DEMO MANUAL
DC1319B-A/DC1319B-B
LT3756-2/LT3756-1
High Voltage LED Controller
DESCRIPTION
Demonstration circuit 1319B-A/1319B-B is a high voltage
and high current LED driver controller. The VIN pin input
voltage is as high as 100V, and the LED output voltage
is also as high as 100V. The demonstration circuit is assembled as a boost topology from 8V to 80V input and up
to 80V LED output at 0.5A with an open-LED status pin
(DC1319B-A) or a sync input pin (DC1319B-B). DC1319B
features PWM dimming, analog dimming, shutdown, and
open-LED overvoltage protection. Efficiency at 12VIN is
as high as 91% for 40W output.
The switching frequency is set at 300kHz to accommodate
the automotive switching frequency range. Small ceramic
input and output capacitors are used to save space and
cost and a high voltage 100V external power switch and
a 100V catch diode are used for up to 40W (80V at 0.5A)
output as assembled. The open-LED overvoltage protection limits the output to approximately 92V if the LED
string is opened.
Note: LED output voltages above 80V, but less than the
open-LED voltage of 92V, are possible with limitations to
low input voltage operation. Please consult the factory.
For low input voltage operation, the CTRL pin voltage is
reduced as the input voltage drops below 10V, reducing
LED brightness and restraining the peak switch currents
in order to limit inductor and switch size. UVLO turns the
LEDs off when VIN drops below 8V.
DC1319B PWM dimming is simple. The boost topology LED
string returns to the LED terminal and the PWM dimming
MOSFET turns the LED string on and off with an input to
the PWM dimming terminal. For the highest PWM dimming
ratio, it is recommended to use 100Hz as a PWM dimming
frequency. Information regarding PWM dimming ratios and
performance can be found in the LT3756-2/LT3756-1 data
sheet in the Applications Information section.
Soft-start is provided with a simple and small capacitor
to maintain control of the switch current during turn on
for high power designs.
Modifications can be made to the DC1319B in order to
convert the board from a boost topology LED driver to any
other topology. Please consult the factory or LT3756-2/
LT3756-1 data sheet for details regarding how to customize the DC1319B or how to design different topologies for
custom specifications.
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.
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DEMO MANUAL
DC1319B-A/DC1319B-B
DESCRIPTION
The LT3756-2/LT3756-1 data sheet gives a complete description of the part, operation and applications information. The data sheet must be read in conjunction with this
Quick Start Guide for demonstration circuit DC1319B-A/
DC1319B-B. The LT3756-2/LT3756-1 is assembled in a
small 16-lead plastic MSOP or QFN package with a thermally
enhanced ground pad. Demonstration circuit 1319B-A/
1319B-B uses the MSOP package. Proper board layout
is essential for maximum thermal performance. See the
data sheet section Layout Considerations.
Design files for this circuit board are available at www.
linear.com. Type in the demo circuit number.
Table 1. Performance Summary
PARAMETER
CONDITION
VALUE (TYPICAL)
Input Voltage PVIN Range
Operating
8V to 80V
Switching Frequency
R8 = 37.4k
Efficiency
PVIN = 12V, VLED = 80V ILED = 0.5A
Undervoltage Lockout
Peak Switch Current Limit
300kHz
0.5A
ILED
91%
8V
RS1 = 0.015Ω
6.6A
dc1319babf
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DEMO MANUAL
DC1319B-A/DC1319B-B
QUICK START PROCEDURE
Demonstration circuit 1319B-A/1319B-B is easy to set up
to evaluate the performance of the LT3756-2/LT3756-1.
Follow the procedure below:
Note: PWM must be pulled high to work. If PWM is not
used, connect PWM to a 5V source or to INTVCC on the
PCB using resistor R21.
1. Connect a string of LEDs with forward voltage less
than 80V, but greater than the PVIN voltage, to the LED+
and LED– (BOOST) terminals on the PCB as shown in
Figure 1.
2. Connect the shutdown terminal to GND.
3. With power off, connect the PVIN power supply to the
PVIN and GND terminals within the ranges specified
on the PCB. Make sure that the PVIN DC input voltage
does not exceed 80V or the forward voltage of the LED
string.
4. Connect the PWM terminal. If PWM is not used, connect
PWM to a 5V source or to INTVCC on the PCB using
resistor R21. PWM must be pulled high to work. For
DC1319B-B, the SYNC input can be left floating but is
best tied to GND if not used.
5. Turn the PVIN power supply on.
6. Release the shutdown-to-GND connection.
7. Observe the LED string running at the programmed
LED current.
8. For PWM dimming, connect a PWM (100Hz or higher)
signal to the PWM terminal.
9. Observe the reduction of brightness in the LED string
when PWM dimming.
+
V
–
–
–
A
+
+
–
A
+
+
V
–
PWM
OPTIONAL
DC1319 F01
Figure 1. Test Setup for the DC1319B-A/DC1319B-B
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3
DEMO MANUAL
DC1319B-A/DC1319B-B
OPERATION
Two ICs, LT3756-2/LT3756-1
Terminal Options
The DC1319B features two build versions. DC1319B-A
uses the LT3756EMSE-2 with an open-LED status and
DC1319B-B which uses the LT3756EMSE-1 with sync.
Each board is clearly marked indicating which IC is used.
The schematic for each is attached to this document. The
open-LED indicator has a pull-up resistor from the terminal
to the internal 7V regulator INTVCC. Note that when PWM
and SYNC are both used, optimal PWM dimming occurs
when there is at least a 200ns delay from the PWM rising edge and the SYNC rising edge—with the PWM edge
occurring first. For more questions regarding this matter,
please consult the factory.
DC1319B-A/DC1319B-B have both PVIN and VIN terminals.
The schematic shows that the PVIN and VIN terminals are
shorted together with a resistor. As assembled, only the
PVIN terminal needs 8V to 80V power in order for the
board to operate. However, resistor R2 can be removed
and the VIN terminal can be connected to a supply that is
separate from the PVIN terminal. The VIN terminal is tied
directly to the VIN pin.
Although DC1319B-A/DC1319B-B are assembled as boost
topology LED drivers, they can be reconfigured for buckboost mode, buck mode and SEPIC LED driver topologies.
Please keep in mind that the chosen topology should reflect
the relationship between the entire input voltage range and
the LED voltage range. Other circuit requirements such as
short circuit between terminals or ground can affect the
choice of LED driver topology.
The VOUT terminal is available for the customer to monitor
the state of the output capacitor directly. The VOUT terminal
can also be used as an input for buck mode topology.
The PWM terminal must be pulled high in order for the
board to operate. It is preferable to tie the PWM terminal/pin to INTVCC of the controller by shorting R21 if PWM
dimming is not used, but for board evaluation it can be
tied to an external 5V source as well.
dc1319babf
4
DEMO MANUAL
DC1319B-A/DC1319B-B
OPERATION
The CTRL terminal is used for analog dimming. The CTRL
pin is tied directly to the terminal and it is already being
used to reduce the LED current when PVIN drops too
low. The CTRL pin voltage can easily be overridden with
an external voltage supply and the resistor divider from
PVIN can be removed.
The shutdown/undervoltage terminal is used to shut down
the demonstration circuit. Tie the terminal to GND and the
converter stops switching. The PWMOUT pin goes low
and the PWM dimming MOSFET is turned off. As long as
the PWM dimming MOSFET is used properly, the LEDs
do not turn on during shutdown.
100
98
EFFICIENCY (%)
96
94
92
90
88
86
84
82
80
0
10
20
30
40 50
VIN (V)
60
70
80
DC1319 F02
Figure 2. DC1319B-A/DC1319B-B Efficiency
with 80V LEDs at 0.5A
0.6
LED CURRENT (A)
0.5
0.4
0.3
0.2
0.1
0
0
10
20
30
50
40
60
70
80
90
VIN (V)
DC1319 F03
Figure 3. DC1319B-A/DC1319B-B LED Current Drops at
Low VIN (CTRL) and Turns Off at Lower VIN (UVLO)
dc1319babf
5
DEMO MANUAL
DC1319B-A/DC1319B-B
PARTS LIST
QTY
6
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
0
0
0
0
0
0
0
0
0
1
0
0
1
1
0
0
1
1
13
REFERENCE
PART DESCRIPTION
REQUIRED ELECTRICAL COMPONENTS
C1, C2, C3, C10, C11, C12
Capacitor., X7R 2.2μF 100V 20% 1210
C4
Capacitor., X7R 1μF 100V 20% 1206
C5
Capacitor., X5R 4.7μF 10V 10% 0603
C6
Capacitor., X7R 4700pF 25V 20% 0402
C7
Capacitor., X5R 0.1μF 16V 20% 0402
D1
Schottky Diode 5A PowerDi5
L1
Inductor, 47μH HC9-SERIES
Q1
MOSFET N-Channel, 100V
Q2
MOSFET N-Channel, 100V
Resistor, 0.015 1/2W 1% 2010
RS1
Resistor, 0.20 0.125W 1% 0805
RS2
R1
Resistor, Chip 499k 0.06W 1% 0402
R4
Resistor, Chip 93.1k 0.06W 1% 0402
R6
Resistor, Chip 1.82M 0.06W 1% 0402
R8
Resistor, Chip 37.4k 0.06W 1% 0402
R9
Resistor, Chip 24.9k 0.06W 1% 0402
R17
Resistor, Chip 10k 0.06W 5% 0402
U1 (DC1319B-A Assembly)
IC, LED Driver MSOP(16)-MSE
U1 (DC1319B-B Assembly)
IC, LED Driver MSOP(16)-MSE
OPTIONAL ELECTRICAL COMPONENTS
C8, C13, C14 (Opt)
Capacitor., 0402
C9, C16, C18 (Opt)
Capacitor., 1210
C15 (Opt)
Capacitor., X5R 0.01μF 100V 20% 0603
C17 (Opt)
Capacitor., Alum 47μF 100V 25%
D2 (Opt)
Diode, SOD-523
FB1 (Opt)
Ferrite Bead, 6A 1806
L2 (Opt)
Inductor, 10μH CDRH104
Q4 (Opt)
MOSFET P SO8-PWRPAK-SGL
Q5 (Opt)
PNP SOT23
R2
Resistor/Jumper, Chip 0Ω 1/4W 1A 1206
R3, R13 (Opt)
Resistor, 1206
R5, R11, R16, R18, R19, R20, R21, R23 (Opt) Resistor, 0402
R7
Resistor, Chip 130k 0.06W 1% 0402
R10 (DC1319B-A assembly)
Resistor, Chip 100k 0.06W 5% 0402
R10 (DC1319B-B assembly)
Resistor, 0402
R14 (Opt)
Resistor, 0805
R15
Resistor, Chip 1M 0.06W 1% 0402
R22
Resistor/Jumper, Chip 0 Ohm 1/16W 1A 0402
HARDWARE
E1, E2, E4, E5, E6, E7, E8, E9, E10, E11, E13,
Turret, Testpoint
E14, E15
MANUFACTURER/PART NUMBER
TDK C3225X7R2A225M
AVX 12061C105MAT2A
Taiyo Yuden LMK107BJ475KA
AVX 04023C472MAT2A
AVX 0402YD104MAT2A
Diodes Inc. PDS5100-13
Cooper HC9-470-R
Siliconix Si2328DS
Siliconix Si7454DP-T1-E3
Vishay Dale WSL2010R0150FEA
Vishay Dale WSL0805R2000FEA
Vishay CRCW0402499KFKED
Vishay CRCW040293K1FKED
Vishay CRCW04021M82FKED
Vishay CRCW040237K4FKED
Vishay CRCW040224K9FKED
Vishay CRCW040210K0JNED
Linear Tech. Corp. LT3756EMSE-2
Linear Tech. Corp. LT3756EMSE-1
TDK C1608X5R2A103M
SUNCON 100CE47BS
Taiyo Yuden FBMJ4516HS720NB
Sumida CDRH104R-100MC
Vishay CRCW1206000Z
Vishay CRCW0402130KFKED
Vishay CRCW0402100KJNED
Vishay CRCW04021M00FKED
Vishay CRCW0402000Z
Mill Max 2501-2-00-80-00-00-07-0
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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.
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This circuit is proprietary to Linear Technology and supplied
for use with Linear Technology parts.
Customer Notice: Linear Technology has made a best effort to
design a circuit that meets customer-supplied specifications;
however, it remains the customers responsibility to verify proper
and reliable operation in the actual application. Component
substitution and printed circuit board layout may significantly
affect circuit performance or reliability. Contact Linear
Applications Engineering for assistance.
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DESCRIPTION
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SD PC FD AD
DEMO MANUAL
DC1319B-A/DC1319B-B
SCHEMATIC DIAGRAM
dc1319babf
7
DEMO MANUAL
DC1319B-A/DC1319B-B
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
dc1319babf
8
Linear Technology Corporation
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