LT3478 Ver la hoja de datos (PDF) - Linear Technology

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componentes Descripción

Fabricante

LT3478

4.5A Monolithic LED Drivers with True Color PWM Dimming

Linear Technology 

LT3478/LT3478-1

PI FU CTIO S

exceeds 6A or VOUT exceeds OVP, an internal soft-start

latch is set, the power NPN is immediately turned off and

the SS pin is discharged. The soft-start latch is also set

if VIN and/or ⎯S⎯H⎯D⎯N do not meet their turn on thresholds.

The SS pin only recharges when all faults are removed

and the pin has been discharged below 0.25V.

Exposed Pad (Pin 17): The ground for the IC and the con-

verter. The FE package has an Exposed Pad underneath the

IC which is the best path for heat out of the package. Pin 17

should be soldered to a continuous copper ground plane

under the device to reduce die temperature and increase

the power capability of the LT3478/LT3478-1.

BLOCK DIAGRA

SHDN

11

10µA

VS

L

4

5

VC

–

1.4V +

VIN

3

REF

1.24V

UVLO

9.5mΩ

–

–+ 57mV

+

INRUSH

CURRENT

PROTECTION

SS

16

SW

1, 2

OVERVOLTAGE

DETECT

SOFT-START

OVPSET

100Ω

VREF

10

CTRL1

12

CTRL2

13

1.05V

+

+

+

–

PWM

DETECT

OSC

PWM

Q2

SLOPE

COMP

Σ

SQ

R

1000Ω

Q1

RS

VOUT

6

RSENSE

0.1Ω

(INTERNAL FOR

LT3478-1)

RSENSE

(EXTERNAL FOR

LT3478)

LED

7

LED

LED

LED

GM

LED

1V

PWM

14

TO OVERVOLTAGE

DETECT CIRCUIT

8

OVPSET

15

RT

17

9

EXPOSED PAD

VC

(GND)

3478 F01

Figure 1

34781f

8

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