DIODES AP8802_0912

AP8802
1A LED Step-down Converter
General Description
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 and DFN3030-10 are available in
“Green” Molding Compound (No Br, Sb)
Lead Free Finish/ RoHS Compliant (Note 1)
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
Typical Application Circuit
Figure 1: Typical Application Circuit
AP8802 Rev. 5
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AP8802
1A LED Step-down Converter
Ordering Information
AP 8802 XX G - X
Device
AP8802SG-13
AP8802SPG-13
AP8802FNG-7
Notes:
Package
Green
Packing
S : SOP-8L
SP : SOP-8L-EP
FN : DFN3030-10
G : Green
7/ 13 : Tape & Reel
Package
Code
Packaging
(Note 2)
S
SP
FN
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. 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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AP8802
1A LED Step-down Converter
Pin Assignments
(1) SOP-8L
(2) SOP-8L-EP
( Top View )
SET 1
2
GND
NC
3
AP8802
VIN 4
( Top View )
8
CTRL
7
GND
6
5
SW
SW
SET 1
GND
NC
2
3
VIN 4
AP8802
8
CTRL
7
GND
6
5
SW
SW
(3) DFN3030-10
( Top View )
SET
1
10
CTRL
GND
2
9
GND
NC
3
8
NC
NC
4
7
SW
VIN
5
6
SW
AP8802
Pin Descriptions
Pin Name
SW
Description
Switch Pin. Connect inductor/freewheeling diode here, minimizing track length at this pin to
reduce EMI.
GND
GND pin
SET
Set Nominal Output Current Pin. Configure the output current of the device.
CTRL
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 50kΩ, and if the pin is left open VCTRL = VREF
VIN
Input Supply Pin. Must be locally bypassed.
NC
No connection
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AP8802
1A LED Step-down Converter
Block Diagram
SET
SW
VIN
Voltage
Regulator
Comparator
CTRL
5V
Sensing
Block
PWM/DC
Control
AP8802
VREF 1.25V
R
GND
Figure 2: AP8802 block diagram
Absolute Maximum Ratings
Symbol
Parameter
Rating
Unit
V
VIN
VIN pin voltage
-0.3~50
VSW
SW voltage
-0.3~50
TJ
TLEAD
TST
o
C
300
o
C
-65 to +150
o
C
Lead Temperature Soldering
Storage Temperature Range
V
150
Junction Temperature
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
Duty Cycle
Notes:
Parameter
Ambient Temperature Range
Using Inductor ≥ 100µH (Note 3)
Min
-40
0.1
Max
105
0.95
Unit
ºC
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.
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AP8802
1A LED Step-down Converter
Electrical Characteristics
Symbol
VIN
IOUT
IQ
FOSC
VTHD
VREF
SET
Rds(on)
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
θJA
Thermal Resistance
Junction-to-Ambient
θJC
Thermal Resistance
Junction-to-Case
ISW
Leakage
Notes:
(VIN =12V, TA=25oC, unless otherwise specified)
Conditions
Min
8.0
Typ.
-
184
-
75
200
1.25
5
0.65
82
45
38
52
7
24
(Note 4)
VSET=VIN-0.2
ISW=0.8A
ON
OFF
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)
1.25
-
Max
48
1
120
0.5
216
1.1
8
0.2
-
Unit
V
A
μA
MHz
mV
V
μA
Ω
μA
V
V
°C/W
°C/W
°C/W
°C/W
°C/W
°C/W
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
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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 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
LED Current [mA]
1000
0.2
0.39
LED current @
VCTRL = 1.25V
0.47
800
0.56
0.33
600
0.2
0.39
0.82
0.47
0.56
0.68
0.33
400
0.47
200
LED current @
VCTRL = 2.5V
0.68
1
0.82
1
0.68 0.82
1
LED current @
VCTRL = 0.625V
1.2
1.5
1.2
1.2
2
1.5
1.5
0
0
2
2
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
3
3
3
RSET value [Ohms]
Figure 3: LED Current setting Vs RSET and VCTRL
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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
Frequency [kHz]
100
47
350
300
68
12V - 3 LEDs
150
250
24V - 5 LEDs
100
200
48V - 10 LEDs
220
150
100
150
47
68
50
470
220
100
150
470
470
220
0
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.
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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
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AP8802
1A LED Step-down Converter
Application Information
(Continued)
AP8802 SOP-8L Minimum Recommended Inductor
8% Accuracy, <70°C Case Temperature
12
Legend
11
47µH
68µH
10
100µH
9
150µH
Number of LEDs
220µH
8
470µH
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
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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
Power (W)
1.6
SOP-8L - EP
1.4
1.2
1
0.8
SOP-8L
0.6
0.4
0.2
0
0
25
50
75
100
125
Ambient Temperature (Deg C)
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.
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AP8802
1A LED Step-down Converter
Application Information
(Continued)
Figure 9: Suggested package for a 1A application
AP8802 - suggested package @
ILED=700mA and 100µH 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
SOP-8L-EP
DFN3030-10
48
46
44
42
40
38
36
34
32
30
28
26
24
22
20
18
16
14
12
10
8
SOP-8L
SOP-8L-EP
DFN3030-10
Vin
Figure 10: Suggested package for a 700mA application
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AP8802
1A LED Step-down Converter
Marking Information
(1) SOP-8L
( Top View )
5
8
Logo
Part Number
AP8802
YY WW X X
1
G : Green
YY : Year : 08, 09,10~
WW : Week : 01~52; 52
represents 52 and 53 week
X : Internal Code
4
(2) SOP-8L-EP
( Top View )
5
8
Logo
Part No.
AP8802
YY WW X X E
1
G : Green
YY : Year : 08, 09,10~
WW : Week : 01~52; 52
represents 52 and 53 week
X : Internal Code
SOP-8L-EP
4
(3) DFN3030-10
( Top View )
XX
YW X
Part Number
AP8802FNG-7
AP8802 Rev. 5
DS31766
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
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Identification Code
A5
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AP8802
1A LED Step-down Converter
Package Information
(All Dimensions in mm)
0.254
0.10/0.20
3.85/3.95
5.90/6.10
(1) Package Type: SOP-8L
Gauge Plane
Seating Plane
0.62/0.82
Detail "A"
7°~9°
7°~9°
0.15/0.25
1.30/1.50
1.75max.
0.35max. 45°
Detail "A"
0°/8°
0.3/0.5
1.27typ
4.85/4.95
5.4
8x-0.60
8x-1.55
6x-1.27
Land Pattern Recommendation
(Unit: mm)
(2) Package Type: SOP-8L-EP
Detail "A"
Exposed pad
2.4Ref.
3.70/4.10
45°
0.35max.
3.85/3.95
5.90/6.10
7°~9°
7°~9° 1
1
0.15/0.25
Bottom View
1.75max.
1.30/1.50
3.3Ref.
0/0.13
0.254
0.3/0.5
1.27typ
4.85/4.95
1
Gauge Plane
Seating Plane
0.62/0.82
Detail "A"
8x-0.60
5.4
Exposed pad
8x-1.55
6x-1.27
Land Pattem Recommendation
(Unit:mm)
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AP8802
1A LED Step-down Converter
Package Information
(Continued)
(3) Package Type: DFN3030-10
0.15Typ.
0/0.05
Seating Plane
Side View
2X-
0.25 A
0.08 C
0.57/0.60
TOP MARK
0.10 C
C
2.9/3.1
2.3/2.5
B
A
R0
.30
0
0.25/0.55
2.9/3.1
1.5/1.7
(Pin #1 ID)
2X-
0.25 B
0.375Typ.
0.50Typ.
0.2/0.3
0.10
C A B
Bottom View
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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.
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AP8802
1A LED Step-down Converter
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DOCUMENT, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
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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
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