03

DFN6 (3x3) MECHANICAL DATA

mm.

inch

TYP.

DIM.

MIN.

TYP

MAX.

MIN.

MAX.

0.80

1.00

0.05

0.75

31.5

0.0

39.4

2.0

0.65

25.6

29.5

0.20

3.00

0.95

0.24

7.9

118.1

37.4

9.4

0.33

2.90

1.92

2.90

1.11

0.43

3.10

2.12

3.10

1.31

13.0

114.2

75.6

16.9

122.0

83.5

114.2

43.7

122.0

51.6

0.20

0.45

0.13

7.9

17.7

5.1

7387339A

8/11

ST1S03

Tape & Reel QFNxx/DFNxx (3x3) MECHANICAL DATA

mm.

TYP

inch

TYP.

DIM.

MIN.

MAX.

330

MIN.

MAX.

12.992

0.519

12.8

20.2

13.2

0.504

0.795

3.898

101

3.976

0.567

14.4

3.3

1.1

0.130

0.043

0.157

0.315

9/11

ST1S03

Table 6: Revision History

Date

Revision

Description of Changes

11-Nov-2004

08-Feb-2005

03-Mar-2005

First Release.

Maturity Change.

Mistake on Figure 1, T is changed 125 ==> 150°C on Table 3.

10/11

ST1S03

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

of use of such information nor for any infringement of patents or other rights of third parties which may result from 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 previously supplied. STMicroelectronics products are not

authorized for use as critical components in life support devices or systems without express written approval of STMicroelectronics.

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11/11

ST1S03 [STMICROELECTRONICS]

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