AL5811 - Diodes Incorporated

AL5811
60V, LINEAR 75mA ADJUSTABLE CURRENT LED DRIVER
Description
Pin Assignments
The AL5811 is a Linear LED driver with an adjustable LED current up
(Top View)
to 75mA offering excellent temperature stability and output handling
capability. The AL5811 simplifies the design of linear and isolated or
VCC 1
8 LED
value resistors.
NC 2
7 NC
The AL5811 has an open drain output that can swing from 1V up to
60V enabling it drive long LED chains. Its low 0.5V RSET pin is
NC 3
6 NC
outside of the LED current path and so accuracy is maintained while
RSET 4
non-isolated LED drivers by setting the LED current with standard
5 GND
minimizing the required overhead to regulate the LED current. This
MSOP-8EP
reduces its power dissipation when compared to traditional linear
LED drivers. This makes it ideal for driving LEDs up to 75mA.
(Top View)
Longer LED chains can be driven by tapping VCC from the chain,
where the chain voltage may exceed 60V.
VCC 1
The AL5811 is available in the exposed pad MSOP-8EP and
U-DFN3030-6 packages.
NC 2
RSET 3
Exposed
Pad
6
LED
5
NC
4
GND
U-DFN3030-6
Features
Applications

Low Reference Voltage (VRSET = 0.5V)

Isolated Offline LED Converters

-40°C to +125°C Temperature Range

Linear LED Driver

±6% Typical LED Current Tolerance

LED Signs

Low Temperature Drift

Instrumentation Illumination

1.0V to 60V Open-Drain Output

High Power Supply Rejection

MSOP-8EP and U-DFN3030-6

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 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 (<1500ppm total Br + Cl)
and <1000ppm antimony compounds.
Typical Applications Circuit
AL5811
Document number: DS35255 Rev. 2 - 2
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AL5811
Pin Descriptions
Pin Number
MSOP-8EP
U-DFN3030-6
Pin
Name
VCC
1
1
RSET
4
3
GND
LED
NC
5
8
2, 3, 6, 7
4
6
2, 5
EP
Exposed Pad
Exposed Pad
Function
Supply Input.
Connect a 0.1μF ceramic capacitor between VCC and GND as close as possible to the device.
LED Current Setting Pin.
Connect a resistor from this pin to GND:
ILED = 750/RSET
May also be used to provide PWM dimming functionality
Ground Reference Point of Device.
LED Current Sink Connection.
Unused
Exposed Pad (bottom).
Used to improve thermal impedance of package.
It must be connected to GND directly underneath the package.
Functional Block Diagram
Absolute Maximum Ratings (@TA = +25°C, unless otherwise specified.)
Symbol
Parameters
Ratings
Unit
VCC
Supply Voltage Relative to GND Pin (Note 4)
-0.3 to +66
V
VLED
LED Voltage Relative to GND Pin (Note 4)
-0.3 to +66
V
RSET Voltage Relative to GND Pin
VRSET
ILED
ESD HBM
ESD CDM
-0.3 to +6
V
LED Pin Current Sink Current Range
85
mA
Human Body Model ESD Protection
Charged Device Model ESD protection
1
1.2
kV
kV
TJ
Operating Junction Temperature
-40 to +150
°C
TST
Storage Temperature
-55 to +150
°C
Notes:
4. VCC pin can be greater or smaller than VLED; neither should go below GND.
Caution:
Stresses greater than the 'Absolute Maximum Ratings' specified above, may cause permanent damage to the device. These are stress ratings only;
functional operation of the device at these or any other conditions exceeding those indicated in this specification is not implied. Device reliability may be
affected by exposure to absolute maximum rating conditions for extended periods of time.
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
AL5811
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AL5811
Package Thermal Data
Package
MSOP-8EP
U-DFN3030-6
Notes:
θJC
Thermal Resistance
Junction-to-case
(Note 5)
37
13
θJA
Thermal Resistance
Junction-to-Ambient
(Note 5)
PDIS
TA = +25°C,
TJ = +125°C
85°C/W (Note 6)
71°C/W (Note 7)
1.2W
1.40W
5. Dominant conduction path via exposed pad.
6. Test condition for MSOP-8EP: 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.
7. Test condition for U-DFN3030-6: Device mounted on FR-4 PCB (51mm x 51mm 2oz copper, minimum recommended pad layout on top layer and
thermal vias to bottom layer with maximum area ground plane. For better thermal performance, larger copper pad for heat-sink is needed
Recommended Operating Conditions (@TA = +25°C, unless otherwise specified.)
Symbol
Min
Max
VCC
Supply Voltage Range Relative to GND Pin
3.5
60
VLED
OUT Voltage Range Relative to GND Pin
1.0
60
ILED
LED Pin Current (Note 8)
10
75
mA
Operating Ambient Temperature Range
-40
+125
°C
TA
Note:
Parameter
Unit
V
8. Maximum LED current is also limited by ambient temperature and power dissipation such that junction temperature should
be kept less than or equal +125°C.
Electrical Characteristics (@TA = +25°C, VCC = 3.5V, VLED = 1.0 (Note 9), RSET = 15kΩ, unless otherwise specified.)
Symbol
VRSET
Parameter
RSET Voltage
Conditions
—
Min
Typ
Max
Unit
—
0.5
—
V
18
20
22
70
75
80
47
50
53
TA = -40°C to +125°C
46
—
54
TA = -40°C to +125°C
RSET = 37.5kΩ
ILED
ILED Current Accuracy
TA = +25°C
RSET = 10kΩ
RSET = 15kΩ
REGLINE
LED Current Line Regulation
VCC = 3.5V to 60V
Supply Current
3.5V ≤ VCC ≤ 60V
ILEAK
LED Pin Leakage Current
VCC = 60V; VLED = 60V
RSET = Open Circuit
TSHDN
Thermal Shutdown
THYS
Thermal Shutdown Hysteresis
ICC
Note:
—
mA
TA = +25°C
—
0.25
—
TA = +25°C
—
200
300
%
TA = -40°C to +125°C
—
—
350
TA = +125°C
—
—
1
—
—
+155
—
°C
—
—
+20
—
°C
µA
µA
9. All voltages unless otherwise stated are measured with respect to GND pin.
AL5811
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AL5811
Typical Performance Characteristics
80
90
70
80
70
LED CURRENT (mA)
60
LED CURRENT (mA)
RSET = 10K
50
40
30
20
60
RSET = 15K
50
40
30
RSET = 37.4K
20
10
10
0
0
VCC = 3.5V
VLED = 1.0V
-40
25
125
AMBIENT TEMPERATURE (°C)
LED Current vs. Ambient Temperature
INPUT VOLTAGE (V)
LED Current vs. Input Voltage
80
60
RSET = 10K
70
RSET = 15K
50
LED CURRENT (mA)
LED CURRENT (mA)
60
40
30
20
RSET = 15K
50
40
30
RSET = 37.4K
20
10
10
VIN = 3.5V
T A = +25°C
0
0
1
2
3
4
7
8
LED PIN VOLTAGE (V)
LED Current vs. LED Pin Voltage
AL5811
Document number: DS35255 Rev. 2 - 2
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10
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0
0.5
VCC = 3.5V
TA = +25°C
1.0
1.5
2.0
2.5
3.0
3.5
INPUT VOLTAGE (V)
LED Current vs. Input Voltage
4.0
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AL5811
Typical Performance Characteristics (cont.)
14
RSET = 15K
0.5
10
0.4
08
Tshdn
06
VRSET (V)
LED CURRENT (mA)
12
0.6
RSET = 75K
VIN = 9V
Thys
0.3
0.2
04
0.1
02
0
125
130
135 140
145 150
155
AMBIENT TEMPERATURE(°C)
Thermal Shutdown MSOP-8EP
0
160
0.494
SUPPLY CURRENT (µA)
RSET VOLTAGE (V)
0.491
0.490
0.489
0.488
0.487
250
3
20
INPUT VOLTAGE (V)
RSET Voltage vs. Input Voltage
45
250
RSET = 15k
0.492
0.485
2
300
0.493
0.486
VLED = 1.0V
T A = +25°C
RSET = 10K
200
150
100
RSET = 15K
RSET = 37.4K
50
VCC = 3.5V
VLED = 1.0V
VLED = 1.0V
TA = +25°C
0
0
-40
25
125
AMBIENT TEMPERATURE (°C)
RSET Voltage vs. Ambient Temperature
5 10 15 20 25 30 35 40 45 50 55 60
INPUT VOLTAGE (V)
Supply Current vs. Input Voltage
RSET = 10K
SUPPLY CURRENT (µA)
200
RSET = 15K
150
RSET = 37.4K
100
50
VCC = 3.5V
VLED = 1.0V
0
25
-40
125
AMBIENT TEMPERATURE (°C)
Supply Current vs. Ambient Temperature
AL5811
Document number: DS35255 Rev. 2 - 2
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AL5811
Application Information
Description
The AL5811 is a Linear LED driver and in normal operation has the LEDs connected to the same potential as its VCC pin and regulates the LED
current by sinking current into to its LED pin. The LED current is set by the use of an external resistor, RSET, connected from the RSET pin to GND.
This resistor supplies the bias current of the AL5811 together with current regulator to set the LED current.
The LED current is determined by this equation:
ILED  1500 *
0 .5
R SET
where 1500 is the current ratio between the LED pin current and RSET pin current.
With RSET = 15k
ILED  1500 *
0 .5
 50mA
15k
The AL5811 with its 60V capability on its supply pin, VCC, and its LED drive pin allows it to operate from supply rails up to 60V and/or directly drive
LED chains up to 60V as shown in Figures 1 and 2. The voltage applied to the VCC pin can be greater or lower than the voltage applied to the LED
string. Figure 2 shows where you might power the AL5811 from a 5V rail and power the LED string from a 12V rail.
VLED
VIN
VCC
CIN 0.1µF
LED
AL5811
RSET
GND
RSET = 10kΩ
Figure 2. Low Side Drive – Separate Supplies
Figure 1. Low Side Current LED Setting
AL5811
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AL5811
Application Information (cont.)
High Voltage Operation
An extension of Figure 2 is to derive the power for the AL5811 from the LED chain itself see Figure 3. LED chains greater than 60V can be driven in
this manner as long PWM dimming is not utilized.
Figure 3. Low Side LED String Tapping
Figure 4. High Side Current LED String
Figure 3 shows the use of RC delay to match the power time delay between Vcc and LED pin The AL5811 can also be used on the high side of the
LEDs, see Figure 4. This is a simple way of extending the maximum LED chain voltage, however, it does increase the minimum system input
voltage to:
VIN(min) = VLED_CHAIN + 3.5V.
Where
VLED_CHAIN is the LED chain voltage.
AL5811
Document number: DS35255 Rev. 2 - 2
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AL5811
Application Information (cont.)
PWM Dimming
LED current dimming can be achieved by driving the RSET pin via the current setting resistor (RSET) and series MOSFET switch to ground
(Figure 5). The RSET pin current is then effectively switched on and off causing the LED current to turn on and off.
80
LED CURRENT (mA)
70
60
50
40
30
20
10
0
0
10
20
30
40 50 60 70 80
DUTY CYCLE (%)
LED Current vs. Duty Cycle
90 100
Frequency = 100Hz; Duty Cycle = 0.1% to 100%;
RSET = 10K; 2LEDs in Series
Figure 5. PWM Dimming
Figure 6. PWM Dimming Linearity
Thermal Considerations
When designing linear LED drivers careful consideration must be given to:
1.
the power dissipation within the LED driver
and
2.
PCB layout/heat sinking.
A Linear LED driver has to be able to handle the large potential input voltage variations due to the supply voltage tolerance and also the variation in
LED forward voltage due to binning and temperature.
This can result in a large potential difference across the LED driver resulting in a larger than anticipated power dissipation.
For example in n 12V powered system with a 5% output voltage tolerance; the input voltage could typically vary from 12.6V down to 11.4V driving
3 LEDs with a voltage varying from 3V to 3.5V at 75mA. This means that the LED driver has to cope with a voltage drop across varying from
approximately 3.6V to 0.9V. This means that the power dissipation of the AL5811 could be as much as 270mW.
Figure 7 below shows how the AL5811’s power dissipation capability varies with package; these values will vary with PCB size and area of metal
associated with the ground plane used for heat sinking. By increasing the area on the top layer the thermal impedance of both packages could be
improved.
1.6
POWER DISSIPATION (W)
1.4
U-DFN3030-6
1.2
MSOP-8EP
1.0
0.8
0.6
0.4
0.2
0.0
-40 -25 -10 5 20 35 50 65 80 95 110 125
AMBIENT TEMPERATURE (°C)
Figure 7. Power Dissipation Derating
AL5811
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AL5811
Ordering Information
Part Number
Package Code
Packaging
AL5811MP-13
AL5811FF-7
MP
FF
MSOP-8EP
U-DFN3030-6
7”/13” Tape and Reel
Quantity
Part Number Suffix
2500/Tape & Reel
-13
3000/Tape & Reel
-7
Marking Information
(1)
MSOP-8EP
( Top View )
8
7
Logo
5
YWXE
AL5811
Part Number
1
(2)
6
2
3
G : Green
MSOP8-EP
Y : Year : 0~9
W : Week : a~z : 1~26 week;
A~Z : 27~52 week; Z represents
52 and 53 week
4
U-DFN3030-6
( Top View )
XX
YW X
Part Number
AL5811FF-7
AL5811
Document number: DS35255 Rev. 2 - 2
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 : G : Green
Package
U-DFN3030-6
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Identification Code
A9
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AL5811
Package Outline Dimensions (All dimensions in mm.)
Please see AP02002 at http://www.diodes.com/datasheets/ap02002.pdf for latest version.
(1)
Package type: MSOP-8EP
D
4X
10
°
x
E
0.25
D1
E2
Gauge Plane
Seating Plane
a
y
1
4X
10
°
8Xb
e
Detail C
E3
A1
A3
c
A2
A
L
D
E1
See Detail C
(2)
Package Type: U-DFN3030-6
MSOP-8EP
Dim Min Max Typ
A
1.10
A1
0.05 0.15 0.10
A2
0.75 0.95 0.86
A3
0.29 0.49 0.39
b
0.22 0.38 0.30
c
0.08 0.23 0.15
D
2.90 3.10 3.00
D1
1.60 2.00 1.80
E
4.70 5.10 4.90
E1
2.90 3.10 3.00
E2
1.30 1.70 1.50
E3
2.85 3.05 2.95
e
0.65
L
0.40 0.80 0.60
a
0°
8°
4°
x
0.750
y
0.750
All Dimensions in mm
3
A
1
A
A
e
n
a
l
P
g
n
i
t
a
e
S
2
D D
D
I
1
#
n
i
P
U-DFN3030-6
Dim Min
Max
Typ
A
0.57 0.63 0.60
A1
0
0.05 0.02
A3
0.15
b
0.35 0.45 0.40
D
2.95 3.05 3.00
D2
2.25 2.45 2.35
E
2.95 3.05 3.00
E2
1.48 1.68 1.58
e
0.95
L
0.35 0.45 0.40
Z
0.35
All Dimensions in mm
︵
︶
5
3
.
0
*
5
3
.
0
°
5
4
︵
︶
L
2
E
E
e
AL5811
Document number: DS35255 Rev. 2 - 2
b
x
4
Z
︵ ︶
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AL5811
Suggested Pad Layout
Please see AP02001 at http://www.diodes.com/datasheets/ap02001.pdf for the latest version.
(1) MSOP-8EP
X
C
Dimensions
Y
G
Y2
C
G
X
X1
Y
Y1
Y2
Y1
X1
Value
(in mm)
0.650
0.450
0.450
2.000
1.350
1.700
5.300
(2) U-DFN3030-6
2 1
X X
C
Dimensions
2
Y
1
Y
C
X
X1
X2
Y
Y1
Y2
Value
(in mm)
0.950
0.500
2.400
2.550
0.600
1.780
3.300
9
0
4
.
0
C
Document number: DS35255 Rev. 2 - 2
Y
X
AL5811
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AL5811
Taping Orientation (Note 10)
For U-DFN3030-6
Note:
10. 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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final and determinative format released by Diodes Incorporated.
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written approval of the Chief Executive Officer of Diodes Incorporated. As used herein:
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1. are intended to implant into the body, or
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failure of the life support device or to affect its safety or effectiveness.
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