AL5802

AL5802
ADVANCE INFORMATION
NEW PRODUCT
30V, ADJUSTABLE CURRENT SINK LINEAR LED DRIVER
Description
Pin Assignments
The AL5802 combines a high gain NPN transistor with a pre-biased
NPN transistor to make a simple small footprint LED driver.
(Top View)
The LED current is set by an external resistor connected from REXT
pin (6) to GND pin (4), the internal high gain transistor develops
approximately 0.6V across the external resistor.
6
5
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.
4
Q1
Q2
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 open-collector NPN transistor or opendrain N-channel MOSFET.
1
The AL5802 is available in a SOT26 package and is ideal for driving
20mA to 120mA LED currents.
Applications

Reference voltage VRSET = 0.65V


-40 to +125°C temperature range

LED signs

0.8V to 30V open-collector output

Offline LED luminaries

Negative temperature co-efficient – automatically reduces the
LED current at high temperatures
Low thermal impedance SOT26 with copper leadframe

Totally Lead-Free & Fully RoHS Compliant (Notes 1 & 2)

Halogen and Antimony Free. “Green” Device (Note 3)

Qualified to AEC-Q101 Standards for High Reliability
3
SOT26
Features

2
Linear LED driver
Typical Application Circuit
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 (<1500ppm total Br + Cl) and
<1000ppm antimony compounds.
AL5802
Document number: DS35516 Rev. 9 - 2
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AL5802
ADVANCE INFORMATION
NEW PRODUCT
Pin Descriptions
Pin Number
1
2
3
4
Name
OUT
BIAS
EN
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 4)
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.
Note:
4. With pins 5 and 6 connected together.
AL5802
Document number: DS35516 Rev. 9 - 2
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AL5802
ADVANCE INFORMATION
NEW PRODUCT
Package Thermal Data
Characteristic
Power Dissipation (Note 5) @ TA = +25°C
Power Dissipation (Note 6) @ TA = +25°C
Power Dissipation (Note 7) @ TA = +25°C
Thermal Resistance, Junction to Ambient Air (Note 5) @ TA = +25°C
Thermal Resistance, Junction to Ambient Air (Note 6) @ TA = +25°C
Thermal Resistance, Junction to Ambient Air (Note 7) @ TA = +25°C
Notes:
Symbol
Value
0.37
0.87
1
PD
Unit
W
335
143
120
RθJA
°C/W
5. Device mounted on FR-4 PCB, 2oz with minimum recommended pad layout.
6. Device mounted on 25mm x 25mm 2oz copper board.
7. Device mounted on 50mm x 50mm 2oz copper board.
Recommended Operating Conditions
Symbol
VBIAS
VOUT
ILED
TA
Note:
Parameter
Supply voltage range
OUT voltage range
LED pin current (Note 8)
Operating ambient temperature range
Min
4.5
0.8
10
-40
Max
30
30
120
+125
Unit
V
mA
°C
8. Subject to ambient temperature, power dissipation and PCB.
Electrical Characteristics – NPN Transistor – Q1 (@TA = +25°C, unless otherwise specified.)
Symbol
V(BR)CEO
V(BR)EBO
ICEX
IBL
Characteristic
Collector-Emitter Breakdown Voltage (Note 9)
Emitter-Base Breakdown Voltage
Collector Cutoff Current
Base Cutoff Current
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
DC Current Gain
hFE
VCE(SAT)
VBE(SAT)
Collector-Emitter Saturation Voltage (Note 9)
Base-Emitter Saturation Voltage
Min
40
6.0
—
—
Typ
—
—
—
—
Max
—
—
50
50
Unit
V
V
nA
nA
40
70
100
—
—
—
—
—
300
—
—
0.65
—
—
0.20
0.85
V
V
Electrical Characteristics – 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 9)
Emitter-Base Breakdown Voltage
Collector Cut-Off Current
Emitter Cut-Off Current
Collector-Emitter Saturation Voltage (Note 9)
DC Current Gain (Note 9)
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
—
13
Unit
V
V
V
µA
µA
V
—
kΩ
*Characteristics of transistor only.
Note:
9. Short duration pulse test used to minimize self-heating effect.
AL5802
Document number: DS35516 Rev. 9 - 2
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AL5802
ADVANCE INFORMATION
NEW PRODUCT
Thermal Characteristics
AMBIENT TEMPERAURE (°C)
Fig. 2 Derating Curve
Fig. 3 Max Power vs. Area
Fig. 4 Thermal Resistance vs. Area
AL5802
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AL5802
ADVANCE INFORMATION
NEW PRODUCT
Typical Performance Characteristics
Fig. 5 Output Current vs. Vout
Fig. 6 Output Current vs. REXT
Fig. 8 Output Current vs. Vout
Fig. 7 Output Current vs. Vout
Fig. 9 Output Current vs. Vout
Note:
Fig. 10 Output Current vs. Vbias
10. Vout in the “Output current Vs Vout” graphs limited by power dissipation in the device.
AL5802
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ADVANCE INFORMATION
NEW PRODUCT
AL5802
Fig. 11 Output Current vs. Vbias
Fig. 12 Output Current vs. Vbias
Fig. 13 Output Current vs. Vbias
AL5802
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AL5802
ADVANCE INFORMATION
NEW PRODUCT
Application Information
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. 14 Typical 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. 15 Application Circuit for Increasing LED Current
AL5802
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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. 16 Application Circuits for LED Driver with PWM Dimming Functionality
60
50
LED CURRENT (mA)
ADVANCE INFORMATION
NEW PRODUCT
AL5802
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
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AL5802
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
AL5802
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AL5802
Device
Qualification
Packaging
AL5802
AL5802
Commercial
Commercial
SOT26
SOT26
Note:
Tape and Reel
Quantity
Part Number Suffix
3,000/Tape & Reel
-7
10,000/Tape & Reel
-13
11. For packaging details, go to our website at http://www.diodes.com/products/packages.html.
Marking Information
L102
Date Code Key
Year
2011
Code
Y
Month
Code
Jan
1
2012
Z
Feb
2
2013
A
Mar
3
L102 = Product Type Marking Code
YM = Date Code Marking
Y = Year (ex: B = 2014)
M = Month (ex: 9 = September)
YM
ADVANCE INFORMATION
NEW PRODUCT
Ordering Information (Note 11)
2014
B
Apr
4
May
5
2015
C
Jun
6
Jul
7
2016
D
Aug
8
2017
E
Sep
9
Oct
O
2018
F
Nov
N
2019
G
Dec
D
Package Outline Dimensions
Please see AP02002 at http://www.diodes.com/datasheets/ap02002.pdf for latest version.
A
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°


All Dimensions in mm
B C
H
K
M
J
L
D
Suggested Pad Layout
Please see AP02001 at http://www.diodes.com/datasheets/ap02001.pdf for the latest version.
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
AL5802
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AL5802
ADVANCE INFORMATION
NEW PRODUCT
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Copyright © 2014, Diodes Incorporated
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AL5802
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