DC1205A - Demo Manual

DEMO MANUAL DC1205A
LT3592: Step-Down 500mA
LED Driver with 10:1 Dimming
DESCRIPTION
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 floating, 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 efficiency 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
100
the LT3592. The minimum input voltage to run the stepdown 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 files for this circuit board are available at
http://www.linear.com/demo
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.
12
4.6V LED
95
11
10
OUTPUT VOLTAGE (V)
EFFICIENCY (%)
90
BRIGHT (500mA)
85
80
75
70
65
9
8
7
6
5
60
4
55
3
50
4
8
12
20
16
INPUT VOLTAGE (V)
24
28
DC1205 F01
Figure 1. Input Voltage vs Efficiency
2
2
4
8
6
10
12
INPUT VOLTAGE (V)
14
16
DC1205 F02
Figure 2. Minimum Input Voltage vs LED Voltage
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1
DEMO MANUAL DC1205A
QUICK START PROCEDURE
Demonstration circuit 1205A is easy to set up for evaluating the LT3592 36V step-down 500mA LED driver with
10:1 dimming. Follow the test procedure outlined below
and see Figure 3.
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 floating or grounding the terminal.
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 constant 500mA through the string of LEDs with BRIGHT
terminal floating.
OPTIONAL
+
A
–
+
+
–
–
V
OPTIONAL
+
V
–
DC1205 F03
Figure 3. Proper Measurement Equipment Setup
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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
5
7
E1-E7
Resistor, Chip, 100k, 1/16W, 1%, 0402
Vishay, CRCW0402100KFKED
HARDWARE FOR DEMO BOARD ONLY
TP, Turret, 0.094"
Mill-Max, 2501-2-00-80-00-00-07-0
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3
A
B
C
E5
E4
E3
E2
E1
C2
2.2uF
50V
1206
1
2
3
R2
48.7k
1%
2.2MHz
R1
100k
5%
4
RT
BRIGHT
SHDN
VIN
U1
LT3592EDDB
5
4
1. ALL RESISTORS ARE IN OHMS, 0402.
ALL CAPACITORS ARE IN MICROFARADS, 0402.
NOTE: UNLESS OTHERWISE SPECIFIED
GND
BRIGHT
SHDN
GND
VIN
6V - 36V
4
VFB
OUT
CAP
DA
SW
3
10
9
8
5
6
3
KIM T.
DESIGNER:
ENGINEER: KEITH S.
APPROVED:
CHECKED:
DRAWN:
APPROVALS
CONTRACT NO.
+
200/20mV
_
D1
DFLS140
SUMIDA
C3
CDRH3D18
0.1uF
L2
16V
4.7uH
1
2
7
BOOST
GND
11
0805
R3
0.4 1%
3
E7
E6
GND
LED +
1630 McCarthy Blvd.
Milpitas, CA 95035
Phone: (408)432-1900
Fax: (408)434-0507
LTC Confidential-For Customer Use Only
LED2
LR W5SM
RED
OSRAM
3
LED1
LR W5SM
RED
OSRAM
1
DATE:
A
SIZE
2
1
SHEET
DC1205A * LT3592EDDB
Wednesday, September 16, 2009
DWG NO.
1
OF
1
A
REV
STEP-DOWN 500mA LED DRIVER WITH 10:1 DIMMING
TECHNOLOGY
R5
10k
1%
R4
51.1k
1%
TITLE: SCHEMATIC
C4
4.7uF
16V
0805
2
2
1
2
4
1
D
5
A
B
C
D
DEMO MANUAL DC1205A
SCHEMATIC DIAGRAM
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DEMO MANUAL DC1205A
PCB LAYOUT AND FILM
Top Silkscreen
Layer 1—Top Layer
Layer 2—GND Plane 1
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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DEMO MANUAL DC1205A
FABRICATION DRAWING
dc1205af
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.
7
DEMO MANUAL DC1205A
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 directive 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 application engineer.
Mailing Address:
Linear Technology
1630 McCarthy Blvd.
Milpitas, CA 95035
Copyright © 2004, Linear Technology Corporation
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8
Linear Technology Corporation
LT 0909 • PRINTED IN USA
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900 ● FAX: (408) 434-0507
●
www.linear.com
© LINEAR TECHNOLOGY CORPORATION 2009
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