FEATURES
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LT3595A
16 Channel
Buck Mode LED Driver
DESCRIPTION
The LT
®
3595A is a high performance LED Driver designed
to drive sixteen independent channels of up to 10 LEDs
at currents up to 50mA. Series connection of the LEDs
provides identical LED currents resulting in uniform bright-
ness. Power switches, Schottky diodes, and compensation
components are all internal, providing a small converter
footprint and lower component cost. The high 2MHz
switching frequency permits the use of tiny, low profile
inductors and capacitors. A fixed frequency, current mode
architecture results in stable operation over a wide range
of supply and output voltage.
A single external resistor sets the LED current for all sixteen
channels, and dimming is then controlled for each chan-
nel by pulse width modulating the individual PWM pins.
LED current accuracy is 7%, channel-to-channel current
matching is
±4%
and the PWM dimming range is 5000:1.
The part is available in a 5mm
×
9mm
×
0.75mm 56-pin
QFN package.
L,
LT, LTC and LTM 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.
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4.5V to 45V Input Supply Range
Up to 50mA LED Current per Channel
100mA, 45V Internal Switches
Improvements vs LT3595
Pinout Allows 1-Sided PCB Layout
Higher Maximum Switch Duty Cycle
LED Current Accuracy (7% vs 8%)
±4%
LED Current Matching
16 Independent LED Channels
5000:1 True Color PWM
TM
Dimming Range
LEDs Disconnected in Shutdown
Internal Schottky Diodes
2MHz Switching Frequency
R
SET
Pin Sets Master LED Current
Typical Efficiency: 92%
Open LED Detection and Thermal Protection
56-Pin 5mm
×
9mm
×
0.75mm QFN Package
APPLICATIONS
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LED Video Billboards
LCD Televisions
Stadium and Advertising Displays
TYPICAL APPLICATION
16-Channel LED Driver (Three LEDs per Channel), 20mA Current
V
IN
15V TO
45V
0.47μF
0.47μF
0.47μF
0.47μF
0.47μF
0.47μF
0.47μF
0.47μF
V
PWM
5V/DIV
5000:1 PWM
Dimming at 100Hz
10μF
100μH
100μH
100μH
100μH
100μH
100μH
100μH
V
CC
100k
100μH
LED
BRIGHTNESS
CONTROL
100μH
100μH
100μH
100μH
100μH
100μH
100μH
0.47μF
0.47μF
0.47μF
0.47μF
0.47μF
0.47μF
0.47μF
100μH
10μF
0.47μF
3595A TA01
75.0k
V
CC
3V TO
5.5V
L1 SW1
OPENLED
PWM1
PWM2
PWM3
PWM4
PWM5
PWM6
PWM7
PWM8
SHDN
V
CC
L16 SW16
L2
SW2
SW3
L3
SW4
L4
L5
SW5
L6
SW6
SW7
L7
SW8
L8
I
SW
20mA/DIV
LT3595A
L15 SW15 V
IN
SW14 L14
SW13
L13
L12
SW12 L11 SW11 V
IN
SW10 L10
PWM9
PWM10
PWM11
PWM12
PWM13
PWM14
PWM15
PWM16
GND
R
SET
SW9 L9
LED
BRIGHT-
NESS
CONTROL
I
LED
10mA/DIV
400ns/DIV
V
IN
= 15V
3 LEDS AT 20mA
T = 10ms
t
ON
= 2μs
3595A TA01b
3595af
1
LT3595A
ABSOLUTE MAXIMUM RATINGS
(Note 1)
PIN CONFIGURATION
TOP VIEW
PWM16
PWM15
PWM14
PWM13
PWM4
PWM3
PWM2
PWM7
PWM1
46 L1
45 SW1
44 L2
43 SW2
42 GND
41 SW3
40 L3
39 SW4
57
38 L4
37 L5
36 SW5
35 L6
34 SW6
33 V
IN
32 SW7
31 L7
30 SW8
29 L8
19 20 21 22 23 24 25 26 27 28
PWM9
PWM10
PWM11
PWM12
PWM5
PWM6
OPENLED
PWM8
SHDN
R
SET
V
CC
Input Voltage (V
IN
) ....................................................45V
L1-16 Voltage ...........................................................45V
Supply Voltage (V
CC
) ..................................................6V
R
SET
,
OPENLED,
PWM1-16,
SHDN
Voltage.................6V
Operating Junction Temperature Range
(Note 2) .............................................–40°C to 125°C
Storage Temperature Range...................–65°C to 125°C
56 55 54 53 52 51 50 49 48 47
L16 1
SW16 2
L15 3
SW15 4
V
IN
5
SW14 6
L14 7
SW13 8
L13 9
L12 10
SW12 11
L11 12
SW11 13
GND 14
SW10 15
L10 16
SW9 17
L9 18
UHH PACKAGE
56-LEAD (5mm 9mm) PLASTIC QFN
T
JMAX
= 125°C,
θ
JA
= 31°C/W,
θ
JC
= 0.5°C/W
EXPOSED PAD (PIN 57) IS GND, MUST BE SOLDERED TO PCB
ORDER INFORMATION
LEAD FREE FINISH
LT3595AEUHH#PBF
TAPE AND REEL
LT3595AEUHH#TRPBF
PART MARKING
3595A
PACKAGE DESCRIPTION
56-Lead (5mm
×
9mm) Plastic QFN
TEMPERATURE RANGE
–40°C to 125°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/
3595af
2
LT3595A
ELECTRICAL CHARACTERISTICS
PARAMETER
V
IN
Operating Voltage
V
CC
Operating Voltage
V
CC
Input Under Voltage Lockout
I
VIN
Quiescent Current ON, No Switching
I
VIN
Quiescent Current in Shutdown
I
VCC
Quiescent Current ON, No Switching
I
VCC
Quiescent Current in Shutdown
I
L1-16
Output Current Accuracy
I
L1-16
Channel-to-Channel Matching
Switching Frequency
Maximum Duty Cycle
Switch Current Limit
Switch V
CESAT
Switch Leakage Current
Schottky Forward Drop
Schottky Leakage Current
SHDN,
PWM1-16 Input Low Voltage
SHDN,
PWM1-16 Input High Voltage
SHDN
Pin Bias Current
PWM1-16 Pin Bias Current
OPENLED
Pin Voltage
OPENLED
Pin Input Leakage Current
SHDN
= 3.3V
PWM1-16 = 3.3V
V
CC
= 3.3V, I
OPENLED
= 200μA
OPENLED
= 3.3V
1.6
35
0.1
0.12
0.1
1
1
I
SW1-16
= 50mA
V
SW1-16
= 45V
I
SCHOTTKY
= 50mA
V
SW1-16
= 0.7V,
SHDN
= 0V
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The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C, V
IN
= 45V, V
CC
= 3.3V, PWM =
SHDN
=
OPENLED
= 3.3V, R
SET
= 75k
Ω
,
GND = 0V, unless otherwise noted.
CONDITIONS
MIN
4.5
3
2.6
0.25
SHDN
= 0V
V
CC
= 3.3V
V
CC
= 3.3V,
SHDN
= 0V
R
SET
= 75kΩ
R
SET
= 75kΩ
l
TYP
MAX
5.5
2.9
40
10
21.4
±4
2.4
150
6
4
0.4
UNITS
V
V
V
mA
μA
mA
μA
mA
%
MHz
%
mA
mV
μA
V
μA
V
V
μA
μA
V
μA
15
17
3
18.6
1.6
80
90
20
±1
2
85
120
450
0.1
0.8
0.1
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 LT3595A is guaranteed to meet performance specifications
from 0°C to 125°C junction temperature. Specifications over the –40°C
to 125°C operating junction temperature range are assured by design,
characterization and correlation with statistical process controls.
3595af
3
LT3595A
TYPICAL PERFORMANCE CHARACTERISTICS
T
A
= 25°C, unless otherwise noted.
Switching Waveforms
10 LEDS
V
SW1
50V/DIV
10 LEDS
I
L1
50mA/DIV
5 LEDS
V
SW2
50V/DIV
5 LEDS
I
L2
50mA/DIV
V
IN
= 45V
I
LED
= 20mA
PWM Dimming Waveforms
(1000:1)
PWM Dimming Waveforms
(10:1)
PWM
5V/DIV
PWM
5V/DIV
I
L
20mA/DIV
I
LED
20mA/DIV
400ns/DIV
3595A G01
I
L
20mA/DIV
I
LED
20mA/DIV
2μs/DIV
3595A G02
2ms/DIV
3595A G03
V
IN
= 40V
PWM FREQUENCY = 100Hz
10 LEDS AT 20mA t
ON
= 10μs
V
IN
= 40V
PWM FREQUENCY = 100Hz
10 LEDS AT 20mA t
ON
= 1ms
LED Current vs PWM Duty Cycle
Wide Dimming Range (5000:1)
100
V
IN
= 45V
10 LEDS AT 20mA
PWM FREQUENCY = 100Hz
LED CURRENT (mA)
60
50
40
30
20
10
0
0.1
10
1
DUTY CYCLE (%)
100
3595A G04
LED Current vs R
SET
Resistance
2.0
V
IN
Quiescent Current
T = 125°C
1.6
V
IN
CURRENT (mA)
T = 25°C
T = –40°C
10
LED CURRENT (mA)
1
1.2
0.1
0.8
0.01
0.4
0.001
0.01
25
50
75
100
125
R
SET
RESISTANCE (kΩ)
150
3595A G05
0
0
10
20
30
V
IN
(V)
40
50
3595A G06
V
CC
Quiescent Current
20
18
16
V
CC
CURRENT (mA)
14
12
10
8
6
4
2
0
0
1
2
0
4
3
V
CC
(V)
5
6
7
20
T = –40°C
I
SHDN
(mA)
V
CC
= 3.3V
100
T = 125°C
T = 25°C
80
SHDN
Pin Bias Current
T = 25°C
60
T = 125°C
40
T = –40°C
0
1
2
3
4
SHDN (V)
5
3595A F08
6
3595A F07
3595af
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LT3595A
TYPICAL PERFORMANCE CHARACTERISTICS
T
A
= 25°C, unless otherwise noted.
Current Limit vs Temperature
150
SWITCHING FREQUENCY (MHz)
140
CURRENT LIMIT (mA)
130
120
110
100
90
–50 –25
2.4
SCHOTTKY LEAKAGE CURRENT (μA)
2.3
2.2
2.1
2.0
1.9
1.8
1.7
50
25
75
0
TEMPERATURE (°C)
100
125
1.6
–50 –25
50
25
75
0
TEMPERATURE (°C)
100
125
Switching Frequency
vs Temperature
1.4
1.2
1.0
Schottky Leakage Current
vs Temperature
V
IN
= 45V
0.8
0.6
V
IN
= 24V
0.4
0.2
0
–50 –25
V
IN
= 4.5V
50
25
75
0
TEMPERATURE (°C)
100
125
3595A G09
3595A G10
3595A G11
Switch Saturation Voltage
(V
CESAT
)
700
600
500
T = –40°C
400
300
200
100
0
0
20
40
60
80
100
3595A G12
Schottky Forward Voltage Drop
100
SCHOTTKY FORWARD CURRENT (mA)
SWITCH SATURATION VOLTAGE (mV)
80
60
T = 125°C
40
T = 25°C
20
T = –40°C
0
0
0.2
0.6
0.8
0.4
SCHOTTKY FORWARD DROP (V)
1
3595A G13
T = 25°C
T = 125°C
SWITCH CURRENT (mA)
Transient Response
V
SHDN
5V/DIV
V
SW
50V/DIV
I
SW
50mA/DIV
I
LED
20mA/DIV
100μs/DIV
V
IN
= 45V
10 LEDS AT 20mA
3595A G14
OPENLED
Waveforms
I
LED
CH 1
20mA/DIV
OPENLED
5V/DIV
V
SW
CH 1
50V/DIV
I
LED
CH 2
20mA/DIV
20μs/DIV
V
IN
= 45V
10 LEDS AT 20mA
3595A G15
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