Diodes AL8806 User Manual

A

L8806

HIGH EFFICIENCY 36V 1.5A BUCK LED DRIVER

Description

The AL8806 is a step-down DC/DC converter designed to drive LEDs
with a constant current. The device can drive up to 8 LEDs,
depending on the forward voltage of the LEDs, in series from a
voltage source of 6V to 36V. The AL8806 switches at frequencies up
to 1MHz. This allows the use of small size external components,
hence minimizing the PCB area needed.

Maximum output current of AL8806 is set via an external resistor
connected between the V
by applying either a DC voltage or a PWM signal at the CTRL input
pin. An input voltage of 0.4V or lower at CTRL switches off the output
MOSFET simplifying PWM dimming.

and SET input pins. Dimming is achieved

IN

Features

 LED driving current up to 1.5A
 Better than 5% accuracy
 High efficiency up to 98%
 Operating input voltage from 6V to 36V
 High switching frequency up to 1MHz
 PWM/DC input for dimming control
 Built-in output open-circuit protection
 MSOP-8EP: Available in “Green” Molding Compound (No Br,

Sb) with lead Free Finish/ RoHS Compliant

 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 (<1500ppm total Br + Cl) and
<1000ppm antimony compounds.

Pin Assignments

SET

SET

GND

GND
GND

GND

CTRL

CTRL

Applications

 High Power MR16 Lamps
 General Illumination Lamps
 Multi-Die LED Driver

1

1
2

2

AL8806

AL8806

3

3
4

4

MSOP-8EP

V

V

8

8

IN

IN

7

7

N/C

N/C

6

6

SW

SW

5

5

SW

SW

Typical Applications Circuit

D2 D3

DFLS230LH

12V

~

AC

x4

D4 D5

AL8806

Document number: DS35144 Rev. 5 - 2

C1

450µF

DFLS230LH

D1

R

SET

0R089

IN

V

AL8806

CTRL

GND

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SET

SW

33µH L1

C2

1µF

Multi-

die

LED

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© Diodes Incorporated

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Pin Descriptions

Pin Number

Pin

Name

GND 2, 3 GND Pin

CTRL 4

SET 1 Set Nominal Output Current Pin. Configure the output current of the device.

N/C 7 no connection

MSOP-8EP

SW 5, 6 Switch Pin. Connect inductor/freewheeling diode here, minimizing track length at this pin to reduce EMI.

Dimming and On/Off Control Input.
 Leave floating for normal operation.

(V

= V

= 2.5V giving nominal average output current I

REF

< 2.5V) to adjust output current from 20% to 100% of I

CTRL

 Drive to voltage below 0.4V to turn off output current
 Drive with DC voltage (0.5V < V
 A PWM signal (low level ≤ 0.4V and high level > 2.6; transition times less than 1us) allows the output current to be

VIN

EP EP

8

Input Supply Pin. Must be locally decoupled to GND with >
more information.

Exposed pad:
Connect to GND and thermal mass for enhanced thermal impedance. It should not be used as electrical ground

conduction path.

CTRL

adjusted below the level set by the resistor connected to SET input pin.

Function

= 0.1/RS)

OUTnom

OUTnom

2.2µF X7R ceramic capacitor – see applications section for

Functional Block Diagram

L8806

AL8806

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L8806

Absolute Maximum Ratings (@T

Symbol Parameter Ratings Unit

ESD HBM Human Body Model ESD Protection 2.5 kV

ESD MM Machine Model ESD Protection 200 V

VIN Continuous VIN pin voltage relative to GND

VSW

V

CTRL

I

SW-RMS

I

SW-PK

TJ

T

LEAD

T

ST

Caution: Stresses greater than the 'Absolute Maximum Ratings' specified above, may cause permanent damage to the device. These are stress ratings only;

SW voltage relative to GND -0.3 to +40 V
CTRL pin input voltage -0.3 to +6 V
DC or RMS switch current 1.65 A
Peak switch current (<10%) 3 A
Junction Temperature 150 °C
Lead Temperature Soldering 300 °C
Storage Temperature Range -65 to +150 °C

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.

Recommended Operating Conditions (@T

Symbol Parameter Min Max Unit

VIN

V

CTRLH

V

CTRLDC

V

CTRLL

ISW

f

OSC

TJ

Operating Input Voltage relative to GND 6.0 36 V
Voltage High for PWM dimming relative to GND 2.6 5.5 V
Voltage range for 20% to 100% DC dimming relative to GND 0.5 2.5 V
Voltage Low for PWM dimming relative to GND 0 0.4 V
DC or RMS switch current 1.5 A
Switching Frequency 1 MHz
Junction Temperature Range -40 +125 °C

Electrical Characteristics (@V

Symbol Parameter Conditions Min Typ Max Unit

V

INSU

V

INSH

IQ

IS

VTH

V

TH-H

I

SET

R

CTRL

V

REF

R

DS(on)

I

SW_Leakage



JA



JC

Notes: 4. AL8806 does not have a low power standby mode but current consumption is reduced when output switch is inhibited: V
tested with V

5. Dominant conduction path via exposed pad. Refer to figure 5 for the device derating curve.

6. Measured on an FR4 51x51mm PCB with 2oz copper standing in still air with minimum recommended pad layout on top layer and thermal vias to
bottom layer maximum area ground plane. For better thermal performance, larger copper pad for heat-sink is needed.

Internal regulator start up threshold
Internal regulator hysteresis threshold
Quiescent current Output not switching
Input supply Current CTRL pin floating f = 250kHz 1.8 5 mA
Set current Threshold Voltage
Set threshold hysteresis ±20 mV
SET pin input current
CTRL pin input resistance Referred to internal reference 50 kΩ
Internal Reference Voltage 2.5 V
On Resistance of SW MOSFET
Switch leakage current
Thermal Resistance Junction-to-Ambient (Note 5) MSOP-8EP (Note 6) 69
Thermal Resistance Junction-to-Case (Note 5) MSOP-8EP (Note 6) 4.3

≤ 2.5V

CTRL

= +25°C, unless otherwise specified.)

A

-0.3 to +40 V

= +25°C, unless otherwise specified.)

A

= 12V, TA = +25°C, unless otherwise specified.)

IN

VIN rising
VIN falling

(Note 4) 350 µA

V

≥ 2.6V or floating.

CTRL

V

= VIN-0.1

SET

ISW = 1A
VIN =36V

5.9 V

100 300 mV

95 100 105 mV

16 22 µA

0.18 0.35 Ω

0.5 μA

C/W

= 0V. Parameter is

SENSE

AL8806

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0

CUR

RENT

Typical Performance Characteristics

40

V = 0V

CTRL

V = V

350

SET IN

°

T = 25C

A

300

250

200



IN

I (µA)

150

100

50

0

0 5 10 15 20 25 30

V (V)

IN

Supply Current (not switching) vs. Input Current

1.6

1.4

T = 25°C

A

L =68µH

R = 68m

SET



L8806

900

L = 33µ H

800
700

600

L = 68µ H

500
400

Frequency (kHz)

300

200

L = 100 µ H

100

0

012345

80

60

Switching Frequency vs. V

V = V = 12V

SET IN



T = 25C

A

V(V)

CTR L

V = 12V

IN

1 LED
R = 150m

SET

T = 25°C

A

CTRL



1.2

R = 100m

(A)

1

0.8

SET

R = 150m

SET

0.6

LED

0.4

0.2

0

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5

CTRL VOLTAGE (V)

2.5

1.5

CTRL

V (V)

0.5

LED Current vs. V

3

2

1

CTRL

V= Open

CTRL

V = V

SET IN

T = 25C

A



40

20



CTRL

I (µA)

0

-20

-40

-60

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5
V (V)

CTRL

I vs V

CTRL CTRL

2.52

V = Open

CTRL

V = V = 12V

SET IN

2.51

2.50

CTRL

V (V)



2.49

0

0 5 10 15 20 25 30

V (V)
V vs. Input Voltage
(CTRL pin open circuit)

IN

CTRL

2.48

-40 -15 10 35 60 85 110
Ambient Temperature (°C)

V vs. Temperature

CTRL

AL8806

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R (m

%

Typical Performance Characteristics (cont.)

5.0

V = 12V

4.5

4.0

IN

1 LE D
R = 150m

SET

L = 68µ H

3.5

3.0

2.5

LED Current E rror

2.0

I

1.5

LED Current Error (%)

LED

1.0

0.5

0.0
0% 20% 40% 60% 80% 100%

PWM Duty Cycle

I vs. PWM Duty Cycle

LED

260
240

220

)

200



180

DS(ON)

160
140
120
100

-40 -15 10 35 60 85 110

V = Open

CTRL

V = V 12V

SET IN

AMBIENT TEMPERATURE (°C)

SW R vs. Temperature

DS(ON)

100

90%
80%

L = 33µ H
R = 150m

SET

T = 25C

A

2 LE D

70%

1

0.9



0.8

0.7

0.6

0.5

0.4

0.3

0.2

0.1
0





L8806

200
180
160
140



120
100

DS(ON)

80

LED Current (A)

R (m)

60
40
20

0

051015

R vs. Input Voltage

DS(ON)

V (V)

IN

V = Open

CTRL

V = V 12V

SET IN



T = 25C

A

20 25 30

130
125
120

V

SEN SE

115

V

110

SW

105

SENSE

100

V (mV)

95
90

85
80

02468

R = 150m

SET

L = 68µ H
V = 12V

IN

1 LED Load

Time (µs)



SW Output Switching Characteristics

18
16

14
12

10

8
6
4

2
0

-2

SW

V

60%
50%

Duty Cycle

40%
30%
20%
10%

0%

6 9 12 15 18 21 24 27 30

Input Voltage (V)

Duty Cycle vs. Input Voltage

AL8806

Document number: DS35144 Rev. 5 - 2

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