LINEAR TECHNOLOGY LT3593 Technical data
LT3593
1MHz White LED Driver with
Output Disconnect and One
Pin Current Programming
FEATURES
n
Drives Up to Ten White LEDs from a 3V Supply
n
One Pin Shutdown and Current Programming
n
LEDs Disconnected in Shutdown
n
32:1 Linear Brightness Control Range
n
VIN Range: 2.7V to 5.5V
n
±5% Output Current Accuracy at Full Scale
n
Low Shutdown Current: 3µA
n
1MHz Switching Frequency
n
Requires Only 1µF Output Capacitor
n
Low Profi le 6-Lead DFN (2mm × 2mm × 0.75mm)
and 6-Lead SOT-23 Packages
APPLICATIONS
n
Cell Phones
n
Digital Cameras
n
PDAs, Handheld Computers
n
MP3 Players
n
GPS Receivers
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 results 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.
TYPICAL APPLICATION
Li-Ion Driver for Ten White LEDs
V
CTRL
IN
10µH
SW
CAP
LT3593
LED
GND
V
IN
3V TO 5V
SHUTDOWN AND
CURRENT CONTROL
1µF 1µF
3593 TA01a
Conversion Effi ciency
90
VIN = 3.6V
10 LEDs
80
70
60
EFFI CIENCY (%)
50
40
30
0
10
LED CURRENT (mA)
20155
3593 TA01b
3593f
1
LT3593
ABSOLUTE MAXIMUM RATINGS
Input Voltage ...............................................................6V
CTRL Voltage ..............................................................6V
SW Voltage ...............................................................45V
CAP Voltage ..............................................................45V
LED Voltage ..............................................................45V
PIN CONFIGURATION
TOP VIEW
6
1
V
IN
GND
CTRL
6-LEAD (2mm × 2mm) PLASTIC DFN
T
EXPOSED PAD (PIN 7) IS GND, MUST BE SOLDERED TO PCB
7
2
3
DC PACKAGE
= 125°C, θJA = 106°C/W
JMAX
SW
5
CAP
LED
4
(Note 1)
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
TOP VIEW
CTRL 1
GND 2
V
3
IN
S6 PACKAGE
6-LEAD PLASTIC TSOT-23
T
= 125°C, θJA = 192°C/W
JMAX
6 LED
5 CAP
4 SW
ORDER INFORMATION
LEAD FREE FINISH TAPE AND REEL PART MARKING PACKAGE DESCRIPTION TEMPERATURE RANGE
LT3593EDC#PBF LT3593EDC#TRPBF LDBR
LT3593ES6#PBF LT3593ES6#TRPBF LTDBS 6-Lead Plastic TSOT-23 –40°C to 85°C
Consult LTC Marketing for parts specifi ed with wider operating temperature ranges.
Consult LTC Marketing for information on non-standard lead based fi nish parts.
For more information on lead free part marking, go to: http://www.linear.com/leadfree/
For more information on tape and reel specifi cations, go to: http://www.linear.com/tapeandreel/
ELECTRICAL CHARACTERISTICS
The l denotes the specifi cations which apply over the full operating
temperature range, otherwise specifi cations are at TA = 25°C. VIN = 3.6V, V
PARAMETER CONDITIONS MIN TYP MAX UNITS
Operating Voltage Range 2.7 5.5 V
Supply Current Not Switching; During Current Programming 300 µA
CTRL = 0 3 10 µA
Switching Frequency 0.85 1 1.15 MHz
Maximum Duty Cycle 92 94 %
Switch Current Limit 550 700 mA
Switch V
CESAT
ISW = 250mA 250 mV
6-Lead (2mm × 2mm) Plastic DFN
= 3.6V, unless otherwise specifi ed.
CTRL
–40°C to 85°C
2
3593f
LT3593
ELECTRICAL CHARACTERISTICS
The l denotes the specifi cations which apply over the full operating
temperature range, otherwise specifi cations are at T
PARAMETER CONDITIONS MIN TYP MAX UNITS
Switch Leakage Current V
– V
LED Pin Voltage Drop (V
LED Pin Leakage Current CTRL = 0, V
CTRL High Threshold 1.6 V
CTRL Low Threshold 0.4 V
CTRL t
PW
CTRL t
SD
CTRL t
EN
Full-Scale LED Current V
LED Current Programming Resolution Linear Increments 625 µA
LED Current Limit 45 mA
CTRL Pin Bias Current V
Overvoltage Protection
CAP
)I
LED
= 25°C. VIN = 3.6V, V
A
= 30V 1 µA
SW
= 20mA 250 mV
LED
= 35V 1 µA
CAP
Programming Pulse Width (Note 3) 250 ns
Time from CTRL = 0 to Shutdown 95 128 200 µs
Time from CTRL = 1 to Enable 95 128 200 µs
= 16V
CAP
V
= 16V
CAP
= 5.5V 1 µA
CTRL
= 3.6V, unless otherwise specifi ed.
CTRL
19
l
18.5
l
36 38 40 V
20
20
21
21.5
mA
mA
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 LTC3593E is guaranteed to meet performance specifi cations
from 0°C to 85°C operating junction temperature range. Specifi cations
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
500
400
300
200
100
SWITCH SATURATION VOLTAGE (mV)
0
0
100 500
SWITCH CURRENT (mA)
LED Pin Voltage Drop
– V
(V
CAP
LED
300
VIN = 3.6V
= 16V
V
CAP
250
200
(mV)
LED
150
– V
CAP
100
V
50
100°C
25°C
–50°C
400200
600300
3593 G01
)
100°C
25°C
–50°C
Shutdown Current (V
6
5
4
3
2
SHUTDOWN CURRENT (µA)
1
0
2
VIN (V)
LED Pin Current Limit
46
45
44
43
LED PIN CURRENT LIMIT (mA)
CTRL
100°C
25°C
= 0V)
53
VIN = 3.6V
V
CAP
= 25°C unless otherwise specifi ed.
T
A
Quiescent Current (V
3.50
3.25
3.00
–50°C
64
3593 G02
2.75
2.50
QUIESCENT CURRENT (mA)
2.25
2.00
2
Switching Current Limit vs
Temperature
750
VIN = 3.6V
= 16V
700
650
600
SWITCH CURRNET LIMIT (mA)
VIN (V)
CTRL
100°C
25°C
–50°C
= 3.6V)
53
3593 G03
64
4
0
0
LED CURRENT (mA)
155
2010
3593 G04
Switching Waveform
I
L
200mA/DIV
V
CAP
200mV/DIV
AC COUPLED
V
SW
20V/DIV
FRONT PAGE
APPLICATION CIRCUIT
1µs/DIVVIN = 3.6V
42
–50
TEMPERATURE (°C)
750–25 25
10050
3593 G05
550
–50
25 50 75–25
TEMPERATURE (°C)
1000
3593 G06
Transient Response
V
CTRL
5V/DIV
I
L
200mA/DIV
V
CAP
10V/DIV
3393 G08
3593f
3393 G07
= 3.6V
IN
FRONT PAGE
APPLICATION CIRCUIT
200µs/DIVV
LT3593
TYPICAL PERFORMANCE CHARACTERISTICS
Open-Circuit Output Clamp
Voltage
40
39
25°C
38
37
OPEN-CIRCUIT CLAMP VOLTAGE (V)
36
2
VIN (V)
Input Current in Output
Open-Circuit vs Temperatue
8
VIN = 3.6V
7
6
100°C
–50°C
543
6
3593 G09
Input Current in Output Open
Circuit
10
9
8
7
6
5
4
3
INPUT CURRENT OUTPUT OPEN-CIRCUIT (mA)
2
2.0 2.5
VIN (V)
5.0 5.53.0 3.5
Switching Frequency vs
Temperature
1150
VIN = 3.6V
1100
1050
TA = 25°C unless otherwise specifi ed.
Open-Circuit Output Clamp
Voltage vs Temperature
40
VIN = 3.6V
39
38
37
OPEN-CIRCUIT CLAMP VOLTAGE (V)
6.04.0 4.5
3593 G10
36
–50
TEMPERATURE (°C)
LED Current vs CTRL Strobe
Pulses
20
15
750–25 25
VIN = 3.6V
10LEDS
10050
3593 G11
5
4
3
INPUT CURRENT OUTPUT OPEN-CIRCUIT (mA)
2
–50
Full-Scale Current vs V
21.0
10 LEDs
20.5
20.0
LED CURRENT (mA)
19.5
19.0
2.5
TEMPERATURE (°C)
IN
5.03.53.0 4.0
VIN (V)
1000
950
SWITCHING FREQUENCY (kHz)
900
750–25 25
10050
3593 G12
850
–50
TEMPERATURE (°C)
10050
750–25 25
3593 G13
10
LED CURRENT (mA)
5
0
0
NUMBER OF CTRL STROBES
16824
32
3593 G14
Full-Scale Current vs
Temperature
21.0
20.5
20.0
19.5
FULL SCALE CURRENT (mA)
19.0
–50
0–25 50 7525
TEMPERATURE (°C)
VIN = 3.6V
10LEDS
100
3593 G17
6.05.54.5
3593 G15
Full-Scale Current vs V
21.0
20.5
20.0
LED CURRENT (mA)
19.5
19.0
5
CAP
35
3593 G16
CAP
25201510 30
(V)
V
3593f
5
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