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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
Ordering Information
AP 8800 XX G - X
Package S : SOP-8L M8 : MSOP-8L FN : DFN3030-10 Green G : Green Packing
7/ 13 : Tape & Reel
Device
AP8800SG-13 AP8800M8G-13 AP8800FNG-7
Notes:
Package Code
S M8 FN
Packaging (Note 2)
SOP-8L MSOP-8L 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. 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.
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AP8800
350mA LED Step-Down Converter
Pin Assignments
(1) SOP-8L (2) MSOP-8L
( Top View ) CTRL 1 RSVD SW 2 3
AP8800
( Top View ) 8 7 6 5 SET NC NC VIN CTRL 1 RSVD SW 2 3
AP8800
8 7 6 5
SET NC NC VIN
GND 4
GND 4
(3) DFN3030-10
( Top View )
CTRL RSVD NC SW GND
1 2 3 4 5 10 9
SET NC NC NC VIN
AP8800
8 7 6
Pin Descriptions
Pin Name SW GND SET CTRL VIN RSVD NC Description Switch Pin. Connect inductor/freewheeling diode here. Minimize trace area at this pin to reduce EMI. GND pin 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 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 200k, and if the pin is left open VCTRL = VREF Input Supply Pin. Must be locally bypassed. Reserved. Normally connected to Ground No Connection.
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AP8800
350mA LED Step-Down Converter
Block Diagram
SET SW
VIN Sensing Block Comparator
Voltage Regulator
5V
CTRL
PWM/DC Control
VREF 1.25V
AP8800
R
GND
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
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 85 Unit C
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350mA LED Step-Down Converter
Electrical Characteristics
Symbol VIN IOUT IQ FOSC VTHD VREF SET Rds(on) ISW
Leakage
(VIN =12V, TA=25oC, unless otherwise specified) Conditions (Note 3) Min 8.0 92 1.25 Typ. 20 0.25 100 1.25 1.3 1.7 92 120 46 60 98 32 Max 28 350 30 108 2.2 5 0.2 Unit V mA A MHz mV V A A V V C/W C/W C/W C/W C/W C/W
EN EN
Parameter Operating Input Voltage Continuous switch Current Quiescient 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
VSET=VIN-0.1
JA JC
Notes:
ON OFF SOP-8L (Note 4) MSOP-8L (Note 4) DFN3030-10 (Note 4) SOP-8L (Note 4) MSOP-8L (Note 4) DFN3030-10 (Note 4)
3. Refer to figure 4 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.
Typical Application Circuit
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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 ) is connected between VIN and SET and defines the nominal average output current in the LED(s) as:
ILED =
VTHD RSET
If the CTRL pin is driven by an external voltage (lower than 2.5V), the average LED current in this case is:
ILED =
VCTRL VTHD VREF RSET
The graph in figure 2 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
400 350 300 LED Current [mA] 250 200 150 100 50 0 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 RSET value [Ohms] 3 0.3 0.56 0.3 0.33 0.39 0.47 0.56 0.68 0.39 0.47 0.56 0.82 0.68 0.82 1 1.2 1.5 1 1.2 1.5 0.68 0.75 0.82 1 1.2 1.5 2 2 2 3 3 3 LED current @ VCTRL = 1.25V LED current @ VCTRL = 2.5V LED current @ VCTRL = 0.625V
Figure 2: LED Current setting Vs RSET and VCTRL
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350mA LED Step-Down Converter
Application Information
(Continued)
Switching Frequency
700 600 500 Frequency [kHz] 400 68 300 100 200 100 470 0 0 50 100 150 200 250 300 350 400 450 500 Inductor Value [uH] 150 220 470 220 47 150 12V - 1LED 24V - 3 LEDs 28V - 4LEDs
100
Figure 3: 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 1F 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.
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AP8800
350mA LED Step-Down Converter
Application Information
Inductor Selection
(Continued)
A 100H 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 4, 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
2 1.8 1.6 1.4 1.2 Power (W ) 1 0.8 0.6 0.4 0.2 0 0 25 50 75 100 125 150
DFN3030-10
SOP8L MSOP8L
Ambient Temperature (D C eg )
Figure 4: Derating curve
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AP8800
350mA LED Step-Down Converter
Marking Information
(1) SOP-8L
( Top View )
8 5
Logo Part Number
AP8800 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) MSOP-8L
( Top View )
8 Logo Part Number 7 6 5 A~Z : Green Y : Year : 0~9 W : Week : A~Z : 1~26 week; a~z : 27~52 week; z represents 52 and 53 week
YWX
AP8800
1 2 3 4
(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 A4
Part Number AP8800FNG-7
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350mA 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: MSOP-8L
8x-0.45 2.9/3.1 4.7/5.1 4.4 6x-0.65 1 0.75/0.95 0.65Bsc. 0.22/0.38 0.15Typ. 0.05/0.15 8x-1.4 Land Pattern Recommendation (Unit:mm) "A" 0/0.15 0.25 Gauge plane
0/8
0.05 2.9/3.1
0.4/0.8 DETAIL "A" 0.95Ref.
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350mA 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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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 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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