preliminary datasheet white led step-up converter general...

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WHITE LED STEP-UP CONVERTER AP3019

Preliminary Datasheet

1

Apr. 2007 Rev. 1. 1 BCD Semiconductor Manufacturing Limited

General Description

The AP3019 is an inductor-based DC/DC converterdesigned to drive up to five white LEDs in series forbacklight. Only one feedback resistor is needed to con-trol the LED current and obtain satisfied brightness.

A constant frequency 1.0MHz PWM control scheme isemployed in this IC, which means the tiny externalcomponents can be used. In fact, 1mm tall inductor and0.22µF output capacitor for the typical application isvery appropriate. Additionally, the schottky diode inboost circuit is integrated in this chip. AP3019 alsoprovides a disable port to ease its use for different sys-tems.

The over output voltage protection is equipped inAP3019. When any LED is broken or in other abnor-mal conditions, the output voltage will be clamped to27V.

The AP3019 is available in standard SOT-23-6 pack-age.

Features

· Inherently Uniform LED Current· High Efficiency up to 84% · No Need for Extra Schottky Diode· Over Output Voltage Protection· Drives 2 to 5 LEDs · Fast 1.0MHz Switching Frequency· Uses Tiny 1mm Tall Inductor· Requires Only 0.22µF Output Capacitor

Applications

· Cellular Phones· Digital Cameras· LCD modules· GPS Receivers· PDAs, Handheld Computers

Figure 1. Package Type of AP3019

SOT-23-6

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Figure 2. Pin Configuration of AP3019 (Top View)

Pin Configuration

Pin Description

Pin Number Pin Name Function

1 SW Switch Pin. Connect external inductor

2 GND Ground Pin

3 FB Voltage Feedback. Reference voltage is 200mV

4 CTRLShutdown and Dimming Pin. Connect to 1.8V or higher to enable device; Connect to 50mV orless to disable device; Connect to a voltage between 1.8V and 50mV to achieve linear dim-ming

5 VOUT Output Pin. Connected to the cathode of internal schottky diode

6 VIN Input Supply Pin. Must be locally bypassed

(SOT-23-6)

VOUT

GND

FB

SW

VIN

CTRL

K Package

2

1

3 4

5

6



3


Functional Block Diagram

Figure 3. Functional Block Diagram of AP3019

GND

FB

VIN

SW

Package Temperature Range Part Number Marking ID Packing Type

SOT-23-6 -40 to 85oC AP3019KTR-E1 E9S Tape & Reel

BCD Semiconductor's Pb-free products, as designated with "E1" suffix in the part number, are RoHS compliant.

Circuit Type

PackageK: SOT-23-6

E1: Lead Free

AP3019 -

TR: Tape and Reel

Ordering Information

VOUT

CTRL

Q1

Σ

A2A1

RS

Q

1.0 MHzOSCILLATOR

RAMPGENERATOR

VREF

3

6

42

5

DRIVER1.25 V

COMPARATOR

OVP200 mV

1SOFT

START



4


Parameter Symbol Value Unit

Input Voltage VIN 20 V

SW Voltage 27 V

FB Voltage 20 V

CTRL Voltage 20 V

Thermal Resistance (Junction to Atmosphere, no Heat sink) RθJA 265 oC/W

Operating Junction Temperature 150 oC

Storage Temperature Range TSTG -65 to 150 oC

Lead Temperature (Soldering, 10sec) TLEAD 260 oC

ESD (Machine Model) 250 V

ESD (Human Body Model) 2000 V

Note 1: Stresses greater than those listed under "Absolute Maximum Ratings" may cause permanent damage to thedevice. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indi-cated under "Recommended Operating Conditions" is not implied. Exposure to "Absolute Maximum Ratings" for extendedperiods may affect device reliability.

Parameter Symbol Min Max Unit

Operating Temperature Range TOP -40 85 oC

Input Voltage VIN 2.5 16 V

CTRL Voltage VCTRL 16 V

Recommended Operating Conditions

Absolute Maximum Ratings (Note 1)



5


(VIN=3V, VCTRL =3V, TA=25oC, unless otherwise specified.)

Parameter Symbol Conditions Min Typ Max Unit

Minimum Operating Voltage VIN(min) 2.5V

Maximum Operating Voltage VIN(max) 16

Feedback Voltage VFBIOUT=20mA, 4 LEDs,

TA=-40oC to 85oC 188 200 212 mV

FB Pin Bias Current IFB 35 100 nA

Supply Current ICC VFB=VIN, Not Switching 1.3 2.0 2.7 mA

Supply Current IQ VCTRL=0V 2.0 3.2 5.0 µA

Switching Frequency f 0.7 1.0 1.3 MHz

Maximum Duty Cycle DMAX 90 93 %

Switch Current Limit (Note 2) ILIMITTA=25oC, D=40% 500

mATA=25oC, D=80% 350

Switch VCE Saturation Voltage VCESAT ISW=250mA 360 mV

Switch Leakage Current VSW=5V 0.01 5 µA

CTRL Pin Voltage VCTRLHigh 1.8

VLow 0.05

CTRL Pin Bias Current ICTRL

40 55 72

µATA=85oC 50

TA=-40oC 75

Schottky Forward Drop VDROP ID=150mA 0.7 V

Schottky Leakage CurrentVR=23V 0.1 4

µAVR=27V 150

Soft Start Time t 300 µS

Electrical Characteristics

Note 2: The Switch Current Limit is related to Duty Cycle. Please refer to Figure 16 for detail.



6


Typical Performance Characteristics

Figure 6. Efficiency vs. LED's Number Figure 7. Schottky Forward Current

Figure 4. Efficiency vs. Junction Temperature Figure 5. Efficiency vs. Input Voltage

vs. Schottky Forward Drop

(VF of WLED is 3.45V @ IF=20mA, unless otherwise noted )

-50 -25 0 25 50 75 10080

81

82

83

84

85

Effic

ienc

y (%

)

VIN=3.6V, IOUT=20mA, 4LEDSCIN=1µF, COUT=0.22µF, L=22µH

Junction Temperature (oC)2.5 3.0 3.5 4.0 4.5 5.0

80

81

82

83

84

85

IOUT=20mA, 4LEDS, TA=25OCCIN=1µF, COUT=0.22µF, L=22µH

Effic

ienc

y (%

)

Input Voltage (V)

0 200 400 600 800 10000

50

100

150

200

250

300

350

Scho

ttky

Forw

ard

Cur

rent

(mA

)

Schottky Forward Drop (mV)2 3 4 5

80

81

82

83

84

85

VIN=3.6V, IOUT=20mA, TA=25OCCIN=1µF, COUT=0.22µF, L=22µH

Effic

ienc

y (%

)

LEDS (PCS)



7


Typical Performance Characteristics (Continued)

Figure 10. Output Clamp Voltage vs. Input Voltage Figure 11. Input Current in Output Open Circuit

Figure 8. Shutdown Quiescent Current vs. Input Voltage

vs. Input Voltage

Figure 9. Supply Current vs. Input Voltage


2 4 6 8 10 12 14 160

5

10

15

20

25

30

Qui

esce

nt C

urre

nt (µ

A)

Input Voltage (V) 0 2 4 6 8 10 12 14 160.0

0.5

1.0

1.5

2.0

2.5

3.0

Sup

ply

Cur

rent

(mA

)

Input Voltage (V)

-50OC 25OC 100OC

2 4 6 8 10 12 14 1625.0

25.5

26.0

26.5

27.0

27.5

28.0

28.5

29.0

Input Voltage (V)

Out

put C

lam

p V

olta

ge (V

)

2.5 3.0 3.5 4.0 4.5 5.02.0

2.2

2.4

2.6

2.8

3.0

3.2

3.4

3.6

3.8

4.0

Inpu

t Cur

rent

(mA

)

Input Voltage (V)



8


Figure 14. Schottky Forward Drop


Figure 12. Switching Frequency Figure 13. Feedback Voltage vs. Junction Temperaturevs. Junction Temperature

vs. Junction Temperature Figure 15. Schottky Leakage Current

vs. Junction Temperature


-50 -25 0 25 50 75 1000.60

0.62

0.64

0.66

0.68

0.70

0.72

0.74

0.76

0.78

0.80

Sch

ottk

y Fo

rwar

d D

rop

(V)

Junction Temperature (oC)

-50 -25 0 25 50 75 1000.70

0.75

0.80

0.85

0.90

0.95

1.00

1.05

1.10

1.15

1.20

Freq

uenc

y (M

Hz)


-50 -25 0 25 50 75 100190

192

194

196

198

200

202

204

206

208

210

Feed

back

Vol

tage

(V)


-50 -25 0 25 50 75 1000.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0.40

0.45

0.50

Sch

ottk

y Le

akag

e C

urre

nt (µ

A)


VR=10V V

R=16V

VR=23V



9



Figure 16. Switch Current Limit vs. Duty Cycle Figure 17. Switch Saturation Voltage

vs. Switch Current

Figure 18. Feedback Voltage vs. CTRL Pin Voltage


30 40 50 60 70 80 90100

200

300

400

500

600

700

-50OC 25OC 100OC

Cur

rent

Lim

it (m

A)

Duty Cycle (%)

50 100 150 200 250 300100

150

200

250

300

350

400

450

500

Sat

urat

ion

Vol

tage

(mV

)

Switch Current (mA)

0.0 0.5 1.0 1.5 2.00

50

100

150

200

250

CTRL Voltage (V)

Feed

back

Vol

tage

(mV

)



10


Application Information

OperationThe AP3019 is a boost DC-DC converter which uses aconstant frequency, current mode control scheme toprovide excellent line and load regulation. Operationcan be best understood by referring to the Figure 3.

At the start of each oscillator cycle, the SR latch is setand switch Q1 turns on. The switch current willincrease linearly. The voltage on sense resistor isproportional to the switch current. The output of thecurrent sense amplifier is added to a stabilizing rampand the result is fed into the non-inversion input of thePWM comparator A2. When this voltage exceeds theoutput voltage level of the error amplifier A1, the SRlatch is reset and the switch is turned off.

It is clear that the voltage level at non-inversion inputof A2 sets the peak current level to keep the output inregulation. This voltage level is the output signal oferror amplifier A1, and is the amplified signal of thevoltage difference between feedback voltage andreference voltage of 200mV. So, a constant outputcurrent can be provided by this operation mode.

Figure 19. Typical Application circuit to Decide R1

LED Current ControlRefer to Figure 19, the LED current is controlled by thefeedback resistor R1. LEDs' current accuracy isdetermined by the regulator's feedback thresholdaccuracy and is independent of the LED's forwardvoltage variation. So the precise resistors are preferred.The resistance of R1 is in inverse proportion to theLED current since the feedback reference is fixed at200mV. The relation for R1 and LED current can beexpressed as below:

Over Voltage ProtectionThe AP3019 has an internal open-circuit protectioncircuit. When the LEDs are disconnected from circuitor fail open, the output voltage is clamped at 27V. TheAP3019 will switch at a low frequency, and minimizeinput current.

Soft StartThe AP3019 has an internal soft start circuit to limitthe inrush current during startup. The time of startup iscontrolled by internal soft start capacitor. Please referto Figure 20.

Figure 20. Soft Start Waveform VIN=3.6V, 4LEDS, ILED=20mA

Dimming ControlTwo typical types of dimming control circuit arepresent as below. First, controlling CTRL Pin voltageto change operation state is a good choice. Second,changing the feedback voltage to get appropriate dutyand luminous intensity is also useful.

(1). Adding a Control Signal to CTRL PinThere are three methods to control CTRL pin signal

First, adding a PWM Signal to CTRL pin directly. TheAP3019 is turned on or off by the PWN signal when itis applied on the CTRL pin. The typical frequency of

LEDImVR 200

1 =

IIN100mA/div

VOUT10V/div

VCTRL2V/div

Time 100µs/div

L1

C1

C2

R1

VINSW VOUT

FBGND

CTRLAP3019Control

Signal

VIN ≥ 3V



11


Application Information (Continued)

this PWM signal is 500Hz to 1KHz. Please refer toFigure 21.

Figure 21. Dimming Control Using a PWM Signal in CTRL Pin

Secondly, adding a constant DC voltage through aresistor divider to CTRL pin can control the dimming.The FB voltage is indirectly adjusted when the CTRLpin voltage is between 50mV to 1.8V, which can beused as dimming control. Please refer Figure 22.

Figure 22. Dimming Control Using a DC Voltage in CTRL Pin

Thirdly, using a filtered PWM signal adding to CTRLpin can achieve dimming control. The filtered PWMsignal can be considered as an adjustable DC voltage.It will change the FB voltage indirectly and achievedimming control. The circuit is shown in Figure 23.

Figure 23. Dimming Control Using a Filtered PWM Signal Voltage in CTRL Pin

(2). Changing the Effective Feedback VoltageThere are three methods to change the effectivefeedback voltage.

First, adding a constant DC voltage through a resistordivider to FB pin can control the dimming. Changingthe DC voltage or resistor between the FB Pin and theDC voltage can get appropriate luminous intensity.Comparing with all kinds of PWM signal control, thismethod features a stable output voltage and LEDscurrent. Please refer Figure 24.

Figure 24. Dimming Control Using DC Voltage

Second, using a filtered PWM signal can do it. Thefiltered PWM signal can be considered as a varyingand adjustable DC voltage.

Figure 25. Dimming Control Using a Filtered PWM Voltage

Third, using a logic signal to change the feedbackvoltage. For example, the FB pin is connected to theGND through a mosFET and a resistor. And thismosFET is controlled a logic signal. The luminousintensity of LEDs will be changed when the mosFETturns on or off.

500Hz to 1KHz

AP3019CTRL

AP3019CTRL

R110K

R210K

VDC0.1 to 3.6V

AP3019CTRLPWM

R5K

C100nF

R110Ω

FB

AP3019

R25K

R390K

PWMR410K

C0.1µF

EffectiveFeedback Voltage

R110Ω

FB

AP3019

R25K

R390K

VDC




12


Application Information (Continued)

Figure 26. Dimming Control Using Logic Signal

R1

FB

AP3019

R2LogicSignal 2N7002




13


Typical Application

A. Four White LEDs Driver

B. Five White LEDs Driver

22µΗ

1µF

0.22µF

10Ω

VINSW VOUT

FBGND

CTRLAP3019Control

Signal

VIN ≥ 3V

10µΗ

1µF

0.22µF

10Ω

VINSW VOUT

FBGND

CTRLAP3019Control

Signal

VIN ≥ 3V

Figure 27. Typical White LED Drivers

C: X5R or X7R DielectricL: SUMIDA CDRH5D28R-220NC or EquivalentThis circuit can work in full temperature

C: X5R or X7R DielectricL: SUMIDA CDRH5D28R-100NC or EquivalentThis circuit can work in full temperature



14


Mechanical Dimensions

SOT-23-6 Unit: mm(inch)

2.820(0.111)3.020(0.119)

2.65

0(0.

104)

2.95

0(0.

116)

1.50

0(0.

059)

1.70

0(0.

067)

0.950(0.037)TYP

1.800(0.071)2.000(0.079)

0.300(0.012)0.400(0.016)

0.700(0.028)REF

0.100(0.004)0.200(0.008)

0°8°

0.200(0.008)

0.300(0.012)0.600(0.024)

0.000(0.000)0.100(0.004)

1.050(0.041)1.150(0.045)

1.050(0.041)1.250(0.049)

1 2 3

456

Pin 1 Dot by Marking

IMPORTANT NOTICE

BCD Semiconductor Manufacturing Limited reserves the right to make changes without further notice to any products or specifi-cations herein. BCD Semiconductor Manufacturing Limited does not assume any responsibility for use of any its products for anyparticular purpose, nor does BCD Semiconductor Manufacturing Limited assume any liability arising out of the application or useof any its products or circuits. BCD Semiconductor Manufacturing Limited does not convey any license under its patent rights orother rights nor the rights of others.

- Wafer FabShanghai SIM-BCD Semiconductor Manufacturing Limited800, Yi Shan Road, Shanghai 200233, ChinaTel: +86-21-6485 1491, Fax: +86-21-5450 0008

BCD Semiconductor Manufacturing LimitedMAIN SITE

REGIONAL SALES OFFICEShenzhen OfficeShanghai SIM-BCD Semiconductor Manufacturing Co., Ltd. Shenzhen OfficeAdvanced Analog Circuits (Shanghai) Corporation Shenzhen OfficeRoom E, 5F, Noble Center, No.1006, 3rd Fuzhong Road, Futian District, Shenzhen 518026, China Tel: +86-755-8826 7951Fax: +86-755-8826 7865

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- IC Design GroupAdvanced Analog Circuits (Shanghai) Corporation8F, Zone B, 900, Yi Shan Road, Shanghai 200233, ChinaTel: +86-21-6495 9539, Fax: +86-21-6485 9673

BCD Semiconductor Manufacturing Limited

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preliminary datasheet white led step-up converter general...

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