DIODES AL5802

AL5802
30V, ADJUSTABLE CURRENT SINK LINEAR LED DRIVER
Description
Pin Assignments
ADVANCE INFORMATION
NEW PRODUCT
The AL5802 combines a high gain NPN transistor with a prebiased NPN transistor to make a simple small footprint LED
driver.
(Top View)
The LED current is set by an external resistor connected to
from REXT pin (6) to GND pin (4), the internal high gain
transistor develops approximately 0.6V across the external
resistor.
6
5
4
Q1
Q2
The AL5802 open-collector output can operate from 0.8V to
30V enabling it to operate from 5V to 24V power supplies
without additional components.
1
PWM dimming of the LED current can be achieved by either
driving the BIAS pin (2) with a low impedance voltage
source, or driving the EN pin (3) with an external opencollector NPN transistor or open-drain N-channel MOSFET.
2
3
SOT26
The AL5802 is available in a SOT26 package and is ideal for
driving 20mA to 120mA LED currents.
Features
Applications
•
Reference voltage VRSET = 0.65V
•
Linear LED driver
•
-40 to 125ºC temperature range
•
LED signs
•
0.8V to 30V open-collector output
•
Offline LED luminaries
•
Negative temperature co-efficient – automatically reduce the LED
current at high temperatures
•
Low thermal impedance SOT26 with copper leadframe
•
SOT26: Available in “Green” Molding Compound (No Br, Sb)
•
Qualified to AEC-Q101 Standards for High Reliability
Typical Application Circuit
AL5802
Document number: DS35516 Rev.4 - 2
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© Diodes Incorporated
AL5802
30V, ADJUSTABLE CURRENT SINK LINEAR LED DRIVER
Pin Descriptions
ADVANCE INFORMATION
NEW PRODUCT
Pin
Number
1
2
Name
OUT
BIAS
3
EN
4
GND
5
FB
6
REXT
Function
Open-collector LED driver output
Biases the open collector output transistor
Enable pin for PWM dimming. Provides access to the base of Q2 and
collector of Q1
Ground reference point for setting LED current
Feedback pin.
Should be connected to pin 6.
Current sense pin. LED current sensing resistor should be connected
from here to GND.
Functional Block Diagram
Fig. 1 Block Diagram
Absolute Maximum Ratings
Symbol
VOUT
VBIAS
VFB
VEN
VREXT
IOUT
TJ
TST
Characteristics
Output voltage relative to GND
BIAS voltage relative to GND (Note 1)
LED voltage relative to GND
EN voltage relative to GND
REXT voltage relative to GND
Output current
Operating junction temperature
Storage temperature
Values
30
30
6
6
6
150
-40 to 150
-55 to 150
Unit
V
V
V
V
V
mA
°C
°C
These are stress ratings only. Operation outside the absolute maximum ratings may cause device failure.
Operation at the absolute maximum rating for extended periods may reduce device reliability.
Notes:
1.With pins 5 and 6 connected together.
AL5802
Document number: DS35516 Rev.4 - 2
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© Diodes Incorporated
AL5802
30V, ADJUSTABLE CURRENT SINK LINEAR LED DRIVER
ADVANCE INFORMATION
NEW PRODUCT
Package Thermal Data
Characteristic
Power Dissipation (Note 2) @ TA = 25°C
Power Dissipation (Note 3) @ TA = 25°C
Power Dissipation (Note 4) @ TA = 25°C
Thermal Resistance, Junction to Ambient Air (Note 2) @ TA = 25°C
Thermal Resistance, Junction to Ambient Air (Note 3) @ TA = 25°C
Thermal Resistance, Junction to Ambient Air (Note 4) @ TA = 25°C
Notes:
Symbol
PD
RθJA
Value
0.37
0.87
1
335
143
120
Unit
W
°C/W
2.Device mounted on FR-4 PCB, 2oz with minimum recommended pad layout.
3.Device mounted on 25mm x 25mm 2oz copper board.
4.Device mounted on 50mm x 50mm 2oz copper board.
Recommended Operating Conditions
Symbol
VBIAS
VOUT
ILED
TA
Notes:
Parameter
Supply voltage range
OUT voltage range
LED pin current (Note 5)
Operating ambient temperature range
Min
4.5
0.8
10
-40
Max
30
30
120
125
Unit
V
mA
°C
5.Subject to ambient temperature, power dissipation and PCB.
Electrical Characteristics
NPN Transistor – Q1 @TA = 25°C unless otherwise specified
Symbol
Characteristic
V(BR)CEO Collector-Emitter Breakdown Voltage (Note 6)
V(BR)EBO Emitter-Base Breakdown Voltage
ICEX
Collector Cutoff Current
IBL
Base Cutoff Current
hFE
VCE(SAT)
VBE(SAT)
DC Current Gain
Collector-Emitter Saturation Voltage
Base-Emitter Saturation Voltage
Test Condition
IC = 1.0mA, IB = 0
IE = 10µA, IC = 0
VCE = 30V, VEB(OFF) = 3.0V
VCE = 30V, VEB(OFF) = 3.0V
IC = 100µA, VCE = 1.0V
IC = 1.0mA, VCE = 1.0V
IC = 10mA, VCE = 1.0V
IC = 10mA, IB = 1.0mA
IC = 10mA, IB = 1.0mA
Min
40
6.0
Typ
Max
50
50
Unit
V
V
nA
nA
⎯
⎯
40
70
100
300
0.20
0.85
0.65
V
V
NPN Pre-biased Transistor – Q2 @TA = 25°C unless otherwise specified
Symbol
V(BR)CBO
V(BR)CEO
V(BR)EBO
ICBO
IEBO
VCE(SAT)
hFE
R1
Characteristic
Collector-Base Breakdown Voltage
Collector-Emitter Breakdown Voltage (Note 6)
Emitter-Base Breakdown Voltage
Collector Cut-Off Current
Emitter Cut-Off Current
Collector-Emitter Saturation Voltage (Note 6)
DC Current Gain (Note 6)
Input Resistance
Test Condition
IC = 50μA, IE = 0
IC = 1mA, IB = 0
IE = 50µA, IC = 0
VCB = 30V, IE = 0
VEB = 4V, IC = 0
IC = 10mA, IB = 1mA
VCE = 5V, IC = 150mA
Min
30
30
5.0
100
7
Typ
10
Max
0.5
0.5
0.3
Unit
V
V
V
µA
µA
V
13
kΩ
*Characteristics of transistor only.
Notes:
6. Measured under pulsed condition. Pulse width = 300µs. Duty cycle ≤2%.
AL5802
Document number: DS35516 Rev.4 - 2
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November 2011
© Diodes Incorporated
AL5802
30V, ADJUSTABLE CURRENT SINK LINEAR LED DRIVER
ADVANCE INFORMATION
NEW PRODUCT
Thermal Characteristics
AMBIENT TEMPERAURE (°C)
Fig. 2Derating Curve
Fig. 3Max Power vs. Area
Fig. 4Thermal Resistance vs. Area
AL5802
Document number: DS35516 Rev.4 - 2
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© Diodes Incorporated
AL5802
30V, ADJUSTABLE CURRENT SINK LINEAR LED DRIVER
ADVANCE INFORMATION
NEW PRODUCT
Typical Performance Characteristics
Fig. 5 Output Current vs. Vout
Fig. 8 Output Current vs. Vout
Fig. 7 Output Current vs. Vout
Fig. 9 Output Current vs. Vout
Notes
Fig. 6 Output Current vs. REXT
Fig. 10 Output Current vs. Vbias
7.Vout in the “Output current Vs Vout“ graphs limited by power dissipation in the device
AL5802
Document number: DS35516 Rev.4 - 2
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© Diodes Incorporated
AL5802
ADVANCE INFORMATION
NEW PRODUCT
30V, ADJUSTABLE CURRENT SINK LINEAR LED DRIVER
Fig. 11 Output Current vs. Vbias
Fig. 12 Output Current vs. Vbias
Fig. 13 Output Current vs. Vbias
AL5802
Document number: DS35516 Rev.4 - 2
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© Diodes Incorporated
AL5802
30V, ADJUSTABLE CURRENT SINK LINEAR LED DRIVER
Application Information
ADVANCE INFORMATION
NEW PRODUCT
The AL5802 has been designed for driving low current LEDs with typical
LED current of 20mA to 100mA. It provides a cost effective way for
driving low current LEDs compared with more complex switching
regulator solutions. Furthermore, it reduces the PCB board area of the
solution as there is no need for external components like inductors,
capacitors and switching diodes.
Figure 14 shows a typical application circuit diagram for driving an LED
or string of LEDs. The NPN transistor Q1 measures the LED current by
sensing the voltage across an external resistor REXT. Q1 uses its VBE as
reference to set the voltage across REXT and controls the base current
into Q2. Q2 operates in linear mode to regulate the LED current. The
LED current is
ILED = VBE(Q1) / REXT
From this, for any required LED current the necessary external resistor
REXT can be calculated from
REXT = VBE(Q1) / ILED
Two or more AL5802 can be connected in parallel to construct higher
current LED strings as shown in Figure 15.
Fig. 14Typical Application Circuit for
Linear Mode Current Sink LED Driver
Consideration of the expected linear mode power dissipation must be
factored into the design, with respect to the AL5802's thermal
resistance. The maximum voltage across the device can be calculated
by taking the maximum supply voltage less the voltage across the LED
string.
VCE(Q2) = VCC – VLED – VBE(Q1)
2
PD = VCE(Q2) * ILED + ( VCC – VBE(Q2) – VBE(Q1)) / R1
As the output current of AL5802 increases, it is necessary to provide
appropriate thermal relief to the device. The power dissipation supported
by the device is dependent upon the PCB board material, the copper
area and the ambient temperature. The maximum dissipation the device
can handle is given by:
PD = ( TJ(MAX) - TA) /RθJA
Refer to the thermal characteristic graphs on page 4 for selecting the
appropriate PCB copper area.
Fig. 15Application Circuit for Increasing LED Current
AL5802
Document number: DS35516 Rev.4 - 2
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© Diodes Incorporated
AL5802
30V, ADJUSTABLE CURRENT SINK LINEAR LED DRIVER
ADVANCE INFORMATION
NEW PRODUCT
PWM dimming can be achieved by driving the EN pin. An external open-collector NPN transistor or open-drain N-channel MOSFET can be
used to drive the EN pin as shown in Figure 16. Dimming is achieved by turning the LEDs ON and OFF for a portion of a single cycle. The
PWM signal can be provided by a micro-controller or analog circuitry. Figure 17 is a typical response of LED current vs PWM duty cycle on the
EN pin.
-or-
Fig. 16Application Circuits for LED Driver with PWM Dimming Functionality
60
LED CURRENT (mA)
50
40
30
20
10
0
0
20
40
60
80
PWM DUTY CYCLE (%)
100
Fig. 17 Typical LED current response vs.PWM duty cycle for
REXT = 13Ω at 400Hz PWM frequency
AL5802
Document number: DS35516 Rev.4 - 2
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© Diodes Incorporated
AL5802
30V, ADJUSTABLE CURRENT SINK LINEAR LED DRIVER
ADVANCE INFORMATION
NEW PRODUCT
SDM10U45LP
VS
To remove the potential of incorrect connection of the power supply
damaging the lamp’s LEDs, many systems use some form of
reverse polarity protection.
One solution for reverse input polarity protection is to simply use a
diode with a low VF in-line with the driver/LED combination. The low
VF increases the available voltage to the LED stack and dissipates
less power. A circuit example is presented in Fig. 18 using Diodes
Inc. SBR® (Super Barrier Rectifier) technology. An SDM10U45LP
(0.1A/45V) is shown, providing exceptionally low VF for its package
size of 1mm x 0.6mm, equivalent to an 0402 chip style package.
Other reverse voltage ratings are also available in Diodes’ website
such as the SBR02U100LP (0.2A/100V) or SBR0220LP (0.2A/20V).
AL5802
RS
Fig. 18 Application circuit for LED driver
with reverse polarity protection
Automotive applications commonly use this method for reverse
battery protection.
A second approach, shown in Fig. 19, improves upon the method
shown in Fig. 18. Whereas the method in Fig. 18 protects the light
engine, it will not function until the problem has been diagnosed and
corrected.
BAS40BRW
VS
The method shown in Fig. 19 not only provides reverse polarity
protection, it also corrects the reversed polarity, allowing the light
engine to function.
The BAS40BRW incorporates four low VF, Schottky diodes into a
single package and allows more voltage available for the LED stack
and dissipates less power that standard rectifier bridges.
AL5802
RS
Fig. 19 Application circuit for LED driver with
assured operation regardless of polarity
SBR is a registered trademark of Diodes Incorporated.
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AL5802
Document number: DS35516 Rev.4 - 2
www.diodes.com
November 2011
© Diodes Incorporated
AL5802
30V, ADJUSTABLE CURRENT SINK LINEAR LED DRIVER
Ordering Information
Packaging
(Notes 8&9)
SOT26
AL5802
Notes:
Quantity
3,000/Tape & Reel
7” Tape and Reel
Part Number Suffix
-7
8.EU Directive 2002/95/EC (RoHS). All applicable RoHS exemptions applied, see EU Directive 2002/95/EC Annex Notes.
9.Pad layout as shown on Diodes Inc. suggested pad layout document AP02001, which can be found on our website athttp://www.diodes.com.
Marking Information
L102
Date Code Key
Year
2011
Code
Y
Month
Code
Jan
1
2012
Z
Feb
2
L102 = Product Type Marking Code
YM = Date Code Marking
Y = Year (ex: Y = 2011)
M = Month (ex: 9 = September)
YM
ADVANCE INFORMATION
NEW PRODUCT
Device
2013
A
Mar
3
Apr
4
2014
B
May
5
Jun
6
2015
C
Jul
7
Aug
8
2016
D
Sep
9
Oct
O
2017
E
Nov
N
Dec
D
Package Outline Dimensions
A
B C
H
K
J
AL5802
Document number: DS35516 Rev.4 - 2
M
D
L
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SOT26
Dim Min Max Typ
A
0.35 0.50 0.38
B
1.50 1.70 1.60
C
2.70 3.00 2.80
D
⎯
⎯ 0.95
H
2.90 3.10 3.00
J
0.013 0.10 0.05
K
1.00 1.30 1.10
L
0.35 0.55 0.40
M
0.10 0.20 0.15
0°
8°
α
⎯
All Dimensions in mm
November 2011
© Diodes Incorporated
AL5802
30V, ADJUSTABLE CURRENT SINK LINEAR LED DRIVER
Suggested Pad Layout
ADVANCE INFORMATION
NEW PRODUCT
C2
Z
C2
C1
G
Y
Dimensions Value (in mm)
Z
3.20
G
1.60
X
0.55
Y
0.80
C1
2.40
C2
0.95
X
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AL5802
Document number: DS35516 Rev.4 - 2
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November 2011
© Diodes Incorporated