FEATURES
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LT3590
48V Buck Mode
LED Driver in SC70
and 2mm x 2mm DFN
DESCRIPTION
The LT
®
3590 is a fixed frequency buck mode converter
specifically designed to drive up to 10 LEDs in series from
a 48V DC source. Series connection of the LEDs provides
identical LED currents of up to 50mA, resulting in uniform
brightness and eliminating the need for ballast resistors.
A fixed frequency, current mode architecture results in
stable operation over a wide range of input voltage and
output voltage.
The high switching frequency of 850kHz permits the use
of tiny, low profile inductors and capacitors. A single pin
performs both shutdown and accurate LED dimming
control. The power switch, Schottky diode and control
circuitry are all contained inside a space saving SC70
package or 2mm × 2mm DFN package to allow a small
converter footprint and lower parts cost.
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
4.5V to 55V Input Voltage Range
Up to 50mA LED Current
80mA, 55V Switch
Internal Schottky Diode
15μA Supply Current in Shutdown
500μA Supply Current Operating, Not Switching
Switching Frequency: 850kHz
200mV Feedback Voltage with ±5% Accuracy
CTRL Input Performs Dimming and Shutdown
91% Efficiency (10 LEDs, 50mA)
Requires Only 1μF Output Capacitor
8-Lead SC70 Package
6-Lead 2mm × 2mm DFN Package
APPLICATIONS
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LED Fixed Signage
Traffic Signs
Neon Sign Replacement
TYPICAL APPLICATION
Buck Mode Driver for Ten White LEDs
1μF
50mA
4Ω
V
IN
48V
1μF
CONTROL
V
IN
CTRL
LT3590
VREG
0.1μF
GND
SW
50
3590 TA01a
Conversion Efficiency
100
90
EFFICIENCY (%)
80
70
60
LED
470μH
40
0
10
20
30
LED CURRENT (mA)
40
50
3590 TA01b
3590f
1
LT3590
ABSOLUTE MAXIMUM RATINGS
(Note 1)
Input Voltage (V
IN
) ..................................... –0.3V to 55V
LED Voltage ............................................... –0.3V to 55V
CTRL Voltage ................................................. 0V to 6.0V
VREG Voltage ................................................. 0V to 4.0V
Operating Junction Temperature Range
(Note 2) ...............................................– 40°C to 85°C
Maximum Junction Temperature........................... 125°C
Storage Temperature Range...................– 65°C to 150°C
Lead Temperature (Soldering, 10 sec)
SC 8 Package Only ............................................ 300°C
PIN CONFIGURATION
TOP VIEW
CTRL 1
GND 2
SW 3
7
6 VREG
5 LED
4 V
IN
SW 1
GND 2
GND 3
GND 4
TOP VIEW
8 V
IN
7 LED
6 VREG
5 CTRL
DC PACKAGE
6-LEAD (2mm
×
2mm) PLASTIC DFN
T
JMAX
= 125°C,
θ
JA
= 65°C/W TO 85°C/W,
θ
JC
= 20°C/W
EXPOSED PAD (PIN 7) IS GND, MUST BE SOLDERED TO PCB
SC8 PACKAGE
8-LEAD PLASTIC SC70
T
JMAX
= 125°C,
θ
JA
= 75°C/W TO 95°C/W
ORDER INFORMATION
LEAD FREE FINISH
LT3590EDC#PBF
LT3590ESC8#PBF
TAPE AND REEL
LT3590EDC#TRPBF
LT3590ESC8#TRPBF
PART MARKING
LCNZ
LCPB
PACKAGE DESCRIPTION
6-Lead (2mm × 2mm) Plastic DFN
8-Lead Plastic SC70
TEMPERATURE RANGE
–40°C to 85°C
–40°C to 85°C
Consult LTC Marketing for parts specified with wider operating temperature ranges.
Consult LTC Marketing for information on non-standard lead based finish parts.
For more information on lead free part marking, go to:
http://www.linear.com/leadfree/
For more information on tape and reel specifications, go to:
http://www.linear.com/tapeandreel/
3590f
2
LT3590
ELECTRICAL CHARACTERISTICS
PARAMETER
Minimum Operating Voltage
LED Current Sense Voltage (V
IN
- V
LED
)
Sense Voltage Load Regulation
Quiescent Current ON, No Switching
Quiescent Current in Shutdown
Switching Frequency
Maximum Duty Cycle
Switch Current Limit
Switch V
CESAT
Switch Leakage Current
V
CTRL
for Full LED Current
V
CTRL
to Shut Down IC
V
CTRL
to Turn on IC
CTRL Pin Bias Current
LED Pin Bias Current
LDO Voltage V
REG
LDO Load Regulation
LDO Current Limit
Schottky Forward Drop
Schottky Leakage Current
I
SCHOTTKY
= 50mA
V
R
= 48V
V
CTRL
= 1V, Current Out of Pin
V
LED
= 47.8V
I
VREG
= 1mA
ΔI
VREG
= 0mA to 1mA
1.5
0.8
4
3.1
150
100
9
3.3
17
14
3.5
I
SW
= 50mA
V
SW
= 48V
●
●
The
●
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C, V
IN
= 48V, V
CTRL
= 3.3V, unless otherwise noted.
CONDITIONS
MIN
4.5
190
200
5
500
15
●
●
TYP
MAX
210
700
20
1050
150
2
100
UNITS
V
mV
mV
μA
μA
kHz
%
mA
mV
μA
V
mV
mV
nA
μA
V
mV
mA
V
μA
ΔI
LED
= 10mA to 50mA
V
LED
= 47.7V
V
CTRL
= 0V
650
90
80
850
115
500
1
1.5
Note 1:
Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
Note 2:
The LT3590E is guaranteed to meet performance specifications
from 0°C to 85°C junction temperature. Specifications over the –40°C
to 85°C operating junction temperature range are assured by design,
characterization and correlation with statistical process controls.
3590f
3
LT3590
TYPICAL PERFORMANCE CHARACTERISTICS
Switch Saturation Voltage
(V
CESAT
)
0.8
SWITCH SATURATION VOLTAGE (V)
0.7
–40°C
0.6
0.5
25°C
0.4
0.3
0.2
125°C
SCHOTTKY FORWARD DROP (V)
1.2
1.1
1.0
0.9
0.8
0.7
0.6
0.5
0.4
20
60
40
80
SWITCH CURRENT (mA)
100
3590 G01
Schottky Forward Voltage Drop
20
Shutdown Quiescent
Current vs V
IN
V
CTRL
= 0V
T
A
= 25°C
–40°C
25°C
SHUTDOWN CURRENT (μA)
18
16
125°C
14
12
0
100
200
50
150
SCHOTTKY FORWARD CURRENT (mA)
3590 G02
10
0
10
20
30
V
IN
(V)
40
50
60
3590 G03
Shutdown Quiescent Current
vs Temperature
20
V
CTRL
= 0V
V
IN
= 48V
QUIESCENT CURRENT (μA)
600
Quiescent Current
2.0
SCHOTTKY LEAKAGE CURRENT (μA)
V
CTRL
= 3.3V
T
A
= 25°C
550
Schottky Leakage Current
SHUTDOWN CURRENT (μA)
18
1.5
V
IN
= 48V
1.0
V
IN
= 24V
0.5
V
IN
= 4.5V
0
–50 –25
0
75
50
25
TEMPERATURE (°C)
100
125
16
500
14
450
12
10
–50 –25
400
0
50
75
25
TEMPERATURE (°C)
100
125
0
10
20
30
V
IN
(V)
40
50
60
3590 G05
3590 G04
3590 G06
Switching Waveform
I
L
20mA/DIV
CTRL
5V/DIV
V
SW
50V/DIV
Transient Response
V
SW
20V/DIV
I
L
50mA/DIV
I
LED
50mA/DIV
V
IN
= 48V
I
LED
= 50mA
10 WHITE LEDs
L = 470μH (COILCRAFT)
1μs/DIV
3590 G07
V
IN
= 48V
I
LED
= 50mA
10 BLUE LEDs
40μs/DIV
3590 G08
3590f
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LT3590
TYPICAL PERFORMANCE CHARACTERISTICS
Sense Voltage (V
IN
– V
LED
)
vs V
CTRL
0.25
SWITCHING CURRENT LIMIT (mA)
V
IN
= 48V
I
LED
= 50mA
T
A
= 25°C
150
140
130
120
110
100
90
80
0
0.5
1
V
CTRL
(V)
3590 G09
Switching Current Limit
vs Duty Cycle
T
A
= 25°C
SWITCHING CURRENT LIMIT (mA)
150
140
130
120
110
100
90
Switching Current Limit
vs Temperature
SENSE VOLTAGE (V
IN
-V
LED
)
0.20
0.15
0.10
0.05
0
1.5
2
0
20
40
60
80
100
3590 G10
80
–50 –25
0
DUTY CYCLE (%)
75
50
25
TEMPERATURE (°C)
100
125
3590 G11
Sense Voltage (V
IN
– V
LED
)
vs V
IN
206
I
LED
= 50mA
10 WHITE LEDs
204 T
A
= 25°C
V
IN
-V
LED
(mV)
202
200
198
196
194
0
10
20
30
V
IN
(V)
206
204
202
200
198
196
Sense Voltage (V
IN
– V
LED
)
vs Temperature
1000
SWITCHING FREQUENCY (KHz)
950
900
850
800
750
Switching Frequency over
Temperature
V
IN
= 48V
V
IN
-V
LED
(mV)
40
50
60
3590 G12
194
–50 –25
0
75
50
25
TEMPERATURE (°C)
100
125
700
–50 –25
0
50
75
25
TEMPERATURE (°C)
100
125
3590 G13
3590 G14
Internal Regulator
Line Regulation
3.40
T
A
= 25°C
3.35
V
REG
(V)
V
REG
(V)
V
CTRL
= 0V
I
LOAD
= 0V
3.35
3.40
Internal Regulator
Load Regulation
3.40
T
A
= 25°C
V
CTRL
= 0V
I
LED
= 0V
3.35
T
REG
(V)
Internal Regulator
V
REG
vs Temperature
V
CTRL
= 3.3V
I
LOAD
= 1mA
3.30
V
CTRL
= 3.3V
I
LOAD
= 1mA
3.25
3.30
V
CTRL
= 3.3V
I
LED
= 50mA
3.25
3.30
3.25
3.20
0
10
20
30
V
IN
(V)
40
50
60
3590 G15
3.20
0
0.2
0.6
0.4
I
LOAD
(mA)
0.8
1
3590 G16
3.20
–50
–25
75
0
25
50
TEMPERATURE (°C)
100
125
3590 G17
3590f
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