Diodes AL5802 User Manual

A

L5802

Description

The AL5802 combines a high gain NPN transistor with a pre-biased
NPN transistor to make a simple small footprint LED driver.

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.

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.

PWM dimming of the LED current can be achieved by either driving

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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.

The AL5802 is available in a SOT26 package and is ideal for driving
20mA to 120mA LED currents.

Features

ADVANCE INFORMATION

 Reference voltage VRSET = 0.65V

 -40 to +125°C temperature range

 0.8V to 30V open-collector output

 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

30V, ADJUSTABLE CURRENT SINK LINEAR LED DRIVER

Pin Assignments

(Top View)

654

Q1

Q2

123

SOT26

Applications

 Linear LED driver

 LED signs

 Offline LED luminaries

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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Pin Descriptions

Pin Number Name Function

1 OUT Open-collector LED driver output
2 BIAS Biases the open collector output transistor
3 EN Enable pin for PWM dimming. Provides access to the base of Q2 and collector of Q1
4 GND Ground reference point for setting LED current

5 FB

6 REXT Current sense pin. LED current sensing resistor should be connected from here to GND.

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Functional Block Diagram

ADVANCE INFORMATION

L5802

Feedback pin.
Should be connected to pin 6.

Fig. 1 Block Diagram

Absolute Maximum Ratings

Symbol Characteristics Values Unit

V

OUT

V

BIAS

V

FB

V

EN

V

REXT

I

OUT

T

J

T

ST

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

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

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30 V
30 V

6 V
6 V
6 V

150 mA

-40 to +150 °C

-55 to +150 °C

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(BR)

(BR)

)

)

(BR)

(BR)

(BR)

)

L5802

Package Thermal Data

Characteristic Symbol Value Unit

Power Dissipation (Note 5) @ TA = +25°C
Power Dissipation (Note 6) @ T
Power Dissipation (Note 7) @ T

= +25°C

A

= +25°C

A

P

D

Thermal Resistance, Junction to Ambient Air (Note 5) @ TA = +25°C
Thermal Resistance, Junction to Ambient Air (Note 6) @ T
Thermal Resistance, Junction to Ambient Air (Note 7) @ T

Notes: 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.

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= +25°C

A

= +25°C

A

R

θJA

0.37

0.87
1

335
143
120

W

°C/W

Recommended Operating Conditions

Symbol Parameter Min Max Unit

V

BIAS

V

ADVANCE INFORMATION

I

OUT

LED

TA

Note: 8. Subject to ambient temperature, power dissipation and PCB.

Electrical Characteristics – NPN Transistor – Q1 (@T

Symbol Characteristic Test Condition Min Typ Max Unit

V
V

I

V

CE(SAT

V

BE(SAT

CEX

IBL

hFE

Collector-Emitter Breakdown Voltage (Note 9)

CEO

Emitter-Base Breakdown Voltage

EBO

Collector Cutoff Current
Base Cutoff Current

DC Current Gain

Collector-Emitter Saturation Voltage (Note 9)
Base-Emitter Saturation Voltage

Electrical Characteristics – NPN Pre-biased Transistor – Q2 (@T

Symbol Characteristic Test Condition Min Typ Max Unit

V
V
V

I

CBO

I

EBO

V

CE(SAT

hFE

R1

*Characteristics of transistor only.

Note: 9. Short duration pulse test used to minimize self-heating effect.

AL5802

Document number: DS35516 Rev. 9 - 2

Collector-Base Breakdown Voltage

CBO

Collector-Emitter Breakdown Voltage (Note 9)

CEO

Emitter-Base Breakdown Voltage

EBO

Collector Cut-Off Current
Emitter Cut-Off Current
Collector-Emitter Saturation Voltage (Note 9)
DC Current Gain (Note 9)
Input Resistance — 7 10 13 kΩ

Supply voltage range 4.5 30
OUT voltage range 0.8 30

V

LED pin current (Note 8) 10 120 mA
Operating ambient temperature range -40 +125 °C

= +25°C, unless otherwise specified.)

A

IC = 1.0mA, IB = 0
IE = 10µA, IC = 0
VCE = 30V, V
VCE = 30V, V

= 100µA, VCE = 1.0V

I

C

= 1.0mA, VCE = 1.0V

I

C

I

= 10mA, VCE = 1.0V

C

IC = 10mA, IB = 1.0mA
IC = 10mA, IB = 1.0mA

IC = 50μA, IE = 0
IC = 1mA, IB = 0
IE = 50μA, IC = 0
VCB = 30V, IE = 0
V

= 4V, IC = 0

EB

IC = 10mA, IB = 1mA
VCE = 5V, IC = 150mA

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EB(OFF)

EB(OFF)

= 3.0V
= 3.0V

= +25°C, unless otherwise specified.)

A

40 — — V

6.0 — — V
— — 50 nA
— — 50 nA

40
70

100

—
—
—

—
—

300

— — 0.20 V

0.65 — 0.85 V

30 — — V
30 — — V

5.0 — — V

— — 0.5 µA
— — 0.5 µA
— — 0.3 V

100 — — —

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Thermal Characteristics

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ADVANCE INFORMATION

AMBIENT TEMPERAURE (°C)

Fig. 2 Derating Curve

L5802

Fig. 3 Max Power vs. Area

Fig. 4 Thermal Resistance vs. Area

AL5802

Document number: DS35516 Rev. 9 - 2

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Typical Performance Characteristics

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L5802

Fig. 5 Output Current vs. V

Fig. 6 Output Current vs. R

out

EXT

ADVANCE INFORMATION

Fig. 7 Output Current vs. V

out

Fig. 8 Output Current vs. V

out

Fig. 9 Output Current vs. V

Note: 10. V

in the “Output current Vs V

out

AL5802

Document number: DS35516 Rev. 9 - 2

Fig. 10 Output Current vs. V

out

” graphs limited by power dissipation in the device.

out

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bias

© Diodes Incorporated

March 2014

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L5802

ADVANCE INFORMATION

AL5802

Document number: DS35516 Rev. 9 - 2

Fig. 11 Output Current vs. V

Fig. 13 Output Current vs. V

bias

bias

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Fig. 12 Output Current vs. V

bias

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Application Information

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ADVANCE INFORMATION

Fig. 14 Typical Application Circuit for

Linear Mode Current Sink LED Driver

L5802

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 R
reference to set the voltage across R

and controls the base current

EXT

into Q2. Q2 operates in linear mode to regulate the LED current. The
LED current is

= V

I

LED

BE(Q1)

/ R

EXT

From this, for any required LED current the necessary external resistor

can be calculated from

R

EXT

= V

R

EXT

BE(Q1)

/ I

LED

Two or more AL5802 can be connected in parallel to construct higher
current LED strings as shown in Figure 15.

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.

V
P

CE(Q2)

= V

D

= VCC – V

* I

CE(Q2)

LED

+ ( VCC – V

LED

– V

BE(Q1)

BE(Q2)

– V

BE(Q1)

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:

P

= ( T

D

J(MAX)

- TA) /R

θJA

Refer to the thermal characteristic graphs on page 4 for selecting the
appropriate PCB copper area.

. Q1 uses its VBE as

EXT

)2 / R1

Fig. 15 Application Circuit for Increasing LED Current

AL5802

Document number: DS35516 Rev. 9 - 2

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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.

NEW PRODUCT

-or-

ADVANCE INFORMATION

L5802

AL5802

Document number: DS35516 Rev. 9 - 2

Fig. 16 Application Circuits for LED Driver with PWM Dimming Functionality

60

50

40

30

20

LED CURRENT (mA)

10

0

Fig. 17 Typical LED current response vs. PWM duty cycle for

200

PWM DUTY CYCLE (%)

= 13Ω at 400Hz PWM frequency

R

EXT

40 60 80 100

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A

A

ADVANCE INFORMATION

L5802

SDM10U45LP

V

S

L5802

R

S

Fig. 18 Application circuit for LED driver

with reverse polarity protection

V

S

BAS40BRW

L5802

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 V

increases the available voltage to the LED stack and dissipates

V

F

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 V
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).

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.

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 V
single package and allows more voltage available for the LED stack
and dissipates less power that standard rectifier bridges.

in-line with the driver/LED combination. The low

F

for its package

F

, Schottky diodes into a

F

Fig. 19 Application circuit for LED driver with

assured operation regardless of polarity

AL5802

Document number: DS35516 Rev. 9 - 2

R

S

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Ordering Information (Note 11)

Device Qualification Packaging

AL5802 Commercial SOT26 3,000/Tape & Reel -7
AL5802 Commercial SOT26 10,000/Tape & Reel -13

Note: 11. For packaging details, go to our website at http://www.diodes.com/products/packages.html.

Marking Information

NEW PRODUCT

L102 = Product Type Marking Code
YM = Date Code Marking
Y = Year (ex: B = 2014)
M = Month (ex: 9 = September)

ADVANCE INFORMATION

L102

Date Code Key

Year 2011 2012 2013 2014 2015 2016 2017 2018 2019

Code Y Z A B C D E F G

Month Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Code 1 2 3 4 5 6 7 8 9 O N D

YM

Package Outline Dimensions

Please see AP02002 at http://www.diodes.com/datasheets/ap02002.pdf for latest version.

K

J

A

B C

H

M

D

L

Suggested Pad Layout

Please see AP02001 at http://www.diodes.com/datasheets/ap02001.pdf for the latest version.

G

Z

C2

C2

C1

AL5802

Document number: DS35516 Rev. 9 - 2

Y

X

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Quantity Part Number Suffix

Tape and Reel

Dim Min Max Typ

Dimensions Value (in mm)

Z 3.20
G 1.60
X 0.55
Y 0.80

C1 2.40
C2 0.95

SOT26

A 0.35 0.50 0.38
B 1.50 1.70 1.60
C 2.70 3.00 2.80
D

 

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

0.95



L5802

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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).

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2. support or sustain life and whose failure to perform when properly used in accordance with instructions for use provided in the

IMPORTANT NOTICE

LIFE SUPPORT

L5802

AL5802

Document number: DS35516 Rev. 9 - 2

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