Diodes AL8807Q User Manual

A

Description

The AL8807Q is a step-down DC/DC converter designed to drive

LEDs with a constant current. The device can drive up to 9 LEDs,

depending on the forward voltage of the LEDs, in series from a

voltage source of 6V to 30V. Series connection of the LEDs provides

identical LED currents resulting in uniform brightness and eliminating

the need for ballast resistors. The AL8807Q switches at frequency up

to 1MHz with controlled rise and fall times to reduce EMI. This allows

the use of small size external components, hence minimizing the PCB

area needed.

Maximum output current of AL8807Q 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 AL8807Q has been qualified to AEC-Q100 Grade 1 and is

Automotive Grade supporting PPAPs

and SET input pins. Dimming is achieved

IN

Features

AUTOMOTIVE GRADE BUCK LED DRIVER

Pin Assignments

SET

GND

CTRL

Applications

L8807Q

HIGH EFFICIENCY LOW 30V 1.3A

(Top View)

V

IN

N/C

SW

MSOP-8EP

 LED driving current up to 1.3A

 Better than 5% accuracy

 High efficiency up to 96%

 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" 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.

4. Automotive products are AEC-Q100 qualified and are PPAP capable. Automotive, AEC-Q100 and standard products are electrically and thermally the same, except where specified. For more information, please refer to http://www.diodes.com/quality/product_compliance_definitions/.

Typical Applications Circuit

 Automotive Interior LED Lamps

 Automotive Exterior LED Lamps

AL8807Q

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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

(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.

8

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

Exposed pad/TAB connect to GND and thermal mass for enhanced thermal impedance. 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)

L8807Q

OUTnom

Absolute Maximum Ratings

Symbol Parameter Ratings Unit

ESD HBM Human Body Model ESD Protection 4000 V

ESD MM Machine Model ESD Protection 300 V

ESD CDM Charged Device Model ESD Protection 1000 V

VIN Continuous VIN pin voltage relative to GND

VSW

V

CTRL

I

SW-RMS

I

SW-PK

TJ

T

LEAD

TST

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

AL8807Q

Document number: DS36904 Rev. 1 - 2

SW voltage relative to GND -0.3 to +40 V

CTRL pin input voltage -0.3 to +6 V

DC or RMS Switch current 1.6 A

Peak Switch current (<10%) 2.5 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.

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

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March 2014

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L8807Q

Recommended Operating Conditions (@T

= +25°C, unless otherwise specified.)

A

Symbol Parameter Min Max Unit

VIN

V

CTRLH

V

CTRLDC

V

CTRLL

fSW

ISW

TJ

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 — 1.3 A

Junction Temperature Range -40 125 °C

Electrical Characteristics (@ V

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

IN

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)

tR

tF

I

SW_Leakage

JA

JC

Notes: 5. AL8807Q does not have a low power standby mode but current consumption is reduced when output switch is inhibited: V tested with V

6. Refer to figure 35 for the device derating curve.

7. Test condition for MSOP-8EP: Device mounted on FR-4 PCB (51mm x 51mm 2oz copper, minimum recommended pad layout on top layer and

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

8. Dominant conduction path via exposed pad.

Internal regulator start up threshold

Internal regulator hysteresis threshold

Quiescent current Output not switching (Note 5) — — 350 µA

Input supply Current CTRL pin floating f = 250kHz — 1.8 5 mA

Set current Threshold Voltage — 95 100 105 mV

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

SW rise time

SW fall time — 20 — ns

Switch leakage current

Thermal Resistance Junction-to-

Ambient (Note 6)

Thermal Resistance Junction-to-case

(Note 8)

≤ 2.5V

CTRL

VIN rising

VIN falling

V

= VIN-0.1

SET

ISW = 1A

= 100±20mV, fSW = 250kHz

V

SENSE

V

= 0.1V~12V~0.1V CL = 15pF

SW

VIN =30V

— — 5.9 V

100 — 300 mV

— 16 22 µA

— 0.25 0.4 Ω

— 12 — ns

— — 0.5 μA

(Note 7) — 69 — C/W

(Note 7) — 4.3 — —

= 0V. Parameter is

SENSE

AL8807Q

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F

REQ

UENCY

H

CUR

REN

T

Typical Performance Characteristics (@T

400

350

300

250

200



IN

I (µA)

150

V = 0V

CTRL

V = V

SET IN

°

T = 25C

A

= +25°C, unless otherwise specified.)

A

900

800

L = 33µH

700

z)

600

(k

L = 68µ H

500

400

300

V = 12V

IN

1 LED R = 150m

SET

T = 25°C

A

L8807Q



100

50

0

0 5 10 15 20 25 30

V (V)

IN

Supp ly Curr ent (not s wit ching) vs . Inpu t Current

100

90

70

(A)

60

40

LED

30

20

0

0.0 0.5 1.0 1.5 2.0 3.0 3.5 4.0 4.5 5.0 5.5

2.5

CTRL PIN VOLTAGE (V)

Figure 3. LED Current vs. V

3

2.5

2

CTRL

200

L = 100µH

100

0

01234

V

CTRL

Figure 2. Switching Frequency vs. V

CTRL

5

80

V = V = 12V

SET IN

60

T = 25°C

A

40

20

CTRL

0

I (µA)

-20

-40

-60

0.0 0.5 1.0 1.5 2.5 3.0 3.5 4.0 4.5 5.0

2.0 5.0 V (V)

Figure 4. I vs. V

CTRL

CTRL CTRL

2.52

V = Open

CTRL

V = V= 12V

SET IN

2.51

1.5

CTRL

V (V)

1

0.5

0

0 5 10 15 20 25 30

V (V) V vs. In put Voltage

(CTRL pin o pen circui t)

IN

CTRL

V= Open

CTRL

V = V

SET IN

T = 25C

A



2.50

CTRL

V (V)

2.49

2.48

-40 -15 10 35 60 85 110 AMBIENT TEMPERATURE (°C)

Figure 6. V VS. TEMPERATURE

CTRL

AL8807Q

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R

DUT

Y CYC

Typical Performance Characteristics

9

L = 68H, R = 150m

S

T = 25C, V = 12V

AIN

8

CTRL = PWM, f = 500Hz 1 LED

7

6

LED Current Error

5

4

3

2

LED CURRENT ERROR (%)

1

0

020406080100

Figure 7. I vs. PWM Duty Cycle

400

350

300



(m )

250

DS(ON)

200

150

100

-40 -15 35 60 11010 85

PWM

LED Current

PWM DUTY CYCLE

LED

V = Open

CTRL

V = V= 12V

SET IN

Ambient Temperature ( C)

Figure 9. SW R vs. Temperature

DS(ON)



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

0.8

0.7

200

180

160

0.6

0.5

0.4

0.3 LED CURRENT (A)

0.2

140



120

100

DS(ON)

80

R (m)

60

40

0.1

0

20

0

0 5 10 15

R vs. Input Voltage

DS(ON)

100

90

80

3 LEDS

70

2 LEDS

60

LE (%)

50

40

30

20

10

0

6 9 12 15 18 21 24 27 30 33 36

INPUT VOLTAGE (V)

Figure 10. Duty Cycle vs. Input Voltage

V (V)

IN

L8807Q

V = Open

CTRL

V = V 12V

SET IN

T = 25C



A

20 25 30

L = 68µH R = 100m



S

T = 25°C

A

V = Open

CTRL

Figure 11 SW Output Rise Time Figure 12 SW Output Fall Time

AL8807Q

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