LTC3454EDD データシートの表示（PDF） - Linear Technology

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LTC3454EDD

1A Synchronous Buck-Boost High Current LED Driver

Linear Technology 

LTC3454

APPLICATIONS INFORMATION

LED Failure Modes

If the LED fails as an open circuit, the safety amplifier takes

control of the regulation loop to prevent VOUT runaway.

The VOUT threshold at which this occurs is about 5.15V.

The safety amplifier has no effect on loop regulation at

VOUT less than 5.15V.

VIN

VOUT

If the LED fails as a short-circuit, the current limiting

circuitry detects this condition and limits the peak input

current to a safe level.

VIN

VOUT

VOLTAGE

DAC

ENx

LTC3454

ISETx

RSET ≥ RMIN

LED

ILED

=

3850

0.8V – VDAC

RSET

VDAC

(3a)

VIN

VOUT

CURRENT

DAC

ENx

LTC3454

ISETx

LED

0.8V

IDAC ≤ RMIN

ILED = 3850 • IDAC

(3b)

VIN

VOUT

ENx

LTC3454

ISETx

RMIN

LED

0.8V

ILED = 3850 RMIN + RPOT

RPOT

(3c)

RSET

100

ENx

LTC3454

ISETx

RSET ≥ RMIN

VPWM

LED

ILED

=

3850

0.8V – VPWM

RSET

=

3850

0.8V

–

(DC% •

RSET

VDVCC)

DVCC

fPWM ≥ 10kHz

(3d)

3454 F03

Figure 3. Brightness Control Methods: (a) Using Voltage DAC, (b) Using Current DAC, (c) Using Potentiometer, (d) Using PWM Input

PACKAGE DESCRIPTION

DD Package

10-Lead Plastic DFN (3mm × 3mm)

(Reference LTC DWG # 05-08-1699)

0.675 p0.05

R = 0.115

TYP

6

0.38 p 0.10

10

3.50 p0.05

1.65 p0.05

2.15 p0.05 (2 SIDES)

0.25 p 0.05

0.50

BSC

2.38 p0.05

(2 SIDES)

PACKAGE

OUTLINE

PIN 1

TOP MARK

(SEE NOTE 6)

0.200 REF

3.00 p0.10 1.65 p 0.10

(4 SIDES) (2 SIDES)

0.75 p0.05

0.00 – 0.05

(DD) DFN 1103

5

1

0.25 p 0.05

0.50 BSC

2.38 p0.10

(2 SIDES)

BOTTOM VIEW—EXPOSED PAD

RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS

NOTE:

1. DRAWING TO BE MADE A JEDEC PACKAGE OUTLINE M0-229 VARIATION OF (WEED-2).

CHECK THE LTC WEBSITE DATA SHEET FOR CURRENT STATUS OF VARIATION ASSIGNMENT

2. DRAWING NOT TO SCALE

3. ALL DIMENSIONS ARE IN MILLIMETERS

4. DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT INCLUDE

MOLD FLASH. MOLD FLASH, IF PRESENT, SHALL NOT EXCEED 0.15mm ON ANY SIDE

5. EXPOSED PAD SHALL BE SOLDER PLATED

6. SHADED AREA IS ONLY A REFERENCE FOR PIN 1 LOCATION ON THE

TOP AND BOTTOM OF PACKAGE

3454fa

Information furnished by Linear Technology Corporation is believed to be accurate and reliable.

However, no responsibility is assumed for its use. Linear Technology Corporation makes no representa-

tion that the interconnection of its circuits as described herein will not infringe on existing patent rights.

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