LT3593
1MHz White LED Driver with
Output Disconnect and One
Pin Current Programming
FEATURES
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DESCRIPTION
The LT
®
3593 is a step-up DC/DC converter designed to
drive up to ten white LEDs in series from a Li-Ion cell.
Series connection of the LEDs provides identical LED
currents and eliminates the need for ballast resistors. The
device features a unique high side LED current sense that
enables the part to function as a “one wire current source”
where the low side of the LED string can be returned to
ground anywhere.
Additional features include output disconnect in shutdown,
open LED protection and 1-pin shutdown/LED current
control. The CTRL pin is toggled to adjust the LED current
via an internal counter and a 5-bit DAC.
The LT3593 switches at 1MHz, allowing the use of tiny
external components. Constant frequency switching re-
sults in low input noise and a small output capacitor. The
LT3593 is available in the 6-lead DFN (2mm
×
2mm) as
well as the 6-lead SOT-23 packages.
L,
LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
Drives Up to Ten White LEDs from a 3V Supply
One Pin Shutdown and Current Programming
LEDs Disconnected in Shutdown
32:1 Linear Brightness Control Range
V
IN
Range: 2.7V to 5.5V
±5% Output Current Accuracy at Full Scale
Low Shutdown Current: 3μA
1MHz Switching Frequency
Requires Only 1μF Output Capacitor
Low Profile 6-Lead DFN (2mm
×
2mm
×
0.75mm)
and 6-Lead SOT-23 Packages
APPLICATIONS
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Cell Phones
Digital Cameras
PDAs, Handheld Computers
MP3 Players
GPS Receivers
TYPICAL APPLICATION
Li-Ion Driver for Ten White LEDs
V
IN
3V TO 5V
10μH
1μF
V
IN
SW
CAP
LT3593
SHUTDOWN AND
CURRENT CONTROL
CTRL
GND
LED
1μF
EFFI CIENCY (%)
90
80
70
60
50
40
30
Conversion Efficiency
V
IN
= 3.6V
10 LEDs
0
5
10
15
LED CURRENT (mA)
20
3593 TA01b
3593 TA01a
3593f
1
LT3593
ABSOLUTE MAXIMUM RATINGS
(Note 1)
Input Voltage...............................................................6V
CTRL Voltage ..............................................................6V
SW Voltage ...............................................................45V
CAP Voltage ..............................................................45V
LED Voltage ..............................................................45V
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)
TSOT Package................................................... 300°C
PIN CONFIGURATION
TOP VIEW
TOP VIEW
V
IN
1
GND 2
CTRL 3
7
6 SW
5 CAP
4 LED
CTRL 1
GND 2
V
IN
3
6 LED
5 CAP
4 SW
DC PACKAGE
6-LEAD (2mm × 2mm) PLASTIC DFN
T
JMAX
= 125°C,
θ
JA
= 106°C/W
EXPOSED PAD (PIN 7) IS GND, MUST BE SOLDERED TO PCB
S6 PACKAGE
6-LEAD PLASTIC TSOT-23
T
JMAX
= 125°C,
θ
JA
= 192°C/W
ORDER INFORMATION
LEAD FREE FINISH
LT3593EDC#PBF
LT3593ES6#PBF
TAPE AND REEL
LT3593EDC#TRPBF
LT3593ES6#TRPBF
PART MARKING
LDBR
LTDBS
PACKAGE DESCRIPTION
6-Lead (2mm
×
2mm) Plastic DFN
6-Lead Plastic TSOT-23
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/
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
IN
= 3.6V, V
CTRL
= 3.6V, unless otherwise specified.
PARAMETER
Operating Voltage Range
Supply Current
Switching Frequency
Maximum Duty Cycle
Switch Current Limit
Switch V
CESAT
I
SW
= 250mA
Not Switching; During Current Programming
CTRL = 0
0.85
92
550
CONDITIONS
MIN
2.7
300
3
1
94
700
250
10
1.15
TYP
MAX
5.5
UNITS
V
μA
μA
MHz
%
mA
mV
3593f
ELECTRICAL CHARACTERISTICS
2
LT3593
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
IN
= 3.6V, V
CTRL
= 3.6V, unless otherwise specified.
PARAMETER
Switch Leakage Current
LED Pin Voltage Drop (V
CAP
– V
LED
)
LED Pin Leakage Current
CTRL High Threshold
CTRL Low Threshold
CTRL t
PW
CTRL t
SD
CTRL t
EN
Full-Scale LED Current
LED Current Programming Resolution
LED Current Limit
CTRL Pin Bias Current
Overvoltage Protection
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.
V
CTRL
= 5.5V
l
ELECTRICAL CHARACTERISTICS
CONDITIONS
V
SW
= 30V
I
LED
= 20mA
CTRL = 0, V
CAP
= 35V
MIN
TYP
250
MAX
1
1
UNITS
μA
mV
μA
V
V
ns
μs
μs
mA
mA
μA
mA
1.6
0.4
Programming Pulse Width (Note 3)
Time from CTRL = 0 to Shutdown
Time from CTRL = 1 to Enable
V
CAP
= 16V
V
CAP
= 16V
Linear Increments
l
250
95
95
19
18.5
128
128
20
20
625
45
1
36
38
40
200
200
21
21.5
μA
V
Note 2:
The LTC3593E is guaranteed to meet performance specifications
from 0°C to 85°C operating junction temperature range. Specifications
over the –40°C to 85°C operating junction temperature range are assured
by design, characterization and correlation with statistical process
controls.
Note 3:
Guaranteed by design.
3593f
3
LT3593
TYPICAL PERFORMANCE CHARACTERISTICS
Switch Saturation Voltage
(V
CESAT
)
600
SWITCH SATURATION VOLTAGE (mV)
500
100°C
400
25°C
300
–50°C
200
100
0
6
5
SHUTDOWN CURRENT (μA)
QUIESCENT CURRENT (mA)
100°C
4
25°C
3
2
1
0
0
100
300
500
400
200
SWITCH CURRENT (mA)
600
3593 G01
T
A
= 25°C unless otherwise specified.
Shutdown Current (V
CTRL
= 0V)
3.50
3.25
Quiescent Current (V
CTRL
= 3.6V)
100°C
3.00
25°C
2.75
–50°C
2.50
2.25
2.00
–50°C
2
3
4
V
IN
(V)
5
6
3593 G02
2
3
4
V
IN
(V)
5
6
3593 G03
LED Pin Voltage Drop
(V
CAP
– V
LED
)
300
250
V
CAP
– V
LED
(mV)
200
150
100
50
0
25°C
–50°C
V
IN
= 3.6V
V
CAP
= 16V
LED PIN CURRENT LIMIT (mA)
100°C
46
LED Pin Current Limit
750
V
IN
= 3.6V
V
CAP
= 16V
45
Switching Current Limit vs
Temperature
V
IN
= 3.6V
SWITCH CURRNET LIMIT (mA)
100
3593 G05
700
44
650
43
600
0
5
10
15
LED CURRENT (mA)
20
3593 G04
42
–50
–25
0
25
50
TEMPERATURE (°C)
75
550
–50
–25
0
25
50
TEMPERATURE (°C)
75
100
3593 G06
Switching Waveform
I
L
200mA/DIV
V
CAP
200mV/DIV
AC COUPLED
V
SW
20V/DIV
V
IN
= 3.6V
1μs/DIV
FRONT PAGE
APPLICATION CIRCUIT
3393 G07
Transient Response
V
CTRL
5V/DIV
I
L
200mA/DIV
V
CAP
10V/DIV
V
IN
= 3.6V
200μs/DIV
FRONT PAGE
APPLICATION CIRCUIT
3393 G08
3593f
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LT3593
TYPICAL PERFORMANCE CHARACTERISTICS
Open-Circuit Output Clamp
Voltage
INPUT CURRENT OUTPUT OPEN-CIRCUIT (mA)
40
OPEN-CIRCUIT CLAMP VOLTAGE (V)
10
OPEN-CIRCUIT CLAMP VOLTAGE (V)
9
8
7
6
5
4
3
2
2.0
2.5
3.0
3.5
4.0 4.5
V
IN
(V)
5.0
5.5
6.0
3593 G10
T
A
= 25°C unless otherwise specified.
Open-Circuit Output Clamp
Voltage vs Temperature
40
V
IN
= 3.6V
39
Input Current in Output Open
Circuit
39
25°C
38
100°C
–50°C
38
37
37
36
2
3
4
V
IN
(V)
5
6
3593 G09
36
–50
–25
0
25
50
TEMPERATURE (°C)
75
100
3593 G11
Input Current in Output
Open-Circuit vs Temperatue
INPUT CURRENT OUTPUT OPEN-CIRCUIT (mA)
8
7
6
5
4
3
2
–50
V
IN
= 3.6V
SWITCHING FREQUENCY (kHz)
1150
1100
Switching Frequency vs
Temperature
20
V
IN
= 3.6V
LED Current vs CTRL Strobe
Pulses
V
IN
= 3.6V
10LEDS
15
LED CURRENT (mA)
1050
1000
950
900
850
–50
10
5
–25
0
25
50
TEMPERATURE (°C)
75
100
3593 G12
0
–25
50
0
25
TEMPERATURE (°C)
75
100
3593 G13
0
8
16
24
NUMBER OF CTRL STROBES
32
3593 G14
Full-Scale Current vs V
IN
21.0
21.0
10 LEDs
Full-Scale Current vs V
CAP
21.0
Full-Scale Current vs
Temperature
V
IN
= 3.6V
10LEDS
LED CURRENT (mA)
LED CURRENT (mA)
20.5
20.5
FULL SCALE CURRENT (mA)
5
10
15
20
25
V
CAP
(V)
30
35
3593 G16
20.5
20.0
20.0
20.0
19.5
19.5
19.5
19.0
2.5
19.0
3.0
3.5
4.0 4.5
V
IN
(V)
5.0
5.5
6.0
3593 G15
19.0
–50
–25
0
25
50
TEMPERATURE (°C)
75
100
3593 G17
3593f
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