LT3596
60V Step-Down LED Driver
FeaTures
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DescripTion
The LT
®
3596 is a 60V step-down LED Driver. It achieves
10,000:1 digital PWM dimming at 100Hz with fast NPN
current sources driving up to 10 LEDs in each channel.
100:1 LED dimming can also be done with analog control
of the CTRL1-3 pin.
The step-down switching frequency is programmable
between 200kHz and 1MHz and is synchronizable to an
external clock. The LT3596 also provides maximum LED
brightness while adhering to manufacturers’ specifica-
tions for thermal derating. The derate temperature is
programmed by placing a negative temperature coefficient
(NTC) resistor on the master control pin.
The LT3596 adaptively controls V
OUT
in order to achieve
optimal efficiency. Other features include: 1.5% LED current
matching between channels, open LED reporting, shorted
LED pin protection and reporting, programmable LED cur-
rent and programmable temperature protection.
L,
LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear
Technology Corporation and True Color PWM is a trademark of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
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300mA Buck Regulator, Drives Up to 10 LEDs per
Channel with Fast NPN Current Sources
Fast Current Sources for <1µs Pulse Widths
(10,000:1 True Color PWM™ Dimming at 100Hz)
LEDs Disconnected in Shutdown
Adaptive V
OUT
for Increased Efficiency
6V to 60V Input Voltage Range
±1.5% Accurate LED Current Matching
External Resistors Set LED Current for Each Channel
Requires No External Compensation
Programmable Switching Frequency (200kHz to 1MHz)
Synchronizable to External Clock
Open, Short LED Detection and Reporting
Programmable LED Thermal Derating and Reporting
Programmable Temperature Protection
5mm
×
8mm Thermally Enhanced QFN Package with
0.6mm High Voltage Pin Spacing
applicaTions
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LED Billboards and Signboards
Mono, Multi, Full Color LED Displays
Large Screen Display LED Backlighting
Automotive, Industrial and Medical Displays
Typical applicaTion
48V 1MHz Step-Down 8W, 100mA LED Driver (Eight White LEDs per Channel)
V
IN
48V
10µF
V
IN
270k
EN/UVLO BOOST
91k
SYNC
33.2k
PWM1
PWM2
PWM3
CTRL1
CTRL2
CTRL3
PWM1
PWM2
PWM3
CTRL1
CTRL2
CTRL3
LED1
LED2
LED3
3696 TA01a
BIAS
4.7µF
100nF 100µH
5V
BIAS
SW
LT3596
DA
SYNC
RT
GND
FB
V
OUT
100k
3.65k
4.7µF
V
OUT
10,000:1 PWM Dimming at 100Hz
28V
PER LED
STRING
PWM
2V/DIV
I
LED
50mA/DIV
BIAS
100k
FAULT
90.9k
10k
FAULT
V
REF
TSET
CTRLM
200ns/DIV
3596 TA01b
I
SET1
I
SET2
I
SET3
20k
20k
20k
49.9k
100k
3596fa
LT3596
absoluTe MaxiMuM raTings
(Note 1)
pin conFiguraTion
TOP VIEW
BOOST
46
SW
V
IN
V
IN
DA
44
43 NC
FB 2
41 NC
EN/UVLO 4
39 NC
TSET 6
V
REF
7
GND 9
NC 11
NC 12
CTRLM 13
I
SET1
14
I
SET2
15
I
SET3
16
RT 17
18 19 20 21 22 23 24 25 26
V
OUT
NC
LED1
LED2
NC
NC
LED3
FAULT
NC
53
GND
37 BIAS
35 NC
34 NC
33 CTRL1
32 CTRL2
31 CTRL3
30 PWM1
29 PWM2
28 PWM3
27 SYNC
Input Voltage (V
IN
), EN/UVLO ..................................60V
BOOST .....................................................................80V
BOOST Pin Above SW Pin ....................................... 25V
LED1-3, V
OUT
............................................................42V
BIAS,
FAULT
.............................................................25V
V
REF
, RT, I
SET1-3
, TSET, CTRLM .................................3V
FB, CTRL1-3, PWM1-3, SYNC ....................................6V
Operating Temperature Range
(Notes 2, 3) ............................................ –40°C to 125°C
Maximum Junction Temperature .......................... 125°C
Storage Temperature Range .................. –65°C to 150°C
51 50
48
UHG PACKAGE
VARIATION: UHG52 (39)
52-LEAD (5mm 8mm) PLASTIC QFN
T
JMAX
= 125°C,
θ
JA
= 32°C/W
EXPOSED PAD (PIN 53) IS GND, MUST BE SOLDERED TO PCB
orDer inForMaTion
LEAD FREE FINISH
LT3596EUHG#PBF
LT3596IUHG#PBF
TAPE AND REEL
LT3596EUHG#TRPBF
LT3596IUHG#TRPBF
PART MARKING*
3596
3596
PACKAGE DESCRIPTION
52-Lead (5mm
×
8mm) Plastic QFN
52-Lead (5mm
×
8mm) Plastic QFN
TEMPERATURE RANGE
–40°C to 125°C
–40°C to 125°C
Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container.
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/
3596fa
LT3596
elecTrical characTerisTics
PARAMETER
V
IN
Operating Voltage
Quiescent Current from V
IN
Minimum BIAS Voltage
Quiescent Current from BIAS
EN/UVLO = 0.4V
BIAS = 5V, Not Switching
BIAS = 0V, Not Switching, Current Out of Pin
0.4
1.47
EN/UVLO = 1.6V
EN/UVLO = 1.4V
FB = 6V
R
T
= 220k (200kHz)
R
T
= 33.2k (1MHz)
I
SW
= 300mA
0.8
500
V
SW
= 0V
I
SW
= 100mA
R
T
= 220k
R
T
= 33.2k
170
900
1.6
R
T
= 220k
R
T
= 47k
V
SYNC
= 3.3V
(Note 4)
I
VREF
= 0µA
R
ISET1-3
= 20k
V
TSET
= 1V
R
ISET1-3
= 20k
l
l
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
IN
= 24V, BOOST = 30V, BIAS = 5V, EN/UVLO = 5V, PWM1-3 = 3.3V,
CTRL1-3 = CTRLM = TSET = 2V, V
OUT
= 24V, SYNC = 0V unless otherwise specified. (Note 2)
CONDITIONS
l
MIN
6
TYP
MAX
55
2
4
5
3.1
2
3
150
1.53
5.75
1.25
200
UNITS
V
µA
mA
mA
V
µA
mA
µA
V
V
nA
µA
V
nA
%
%
mV
EN/UVLO = 0.4V
BIAS = 5V, Not Switching
BIAS = 0V, Not Switching
1.3
3
3
1.4
70
0.7
1.51
10
5.1
1.21
99
90
330
1.0
650
3
200
1000
EN Threshold
UVLO Threshold (Falling)
EN/UVLO Pin Current (Hysteresis)
FB Regulation Voltage
FB Pin Bias Current
Maximum Duty Cycle
Switch Saturation Voltage
Switch Current Limit
DA Pin Current to Stop OSC
Switch Leakage
BOOST Pin Current
Switching Frequency
SYNC Input Low
SYNC Input High
SYNC Frequency Range
SYNC Pin Bias Current
Soft-Start Time
V
REF
Voltage
Maximum V
REF
Current
I
SET1-3
Pin Voltage
TSET Voltage for LED Current Derating
TSET Pin Leakage Current
I
LED1-3
LED Current
LED String Current Matching
LED Pin Voltage
LED1-3 Open Detection Threshold
LED1-3 Short Protection Threshold (from GND)
LED1-3 Short Protection Threshold (from V
OUT
)
LED1-3 Pin Leakage Current
V
OUT
= 6V, V
OUT
> V
LED1-3
V
LED1-3
= 42V, PWM1-3 = 0V
4.25
1.15
90
80
1.25
750
700
230
1100
0.4
A
mA
nA
mA
kHz
kHz
V
V
kHz
kHz
nA
ms
V
µA
V
mV
240
1000
200
2.2
1.96
200
2.0
1.0
540
2.04
200
98
97
100
100
±0.35
±0.35
1.07
0.29
10
1
1.2
15
1.6
200
102
103
±1.5
±2
nA
mA
mA
%
%
V
V
V
V
nA
3596fa
R
ISET1-3
= 20k
l
Adaptive V
OUT
Loop Enabled
LT3596
elecTrical characTerisTics
PARAMETER
PWM1-3 Input Low Voltage
PWM1-3 Input High Voltage
PWM1-3 Pin Bias Current
CTRL1-3 Voltage for Full LED Current
CTRL1-3 Pin Bias Current
CTRLM Voltage for Full LED Current
CTRLM Pin Bias Current
FAULT
Output Voltage Low
FAULT
Pin Input Leakage Current
V
CTRLM
= 3V
I
FAULT
= 200µA
V
FAULT
= 25V
0.10
200
Note 3:
For maximum operating ambient temperature, see the High
Temperature Considerations section in the Applications Information
section.
Note 4:
Guaranteed by design.
V
CTRL1-3
= 6V
1.2
200
1.2
200
1.6
200
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
IN
= 24V, BOOST = 30V, BIAS = 5V, EN/UVLO = 5V, PWM1-3 = 3.3V,
CTRL1-3 = CTRLM = TSET = 2V, V
OUT
= 24V, SYNC = 0V unless otherwise specified. (Note 2)
CONDITIONS
MIN
TYP
MAX
0.4
UNITS
V
V
nA
V
nA
V
nA
V
nA
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 LT3596E 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. The
LT3596I specifications are guaranteed over the full –40°C to 125°C
operating junction temperature range.
3596fa
LT3596
Typical perForMance characTerisTics
V
IN
Quiescent Current
2.0
1.8
1.6
BIAS CURRENT (mA)
V
IN
CURRENT (mA)
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0
0
10
30
40
20
V
IN
VOLTAGE (V)
T = 125°C
T = 25°C
T = –40°C
50
60
3596 G01
T
A
= 25°C, unless otherwise noted
V
IN
, BIAS Shutdown Current
1.4
1.2
1.0
V
IN
= 55V
V
BIAS
= 25V
BIAS Quiescent Current
2.0
V
IN
= 24V
V
BIAS
= 5V
1.5
CURRENT (µA)
T = 125°C
T = 25°C
T = –40°C
0
5
15
10
BIAS VOLTAGE (V)
20
25
3596 G02
1.0
0.8
0.6
0.4
0.5
0
0.2
0
–50 –25
I
VBIAS
50
25
75
0
TEMPERATURE (°C)
I
VIN
125
–0.5
100
3596 G03
UVLO Threshold
1.8
1.7
EN/UVLO CURRENT (µA)
UVLO THRESHOLD (V)
1.6
1.5
1.4
1.3
1.2
1.1
1.0
–50 –25
0
50
75
25
TEMPERATURE (°C)
100
125
6
5
4
3
2
1
EN/UVLO Pin Current
V
EN/UVLO
= 1.4V
2.04
2.03
2.02
V
REF
VOLTAGE (V)
2.01
2.00
1.99
1.98
1.97
50
25
75
0
TEMPERATURE (°C)
100
125
V
REF
Voltage
0
–50 –25
1.96
–50 –25
V
IN
= 55V
V
IN
= 24V
V
IN
= 6V
0
50
75
25
TEMPERATURE (°C)
100
125
3596 G04
3596 G05
3596 G06
Switching Frequency
1.4
SWITCHING FREQUENCY (MHz)
1.2
1.0
0.8
0.6
0.4
0.2
0
–50 –25
R
T
= 220k
R
T
= 33.2k
1100
1000
CURRENT LIMIT (mA)
900
800
700
600
SW and DA Current Limit
1000
I
SW
SWITCH VOLTAGE (mV)
900
800
700
600
500
400
300
200
100
50
25
75
0
TEMPERATURE (°C)
100
125
0
Switch Voltage Drop
I
DA
50
25
75
0
TEMPERATURE (°C)
100
125
500
–50 –25
T = 125°C
T = 25°C
T = –40°C
0
100 200 300 400 500 600 700 800
SWITCH CURRENT (mA)
3596 G09
3596 G07
3596 G08
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