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AP8802
1A LED Step-Down Converter
Features
* * * * * * * * 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 (Preview) and DFN3030-10 are available in "Green" Molding Compound (No Br, Sb) Lead Free Finish/RoHS Compliant (Note 1)
General Description
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. Maximum output current of AP8802 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 Appliances interior lighting Architecture Detail lighting
Ordering Information
AP 8802 XX G - X
Package
S : SOP-8L SP : SOP-8L-EP (Preview) FN : DFN3030-10
Green
G : Green
Packing
7/ 13 : Tape & Reel
Device
AP8802SG-13 AP8802SPG-13 AP8802FNG-7
Notes:
Package Code
S SP FN
Packaging (Note 2)
SOP-8L SOP-8L-EP DFN3030-10
7"/13" Tape and Reel Quantity Part Number Suffix
2500/Tape & Reel 2500/Tape & Reel 3000/Tape & Reel -13 -13 -7
1. EU Directive 2002/95/EC (RoHS). All applicable RoHS exemptions applied, see EU Directive 2002/95/EC Annex Notes. 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.
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AP8802
1A LED Step-Down Converter
Pin Assignments
(1) SOP-8L (2) SOP-8L-EP (Preview)
( Top View ) SET 1 GND NC 2 3
AP8802
( Top View )
ew
AP8802
8 7 6 5
CTRL GND SW SW
SET 1 GND NC 2 3
8 7 6 5
CTRL GND SW SW
VIN 4
VIN 4
(3) DFN3030-10
( Top View )
SET GND NC NC VIN
1 2 3 4 5 10 9
CTRL GND NC SW SW
AP8802
8 7 6
Pin Descriptions
Pin Name SW GND SET CTRL VIN NC Description Switch Pin. Connect inductor/freewheeling diode here, minimizing track length at this pin to reduce EMI. 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 shut 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 50k, and if the pin is left open VCTRL = VREF Input Supply Pin. Must be locally bypassed. No connection
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AP8802
1A LED Step-Down Converter
Block Diagram
SET SW
VIN Sensing Block Comparator
Voltage Regulator
5V
CTRL
PWM/DC Control
VREF 1.25V
AP8802
R
GND
Figure 1: AP8802 block diagram
Absolute Maximum Ratings
Symbol VIN VSW TJ TLEAD TST VIN pin voltage SW voltage Junction Temperature Lead Temperature Soldering Storage Temperature Range Parameter Rating -0.3~50 -0.3~50 150 300 -65 to +150 Unit V V
o o o
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 Parameter Ambient Temperature Range Min -40 Max 105 Unit C
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AP8802
1A LED Step-Down Converter
Electrical Characteristics
Symbol VIN IOUT IQ FOSC VTHD VREF SET Rds(on) ISW
Leakage
(VIN =12V, TA=25 C, unless otherwise specified)
o
EN EN
Parameter Operating Input Voltage Continuous switch current Quiescent Current Switching Frequency Internal Threshold Voltage Internal Reference Voltage SET pin input current On Resistance of MOSFET Switch leakage current Voltage High Voltage Low Thermal Resistance Junction-to-Ambient Thermal Resistance Junction-to-Case
Conditions (Note 3)
Min 8.0 184 1.25 -
Typ. 75 200 1.25 5 0.65 82 TBD 38 52 TBD 24
VSET=VIN-0.2 ISW=0.8A ON OFF SOP-8L (Note 4) SOP-8L-EP (Preview)(Note 4) DFN3030-10 (Note 4) SOP-8L (Note 4) SOP-8L-EP (Preview)(Note 4) DFN3030-10 (Note 4)
JA JC
Notes:
Max 48 1 120 0.5 216 1.1 8 0.2 -
Unit V A A MHz mV V A A V V C/W C/W C/W C/W C/W C/W
3. Refer to figure 7 for the device derating curve. 4. Test condition for SOP-8L, SOP-8L-EP (Preview) 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.
Typical Application Circuit
Figure 2: Typical Application Circuit
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1A LED Step-Down Converter
Application Information
LED Current Control The LED current is controlled by the resistor RSET in Figure 2. Connected between VIN and SET the nominal average output current in the LED(s) is defined as:
ILED =
VTHD RSET
If the CTRL pin is driven by an external voltage (lower than 2.5V), the average LED current is:
ILED =
VCTRL VTHD VREF RSET
LED current Versus RSET and VCTRL
1200 0.39 0.47 0.56 600 0.2 400 0.33 0.39 0.47 0.56 0.68 0.33 0.47 0.68 0.82 1 0.82 1 1.2 1.2 1.2 1.5 2 1.5 1.5 2 2 3 3 3 3 LED current @ VCTRL = 1.25V LED current @ VCTRL = 2.5V LED current @ VCTRL = 0.625V
1000 LED Current [mA]
0.2
800
200
0.68 0.82 1 0
0 RSET value [Ohms]
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
Figure 3: LED Current setting Vs RSET and VCTRL
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1A LED Step-Down Converter
Application Information
Inductor Selection
(Continued)
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
500 450 400 350 Frequency [kHz] 300 68 250 200 150 100 50 0 0 50 100 150 200 250 300 350 400 450 Inductor Value [uH] 47 68 100 150 220 150 220 470 470 470 500 100 150 220 47 100 12V - 3 LEDs 24V - 5 LEDs 48V - 10 LEDs 68
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 70C.
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AP8802
1A LED Step-Down Converter
Application Information
(Continued)
AP8802 DFN3030-10 Minimum Recommended Inductor - LED Current 1A
8% Accuracy, <70C Case Temperature
12 11 10 9 8 7 6 5 4 3 2 1 0.00 5.00 10.00 15.00 20.00 25.00
47uH 68uH 100uH 150uH
Legend 47H 68H 100H 150H 220H 470H
Number of LEDs
30.00
35.00
40.00
45.00
Supply Voltage (V)
Figure 5: DFN3030-10 recommended inductor with 1A LED current
AP8802 SOP-8L Minimum Recommended Inductor
8% Accuracy, <70C Case Temperature
12 11 10 9 8 7 6 5 4 3 2 1 0.00 5.00 10.00 15.00 20.00
47uH 68uH 100uH 150uH 220uH 470uH
Legend 47H 68H 100H 150H 220H 470H
Number of LEDs
25.00
30.00
35.00
40.00
45.00
Supply Voltage (V)
Figure 6: SOP-8L recommended inductor with 700mA LED current
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1A LED Step-Down Converter
Application Information
Capacitor Selection
(Continued)
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 2.2F input capacitor is sufficient for most intended applications of AP8802. A 4.7F 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 7, 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 Dis ipation s
3 2.8 2.6 2.4 2.2 2 1.8 Power (W ) 1.6 1.4 1.2 1 0.8 0.6 0.4 0.2 0 0 25 50 75 100 125 150
DFN3030-10
SOP8L
A mbient Temperature (Deg C )
Figure 7: 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 70C (with an ambient temperature of 25C) for the combination of input voltage and load requested.
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AP8802
1A LED Step-Down Converter
Application Information
(Continued)
AP8802 - suggested package @ ILED=1A and 100H Inductor
12 LEDs 11 LEDs 10 LEDs 9 LEDs 8 LEDs 7 LEDs 6 LEDs 5 LEDs 4 LEDs 3 LEDs 2 LEDs 1 LED 40 42 44 46 48
SOP-8L-EP DFN3030-10
SOP-8L / SOP-8L-EP / DFN3030-10 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38
Vin
Figure 8: Suggested package for a 1A application
AP8802 - suggested package @ ILED=700mA and 100H Inductor
12 LEDs 11 LEDs 10 LEDs 9 LEDs 8 LEDs 7 LEDs 6 LEDs 5 LEDs 4 LEDs 3 LEDs 2 LEDs 1 LED 46 48
SOP-8L-EP DFN3030-10 SOP-8L SOP-8L-EP DFN3030-10 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44
Vin
Figure 9: Suggested package for a 700mA application
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AP8802
1A LED Step-Down Converter
Marking Information
(1) SOP-8L
( Top View )
8 5
Logo Part Number
AP8802 YY WW X X
1 4
G : Green YY : Year : 08, 09,10~ WW : Week : 01~52; 52 represents 52 and 53 week X : Internal Code
(2) SOP-8L-EP (Preview)
( Top View )
8 5
Logo Part No. AP8802 YY WW X X E
1 4
G : Green YY : Year : 08, 09,10~ WW : Week : 01~52; 52 represents 52 and 53 week X : Internal Code SOP-8L-EP
(3) DFN3030-10
( Top View ) XX YW X XX : Identification Code Y : Year : 0~9 W : Week : A~Z : 1~26 week; a~z : 27~52 week; z represents 52 and 53 week X : A~Z : Green
Package DFN3030-10 Identification Code A5
Part Number AP8802FNG-7
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AP8802
1A LED Step-Down Converter
Package Information
(1) Package Type: SOP-8L
(All Dimensions in mm)
3.85/3.95
5.90/6.10
0.10/0.20
0.254 0.62/0.82
Gauge Plane Seating Plane
Detail "A"
7~9 1.30/1.50 1.75max. 0.15/0.25
0.35max. 45
7~9
Detail "A"
0/8
1.27typ 4.85/4.95
0.3/0.5
8x-0.60 5.4 6x-1.27 8x-1.55
Land Pattern Recommendation (Unit: mm)
(2) Package Type: SOP-8L-EP (Preview)
Detail "A"
0/8
Exposed pad
7~9
3.85/3.95
5.90/6.10
3.70/4.10
45 0.35max.
7~9 1 1.30/1.50 1.75max.
0.15/0.25
1 3.3Ref.
Bottom View
0/0.13
0.254
1.27typ 4.85/4.95 1
0.3/0.5
Gauge Plane Seating Plane
0.62/0.82
Detail "A"
8x-0.60
Exposed pad
6x-1.27 8x-1.55
Land Pattem Recommendation (Unit:mm)
5.4
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AP8802
1A LED Step-Down Converter
Package Information
(3) Package Type: DFN3030-10
(Continued)
0.57/0.60
0.08 C
0/0.05
0.10 C
0.15Typ.
Seating Plane C A 0.10 CAB
TOP MARK
2X-
0.25 A
Side View
B
2.9/3.1 2.3/2.5
R0 .30 0
(Pin #1 ID)
2.9/3.1
1.5/1.7
2X-
0.25 B
0.375Typ.
0.50Typ.
0.2/0.3
Bottom View
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AP8802
1A 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 Diodes Incorporated and its subsidiaries reserve the right to make modifications, enhancements, improvements, corrections or other changes without further notice to any product herein. Diodes Incorporated does not assume any liability arising out of the application or use of any product described herein; neither does it convey any license under its patent rights, nor the rights of others. The user of products 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 our website, harmless against all damages. LIFE SUPPORT Diodes Incorporated products are not authorized for use as critical components in life support devices or systems without the expressed written approval of the President of Diodes Incorporated.
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