AL8821SP-13 [DIODES]
40V, 2A BOOST LED DRIVER;
| 型号： | AL8821SP-13 |
| 厂家： | 
DIODES INCORPORATED |
| 描述： | 40V, 2A BOOST LED DRIVER 驱动 |
| 文件： | 总14页 (文件大小：270K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
AL8821
50V, 2A BOOST LED DRIVER
Description
Pin Assignments
The AL8821 is a boost converter that delivers an accurate constant
current for MR16 and similar LED Lamps. With proprietary control
scheme, the LED driver is compatible with many commonly used
electronic transformers and provides designs with High Power Factor
(PF) and low Total Harmonic Distortion (THD) for these applications.
The operation frequency is up to 1MHz that allows the use of small
size inductor. With the package of SO-8EP, the AL8821 has small
thermal resistance and can be used for wide range of output power.
The driver can be used for dimmable MR16 application and can be
compatible with leading-edge dimmer and trailing-edge dimmer.
(Top View)
8
SW
CS
NC
1
2
3
4
7
6
5
VCC
VIN
NC
EP
FB
COMP
Features
Wide Input Voltage Range: 5V to 36V
Internal 50V NDMOS Switches
SO-8EP
Continuous Conduction Mode (CCM) Operation
Up to 1MHz Switching Frequency
Applications
High PF > 0.9 and Low THD < 30% and Low Ripple < 20%
Compatible With Leading-edge Dimmer And Trailing-edge
Dimmer
Non-dimmable MR16 Lamps
Dimmable MR16 Lamps
General Illumination Lamps
Internal Protections
.
Under Voltage Lock Out (UVLO)
Output Open
.
.
Over Temperature Protection (OTP)
Pb-free SO-8EP
Totally Lead-Free & Fully RoHS Compliant (Notes 1 & 2)
Halogen and Antimony Free. “Green” Device (Note 3)
Notes:
1. No purposely added lead. Fully EU Directive 2002/95/EC (RoHS) & 2011/65/EU (RoHS 2) compliant.
2. See http://www.diodes.com/quality/lead_free.html for more information about Diodes Incorporated’s definitions of Halogen- and Antimony-free, "Green"
and Lead-free.
3. Halogen- and Antimony-free "Green” products are defined as those which contain <900ppm bromine, <900ppm chlorine (<1η00ppm total Br + Cl) and
<1000ppm antimony compounds.
Typical Applications Circuit
L
D2
D1
Vac
D5
D3
D4
CO
RSET
RHYS
SW
VIN
CS
VCC
FB
RFB
C3
C4
COMP
(Exposed Pad)
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© Diodes Incorporated
AL8821
Document number: DS37671 Rev. 2 - 2
AL8821
Pin Descriptions
Pin Number
Pin Name
Function
1
SW
Integrated MOS Drain
2
3
4
5
6
7
8
9
CS
FB
Input Current Sense Pin
LED Output Current Feedback Pin
Control Loop Compensation Pin
Not Connected
COMP
NC
VIN
IC Input Voltage, Adding from Boost Output Voltage
Supply Voltage For Internal Circuit
Not Connected
VCC
NC
Exposed Pad
Connected to Ground
Functional Block Diagram
VIN
6
VCC
7
VCC
Internal
Regulator
VREF
VBG
Chip_EN
UVLO
VBG
Bandgap
VIN
PWM1
9
VFB
OVP
Exposed
Pad
OVP
LOGIC
2
OTP
CS
VCS1
1
CS1
SW
VCC
Driver
COMPARATOR
3
FB
PWM1
EA
VBG
4
COMP
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© Diodes Incorporated
AL8821
Document number: DS37671 Rev. 2 - 2
AL8821
Absolute Maximum Ratings (@TA = +25°C, unless otherwise specified. Note 4)
Symbol
VIN
Parameter
Rating
-0.3 to 40
-0.3 to 50
-0.3 to 6
-0.3 to 6
-0.3 to 6
-0.3 to 6
+150
Unit
V
VIN Pin Voltage
SW Pin Voltage
COMP Pin Voltage
CS Pin Voltage
FB Pin Voltage
VCC Pin Voltage
VSW
VCOMP
VCS
VFB
V
V
V
V
VCC
TJ
V
Operating Junction Temperature
Storage Temperature
°C
°C
°C/W
°C
V
TSTG
ꢀJA
-65 to +150
66
Thermal Resistance (Junction to Ambient) (Note 5)
Lead Temperature (Soldering, 10sec)
ESD (Machine Model)
TLEAD
—
+300
200
—
ESD (Human Body Model)
2000
V
Notes:
4. Stresses greater than those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only and
functional operation of the device at these or any other conditions beyond those indicated under “Recommended Operating Conditions” is not implied.
Exposure to “Absolute Maximum Ratings” for extended periods may affect device reliability.
5. Device mounted on FR-4 PCB (51mm x 51mm) 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.
Recommended Operating Conditions
Symbol
Parameter
Min
5
Max
36
Unit
V
VIN
TA
VIN Pin Voltage
Ambient Temperature
-40
+105
°C
Electrical Characteristics (@TA = +25°C, unless otherwise specified.)
Symbol
Input Supply
Parameters
Conditions
Min
Typ
Max
Unit
—
5
—
1
36
—
—
—
V
mA
V
VIN
IQ
VIN Pin Voltage
Quiescent Current
No Switching
VIN Rising
—
—
—
—
Under-Voltage Lockout
Voltage
4.2
500
VUVLO
VHYS
VCC Regulator
UVLO Hysteresis
mV
VCC
—
VCC Pin Voltage
—
4.5
10
—
5
—
4
5.5
—
V
mA
%
Source Current Capability
Load Regulation
VCC = 5V
—
—
—
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© Diodes Incorporated
AL8821
Document number: DS37671 Rev. 2 - 2
AL8821
Electrical Characteristics (Cont. @TA = +25°C, unless otherwise specified.)
Symbol
Parameters
Conditions
Min
Typ
Max
Unit
Integrated NMOS_BOOST
MOS Voltage Stress (Note 6)
MOS Current Stress (Note 6)
MOS RDSON
—
—
—
—
—
—
50
2
—
—
—
V
A
VDS
IDS
250
mΩ
RDSON
Compensation and Soft Start (COMP Pin)
Error Amplifier Trans-
conductance
GEA
—
—
—
—
—
1000
68
—
—
—
—
µA/V
µA
Sourcing Current
IO-H
VCOMP = 0.5V
VCOMP = 4.5V
—
Sinking Current
FB Pin Voltage
68
µA
IO-L
VFB
444
mV
Hysteresis Competitor
Boost Sense Voltage Low
Level
—
-90
—
mV
µA
VCS MIN
VCOMP = 0V
_
Hysteresis Current
—
85
100
115
IHYS
Over-Temperature Protection
Thermal Shutdown (Note 6)
—
—
—
—
+160
+40
—
—
°C
°C
TOTSD
THYS
Thermal Shutdown
Hysteresis (Note 6)
Note 6:
These parameters, although guaranteed by design, are not 100% tested in production.
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© Diodes Incorporated
AL8821
Document number: DS37671 Rev. 2 - 2
AL8821
Performance Characteristics
Quiescent Current vs. VIN Pin Voltage
Quiescent Current vs. Ambient Temperature
1.2
1.1
1.0
0.9
0.8
0.7
0.6
1.4
1.2
1.0
VIN = 12V
0.8
0.6
-45
-30
-15
0
15
30
45
60
75
90
105
4
8
12
16
20
24
28
32
36
Ambient Temperature (oC)
VIN Pin Voltage (V)
VCC Pin Voltage vs. VIN Pin Voltage
VCC Pin Voltage vs. Ambient Temperature
5.5
5.2
5.4
VIN = 12V
5.1
5.0
4.9
4.8
4.7
4.6
4.5
5.3
5.2
5.1
5.0
4.9
4.8
-45
-30
-15
0
15
30
45
60
75
90
105
4
8
12
16
20
24
28
32
36
Ambient Temperature (oC)
VIN Pin Voltage (V)
FB Pin Voltage vs.VIN Pin Voltage
FB Pin Voltage vs. Ambient Temperature
0.50
0.48
0.46
0.44
0.42
0.40
0.50
0.48
0.46
0.44
0.42
0.40
VIN = 12V
-45
-30
-15
0
15
30
45
60
75
90
105
4
8
12
16
20
24
28
32
36
Ambient Temperature (oC)
VIN Pin Voltage (V)
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AL8821
Document number: DS37671 Rev. 2 - 2
AL8821
Performance Characteristics (Cont.)
Boost Sense Voltage Low Level vs.
VIN Pin Voltage
Boost Sense Voltage Low Level vs.
Ambient Temperature
-80
-82
-84
-86
-88
-90
-80
-82
-84
-86
-88
-90
V
= 12V
IN
-45
-30
-15
0
15
30
45
60
75
90
105
4
8
12
16
20
24
28
32
36
VIN Pin Voltage (V)
Ambient Temperature (oC)
Hysteresis Current vs. VIN Pin Voltage
Hysteresis Current vs. Ambient Temperature
114
112
110
108
106
104
102
116
114
112
110
108
106
104
V
= 12V
IN
-45
-30
-15
0
15
30
45
60
75
90
105
Ambient Temperature (oC)
4
8
12
16
20
24
28
32
36
VIN Pin Voltage (V)
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© Diodes Incorporated
AL8821
Document number: DS37671 Rev. 2 - 2
AL8821
Application Information
AL8821 Operation
The AL8821 is a boost converter that delivers an accurate constant current for driving LEDS. With hysteretic control scheme, the LED driver is
compatible with most of commonly used electronic transformers. The driver can be compatible with leading-edge dimmer and trailing-edge dimmer.
L
D2
D1
Vac
D5
D3
D4
CO
RSET
RHYS
SW
VIN
CS
VCC
FB
RFB
C3
C4
COMP
(Exposed Pad)
Figure 1. Typical Application Circuit
LED Current Control
The LED current is controlled by the resistor RFB in Figure 1.
Connected between FB pin and Ground, the nominal average output current in the LED(s) is defined as:
0.444V
Ｉ
LED
RFB
RSET and RHYS Setting
The Boost converter of the AL8821 operates at continuous conduction mode and is based on hysteresis schematic which has lower threshold and
upper threshold. Refer to Figure 2 depicting the inductor current waveform.
IL
Peak or Upper Threshold
IL(peak)
IL(ave)
IL(val)
Valley or Lower Threshold
tON
tOFF
Time
Figure 2. Inductor Current
When switch SW is turned on, the inductor current flows through RSET and ramps up linearly. The rising current produces a voltage ramp across
RSET. When the voltage across RSET reaches the upper threshold, switch SW is turned off. The inductor current continues to flow through RSET but
decays. The decaying current produces a falling voltage at RSET. When the voltage across RSET falls to the lower threshold, switch SW is turned
on again.
The lower threshold voltage VLT depends on the voltage VCOMP at COMP pin that varies with the input voltage and output load. The equation is
shown as below.
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© Diodes Incorporated
AL8821
Document number: DS37671 Rev. 2 - 2
AL8821
Application Information (Cont.)
(VCOMP 1.5)0.61.4
V,1.5V VCOMP 5V
V
16
LT
0.088V,0V VCOMP 1.5V
The range of VCOMP is from 0V to 5V.
The upper threshold depends on the lower threshold and the hysteresis value. The hysteresis value is set by external resister RHYS. It is defined as
below.
VHYS RHYS 100A
According to the operation principle , the peak to peak current ∆IL and the valley current IL(val) can be obtained by the below equations.
VLT
IL(val)
RSET
VHYS
IL
RSET
Where:
∆IL is the peak to peak current of inductor.
IL(val) is the valley current of inductor.
From the Figure 2, the relationship between IL(peak), IL(val), IL(ave) and ∆IL can be obtained as below.
IL( peak) IL(val) IL
1
IL(ave) IL(val) IL
2
Where:
IL(peak) is the peak current of inductor.
IL(ave) is the average current of inductor.
As we know the average current IL(ave) depends on the output power, rated input voltage VIN1 of step-up converter and total efficiency ꢁ. So the
average current IL(ave) can be obtained by the following equation.
(VLED 0.444) ILED
IL(ave)
VIN1
Where: VLED is the voltage in LEDs.
Set ratio of ∆IL to IL(peak) as K.
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AL8821
Document number: DS37671 Rev. 2 - 2
AL8821
Application Information (Cont.)
IL
K
IL( peak)
RSET and RHYS can be obtained from above equations:
((VCOMP 1.5)0.6 1.4)(2 K)
V
IN1 ,1.5V VCOMP 5V
32(VLED 0.444) ILED ꢀ1-Kꢁ
0.044(2 K) VIN1
(VLED 0.444) ILED ꢀ1-Kꢁ
RSET
=
=
,0V VCOMP 1.5V
2(VLED 0.444)ILED K RSET 104
RHYS
VIN1 (2 K)
When the value of K, ꢁ and VCOMP are provided, the value of resister RSET and RHYS can be calculated according to these above equations. In
order to get appropriate efficiency and Electronic Transformer (ET) compatibility, generally K is set between 0.4 and 0.8. Due to the range of
VCOMP is from 0V to 5V, in order to get output voltage regulation, generally VCOMP is set as 3V at rated input voltage.
Inductor Selection
Because of the using of the hysteretic control scheme, the switching frequency in a boost configuration can be adjusted in accordance to the value
of the inductor being used. The value of the inductor can be determined on the desired switching frequency by using the following equation:
[VIN1 (RSET RL RDSON ) IL(ave) ][VLED 0.444VF (RL RSET ) IL(ave) VIN1]
L
I VLED 0.444VF RDSON IL(ave) f
L
SW
Where:
L is the coil inductance.
RL is the coil resistance.
RDSON is the switch SW resistance.
VIN1 is the rated input voltage.
VF is the diode forward voltage.
fSW is the desired switching frequency. Generally 500kHz to 800kHz switching frequency is suggested. Low switching frequency can decrease the
switching loss but need to choose higher inductor values that will result in larger size in order to meet the saturation current. For example the
relationship between switching frequency and inductor value is shown as below Table 1 in the same application system. Considering these factors,
500kHz switching frequency is recommend in typical application.
Inductance Value of L @ Vac = 12Vac, VIN = 22V
Operation Frequency of SW at Peak Voltage Of Vac
VLED = 28V, ILED = 180mA
10µH
15µH
22µH
33µH
840kHz
800kHz
680kHz
465kHZ
Table 1
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© Diodes Incorporated
AL8821
Document number: DS37671 Rev. 2 - 2
AL8821
Application Information (Cont.)
VIN OVP Protection
AL8821 has an internal over voltage protection to protect IC from excessive input voltage. When the voltage applied at VIN pin exceeds 39V, it will
turn off the power switch SW. The power switch SW will be turned on again once the voltage at VIN drops below 34V.
VCC Regulator
The VCC pin requires a capacitor C3 for stable operation and to store the charge for the large GATE switching currents. Choose a 10V rated low
ESR, X7R or X5R, ceramic capacitor for best performance. A 4.7µF capacitor will be adequate for many applications. Place the capacitor close to
the IC to minimize the trace length to the VCC pin and to the IC ground.
An internal current limit on the VCC output protects the excessive on-chip power dissipation. The VCC pin has set the output to 5V (typ.) to protect
the internal FETs from excessive power dissipation caused by not being fully enhanced. If the VCC pin is used to drive extra circuits beside the
AL8821, the extra loads should be limited to less than 8mA.
Output Capacitor CO
The capacitor CO is used to hold the bus voltage and reduce the ripple of LED current when the electronic transformer has no output. For most
applications, it is recommended to use an aluminum electrolytic capacitor with greater than 220µF capacitance.
Compensation Capacitor C4
In applications powered by electronic transformer, the input voltage can change roughly in one cycle of AC power frequency. A 1µF ceramic
capacitor C4 connected from COMP pin to ground help to stabilize the control loop of the regulator.
Diode Selection
For maximum efficiency and performance, the rectifiers (D5) should be fast low capacitance Schottky diodes with low reverse leakage at
maximum operating voltage and temperature. With its low power dissipation, the Schottky diode outperforms other silicon diodes and increases
overall efficiency.
Over Temperature Protection
A over temperature protection feature is to protect the AL8821 from excessive heat damage. When the junction temperature exceeds +160°C, the
internal FET will be turned off. When junction temperature drops below +120°C, IC will turn on both FETs and return to normal operation.
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© Diodes Incorporated
AL8821
Document number: DS37671 Rev. 2 - 2
AL8821
Ordering Information
AL8821 XX - XX
Package
Packing
13 :13" Tape & Reel
SP : SO-8EP
13” Tape and Reel
Part Number
Package Code
Package
Quantity
Part Number Suffix
AL8821SP-13
SP
SO-8EP
2500/Tape & Reel
-13
Marking Information
(Top View)
8
7
6
5
Logo
Part Number
YY : Year : 08, 09, 10~
WW : Week : 01~52; 52
AL8821
YY WW X X E
Represents 52 and 53 Week
X X : Internal Code
E : SO-8EP
2
3
4
1
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AL8821
Document number: DS37671 Rev. 2 - 2
AL8821
Package Outline Dimensions (All dimensions in mm(inch).)
(1) Package Type: SO-8EP
3.800(0.150)
4.000(0.157)
2.110(0.083)
2.710(0.107)
4.700(0.185)
5.100(0.201)
1.270(0.050)
TYP
0.300(0.012)
0.510(0.020)
0.050(0.002)
0.150(0.006)
5.800(0.228)
6.200(0.244)
1.350(0.053)
1.550(0.061)
0.400(0.016)
1.270(0.050)
0.150(0.006)
0.250(0.010)
Note: Eject hole, oriented hole and mold mark is optional.
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AL8821
Document number: DS37671 Rev. 2 - 2
AL8821
Suggested Pad Layout
(1) Package Type: SO-8EP
Y1
G
Z
X1
Y
E
X
Z
G
X
Y
X1
Y1
E
Dimensions
(mm)/(inch)
6.900/0.272
(mm)/(inch)
3.900/0.154
(mm)/(inch)
0.650/0.026
(mm)/(inch)
1.500/0.059
(mm)/(inch)
3.600/0.142
(mm)/(inch)
(mm)/(inch)
1.270/0.050
Value
2.700/0.106
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AL8821
Document number: DS37671 Rev. 2 - 2
AL8821
IMPORTANT NOTICE
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.
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Should Customers purchase or use Diodes Incorporated products for any unintended or unauthorized application, Customers shall indemnify and
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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
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This document is written in English but may be translated into multiple languages for reference. Only the English version of this document is the
final and determinative format released by Diodes Incorporated.
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.
Copyright © 2017, Diodes Incorporated
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