AP8802_0912_技术文档

AP8802

1A LED Step-down Converter

General Description

Features

The AP8802 is a step-down DC/DC converter designed to drive

LEDs with a constant current. The device can drive up to thirteen

LEDs, depending on the forward voltage of the LEDs, in series

from a voltage source of 8V to 48V. Series connection of the

LEDs provides identical LED currents resulting in uniform

brightness and eliminating the need for ballast resistors. The

AP8802 switches at frequency up to 500kHz. This allows the

use of small size external components, hence minimizing the

PCB area needed.

•

LED driving current up to 1A

High efficiency up to 92%

Operating input voltage up to 48V

High switching frequency up to 500kHz

PWM/DC input for dimming control

Built-in output open-circuit protection

SOP-8L, SOP-8L-EP and DFN3030-10 are available in

“Green” Molding Compound (No Br, Sb)

Lead Free Finish/ RoHS Compliant (Note 1)

•

Maximum output current of AP8802 is set via an external resistor

connected between the V_INand SET input pins. Dimming is

achieved by applying either a DC voltage or a PWM signal at the

CTRL input pin. An input voltage of 0.2V or lower at CTRL shuts

down the output at SW and puts the device into a low-current

standby state.

Applications

•

Commercial & industrial lighting

Small LCD panel backlight

Appliances interior lighting

Architecture Detail lighting

Typical Application Circuit

Figure 1: Typical Application Circuit

AP8802 Rev. 5

DS31766

1 of 16

www.diodes.com

DECEMBER 2009

AP8802

1A LED Step-down Converter

Ordering Information

AP 8802 XX G - X

Package

Green

Packing

7/ 13 : Tape & Reel

S : SOP-8L

G : Green

SP : SOP-8L-EP

FN : DFN3030-10

7”/13” Tape and Reel

Package

Code

S

Packaging

(Note 2)

SOP-8L

SOP-8L-EP

DFN3030-10

Device

Quantity

Part Number Suffix

AP8802SG-13

AP8802SPG-13

AP8802FNG-7

2500/Tape & Reel

3000/Tape & Reel

-13

-7

SP

FN

Notes:

1. EU Directive 2002/95/EC (RoHS). All applicable RoHS exemptions applied. Please visit our website at

http://www.diodes.com/products/lead_free.html.

2. Pad layout as shown on Diodes Inc. suggested pad layout document AP02001, which can be found on our website at

http://www.diodes.com/datasheets/ap02001.pdf.

AP8802 Rev. 5

DS31766

2 of 16

www.diodes.com

DECEMBER 2009

AP8802

1A LED Step-down Converter

Pin Assignments

(1) SOP-8L

(2) SOP-8L-EP

( Top View )

SET 1

8

7

6

5

8

7

6

5

CTRL

GND

SW

CTRL

GND

SW

2

GND

NC 3

V_IN

GND

NC 3

V_IN

AP8802

4

SW

(3) DFN3030-10

( Top View )

AP8802

1

SET

10

9

CTRL

GND

NC

2

GND

8

3

NC

7

4

SW

NC

5

6

SW

V_IN

Pin Descriptions

Pin Name

Description

Switch Pin. Connect inductor/freewheeling diode here, minimizing track length at this pin to

reduce EMI.

SW

GND

SET

GND pin

Set Nominal Output Current Pin. Configure the output current of the device.

Dimming and On/Off Control Input. Input voltage of 0.2V or lower forces the device into low

current standby mode and shuts off the output. A PWM signal allows the output current to be

adjusted above or below the level set by the resistor connected to SET input pin.

CTRL

The input impedance is about 50kΩ, and if the pin is left open V_CTRL= V_REF

Input Supply Pin. Must be locally bypassed.

No connection

V_IN

NC

AP8802 Rev. 5

DS31766

3 of 16

www.diodes.com

DECEMBER 2009

AP8802

1A LED Step-down Converter

Block Diagram

SET SW

V

IN

Sensing

Block

Voltage

Regulator

5V

PWM/DC

Control

CTRL

GND

R

V_REF1.25V

AP8802

Figure 2: AP8802 block diagram

Absolute Maximum Ratings

Symbol

V_IN

Parameter

Rating

-0.3~50

150

Unit

V

VIN pin voltage

VSW

SW voltage

V

T_J

Junction Temperature

Lead Temperature Soldering

Storage Temperature Range

^oC

T_LEAD

T_ST

300

-65 to +150

Caution: The absolute maximum ratings are rated values exceeding which the product could suffer physical damage. These values must therefore not be

exceeded under any condition.

Semiconductor devices are ESD sensitive and may be damaged by exposure to ESD events. Suitable ESD precautions should be taken when

handling and transporting these devices

Recommended Operating Conditions

Symbol

Parameter

Ambient Temperature Range

Min

Max

Unit

T_A

-40

0.1

105

0.95

ºC

Duty Cycle Using Inductor ≥ 100µH (Note 3)

Notes:

3. For most applications the LED current will be within 8% over the duty cycle range specified. Duty cycle accuracy is also dependent on

propagation delay. Smaller size inductors can be used but LED current accuracy may be greater than 8% at extremes of duty cycle. This is

most noticeable at low duty cycles (less than 0.1) or when the input voltage is high and only one LED is being driven.

AP8802 Rev. 5

DS31766

4 of 16

www.diodes.com

DECEMBER 2009

AP8802

1A LED Step-down Converter

Electrical Characteristics (V_IN=12V, T_A=25^oC, unless otherwise specified)

Symbol

V_IN

I_OUT

Parameter

Operating Input Voltage

Continuous switch current

Quiescent Current

Conditions

Min

8.0

Typ.

-

Max Unit

48

1

V

A

(Note 4)

I_Q

-

75

-

200

1.25

5

120

μA

F_OSC

V_THD

V_REF

SET

Switching Frequency

0.5

216

-

MHz

mV

V

Internal Threshold Voltage

Internal Reference Voltage

SET pin input current

184

-

V_SET=V_IN-0.2

I_SW=0.8A

-

μA

Rds(on) On Resistance of MOSFET

I_{SW Leakage}Switch leakage current

0.65

-

1.1

Ω

-

8

μA

EN

Voltage High

Voltage Low

ON

OFF

1.25

-

V

-

0.2

SOP-8L (Note 5)

SOP-8L-EP (Note 5)

DFN3030-10 (Note 5)

SOP-8L (Note 5)

SOP-8L-EP (Note 5)

DFN3030-10 (Note 5)

82

45

38

52

7

-

°C/W

Thermal Resistance

Junction-to-Ambient

θ_JA

θ_JC

Thermal Resistance

Junction-to-Case

24

Notes:

4. Refer to figure 8 for the device derating curve.

5. Test condition for SOP-8L, SOP-8L-EP and DFN3030-10: Device mounted on FR-4 PCB, 2”x2”, 2oz copper, minimum recommended pad layout

on top layer and thermal vias to bottom layer ground plane. For better thermal performance, larger copper pad for heat-sink is needed.

AP8802 Rev. 5

DS31766

5 of 16

www.diodes.com

DECEMBER 2009

AP8802

1A LED Step-down Converter

Application Information

LED Current Control

The LED current is controlled by the resistor RSET in Figure 1 connected between V_INand SET. The nominal

average output current in the LED(s) is defined as:

V_THD

I_LED

=

R_SET

If the CTRL pin is driven by an external voltage (lower than 2.5V), the average LED current is:

V_CTRLV_THD

I_LED

=

V_REFR_SET

LED current Versus RSET and VCTRL

1200

1000

800

600

400

200

0

0.39

0.2

LED current @

VCTRL = 1.25V

0.47

0.56

LED current @

VCTRL = 2.5V

0.33

0.39

0.47

0.56

0.68

0.82

LED current @

VCTRL = 0.625V

1

1.2

1.5

0.68

0.33

0.82

1

2

0.47

1.2

1.5

2

0.68

3

1.2

1.5

2

0

0.15 0.3 0.45 0.6 0.75 0.9 1.05 1.2 1.35 1.5 1.65 1.8 1.95 2.1 2.25 2.4 2.55 2.7 2.85

3

RSET value [Ohms]

Figure 3: LED Current setting Vs R_SETand V_CTRL

AP8802 Rev. 5

DS31766

6 of 16

www.diodes.com

DECEMBER 2009

AP8802

1A LED Step-down Converter

Application Information (Continued)

Inductor Selection

This section highlights how to select the inductor suitable for the application requirements in terms of

switching frequency, LED current accuracy and temperature.

Switching Frequency @ILED = 700mA

500

68

450

400

100

47

350

300

250

200

150

100

50

12V - 3 LEDs

24V - 5 LEDs

48V - 10 LEDs

68

150

100

220

150

47

470

220

470

0

50

100

150

200

250

300

350

400

450

500

Inductor Value [uH]

Figure 4: Switching Frequency Vs Inductor Value

The inductor influences the LED current accuracy that the system is able to provide. The following section

highlights how to select the inductor in relation to the device packages and the LED current, while maintaining

the chip temperature below 70˚C.

AP8802 Rev. 5

DS31766

7 of 16

www.diodes.com

DECEMBER 2009

AP8802

1A LED Step-down Converter

Application Information (Continued)

Figure 5: DFN3030-10 recommended inductor with 1A LED current

Figure 6: SOP8L-EP recommended inductor with 1A LED current

AP8802 Rev. 5

DS31766

8 of 16

www.diodes.com

DECEMBER 2009

AP8802

1A LED Step-down Converter

Application Information (Continued)

AP8802 SOP-8L Minimum Recommended Inductor

8% Accuracy, <70°C Case Temperature

12

11

10

9

Legend

47µH

68µH

100µH

150µH

220µH

470µH

8

7

470uH

6

220uH

5

150uH

4

100uH

3

2

68uH

47uH

1

0.00

5.00

10.00

15.00

20.00

25.00

30.00

35.00

40.00

45.00

Supply Voltage (V)

Figure 7: SOP-8L recommended inductor with 700mA LED current

AP8802 Rev. 5

DS31766

9 of 16

www.diodes.com

DECEMBER 2009

AP8802

1A LED Step-down Converter

Application Information (Continued)

Capacitor Selection

The small size of ceramic capacitors makes them ideal for AP8802 applications. X5R and X7R types are

recommended because they retain their capacitance over wider voltage and temperature ranges than other

types such as Z5U. A 2.2μF input capacitor is sufficient for most intended applications of AP8802.

A 4.7μF input capacitor is suggested for application with an input voltage equal or higher than 40V.

Diode Selection

Schottky diodes, e.g. B2100 or B1100, with their low forward voltage drop and fast reverse recovery, are the

ideal choice for AP8802 applications.

PWM Dimming

A Pulse Width Modulated (PWM) signal with a max resolution of 8bit, can be applied to the CTRL pin to

change the output current to a value above or below the nominal average value set by resistor RSET. To

achieve this resolution the PWM frequency has to be lower than 500Hz.

Thermal Considerations

The graph below in figure 8, gives details for power derating. This assumes the device to be mounted on a

25x25mm PCB with 1oz copper standing in still air.

Maximum Power Dissipation

2.6

2.4

2.2

DFN3030-10

2

1.8

1.6

SOP-8L - EP

1.4

1.2

1

0.8

0.6

SOP-8L

0.4

0.2

0

25

50

75

100

125

Ambient Temperature (DegC)

Figure 8: AP8802 derating curves

Package Selection

The device comes with a wide selection of packages. The suggested package is able to provide a case

temperature below 70˚C (with an ambient temperature of 25˚C) for the combination of input voltage and load

requested.

AP8802 Rev. 5

DS31766

10 of 16

www.diodes.com

DECEMBER 2009

AP8802

1A LED Step-down Converter

Application Information (Continued)

Figure 9: Suggested package for a 1A application

AP8802 - suggested package @

ILED=700mA and 100µHInductor

12 LEDs

11 LEDs

10 LEDs

9 LEDs

8 LEDs

7 LEDs

6 LEDs

5 LEDs

4 LEDs

3 LEDs

2 LEDs

1 LED

SOP-8L-EP

DFN3030-10

SOP-8L

SOP-8L-EP

DFN3030-10

Vin

Figure 10: Suggested package for a 700mA application

AP8802 Rev. 5

DS31766

11 of 16

www.diodes.com

DECEMBER 2009

AP8802

1A LED Step-down Converter

Marking Information

(1) SOP-8L

( Top View )

5

8

Logo

G : Green

YY : Year : 08, 09,10~

WW : Week : 01~52; 52

represents 52 and 53 week

X : Internal Code

AP8802

YYWWX X

Part Number

1

4

(2) SOP-8L-EP

( Top View )

5

8

G : Green

Logo

YY : Year : 08, 09,10~

WW : Week : 01~52; 52

represents 52 and 53 week

X : Internal Code

AP8802

YYWWX X

Part No.

E

SOP-8L-EP

1

4

(3) DFN3030-10

( Top View )

XX : Identification Code

Y : Year : 0~9

X X

W : Week : A~Z : 1~26 week;

Y X

W

a~z : 27~52 week; z represents

52 and 53 week

X : A~Z : Green

Part Number

Package

Identification Code

AP8802FNG-7

DFN3030-10

A5

AP8802 Rev. 5

DS31766

12 of 16

www.diodes.com

DECEMBER 2009

AP8802

1A LED Step-down Converter

Package Information (All Dimensions in mm)

(1) Package Type: SOP-8L

Gauge Plane

Seating Plane

0.62/0.82

Detail "A"

7°~9°

0.35max.

45°

Detail "A"

0°/8°

0.3/0.5

1.27typ

4.85/4.95

8x-0.60

6x-1.27

Land Pattern Recommendation

(Unit: mm)

(2) Package Type: SOP-8L-EP

Detail "A"

Exposed pad

7°~9°

45°

1

7°~9°

0.15/0.25

3.3Ref.

Bottom View

0.3/0.5

1.27typ

Gauge Plane

Seating Plane

4.85/4.95

0.62/0.82

1

Detail "A"

8x-0.60

Exposed pad

6x-1.27

Land Pattem Recommendation

(Unit:mm)

AP8802 Rev. 5

DS31766

13 of 16

www.diodes.com

DECEMBER 2009

AP8802

1A LED Step-down Converter

Package Information (Continued)

(3) Package Type: DFN3030-10

TOP MARK

0.10

0.08

C

Seating Plane

Side View

C

2.9/3.1

2.3/2.5

B

A

(Pin #1 ID)

2X-

0.25

B

0.50Typ.

Bottom View

0.375Typ.

0.2/0.3

0.10

C

A B

AP8802 Rev. 5

DS31766

14 of 16

www.diodes.com

DECEMBER 2009

AP8802

1A LED Step-down Converter

Taping Orientation (Note 6)

For DFN3030-10

Notes:

6. The taping orientation of the other package type can be found on our website at http://www.diodes.com/datasheets/ap02007.pdf.

AP8802 Rev. 5

DS31766

15 of 16

www.diodes.com

DECEMBER 2009

AP8802

1A LED Step-down Converter

IMPORTANT NOTICE

DIODES INCORPORATED MAKES NO WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, WITH REGARDING TO THIS

DOCUMENT, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A

PARTICULAR PURPOSE (AND THEIR EQUIVALENTS UNDER THE LAWS OF ANY JURISDICTION).

Diodes Incorporated and its subsidiaries reserve the right to make modifications, enhancements, improvements, corrections or other

changes without further notice to this document and any product described herein. Diodes Incorporated does not assume any

liability arising out of the application or use of this document or any product described herein; neither does Diodes Incorporated

convey any license under its patent or trademark rights, nor the rights of others. Any Customer or user of this document or products

described herein in such applications shall assume all risks of such use and will agree to hold Diodes Incorporated and all the

companies whose products are represented on Diodes Incorporated website, harmless against all damages.

Diodes Incorporated does not warrant or accept any liability whatsoever in respect of any products purchased through unauthorized

sales channel.

Should Customers purchase or use Diodes Incorporated products for any unintended or unauthorized application, Customers shall

indemnify and hold Diodes Incorporated and its representatives harmless against all claims, damages, expenses, and attorney fees

arising out of, directly or indirectly, any claim of personal injury or death associated with such unintended or unauthorized

application.

Products described herein may be covered by one or more United States, international or foreign patents pending. Product names

and markings noted herein may also be covered by one or more United States, international or foreign trademarks.

LIFE SUPPORT

Diodes Incorporated products are specifically not authorized for use as critical components in life support devices or systems

without the express written approval of the Chief Executive Officer of Diodes Incorporated. As used herein:

A. Life support devices or systems are devices or systems which:

1. are intended to implant into the body, or

2. support or sustain life and whose failure to perform when properly used in accordance with instructions for use provided

in the labeling can be reasonably expected to result in significant injury to the user.

B. A critical component is any component in a life support device or system whose failure to perform can be reasonably expected

to cause the failure of the life support device or to affect its safety or effectiveness.

Customers represent that they have all necessary expertise in the safety and regulatory ramifications of their life support devices or

systems, and acknowledge and agree that they are solely responsible for all legal, regulatory and safety-related requirements

concerning their products and any use of Diodes Incorporated products in such safety-critical, life support devices or systems,

notwithstanding any devices- or systems-related information or support that may be provided by Diodes Incorporated. Further,

Customers must fully indemnify Diodes Incorporated and its representatives against any damages arising out of the use of Diodes

Incorporated products in such safety-critical, life support devices or systems.

www.diodes.com

AP8802 Rev. 5

DS31766

16 of 16

www.diodes.com

DECEMBER 2009


型号：	AP8802_0912
厂家：	DIODES INCORPORATED
描述：	1A LED Step-down Converter 1A LED降压转换器转换器
文件：	总16页 (文件大小：228K)
中文：	中文翻译
下载：	下载PDF数据表文档文件

AP8802_0912 [DIODES]

相关型号：

AP8803

AP8803-WTG-7

AP8803WTG-7

AP8821

AP8836

AP8836P8U

AP8836P8VU

AP8842

AP88N30W

AP89010

AP89010_15

AP89021