Diodes AL8806Q User Manual

Description

The AL8806Q 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 30V. The AL8806Q 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 AL8806Q 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.

The AL8806Q has been qualified to AEC-Q100 Grade 1 and is

Automotive Grade supporting PPAPs

and SET input pins. Dimming is achieved

Features

AUTOMOTIVE GRADE BUCK LED DRIVER

Pin Assignments

Applications

L8806Q

HIGH EFFICIENCY 30V 1.6A

• LED driving current up to 1.5A

• Better than 5% accuracy

• High efficiency up to 98%

• Optimally controlled switching speeds

• Operating input voltage from 6V to 30V

• PWM/DC input for dimming control

• Built-in output open-circuit protection

• Automotive Grade with AEC-Q100 Qualification

• MSOP-8EP: Available in “Green” Molding Compound (No Br, Sb)

 Totally Lead-Free & Fully RoHS Compliant (Notes 1 & 2)

 Halogen and Antimony Free. “Green” Device (Note 3)

• Automotive Grade

 Qualified to AEC-Q100 Standards for High Reliability

 PPAP Capable (Note 4)

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"

3. Halogen- and Antimony-free "Green” products are defined as those which contain <900ppm bromine, <900ppm chlorine (<1500ppm total Br + Cl) and

4. Automotive products are AEC-Q100 qualified and are PPAP capable. Automotive, AEC-Q100 and standard products are electrically and thermally the same,

Typical Applications Circuit

and Lead-free.

<1000ppm antimony compounds.

except where specified. For more information, please refer to http://www.diodes.com/quality/product_compliance_definitions/.

• Automotive LED Lamps

• Multi-Die LED Driver

AL8806Q

Document number: DS36905 Rev. 1 - 2

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Pin Descriptions

Pin Name Pin Number Functions

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

GND 2, 3 GND Pin

CTRL 4

SW 5, 6 Switch Pin. Connect inductor/freewheeling diode here, minimizing track length at this pin to reduce EMI. N/C 7 No Connection

VIN

EP EP

Functional Block Diagram

Dimming and On/Off Control Input.

• Leave floating for normal operation.

= V

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

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

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

ground conduction path.

= 2.5V giving nominal average output current I

REF

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

CTRL

2.2µF X7R ceramic capacitor – see applications

OUTnom

= 0.1/RS)

L8806Q

OUTnom

Absolute Maximum Ratings

Symbol Parameter Ratings Unit

ESD HBM Human Body Model ESD Protection 2.5 kV

ESD MM Machine Model ESD Protection 200 V

ESD CDM Charged Device Model ESD Protection — V

VIN

VSW

CTRL

SW-RMS

SW-PK

LEAD

TST

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

AL8806Q

Document number: DS36905 Rev. 1 - 2

Continuous V

Transient VIN pin voltage relative to GND

SW voltage relative to GND -0.3 to +36 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.

pin voltage relative to GND

(@TA = +25°C, unless otherwise specified.)

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-0.3 to +36

-0.3 to +40

April 2014

L8806Q

Recommended Operating Conditions (@T

Symbol Parameter Min Max Unit

VIN

CTRLH

CTRLDC

CTRLL

fSW

ISW

Electrical Characteristics (@ V

Symbol Parameter Conditions Min Typ. Max Unit

INSU

INSH

VTH

TH-H

SET

CTRL

REF

DS(on)

SW_Leakage

θJA

θJC

Notes: 5. AL8806Q does not have a low power standby mode but current consumption is reduced when output switch is inhibited: V

6. Refer to figure 5 for the device derating curve.

7. 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

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

Operating Input Voltage relative to GND 6.0 30 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

Maximum Switching Frequency — 1 MHz

Continuous Switch Current — 1.5 A

Junction Temperature Range -40 +125 °C

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

Internal regulator start up threshold

Internal regulator hysteresis threshold

VIN rising

VIN falling

Quiescent current Output not switching

Input supply Current CTRL pin floating f = 250kHz

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-toAmbient (Note 6)

Thermal Resistance Junction-to-Case (Note 6)

with V

layer maximum area ground plane. For better thermal performance, larger copper pad for heat-sink is needed.

CTRL

≤ 2.5V

ISW = 1A

VIN = 30V

(Note 7) — 69 —

(Note 7) — 4.3 —

= +25°C, unless otherwise specified.)

(Note 5)

≥ 2.6V or floating.

CTRL

= VIN-0.1

SET

—

100

—

5.9 V

300 mV

— 350 µA

1.8 5 mA

95 100 105 mV

— 16 22 µA

— 0.18 0.35 Ω

— — 0.5 μA

°C/W

= 0V. Parameter is tested

SENSE

AL8806Q

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CUR

RENT

Typical Performance Characteristics (@T

V = 0V

CTRL

V = V

350

300

250

200



I (µA)

150

100

SET IN

T = 25C

0 5 10 15 20 25 30

V (V)

Supp ly Curr ent (not switching) v s. Input Current

1.6

1.4

T = 25°C

L =68 µH

R = 68m

SET

= +25°C, unless otherwise specified.)

L = 33µ H

800

700

600

L = 68µ H

500

400

Freque ncy (kHz)

300

200

L = 100 µ H

100

012 34 5

V = V = 12V

SE T I N

T = 25C

V(V)

CTRL

Switching Frequency vs. V

L8806Q

V = 12V

1 LED R = 150m

SET

T = 25°C

CTRL

1.2

R = 100m

(A)

0.8

SET

R = 150m

SET

0.6

LED

0.4

0.2

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

CTRL VOLTAGE (V)

LED Current vs. V

CTRL

2.5

1.5

CTRL

V (V)

0.5

V= Open

CTRL

V = V

SE T IN

T = 25C

CTRL

I (µA)

-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 I N

2.51

2.50

CTRL

V (V)

2.49

0 5 10 15 20 25 30

V (V) V vs. In put Voltag e (CTRL pin o pen circuit)

CTRL

2.48

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

V vs. Temperature

CTRL

AL8806Q

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