DC1319B-A Linear Technology, DC1319B-A Datasheet

BOARD EVAL LED DRIVER LT3756

DC1319B-A

Manufacturer Part Number
DC1319B-A
Description
BOARD EVAL LED DRIVER LT3756
Manufacturer
Linear Technology
Datasheets

Specifications of DC1319B-A

Current - Output / Channel
500mA
Outputs And Type
1, Non-Isolated
Voltage - Output
100V
Features
Dimmable
Voltage - Input
8 ~ 80V
Utilized Ic / Part
LT3756
Lead Free Status / RoHS Status
Lead free / RoHS Compliant
Other names
DC1319A-A
DC1319A-A
FeaTures
applicaTions
n
n
n
n
n
n
n
n
n
n
n
n
n
n
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Typical applicaTion
3000:1 True Color PWM™ Dimming
Wide Input Voltage Range: 6V to 100V
Output Voltage Up to 100V
Constant-Current and Constant-Voltage Regulation
100mV High Side Current Sense
Drives LEDs in Boost, Buck Mode, Buck-Boost Mode,
SEPIC or Flyback Topology
Adjustable Frequency: 100kHz to 1MHz
Open LED Protection
Programmable Undervoltage Lockout with Hysteresis
Improved Open LED Status Pin (LT3756-2)
Frequency Synchronization (LT3756-1)
PWM Disconnect Switch Driver
CTRL Pin Provides Analog Dimming
Low Shutdown Current: <1µA
Programmable Soft-Start
Thermally Enhanced 16-Lead QFN (3mm × 3mm)
and MSOP Packages
High Power LED Applications
Current Limited Constant Voltage Applications
Battery Charging
V
8V TO 60V
(100V TRANSIENT)
IN
4.7µF
INTV
CC
100k
1M
185k
0.01µF
94% Efficient 30W White LED Headlamp Driver
332k
40.2k
28.7k
375kHz
1%
SHDN/UVLO
V
CTRL
OPENLED
PWM
SS
RT
V
REF
C
10k
0.001µF
LT3756-2
V
GND
IN
PWMOUT
INTV
SENSE
GATE
ISN
22µH
ISP
FB
CC
INTV
4.7µF
CC
0.018
0.27
370mA
1M
14k
DescripTion
375612 TA01a
The LT
lers designed to operate as a constant-current source for
driving high current LEDs. They drive a low side external
N-channel power MOSFET from an internal regulated 7.15V
supply. The fixed frequency, current-mode architecture
results in stable operation over a wide range of supply
and output voltages. A ground referenced voltage FB pin
serves as the input for several LED protection features,
and also makes it possible for the converter to operate
as a constant-voltage source. A frequency adjust pin
allows the user to program the frequency from 100kHz
to 1MHz to optimize efficiency, performance or external
component size.
The LT3756/LT3756-1/LT3756-2 sense output current at
the high side of the LED string. High side current sensing
is the most flexible scheme for driving LEDs, allowing
boost, buck mode or buck-boost mode configuration.
The PWM input provides LED dimming ratios of up to
3000:1, and the CTRL input provides additional analog
dimming capability.
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear
Technology Corporation. True Color PWM is a trademark of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
Protected by U.S. Patents, including 7199560 and 7321203.
4.7µF
30W
LED
STRING
LT3756/LT3756-1/LT3756-2
®
3756, LT3756-1 and LT3756-2 are DC/DC control-
100
100V
96
92
88
84
80
0
LED Controller
20
Efficiency vs V
IN
, 100V
V
IN
40
(V)
IN
60
375612 TA01b
OUT
375612fb
80


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DC1319B-A Summary of contents

Page 1

... CTRL input provides additional analog dimming capability. L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear Technology Corporation. True Color PWM is a trademark of Linear Technology Corporation. All other trademarks are the property of their respective owners. ...

Page 2

LT3756/LT3756-1/LT3756-2 absoluTe MaxiMuM raTings V ..........................................................................100V IN SHDN/UVLO ............................................................100V ISP , ISN ...................................................................100V INTV ...................................................... V CC GATE, PWMOUT (Note 4) ..........................INTV CTRL, PWM, OPENLED .............................................12V VC SS, FB .........................................................3V REF SYNC ..........................................................................8V pin conFiguraTion TOP VIEW 1 ...

Page 3

T noted. PARAMETER V Minimum Operating Voltage IN V Shutdown Operating I (Not Switching Voltage REF V Line Regulation REF SENSE Current Limit Threshold SENSE ...

Page 4

LT3756/LT3756-1/LT3756-2 elecTrical characTerisTics temperature range, otherwise specifications are at T noted. PARAMETER Logic Inputs/Outputs PWM Input High Voltage PWM Input Low Voltage PWM Pin Resistance to GND PWMOUT Output Low ( PWMOUT Output High ( SHDN/UVLO ...

Page 5

Typical perForMance characTerisTics V Threshold vs V (ISP – ISN) CTRL 120 100 –20 0 0.5 1 1.5 V (V) CTRL 375612 G01 FB Regulation Voltage vs Temperature 1.28 1.27 1.26 1.25 1.24 1.23 1.22 ...

Page 6

LT3756/LT3756-1/LT3756-2 Typical perForMance characTerisTics Quiescent Current 2.0 PWM = 0V 1.5 1.0 0 (V) IN 375612 G10 INTV Voltage ...

Page 7

Typical perForMance characTerisTics ISP/ISN Input Bias Current vs CTRL Voltage 0.5 1 CTRL (V) pin FuncTions (MSOP/QFN) PWMOUT (Pin 1/Pin 11): Buffered Version of PWM Signal for Driving LED Load Disconnect NMOS or Level ...

Page 8

LT3756/LT3756-1/LT3756-2 pin FuncTions CTRL (Pin 6/Pin 16): Current Sense Threshold Adjustment Pin. Regulating threshold V (ISP – ISN) an offset for 0V < V < 1V. For V CTRL CTRL sense threshold is constant at the full-scale value of 100mV. ...

Page 9

DiagraM SHDN/UVLO A6 – SHDN 1.22V + 2.1µA 1.25V SHORT-CIRCUIT DETECT + SCILMB A10 + – 150mV – ISN 5k ISP CTRL BUFFER CTRL + + 1.1V A3 – 140µA V REF – 170k LT3756/LT3756-1/LT3756-2 FB ...

Page 10

LT3756/LT3756-1/LT3756-2 operaTion The LT3756 is a constant-frequency, current mode control- ler with a low side NMOS gate driver. The GATE pin and PWMOUT pin drivers, and other chip loads, are powered from INTV , which is an internally regulated supply. ...

Page 11

INTV Regulator Bypassing and Operation CC The INTV pin requires a capacitor for stable operation CC and to store the charge for the large GATE switching cur- rents. Choose a 10V rated low ESR, X7R or X5R ceramic ...

Page 12

LT3756/LT3756-1/LT3756-2 applicaTions inForMaTion When V is higher than 1.2V, the LED current is regu- CTRL lated to: 100mV = I LED R LED The LED current programming feature can increase total dimming range by a factor of 10. The CTRL ...

Page 13

PWM pin to modulate the current source between zero and full current to achieve a precisely pro- grammed average current. To make PWM dimming more accurate, the switch demand current is stored on the VC ...

Page 14

LT3756/LT3756-1/LT3756-2 applicaTions inForMaTion important when operating at high ambient temperatures. The majority of the power dissipation in the IC comes from the supply current needed to drive the gate capacitance of the external power MOSFET. This gate drive current can ...

Page 15

Therefore, a 4.7µF capacitor is an appropriate selection for a 400kHz boost regulator with 12V input, 48V output and 1A load. voltage ripple of 100mV, the input capaci- With the same V IN tor for a buck converter ...

Page 16

LT3756/LT3756-1/LT3756-2 applicaTions inForMaTion Schottky Rectifier Selection The power Schottky diode conducts current during the interval when the switch is turned off. Select a diode rated for the maximum SW voltage. If using the PWM feature for dimming important ...

Page 17

Loop Compensation The LT3756 uses an internal transconductance error ampli- fier whose VC output compensates the control loop. The external inductor, output capacitor and the compensation resistor and capacitor determine the loop stability. The inductor and output capacitor ...

Page 18

LT3756/LT3756-1/LT3756-2 applicaTions inForMaTion GND COMPONENT DESIGNATIONS ...

Page 19

Typical applicaTions 30W White LED Headlamp Driver with Thermal Derating 60V IN (100V TRANSIENT 4.7µF LT3756/LT3756-1/LT3756-2 L1, 22µ SHDN/UVLO ISP REF 185k 16.9k LT3756-2 CTRL 100k ISN INTV ...

Page 20

LT3756/LT3756-1/LT3756-2 Typical applicaTions Buck-Boost Mode LED Driver 65V V 4.7µ SHDN/UVLO V 185k REF LT3756-2 CTRL INTV CC 100k OPENLED PWM SS RT PWMOUT 0.1µF V GND C 35.7k 300kHz 39k 4700pF L1: ...

Page 21

DescripTion 2.845 0.102 (.112 .004) 5.23 (.206) MIN 0.305 0.038 (.0120 .0015) TYP RECOMMENDED SOLDER PAD LAYOUT DETAIL “A” 0.254 (.010) GAUGE PLANE DETAIL “A” 0.18 (.007) NOTE: 1. DIMENSIONS IN MILLIMETER/(INCH) 2. DRAWING NOT TO SCALE 3. DIMENSION ...

Page 22

LT3756/LT3756-1/LT3756-2 package DescripTion 3.50 ± 0.05 1.45 ± 0.05 (4 SIDES) 2.10 ± 0.05 RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS PIN 1 TOP MARK (NOTE 6) NOTE: 1. DRAWING CONFORMS TO JEDEC PACKAGE OUTLINE MO-220 VARIATION (WEED-2) 2. DRAWING NOT ...

Page 23

... Revised Entire Data Sheet to Include H-Grade 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. ...

Page 24

... OUT(MAX) = 45V, Dimming = 3000:1, I < 1µ 45V, Dimming = 3000:1, I < 1µ 45V, Dimming = 3000:1, I < 1µ 75V, True Color PWM Dimming = 3000:1, OUT(MAX) = Ext FET, True Color PWM Dimming = 3000:1, LT 0310 REV B • PRINTED IN USA  LINEAR TECHNOLOGY CORPORATION 2008 80 375612fb ...

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