lt3518euf-trpbf Linear Technology Corporation, lt3518euf-trpbf Datasheet

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lt3518euf-trpbf

Manufacturer Part Number
lt3518euf-trpbf
Description
Full-featured Led Driver With 2.3a Switch Current
Manufacturer
Linear Technology Corporation
Datasheet
FEATURES
APPLICATIONS
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TYPICAL APPLICATION
3000:1 True Color PWM™ Dimming Ratio
2.3A, 45V Internal Switch
100mV High Side Current Sense
Open LED Protection
Adjustable Frequency: 250kHz to 2.5MHz
Wide Input Voltage Range:
Operates in Boost, Buck Mode and Buck-Boost Mode
Gate Driver for PMOS LED Disconnect*
Constant-Current and Constant-Voltage Regulation
CTRL Pin Provides 10:1 Analog Dimming
Low Shutdown Current: <1μA
Available in (4mm × 4mm) 16-Lead QFN and 16-Pin
TSSOP Packages
Display Backlighting
Automotive and Avionic Lighting
Illumination
Scanners
PV
3.3V
24V
V
2.2μF
IN
Operation from 3V to 30V
Transient Protection to 40V
IN
PWM
V
REF
2.2μF
1.5A Buck Mode LED Driver
V
SHDN
CTRL
PWM
SYNC
TGEN
IN
ISP
68mΩ
0.1μF
V
LT3518
REF
ISN
V
C
M1
TG
GND
SW
SS
R
FB
T
1.5A
16.9k
1MHz
0.1μF
15μH
10μF
3518 TA01a
DESCRIPTION
The LT
internal 2.3A, 45V switch specifi cally designed to drive
LEDs. The LT3518 operates as a LED driver in boost, buck
mode and buck-boost mode. It combines a traditional
voltage loop and a unique current loop to operate as a
constant-current source or constant-voltage source. Pro-
grammable switching frequency allows optimization of the
external components for effi ciency or component size. The
switching frequency of the LT3518 can be synchronized
to an external clock signal. The LED current is externally
programmable with a 100mV sense resistor. The external
PWM input provides 3000:1 LED dimming. The CTRL pin
provides further 10:1 dimming ratio.
The LT3518 is available in the tiny footprint 16-Lead QFN
(4mm × 4mm) and the 16-Pin TSSOP package. The LT3518
provides a complete solution for both constant-voltage
and constant-current applications.
L, LT, LTC and LTM are registered trademarks of Linear Technology Corporation. True Color
PWM is a trademark of Linear Technology Corporation. Patent Pending. All other trademarks are
the property of their respective owners. *Patents Pending.
with 2.3A Switch Current
Full-Featured LED Driver
®
3518 is a current mode DC/DC converter with an
100
90
80
70
60
50
40
0
CTRL = V
20
REF
PWM DUTY CYCLE (%)
Effi ciency
40
60
80
3518 TA01b
100
LT3518
3518fb
1

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lt3518euf-trpbf Summary of contents

Page 1

... L, LT, LTC and LTM are registered trademarks of Linear Technology Corporation. True Color PWM is a trademark of Linear Technology Corporation. Patent Pending. All other trademarks are the property of their respective owners. *Patents Pending. 100 10μ ...

Page 2

... T = 36°C/W JMAX JA EXPOSED PAD (PIN 17) IS GND, MUST BE SOLDERED TO PCB ORDER INFORMATION LEAD FREE FINISH TAPE AND REEL LT3518EUF#PBF LT3518EUF#TRPBF LT3518IUF#PBF LT3518IUF#TRPBF LT3518EFE#PBF LT3518EFE#TRPBF LT3518IFE#PBF LT3518IFE#TRPBF LT3518HFE#PBF LT3518HFE#TRPBF Consult LTC Marketing for parts specifi ed with wider operating temperature ranges. *The temperature grade is identifi label on the shipping container. ...

Page 3

ELECTRICAL CHARACTERISTICS temperature range, otherwise specifi cations are at T PARAMETER Minimum V Operating Voltage IN Maximum V Operating Voltage IN Current Sense Voltage (V – ISP ISN 10% Scale Current Sense Voltage (V – V ISP ISN ...

Page 4

LT3518 ELECTRICAL CHARACTERISTICS temperature range, otherwise specifi cations are at T PARAMETER V Pin Voltage Line Regulation REF Gate Turn-On Delay Gate Turn-Off Delay Top Gate Drive V (V – ISP TG Note 1: Stresses beyond those ...

Page 5

TYPICAL PERFORMANCE CHARACTERISTICS V – V Threshold vs V ISP ISN 120 24V ISP 100 25° 1.0 0 0.2 0.4 0.6 0.8 ...

Page 6

LT3518 TYPICAL PERFORMANCE CHARACTERISTICS V – V Threshold vs V ISP ISN 105 CTRL 104 25°C A 103 102 101 100 ...

Page 7

PIN FUNCTIONS SW: Switch Pin. Minimize trace at this pin to reduce EMI Input Supply Pin. Must be locally bypassed. IN SHDN: Shutdown Pin. Tie to 1.5V or higher to enable device or 0.4V or less to disable ...

Page 8

LT3518 BLOCK DIAGRAM R SENSE PV IN ISP ISN + – CURRENT X10 SENSE AMPLIFIER SHDN – CTRL + 1.01V A2 FB – SYNC + A5 – 10μ ...

Page 9

OPERATION The LT3518 is a constant frequency, current mode regula- tor with an internal power switch. Operation can be best understood by referring to the Block Diagram in Figure 1. At the start of each oscillator cycle, the SR latch ...

Page 10

LT3518 APPLICATIONS INFORMATION Dimming Control There are two methods to control the current source for dimming using the LT3518. The fi rst method uses the PWM pin to modulate the current source between zero and full current to achieve a ...

Page 11

APPLICATIONS INFORMATION For a buck or a buck-boost confi guration, the output voltage is typically level-shifted to a signal with respect to GND as illustrated in the Figure 4. The output can be expressed as • 1.01V + ...

Page 12

LT3518 APPLICATIONS INFORMATION Use only ceramic capacitors with X7R, X5R or better dielec- tric as they are best for temperature and DC bias stability of the capacitor value. All ceramic capacitors exhibit loss of capacitance value with increasing DC voltage ...

Page 13

APPLICATIONS INFORMATION Switching Frequency There are two methods to set the switching frequency of LT3518. Both methods require a resistor connected at R pin. Do not leave the R pin open. Also, do not load this pin T with a ...

Page 14

LT3518 TYPICAL APPLICATIONS Buck Mode 1.5A LED Driver R SENSE 68mΩ 24V C2 2.2μF ISP ISN 3.3V C1 SHDN 2.2μF LT3518 V CTRL FB REF PWM PWM SS SYNC R T ...

Page 15

TYPICAL APPLICATIONS 16V C1 2.2μF C1: KEMET C0806C225K4RAC C2: KEMET C1206C475K3RAC C3, C4: MURATA GRM21BR71H104KA01B C5: MURATA GRM21BR71H224KA01B D1: ZETEX ZLLS2000TA L1: TOKO B992AS-4R3N LEDS: LUXEON I (WHITE) M1: ZETEX ZXMP6A13GTA 3000:1 PWM Dimming at 120Hz ...

Page 16

LT3518 TYPICAL APPLICATIONS Buck Mode 1A LED Driver with Open LED Protection and Sync Input PV IN 32V C2 2.2μ 3.3V C1 2.2μF V REF PWM SYNC 3.3V, 1.2MHz 1000:1 PWM Dimming at 120Hz PWM 5V/DIV I LED ...

Page 17

TYPICAL APPLICATIONS 16V PWM C1 2.2μF C4 0.1μF 3000:1 PWM Dimming at 100Hz PWM 5V/DIV I LED 200mA/DIV I L1 1A/DIV V = 12V 1μs/DIV 1MHz OSC I = 300mA LED Boost 300mA ...

Page 18

LT3518 PACKAGE DESCRIPTION 4.35 ± 0.05 2.15 ± 0.05 2.90 ± 0.05 (4 SIDES) RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS 4.00 ± 0.10 (4 SIDES) PIN 1 TOP MARK (NOTE 6) NOTE: 1. DRAWING CONFORMS TO JEDEC PACKAGE OUTLINE MO-220 ...

Page 19

... DIMENSIONS ARE IN 3. DRAWING NOT TO SCALE 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. FE Package ...

Page 20

... Dimming = 1000:1 True Color PWM, OUT(MAX) = 45V, Dimming = 3000:1 True Color PWM, OUT(MAX) = 45V, Dimming = 5000:1 True Color PWM, OUT(MAX) = Ext FET, Dimming = 3000:1 True Color PWM, OUT(MAX) LT 0308 REV B • PRINTED IN USA © LINEAR TECHNOLOGY CORPORATION 2007 < 1μA, 3518fb ...

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