LT3478-1 データシートの表示（PDF） - Linear Technology

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LT3478-1

4.5A Monolithic LED Drivers with True Color PWM Dimming

Linear Technology 

LT3478/LT3478-1

APPLICATIO S I FOR ATIO

CVS

VS

CVIN

VIN

SCHOTTKY

DIODE

SW

INDUCTOR

L

RSENSE

(LT3478 ONLY)

R

(CONNECT MULTIPLE GROUND PLANES

THROUGH VIAS UNDERNEATH THE IC)

VOUT

GND

OUTPUT CAPACITOR

SOLDER THE EXPOSED PAD (PIN 17)

TO THE ENTIRE COPPER GROUND PLANE

LT3478/LT3478-1 UNDERNEATH THE DEVICE

SW 1 POWER GND 16 SS

CSS

SW 2

VIN 3

VS 4

15 RT

RT

14 PWM

R

13 CTRL2

R

L5

12 CTRL1

R

VOUT 6

11 SHDN

LED

7

EXPOSED PAD

PIN 17

10

VREF

OVPSET 8 ANALOG GND 9 VC

R

C VIN BYPASS CAP

R

CF

CC

RC

3252 F08

Figure 12. Recommended Layout for LT3478/LT3478-1 (Boost Configuration)

TYPICAL APPLICATIO S

15W, 6 LEDs at 700mA, Boost LED Driver

VIN

8V TO 16V

C1

4.7µF

25V

R1

45.3k

R4

54.9k

R2

130k

L1: CDRH104R-100NC

D1: PDS560

Q1: Si2318DS

LEDs: LUXEON III (WHITE)

L1

10µH

D1

VIN VS L

SHDN

VREF

CTRL2 LT3478-1

OVPSET

SW

OUT

700mA

LED

CTRL1

PWM SS

CSS

1µF

VC

RT

CC

RT

0.1µF 69.8k

fOSC = 500kHz

3.3V

0V

100Hz

PWM

Q1

DIMMING RATIO = 1000:1

R3

10k

C2

10µF

25V

LT3478-1 PWM Dimming

Waveforms

PWM

5V/DIV fPWM = 100Hz

INDUCTOR

CURRENT

1A/DIV

ILED

0.5A/DIV

2µs/DIV

PWM DIMMING RATIO = 1000:1

(SEE EFFICIENCY ON PAGE 1)

3478 TA02b

3478 TA02a

34781f

19

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