As1003

Page 1

AS1003 350KHz, 23V/3A Step-down Converter FEATURES           

GENERAL DESCRIPTION The AS1003 is a buck topology of switching regulator for wide operating voltage field.

Input Voltage Range: 3V to 23V Feedback Voltage: 0.5V ± 2% Low Quiescent Current: 5mA(Typ.) Fixed Operating Frequency: 350KHz(Typ.) Output Current: 3A Programmable Soft Start Function Short Circuit Protection Auto Restart Function Short Circuit Protection Internal Built-in P-MOSFET Package: SOP-8L

The AS1003 includes a high current P-MOSFET, high precision reference (0.5V) for comparing output voltage with feedback amplifier, an internal dead time control and oscillator for controlling the maximum duty cycle and PWM frequency, and has power on programmable soft start time and short circuit P-MOSFET turn off and auto restart protections. The AS1003 is available in a low profile SOP-8L package.

APPLICATIONS    

Distributed Power System Pre-regulator for Linear regulator Monitor/TV Battery Charger

TYPICAL APPLICATION CIRCUIT

SK34 1

IN

SW

22uH

7,8

AS1003

470uF 25V

FB 2

SCP/SS

GND

COMP

56K 1%

3

10K 1%

4

5, 6 0.1uF

0.1uF

100 Vout

95

3.3V

90

470uF 16V

Efficiency (%)

Vin

Efficiency vs Load Current VOUT=5V

85 80

VOUT=3.3V

75 70 65

VIN=12V L=22uH

60 55 50 0

0.5

1

1.5

2

2.5

3

Load Current (A)

AS1003 Rev2.4 05/05/2015

www.anisem.com © 2015 AniSem All Rights Reserved.

1

AS1003 350KHz, 23V/3A Step-down Converter PIN CONFIGURATION TOP VIEW IN SCP/SS FB COMP

1

8

SW

2

7

SW

3

6

GND

4

5

GND

PIN

SYMBOL

FUNCTION

1

IN

Power Supply Input.

2

SCP/SS

Short Circuit/Soft Start. Connecting with a SCP/SS timing Capacitor.

3

FB

Feedback Input.

4

COMP

Compensation Output.

5, 6

GND

Ground.

7, 8

SW

Switching Output.

BLOCK DIAGRAM IN

1 0.5V VOLTAGE REFERENCE

OSC

THERMAL SHUTDOWN

0.5V

FB

COMP

3

4

SCP/SS 2

AS1003 Rev2.4 05/05/2015

+ ERROR AMP -

+

PWM CMP

OUTPUT DRIVER CONTROL

7

SW

8

SW

0.7V

SHORT CIRCUIT PROTECTION SOFT START CIRCUIT

www.anisem.com © 2015 AniSem All Rights Reserved.

5

6

GND

GND

2

AS1003 350KHz, 23V/3A Step-down Converter ORDER INFORMATION

AS1003EBT Packing: T=T/R Package: B = SOP-8L Operating Temperature: E = -40°C ~ +85°C Part Number

ABSOLUTE MAXIMUM RATINGS1)

(TA=25°C)

Parameter

Symbol

Supply Voltage Switch Output Voltage Output Source Current Feedback Voltage Power Dissipation

Rating

VIN VSW IOUT VFB PD ƟJA ƟJC TJ TST

Package Thermal Resistance2) Junction Temperature Storage temperature Range

-0.3 to 23 -0.3 to VIN +0.3 3 -0.3 to +1.2 650 90 45 125 -55~+125

Unit

V V A V mW °C/W °C/W °C °C

RECOMMENDED OPERATING CONDITIONS3) Parameter

Supply Voltage Operating Temperature

Symbol VIN TA

Min 3 -40

Max

Unit

20 +85

V °C

NOTEs: 1) Exceeding these ratings may damage the device. 2) Measure on approximately 1’’square of 1 oz copper. 3) The device is not guaranteed to function outside of its operating conditions.

AS1003 Rev2.4 05/05/2015

www.anisem.com © 2015 AniSem All Rights Reserved.

3

AS1003 350KHz, 23V/3A Step-down Converter ELECTRICAL CHARACTERISTICS (TA=25°C) VIN = 6V, TA = 25°C Unless otherwise noted.

Parameter

Supply Current Max. Duty Cycle PFET RDS(ON)

Symbol IQ D

RDS(ON)-P

PFET Leakage Reference Voltage

Conditions

Min

Max

Unit

VFB=0.2V VIN=10V, VFB=0V

-

Typ.

SCP Active

-

5

-

uA

0.490

0.5

0.51

V

VREF

4.5 80 42

6 65

mA % mΩ

VREF change with VIN

VIN=3V ~ 20V

-

2

12.5

mV

VREF change with TA

TA=-40°C~85°C

-

1

2

%

300

350

400

KHz

Oscillation Frequency

fOSC

fOSC change with VIN

VIN=3V ~ 20V

-

5

-

%

fOSC change with TA

TA=-40°C~85°C

-

5

-

%

-15

-10

-7

uA

-

1/20

-

-

0.9 -15

1.0 0.1 -10

1.1 0.15 -7

uA

0.8

0.9

1.0

V

VCOMP=450mV

0.49

0.5

0.51

V

VT Change with VIN

VIN=3V ~ 20V

-

5

20

mV

VT Change with TA

TA=-40°C~85°C

-

1

-

%

EA Input Bias Current

-1

-0.2

1

uA

EA Voltage Gain

-

100

-

V/V MHz

SCP Source Current SCP Restart/Hold Time

ISCP VRS /VHD

SS Source Current

VSCP VSB ISS

SS Threshold Voltage

VSST

SCP Threshold Voltage

Input Threshold Voltage

VT

VSCP=0V VCOMP>0.8V VCOMP > 450mV VCOMP < 450mV VSS = 0V

V

Frequency Bandwidth

AV=0dB

-

6

-

EA Output Swing Positive

VFB=0.3V

0.78

0.87

-

EA Output Swing Negative

VFB=0.7V

-

0.05

0.2

EA Output Source Current

VCOMP=450mV

-

-45

-30

uA

EA Output Sink Current

VCOMP=450mV

30

45

-

uA

AS1003 Rev2.4 05/05/2015

www.anisem.com © 2015 AniSem All Rights Reserved.

4

V

AS1003 350KHz, 23V/3A Step-down Converter TYPICAL PERFORMANCE CHARACTERISTICS

VIN = 12V, L=22uH, CIN =470uF, COUT =470uF, TA = 25°C Unless otherwise noted. Efficiency vs Load Current

100 95

5.20

VOUT=5V

90

5.10

85 80

Output Voltage (V)

Efficiency (%)

Output Voltage vs Load Current

VOUT=3.3V

75 70 65

VIN=12V L=22uH

60 55

5.00 4.90 4.80 4.70

VOUT=5.0V

4.60

50 0

0.5

1

1.5

2

2.5

3

4.50 0

Load Current (A)

0.5

1

1.5

2

2.5

3

Load Current (mA)

Output Voltage vs Supply Voltage 3.90

380 Oscillator Frequency (KHz)

3.70 Output Voltage (V)

Oscillator Frequency vs Supply Voltage

3.50 3.30 3.10 2.90

ILOAD=0.8A

2.70 2.50 5

10

15

20

370 360 350 340 330 ILOAD=0.8A

320 310 300 5

Supply Voltage (V)

10

15

20

Supply Voltage (V)

AS1003 Rev2.4 05/05/2015

www.anisem.com © 2015 AniSem All Rights Reserved.

5

AS1003 350KHz, 23V/3A Step-down Converter MARKING INFORMATION 8

7

6

5

1003 1206A

Pin1 1

2

3

1003: Part Number

4

A: Internal Code 06: Week (0~52) 12: Year (11=2011,12=2012ďźŒ...)

OPERATION

Calculation Formula:

FUNCTION DESCRIPTION Soft-Start & Short Circuit Protection functions are built in the same internal block circuit and using the same pin.

đ?‘„đ?‘„ = đ??śđ??ś Ă— đ?‘‰đ?‘‰ = đ??źđ??ź Ă— đ?‘Ąđ?‘Ą

SOFT-START(SS) The error amplifier VFB < VREF(0.5V), because the output voltage hasn’t built When power on. If the device has not soft start function, the PWM duty cycle will be up to maximum directly. SS/SCP charges the external capacitor voltage up to 1V with constant current. This charge voltage pushes PWM comparator to limit the linear proportional of the comparator output. After finished soft start, this pin voltage reset to standby 0.1V and enter detection status of Short Circuit Protection.

������ =

AS1003 Rev2.4 05/05/2015

C: Capacitor connecting Pin2; I,V: Charger current & Voltage; t : Soft Start time đ?‘‰đ?‘‰ Ă— đ??śđ??ś ďż˝đ?‘‰đ?‘‰đ?‘Ąđ?‘Ąâ„Ž − đ?‘‰đ?‘‰đ?‘†đ?‘†đ?‘†đ?‘†đ?‘ đ?‘ đ?‘ đ?‘ đ?‘ đ?‘ đ?‘ đ?‘ đ?‘ đ?‘ ďż˝ Ă— đ??śđ??ś (1đ?‘‰đ?‘‰ − 0.3đ?‘‰đ?‘‰) Ă— đ??śđ??ś = = đ??źđ??źđ?‘†đ?‘†đ?‘†đ?‘†đ?‘†đ?‘†đ?‘†đ?‘†đ?‘†đ?‘†đ?‘†đ?‘† đ??źđ??ź 10đ?‘˘đ?‘˘đ?‘˘đ?‘˘ = 0.07 Ă— đ??śđ??ś

For example: if C=1uF, then the soft start time tSS=0.08s.

SHORT CIRCUIT PROTECTION After finished soft start, the device enters the detection status of short circuit protection. If the system suddenly short circuit or overloading, SS/SCP begins to charge the capacitor with constant current. The PWM will be closed as soon as the voltage up to 1.2V. then the device discharges the external capacitor, until the voltage down to 0.3v, the device will soft start again. If the system is normal, the device will enter detection status of SCP, otherwise restart again until system recovered.

www.anisem.com Š 2015 AniSem All Rights Reserved.

6

AS1003 350KHz, 23V/3A Step-down Converter

D1 Vin

1

IN

SW

L1

7,8

AS1003

R1

C1

FB 2

SCP/SS

�������� = �1 +

đ?‘„đ?‘„ = đ??śđ??ś Ă— đ?‘‰đ?‘‰ = đ??źđ??ź Ă— đ?‘Ąđ?‘Ą

C: Capacitor connecting Pin2; I,V: Charger current & Voltage; t : Soft Start time

��������

t RESTART = 1.8 Ă— C For

example:

if

C=1uF,

C2

4

R2 C4

��1 � × �������� ��2

APPLICATION INFORMATION TYPICAL APPLICATION CIRCUIT

đ?‘‰đ?‘‰ Ă— đ??śđ??ś ďż˝đ?‘‰đ?‘‰đ?‘Ąđ?‘Ąâ„Ž − đ?‘‰đ?‘‰đ?‘†đ?‘†đ?‘†đ?‘†đ?‘ đ?‘ đ?‘ đ?‘ đ?‘ đ?‘ đ?‘ đ?‘ đ?‘ đ?‘ ďż˝ Ă— đ??śđ??ś (1.2đ?‘‰đ?‘‰ − 0.3đ?‘‰đ?‘‰) Ă— đ??śđ??ś = = = đ??źđ??źđ?‘†đ?‘†đ?‘†đ?‘†đ?‘†đ?‘†đ?‘†đ?‘†đ?‘†đ?‘†đ?‘†đ?‘† đ??źđ??ź 10đ?‘˘đ?‘˘đ?‘˘đ?‘˘ = 0.09 Ă— đ??śđ??ś

3

5, 6

C3

Calculation Formula:

COMP

GND

Vout

then

the

soft

start

L1 22uH

Vin

1

ON/OFF

R5 4.7K

8

SW

6

Q1 3904

4

R2 10K 1%

D1 SK34

R3 1K C4 22nF

REFERENCE VOLTAGE DIVIDER AS1003 provide a internal 0.5V reference voltage for adjusting the output voltage. Output voltage of the converter is setting with the resistor divider using the following expression.

AS1003 Rev2.4 05/05/2015

www.anisem.com Š 2015 AniSem All Rights Reserved.

7

Vout 3.3V

R1 56K 1%

3

FB SCP/SS GND GND COMP 5

C3 0.1uF

tSCP=0.09s.tRESTART=1.8s.

OVER TEMPERATURE PROTECTION (OTP) This device is internal built-in Over Temperature Protection circuit. The OTP is functional due to a heavy loading drop and junction temperature achieves 125ÂşC, then the device output turn off. This action is linkage Short circuit protection. So, SCP pin also has the waveform of short circuit protection. Then continue to restart the device. To soft-start the device after the temperature is down to normal.

AS1003 2

7

SW

C2 0.1uF

C1 470uF /25V

time

IN

C7 470uF /16V

C6 0.1uF

AS1003 350KHz, 23V/3A Step-down Converter PACKAGE INFORMATION

SOP-8L

0.189(4.80) 0.197(5.00)

0.024(0.61)

8

0.050(1.27)

5 0.063(1.60)

0.150(3.80) 0.157(4.00)

PIN1 ID

0.228(5.80) 0.244(6.20)

0.213(5.40)

4

1

RECOMMEND LAND PATTERN

TOP VIEW

0.053(1.35) 0.069(1.75) 0.013(0.33) 0.020(0.51)

0.050(1.27) BSC

0.0075(0.19) 0.0098(0.25)

0.004(0.10) 0.010(0.25)

SEE DETAIL “A”

SIDE VIEW

FRONT VIEW

0.010(0.25) X 45º 0.020(0.50)

GAUGE PLANE 0.010(0.25) BSC

0º~8º

0.016(0.41) 0.050(1.27)

DETAIL “A”

NOTE: 1. CONTROL DIMENSION IS IN INCHES. DEMENSION IN BRACKET IS IN MILLIMETERS. 2. PACKAGE LENGTH DOES NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS. 3. PACKAGE WIDTH DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSIONS. 4. LEAD COPLANARITY (BOTTOM OF LEADS AFTER FORMING) SHALL BE 0.004" INCHES MAX. 5. DRAWING CONFORMS TO JEDEC MS-012, VARIATION AA. 6. DRAWING IS NOT TO SCALE.

NOTICE: The information in this document is subject to change without notice. Please contact AniSem for current specifications. Users should warrant and guarantee that third party Intellectual Property rights are not infringed upon when integrating AniSem products into any application. AniSem will not assume any legal responsibility for any said applications. AS1003 Rev2.4 05/05/2015

www.anisem.com © 2015 AniSem All Rights Reserved.

8

Turn static files into dynamic content formats.

Create a flipbook
Issuu converts static files into: digital portfolios, online yearbooks, online catalogs, digital photo albums and more. Sign up and create your flipbook.