1
dc1205af
DEMO MANUAL DC1205A
DESCRIPTION
LT3592: Step-Down 500mA
LED Driver with 10:1 Dimming
Demonstration circuit 1205A features the LT3592 36V
step-down 500mA LED driver with 10:1 dimming. The
demonstration circuit is designed to drive two red 500mA
LEDs mounted on the PCB from a wide input voltage range.
The high 2.2MHz switching frequency permits the use of
a small inductor and ceramic capacitors to save space
and cost. Current mode control provides fast transient
response and cycle-by-cycle current limit for short-circuit
protection. The LEDs have two brightness settings. With
BRIGHT pulled high or left fl oating, the two red LEDs are
driven with 500mA. With BRIGHT pulled to GND, the LED
current drops to 50mA for 10:1 analog dimming.
The typical effi ciency of the LT3592 DC1205A is 85%
with 12VIN and the two LEDs at 4.6V total with 500mA
as shown in Figure 1. Although the board is stuffed with
two red LEDs, different LED strings can be powered from
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear
Technology Corporation. All other trademarks are the property of their respective owners.
the LT3592. The minimum input voltage to run the step-
down converter at 2.2MHz with a given string of LEDs is
shown in Figure 2.
The LT3592 data sheet gives a complete description of
the part, operation and applications information. The
data sheet must be read in conjunction with this Demo
Manual for DC1205A. The LT3592 is assembled in a 10-lead
plastic DFN (3mm × 2mm) DDB package with a thermally
enhanced ground pad. Proper board layout is essential
for maximum thermal performance. See the data sheet
section Layout Hints.
Design fi les for this circuit board are available at
http://www.linear.com/demo
INPUT VOLTAGE (V)
4
EFFICIENCY (%)
100
95
90
60
75
70
65
80
85
55
50 2012 24
DC1205 F01
28168
BRIGHT (500mA)
4.6V LED
INPUT VOLTAGE (V)
2
OUTPUT VOLTAGE (V)
12
11
10
4
7
6
5
8
9
3
28
DC1205 F02
1610 12 1446
Figure 1. Input Voltage vs Effi ciency Figure 2. Minimum Input Voltage vs LED Voltage
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dc1205af
DEMO MANUAL DC1205A
QUICK START PROCEDURE
Demonstration circuit 1205A is easy to set up for evalu-
ating the LT3592 36V step-down 500mA LED driver with
10:1 dimming. Follow the test procedure outlined below
and see Figure 3.
1. Set up DC1205A as shown in Figure 3 with hand-held
multimeters, and a bench supply (power turned off)
with voltage greater than the LED string (approximately
3.5V to 5V) and less than 36V.
2. Turn on the bench power supply and observe a con-
stant 500mA through the string of LEDs with BRIGHT
terminal fl oating.
3. Tie BRIGHT terminal to GND terminal and observe
the LED current dropping to 50mA as brightness also
decreases.
4. Use the SHDN terminal to turn the LEDs on and off by
respectively fl oating or grounding the terminal.
Figure 3. Proper Measurement Equipment Setup
+
–
A
+–
+
–
V
+
–V
OPTIONAL
OPTIONAL
DC1205 F03
3
dc1205af
DEMO MANUAL DC1205A
PARTS LIST
ITEM QTY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER
REQUIRED CIRCUIT COMPONENTS
1 1 C2 Capacitor, X7R, 2.2μF, 50V, 10%, 1206 Murata, GCM31CR71H225KA55
2 1 C3 Capacitor, X7R, 0.1μF, 16V, 10%, 0402 TDK, C1005X7R1C104K
3 1 C4 Capacitor, X5R, 4.7μF, 16V, 10%, 0805 TDK, C2012X5R1C475K
4 1 D1 Diode, Schottky, 1A, POWERDI123 Diode Inc., DFLS140-7-F
6 2 LED2, LED1 LED, Golden Dragon, Red, LED-SFH4230 Osram, LR W5SM-HYJY-1
7 1 L2 Inductor, PWR, 4.7μH, L-CDRH3D18 Sumida, CDRH3D18NP-4R7NC
9 1 R2 Resistor, Chip, 48.7k, 1/16W, 2.2MHz, 1%, 0402 Vishay, CRCW040248K7FKED
10 1 R3 Resistor, 0.4Ω, 1%, 1/4W, 0805 Susumu International USA Inc., RL1220S-R40-F
11 1 R4 Resistor, Chip, 51.1k, 1/16W, 1%, 0402 Vishay, CRCW040251K1FKED
12 1 R5 Resistor, Chip, 10k, 1/16W, 1%, 0402 Vishay, CRCW040210K0FKED
13 1 U1 IC, LT3592EDDB#PBF, DFN10DDB Linear Tech, LT3592EDDB#PBF
ADDITIONAL DEMO BOARD CIRCUIT COMPONENTS
8 1 R1 Resistor, Chip, 100k, 1/16W, 1%, 0402 Vishay, CRCW0402100KFKED
HARDWARE FOR DEMO BOARD ONLY
5 7 E1-E7 TP, Turret, 0.094" Mill-Max, 2501-2-00-80-00-00-07-0
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dc1205af
DEMO MANUAL DC1205A
SCHEMATIC DIAGRAM
5
5
4
4
3
3
2
2
1
1
D D
C C
B B
A A
1. ALL RESISTORS ARE IN OHMS, 0402.
ALL CAPACITORS ARE IN MICROFARADS, 0402.
NOTE: UNLESS OTHERWISE SPECIFIED
+
_
200/20mV
SIZE
DATE:
DWG NO.
REV
SHEET OF
TITLE:
CONTRACT NO.
APPROVALS
DRAWN:
CHECKED:
APPROVED:
ENGINEER:
DESIGNER:
TECHNOLOGY
Fax: (408)434-0507
Milpitas, CA 95035
Phone: (408)432-1900
1630 McCarthy Blvd.
LTC Confidential-For Customer Use Only
A
Wednesday, September 16, 2009
11
STEP-DOWN 500mA LED DRIVER WITH 10:1 DIMMING
KIM T.
KEITH S.
A
DC1205A * LT3592EDDB
SCHEMATIC
SIZE
DATE:
DWG NO.
REV
SHEET OF
TITLE:
CONTRACT NO.
APPROVALS
DRAWN:
CHECKED:
APPROVED:
ENGINEER:
DESIGNER:
TECHNOLOGY
Fax: (408)434-0507
Milpitas, CA 95035
Phone: (408)432-1900
1630 McCarthy Blvd.
LTC Confidential-For Customer Use Only
A
Wednesday, September 16, 2009
11
STEP-DOWN 500mA LED DRIVER WITH 10:1 DIMMING
KIM T.
KEITH S.
A
DC1205A * LT3592EDDB
SCHEMATIC
SIZE
DATE:
DWG NO.
REV
SHEET OF
TITLE:
CONTRACT NO.
APPROVALS
DRAWN:
CHECKED:
APPROVED:
ENGINEER:
DESIGNER:
TECHNOLOGY
Fax: (408)434-0507
Milpitas, CA 95035
Phone: (408)432-1900
1630 McCarthy Blvd.
LTC Confidential-For Customer Use Only
A
Wednesday, September 16, 2009
11
STEP-DOWN 500mA LED DRIVER WITH 10:1 DIMMING
KIM T.
KEITH S.
A
DC1205A * LT3592EDDB
SCHEMATIC
E4
BRIGHT
E4
BRIGHT
C3
0.1uF
16V
C3
0.1uF
16V
R4
51.1k
1%
R4
51.1k
1%
E3
SHDN
E3
SHDN
LED2
LR W5SM
OSRAM
RED
LED2
LR W5SM
OSRAM
RED
1 2
3
R5
10k
1%
R5
10k
1%
U1
LT3592EDDB
U1
LT3592EDDB
VIN
4
BRIGHT
2
CAP 8
OUT 9
BOOST 7
SW 6
SHDN
3
DA 5
RT
1VFB 10
GND
11
E1
VIN
6V - 36V
E1
VIN
6V - 36V
L2
4.7uH
CDRH3D18
SUMIDA
L2
4.7uH
CDRH3D18
SUMIDA
C4
4.7uF
16V
0805
C4
4.7uF
16V
0805
R1
100k
5%
R1
100k
5%
C2
2.2uF
50V
1206
C2
2.2uF
50V
1206
LED1
LR W5SM
OSRAM
RED
LED1
LR W5SM
OSRAM
RED
1 2
3
D1
DFLS140
D1
DFLS140
12
R2
48.7k
2.2MHz
1%
R2
48.7k
2.2MHz
1% E7
GND
E7
GND
R3
0.4
0805
1%
R3
0.4
0805
1% E6
LED +
E6
LED +
E2
GND
E2
GND
E5
GND
E5
GND
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DEMO MANUAL DC1205A
Top Silkscreen Layer 1—Top Layer
Layer 2—GND Plane 1
PCB LAYOUT AND FILM
Layer 3—GND Plane 2
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DEMO MANUAL DC1205A
PCB LAYOUT AND FILM
Layer 4—Bottom Layer Top Solder Mask
Bottom Solder Mask Top Solder Paste Mask
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dc1205af
DEMO MANUAL DC1205A
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 representation
that the interconnection of its circuits as described herein will not infringe on existing patent rights.
FABRICATION DRAWING
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dc1205af
DEMO MANUAL DC1205A
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com
© LINEAR TECHNOLOGY CORPORATION 2009
LT 0909 • PRINTED IN USA
DEMONSTRATION BOARD IMPORTANT NOTICE
Linear Technology Corporation (LTC) provides the enclosed product(s) under the following AS IS conditions:
This demonstration board (DEMO BOARD) kit being sold or provided by Linear Technology is intended for use for ENGINEERING DEVELOPMENT
OR EVALUATION PURPOSES ONLY and is not provided by LTC for commercial use. As such, the DEMO BOARD herein may not be complete
in terms of required design-, marketing-, and/or manufacturing-related protective considerations, including but not limited to product safety
measures typically found in finished commercial goods. As a prototype, this product does not fall within the scope of the European Union direc-
tive on electromagnetic compatibility and therefore may or may not meet the technical requirements of the directive, or other regulations.
If this evaluation kit does not meet the specifications recited in the DEMO BOARD manual the kit may be returned within 30 days from the date
of delivery for a full refund. THE FOREGOING WARRANTY IS THE EXCLUSIVE WARRANTY MADE BY THE SELLER TO BUYER AND IS IN LIEU
OF ALL OTHER WARRANTIES, EXPRESSED, IMPLIED, OR STATUTORY, INCLUDING ANY WARRANTY OF MERCHANTABILITY OR FITNESS
FOR ANY PARTICULAR PURPOSE. EXCEPT TO THE EXTENT OF THIS INDEMNITY, NEITHER PARTY SHALL BE LIABLE TO THE OTHER FOR
ANY INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES.
The user assumes all responsibility and liability for proper and safe handling of the goods. Further, the user releases LTC from all claims
arising from the handling or use of the goods. Due to the open construction of the product, it is the user’s responsibility to take any and all
appropriate precautions with regard to electrostatic discharge. Also be aware that the products herein may not be regulatory compliant or
agency certified (FCC, UL, CE, etc.).
No License is granted under any patent right or other intellectual property whatsoever. LTC assumes no liability for applications assistance,
customer product design, software performance, or infringement of patents or any other Intellectual property rights of any kind.
LTC currently services a variety of customers for products around the world, and therefore this transaction is not exclusive.
Please read the DEMO BOARD manual prior to handling the product. Persons handling this product must have electronics training and
observe good laboratory practice standards. Common sense is encouraged.
This notice contains important safety information about temperatures and voltages. For further safety concerns, please contact a LTC applica-
tion engineer.
Mailing Address:
Linear Technology
1630 McCarthy Blvd.
Milpitas, CA 95035
Copyright © 2004, Linear Technology Corporation
