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AP8800 Rev.3

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AP8800

350mA LED Step-down Converter

Features

• LED driving current up to 350mA • Compatible with 12V & 24V standard systems • High efficiency up to 92% • High switching frequency up to 0.6MHz • PWM/DC input for dimming control • Built-in soft-start function • Built-in output open-circuit protection • SOP-8L, MSOP-8L and DFN3030-10 are available in

“Green” Molding Compound (No Br, Sb) • Lead Free Finish/RoHS Compliant (Note 1)

General Description

The AP8800 is a step-down DC/DC converter designed to drive LEDs with a constant current. The device can drive up to seven LEDs, depending on the forward voltage of the LEDs, in series from a voltage source of 8V to 28V. Series connection of the LEDs provides identical LED currents resulting in uniform brightness and eliminates the need for ballast resistors. The AP8800 switches at frequency up to 0.6MHz. This allows the use of small size external components, hence minimizing the PCB area needed.

Maximum output current of AP8800 is set via an external resistor connected between the VIN and 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 • Architecture Detail lighting • Appliances interior lighting

Typical Application Circuit

Figure 1: Typical Application Circuit

AP8800 Rev. 3 1 of 13 MARCH 2009 DS31764 www.diodes.com © Diodes Incorporated

AP8800

350mA LED Step-down Converter

Ordering Information

AP 8800 XX G - XPackageS : SOP-8LM8 : MSOP-8LFN : DFN3030-10

GreenG : Green

Packing

7/ 13 : Tape & Reel

7”/13”Tape and Reel

QuantityPart Number Suffix

-13 -13 -7

Device

Package Code Packaging (Note 2)

AP8800SG-13 S SOP-8L 2500/Tape & Reel AP8800M8G-13 M8 MSOP-8L 2500/Tape & Reel AP8800FNG-7 FN DFN3030-10 3000/Tape & Reel 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.

AP8800 Rev. 3 2 of 13 MARCH 2009 DS31764 www.diodes.com © Diodes Incorporated

AP8800

350mA LED Step-down Converter

Pin Assignments

(1) SOP-8L

(2) MSOP-8L

( Top View )

CTRL1RSVDSW

23AP8800( Top View )

8765SETNCNCVIN

CTRL1RSVDSW

23AP88008765SETNCNCVIN

GND4GND4(3) DFN3030-10

( Top View )

CTRLRSVDNCSWGND

12345109

SETNC NCNCVIN

AP8800876

Pin Descriptions

Pin Name Description

Switch Pin. Connect inductor/freewheeling diode here. Minimize trace area at this pin to reduce SW

EMI. GND GND pin SET CTRL VIN RSVD AP8800 Rev. 3 3 of 13 MARCH 2009 DS31764 www.diodes.com © Diodes Incorporated

Set Nominal Output Current Pin. To 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. The input impedance is about 200kΩ, and if the pin is left open VCTRL = VREF Input Supply Pin. Must be locally bypassed. Reserved. Normally connected to Ground

NC No Connection.

AP8800

350mA LED Step-down Converter

Block Diagram

SETSWVIN

Sensing BlockComparatorVoltage Regulator5VCTRL

PWM/DCControlVREF 1.25VAP8800RGND

Figure 2: AP8800 Block Diagram

Absolute Maximum Ratings

Symbol VIN VSW TJ TLEAD TST

VIN pin voltage SW voltage

Maximum Junction Temperature Maximum Lead Temperature Storage Temperature Range

Parameter

Rating -0.3~30 -0.3~30 125 300 -65 to +125

Unit V V

ooo

C C C

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 TA AP8800 Rev. 3 4 of 13 MARCH 2009 DS31764 www.diodes.com © Diodes Incorporated

Parameter

Ambient Temperature Range Min -40 Max 85 Unit ºC

AP8800

350mA LED Step-down Converter

Electrical Characteristics (VIN =12V, TA=25oC, unless otherwise specified)

Symbol Parameter VIN Operating Input Voltage IOUT Continuous switch Current IQ Quiescient Current FOSC Switching Frequency VTHD Internal Threshold Voltage VREF Internal Reference Voltage SET SET pin input current

Rds(on) On Resistance of MOSFET ISWLeakage Switch leakage current EN Voltage High EN Voltage Low

Min Typ. Max Unit

8.0 - 28 V (Note 3) - - 350 mA - 20 30 μA - 0.25 - MHz 92 100 108 mV - 1.25 - V VSET=VIN-0.1 - 1.3 - μA 1.7 2.2 Ω

-- 5μA

ON 1.25 - - V OFF - - 0.2 V SOP-8L (Note 4) - 92 - °C/W

120 MSOP-8L (Note 4) - - °C/W46 DFN3030-10 (Note 4) - - °C/W60 SOP-8L (Note 4) - - °C/W98 MSOP-8L (Note 4) - - °C/W32 DFN3030-10 (Note 4) - - °C/W

Conditions

θJA θJC

Thermal Resistance

Junction-to-Ambient Thermal Resistance Junction-to-Case

Notes: 3. Refer to figure 5 for the device derating curve.

4. Test condition for SOP-8L, MSOP-8L 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.

AP8800 Rev. 3 5 of 13 MARCH 2009 DS31764 www.diodes.com © Diodes Incorporated

AP8800

350mA LED Step-down Converter

Application Information

LED Current Control

The LED current is controlled by the resistor RSET in Figure 1.

If the CTRL pin is floating and at a nominal voltage of VREF, the external current sense resistor RSET (greater than 0.3 Ω) is connected between VIN and SET and defines the nominal average output current in the LED(s) as:

ILED=

VTHDRSET

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

ILED=

VCTRLVTHDVREFRSET

The graph in figure 3 gives values of nominal average output current for several values of current setting resistor (RSET) in the typical application circuit shown on Figure 1, for different voltages applied on the CTRL pin.

LED current Versus RSET and VCTRL 400350300LED Current [mA] 25020015010050000.150.30.450.60.750.91.051.21.351.51.651.81.952.12.252.42.552.72.85RSET value [Ohms]30.30.30.330.390.470.560.680.390.470.560.820.680.82110.560.680.750.8211.21.51.21.221.51.522333LED current @VCTRL = 1.25VLED current @VCTRL = 2.5VLED current @VCTRL = 0.625VFigure 3: LED Current setting Vs RSET and VCTRL

AP8800 Rev. 3 6 of 13 MARCH 2009 DS31764 www.diodes.com © Diodes Incorporated

AP8800

350mA LED Step-down Converter

Application Information (Continued)

Switching Frequency700600Frequency [kHz] 500400683001002001000050100150200250300350400450500Inductor Value [uH]1502204704702204715012V - 1LED24V - 3 LEDs28V - 4LEDs100Figure 4: Switching Frequency Vs Supply voltage, Inductor, and number of LEDs

Capacitor Selection

The small size of ceramic capacitors makes them ideal for AP8800 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 1μF input capacitor is sufficient for most intended applications of AP8800.

Diode Selection

Schottky diode, e.g. B140, with their low forward voltage drop and fast reverse recovery, is the ideal choice for AP8800 applications.

PWM Dimming

A Pulse Width Modulated (PWM) signal with a max resolution of 8bit can be applied to the CTRL pin to regulate the output current to a value above or below the nominal average value set by resistor RSET.

Miscellaneous

To ensure optimal performance, RSVD pin should be connected to the GND pin with the shortest trace length

AP8800 Rev. 3 7 of 13 MARCH 2009 DS31764 www.diodes.com © Diodes Incorporated

AP8800

350mA LED Step-down Converter

Application Information (Continued)

Inductor Selection

A 100μH inductor is recommended for most AP8800 applications with input voltage at 24V.

Figure 4 displays the resulting switching frequency varying the main circuit parameters: Supply voltage, Inductor value and number of LEDs to be driven.

Thermal Considerations

The graph below in figure 5, 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 Dissipation21.81.6Power (W) 1.41.210.80.60.40.200255075100125150Ambient Temperature (Deg C)DFN3030-10SOP8LMSOP8LFigure 5: Derating curve

AP8800 Rev. 3 8 of 13 MARCH 2009 DS31764 www.diodes.com © Diodes Incorporated

AP8800

350mA LED Step-down Converter

Marking Information

(1) SOP-8L

( Top View )

85Logo

Part Number

AP8800XXYY WW 14

G : Green

YY : Year : 08, 09,10~WW : Week : 01~52; 52represents 52 and 53 weekX : Internal Code

(2) MSOP-8L

( Top View )

8Logo

Part Number

765A~Z : GreenY : Year : 0~9W : Week : A~Z : 1~26 week;a~z : 27~52 week; z represents 52 and 53 weekY W X AP88001234

(3) DFN3030-10

( Top View )

X XYWXXX : Identification Code Y : Year : 0~9 W : Week : A~Z : 1~26 week; a~z : 27~52 week; z represents52 and 53 week X : A~Z : Green

Part Number Package Identification Code AP8800FNG-7 DFN3030-10 A4

AP8800

350mA LED Step-down Converter

Package Information (All Dimensions in mm)

(1) Package Type: SOP-8L

3.85/3.955.90/6.100.10/0.200.2540.62/0.82Gauge PlaneSeating PlaneDetail \"A\"7°~9°1.30/1.501.75max.0.15/0.250.35max.45°7°~9°Detail \"A\"0°/8°1.27typ4.85/4.950.3/0.58x-0.605.46x-1.278x-1.55Land Pattern Recommendation(Unit: mm)

(2) Package Type: MSOP-8L

8x-0.452.9/3.14.7/5.14.46x-0.65 10.75/0.950.65Bsc.0.22/0.380.15Typ.0.05/0.158x-1.4Land Pattern Recommendation(Unit:mm)\"A\"0/0.150.25Gauge plane0°/80.052.9/3.10.4/0.8DETAIL \"A\"0.95Ref.°

AP8800

350mA LED Step-down Converter

Package Information (Continued)

(3) Package Type: DFN3030-10

0.57/0.600/0.050.10C0.08C0.15Typ.Seating PlaneCA0.10CABTOP MARK2X-0.25ASide ViewB2.9/3.12.3/2.5R0.300(Pin #1 ID)2.9/3.11.5/1.72X-0.25B0.375Typ.0.50Typ.0.2/0.3Bottom View

0.25/0.55

AP8800

350mA LED Step-down Converter

Taping Orientation

For DFN3030-10

Notes: 5. The taping orientation of the other package type can be found on our website at http://www.diodes.com/datasheets/ap02007.pdf.

IMPORTANT NOTICE

AP8800

350mA LED Step-down Converter

DIODES INCORPORATED MAKES NO WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, WITH REGARDS 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.

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