Datasheet
LTC3454
11
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.
LED Failure Modes
If the LED fails as an open circuit, the safety amplifi er takes
control of the regulation loop to prevent V
OUT
runaway.
The V
OUT
threshold at which this occurs is about 5.15V.
The safety amplifi er has no effect on loop regulation at
V
OUT
less than 5.15V.
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.
Figure 3. Brightness Control Methods: (a) Using Voltage DAC, (b) Using Current DAC, (c) Using Potentiometer, (d) Using PWM Input
V
OUT
LED
LTC3454
(
3d
)
V
PWM
f
PWM
≥ 10kHz
DV
CC
R
SET
100
V
IN
R
SET
≥ R
MIN
3454 F03
ENx
I
SETx
I
LED
= 3850
0.8V – V
PWM
R
SET
= 3850
0.8V – (DC% • V
DVCC
)
R
SET
V
OUT
LED
LTC3454
(
3c
)
R
MIN
V
IN
R
POT
ENx
I
SETx
I
LED
= 3850
0.8V
R
MIN
+ R
POT
V
OUT
LED
LTC3454
(3b)
V
IN
ENx
I
SETx
I
LED
= 3850 • IDAC
IDAC ≤
0.8V
R
MIN
(3a)
I
LED
= 3850
0.8V – V
DAC
R
SET
CURRENT
DAC
V
OUT
LED
LTC3454
V
IN
ENx
I
SETx
V
DAC
VOLTAGE
DAC
R
SET
≥ R
MIN
DD Package
10-Lead Plastic DFN (3mm × 3mm)
(Reference LTC DWG # 05-08-1699)
APPLICATIONS INFORMATION
PACKAGE DESCRIPTION
3.00 p0.10
(4 SIDES)
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
0.38 p 0.10
BOTTOM VIEW—EXPOSED PAD
1.65 p 0.10
(2 SIDES)
0.75 p0.05
R = 0.115
TYP
2.38 p0.10
(2 SIDES)
15
106
PIN 1
TOP MARK
(SEE NOTE 6)
0.200 REF
0.00 – 0.05
(DD) DFN 1103
0.25 p 0.05
2.38 p0.05
(2 SIDES)
RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS
1.65 p0.05
(2 SIDES)2.15 p0.05
0.50
BSC
0.675 p0.05
3.50 p0.05
PACKAGE
OUTLINE
0.25 p 0.05
0.50 BSC