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DEMO MANUAL DC1511A
DESCRIPTION
LTM8042, LTM8042-1
1A, 350mA µModule LED Driver
Demonstration circuits 1511A-A and 1511A-B feature the
LT M
®
8042 and the LTM8042-1, which are respectively com-
plete 1A and 350mA µModule LED drivers. The demonstra-
tion circuits are assembled as boost topologies, accepting
an input voltage from 3V to 30V and supporting an output
up to 32V (see Table 1). The default switching frequency is
600kHz for DC1511A-A and 950kHz for DC1511A-B, but
can be adjusted by changing the value of RT.
DC1511A is easily configured to support other features,
including PWM dimming, analog dimming, buck-boost
mode and buck mode (step-down). DC1511A includes a L, LT, LTC, LTM, µModule, Linear Technology and the Linear logo are registered trademarks of
Linear Technology Corporation. All other trademarks are the property of their respective owners.
PARAMETER CONDITIONS/NOTES VALUE
Input Voltage Range, VIN (BSTIN) 3V to 30V (See Table 1)
ILED DC1511A-A (LTM8042)
DC1511A-B (LTM8042-1)
Current Derating May Be Necessary Under Certain VIN, VOUT , Frequency
and Thermal Conditions
1A
350mA
Switching Frequency RT = 30.1k (DC1511A-A)
RT = 16.9k (DC1511A-B)
600kHz
950kHz
Maximum Output Voltage (Open LED Voltage) 36V
Efficiency VIN = 12V, VLED = 16.7V, ILED = 1A
VIN = 12V, VLED = 24.8V, ILED = 350mA
91.5% (See Figure 2)
89% (See Figure 3)
BOARD PHOTO
PERFORMANCE SUMMARY
P-channel MOSFET that is necessary for PWM dimming.
The RADJ pin/terminal voltage controls the output current.
Voltage is either applied directly to the terminal or set by
a divider that includes resistor RADJ and the LTM8042’s
internal 2V reference and divider resistor. Open LED over-
voltage protection is also included. Consult the LTM8042/
LTM8042-1 datasheet for further information on how to
properly use or modify the circuit.
Design files for this circuit board are available at
http://www.linear.com/demo
Specifications are at TA = 25°C
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DEMO MANUAL DC1511A
QUICK START PROCEDURE
Demonstration circuit 1511A is easy to set up to evaluate
the performance of the LTM8042EV/LTM8042EV-1. Refer
to Figure 1 for the proper measurement equipment set-
up and follow the procedure below for a boost (step-up)
topology.
1. Connect a string of LEDs with forward voltage 32V or
less, but greater than the input voltage, to the LED+
(LED anode) and GND (LED cathode) terminals on the
PCB, as shown in Figure 1.
2. With the power off, connect the input power supply
to the BSTIN/BKLED– and GND terminals within the
ranges specified in Table 1. Preset the DC input volt-
age within the recommended input voltage range for
the appropriate forward voltage of the LED string.
Table 1. Input Range for Proper Operation (Refer to the
LTM8042/LTM8042-1 Datasheet)
DC1511A-A LTM8042 DC1511A-B LTM8042-1
INPUT VOLTAGE
(BSTIN/BKLED–
TO GND)
LED STRING
VOLTAGE
(LED+ TO GND)
INPUT VOLTAGE
(BSTIN/BKLED–
TO GND)
LED STRING
VOLTAGE
(LED+ TO GND)
5V to 5.8V 6V to 9V 3.2V to 7V 8V to 12V
6.4V to 7.7V 8V to 12V 4.1V to 10V 12V to 16V
8.6V to 11.3V 12V to 16V 4.8V to 12.3V 15V to 21V
11.3V to 13.8V 15V to 21V 5.8V to 15V 18V to 24V
13.4V to 16.5V 18V to 24V 8.5V to 20.8V 24V to 32V
20.5V to 22.5V 24V to 32V
3. Connect the PWM terminal. If PWM is not used, con-
nect PWM to a 5V source or to the input voltage. PWM
must be pulled high or the LEDs will remain off.
4. Turn the input power supply on.
5. Observe the LED string running at the programmed
LED current.
6. For PWM dimming, connect a PWM 100Hz or higher
frequency signal to the PWM terminal.
7. Observe the reduction of brightness in the LED string
by varying the duty cycle of the PWM signal.
To use the DC1511A in a buck-boost mode topology, make
the following modifications to the procedure.
1. At step 1, connect the cathode of the LED string to
the BSTIN/BKLED– terminal. The LED forward voltage
may be greater than the input voltage for buck-boost
mode.
2. At step 2, refer to the datasheet buck-boost mode
applications information table. Preset the DC input
voltage within the recommended input voltage range
for the appropriate forward voltage and current of the
LED string.
To use the DC1511A in a buck mode (step-down) topology,
make the following modifications to the procedure.
1. Remove the 0Ω jumper at location R8 and instead
install the jumper at location R4. This shorts the VCC,
TGEN and RUN pins/terminals to BSTOUT/BKIN
instead of BSTIN/BKLED–.
2. At step 1, connect the cathode of the LED string to
the BSTIN/BKLED– terminal. The LED forward voltage
must be less than the input voltage for buck mode.
3. At step 2, connect the input power supply to BSTOUT/
BKIN and GND. Refer to the datasheet buck mode
applications information table. Preset the DC input
voltage within the recommended input voltage range
for the appropriate forward voltage and current of the
LED string.
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DEMO MANUAL DC1511A
VIN
IIN
VLED
ILED
*Refer to Table 1 for
Proper Input Range
*
**32V Max VLED
**
DC1511A F01
+
–
+
–
+
–
+
–
5V or
+
–
QUICK START PROCEDURE
Figure 1. Proper Measurement Equipment Set-Up (Boost Topology)
Figure 2. DC1511A-A Efficiency vs VIN Boost
Operation, 16.7V at 1A LED String
VIN (V)
8
80
EFFICIENCY (%)
1413
94
90
92
1211109 15 16
84
82
86
88
DC1511A F02
VIN (V)
6
75
EFFICIENCY (%)
128 10
93
91
DC1511A F03
14 16 18 20 22 24
77
81
89
79
85
83
87
Figure 3. DC1511A-B Efficiency vs VIN
Boost
Operation, 24.8V at 350mA LED String
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DEMO MANUAL DC1511A
PARTS LIST
ITEM QTY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER
Required Circuit Components
1 1 C1 Cap., X5R, 4.7µF, 50V, 20%, 1206 Taiyo Yuden UMK316BJ475ML-T
2 1 C2 Cap., X5R, 10µF, 50V, 20%, 1210 Taiyo Yuden UMK325BJ106MM-T
3 1 C4 Cap., X7R, 0.01µF, 25V, 10%, 0603 AVX 06033C103KAT2A
4 1 RT Res., Chip, 30.1k, 0.06W, 1%, 0603 NIC NRC06F3012TRF
5 1 U1 I.C., LED Driver, LGA (77),15mm × 9mm × 4.32mm Linear Technology Corporation LTM8042EV
Additional Demo Board Circuit Components
1 1 C3 Cap., X5R, 1µF, 50V, 20%, 1206 TDK C3216X5R1H105M
2 0 C5 (OPT) Cap., 1206
3 0 RADJ, R2, R3, R5, R7 (OPT) Res., 0603
4 1 RSYNC Res., Chip, 100k, 0.06W, 5%, 0603 NIC NRC06J104TRF
5 2 R1, R6 Res./Jumper, Chip, 0Ω, 1/16W, 1A, 0603 Vishay CRCW06030000Z0EA
6 0 R4 (OPT) Res., 1206
7 1 R8 Res./Jumper, Chip, 0Ω, 1/4W, 1A, 1206 Vishay CRCW12060000ZOEA
8 1 M1 P-Channel MOSFET, 40V, SOT-23 Vishay Si2319DS-T1-E3 #PBF
Hardware, for Demo Board Only
1 13 E1, E2, E3, E4, E5, E6, E7, E8,
E9, E10, E11, E12, E13
Turret, Testpoint 0.094" Mill-Max 2501-2-00-80-00-00-07-0
ITEM QTY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER
Required Circuit Components
1 1 C1 Cap., X5R, 2.2µF, 50V, 20%, 1206 Taiyo Yuden UMK316BJ225MD-T
2 1 C2 Cap., X5R, 10µF, 50V, 20%, 1210 Taiyo Yuden UMK325BJ106MM-T
3 1 C4 Cap., X7R, 0.01µF, 25V, 10%, 0603 AVX 06033C103KAT2A
4 1 RT Res., Chip, 16.9k, 0.06W, 1%, 0603 Vishay CRCW060316K9FKEA
5 1 U1 I.C., LED Driver, LGA (77),15mm × 9mm × 4.32mm Linear Technology Corporation LTM8042EV-1
Additional Demo Board Circuit Components
1 1 C3 Cap., X5R, 1µF, 50V, 20%, 1206 TDK C3216X5R1H105M
2 0 C5 (OPT) Cap., 1206
3 0 RADJ, R2, R3, R5, R7 (OPT) Res., 0603
4 1 RSYNC Res., Chip, 100k, 0.06W, 5%, 0603 NIC NRC06J104TRF
5 2 R1, R6 Res./Jumper, Chip, 0Ω, 1/16W, 1A, 0603 Vishay CRCW06030000Z0EA
6 0 R4 (OPT) Res., 1206
7 0 R8 Res./Jumper, Chip, 0Ω, 1/4W, 1A, 1206 Vishay CRCW12060000ZOEA
8 1 M1 P-Channel MOSFET, 40V, SOT-23 Vishay Si2319DS-T1-E3 #PBF
Hardware, for Demo Board Only
1 13 E1, E2, E3, E4, E5, E6, E7, E8,
E9, E10, E11, E12, E13
Turret, Testpoint, 0.094" Mill-Max 2501-2-00-80-00-00-07-0
LTM8042EV
LTM8042EV-1
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DEMO MANUAL DC1511A
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.
SCHEMATIC DIAGRAM
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DEMO MANUAL DC1511A
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com
LINEAR TECHNOLOGY CORPORATION 2010
LT 1010 • 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:
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1630 McCarthy Blvd.
Milpitas, CA 95035
Copyright © 2004, Linear Technology Corporation
