DATASHEET
ISL97634
White LED Driver with Wide PWM Dimming Range
The ISL97634 represents an efficient and highly integrated
PWM boost LED driver that is suitable for LED backlighting in
small size LCD panels. With integrated Schottky diode, OVP,
and wide range of PWM dimming capability, the ISL97634
provides a simple, reliable, and flexible solution to the
backlight designers.
The ISL97634 features a wide range of PWM dimming control
capability. It allows dimming frequency as low as DC to 32kHz
beyond audible spectrum. The ISL97634 also features a
feedback disconnect switch to prevent the output from being
modulated by the PWM dimming signal that minimizes system
disturbance.
The ISL97634 is available in the 8 Ld TDFN (2mmx3mm)
package. There are 14V, 18V, and 26V OVP options that are
suitable for various number of LEDs in series. The ISL97634 is
specified for operation over the -40°C to +85°C ambient
temperature at input voltage from 2.4V to 5.5V.
FN6264
Rev 4.00
August 27, 2013
Features
•Drives Up to 26V Output
•Integrated over-voltage protection (OVP) of 14V, 18V, and
26V for various number of LEDs in series
• PWM Dimming Control From DC to 32kHz
• Output Disconnect Switch
• Integrated Schottky Diode
• 2.4V to 5.5V Input
• 85% Efficiency
• 1.4MHz Switching Frequency Allows Small LC
• 1µA Shutdown Current
• Internally Compensated
• 8 Ld TDFN (2mmx3mm)
• Pb-Free (RoHS Compliant)
Related Literature
• See
TB470,
“Using the ISL97634 White LED Driver Demo
Board”
Applications
• LED Backlighting for:
- Cell phones
- Smartphones
- MP3
- PMP
- Automotive Navigation Panel
- Portable GPS
VIN
10µH or 22µH
VIN
PWM/EN
NC
LX
VOUT
FBSW
FB
GND
FIGURE 1. TYPICAL APPLICATION CIRCUIT
FN6264 Rev 4.00
August 27, 2013
Page 1 of 12
ISL97634
Block Diagram
VIN (2.4V TO 5.5V)
CIN
VIN
1.4MHZ OSCILLATOR AND RAMP
GENERATOR
PWM/EN
L
LX
ISL97634
VOUT
COUT
PWM
COMPARATOR
PWM LOGIC
CONTROLLER
FET
DRIVER
2 LEDs to 7 LEDS
CURRENT
SENSE
GND
FBSW
PWM/EN
GM
AMPLIFIER
FB
95mV
BANDGAP
REFERENCE
GENERATOR
RSET
GM AMP
COMPENSATION
FN6264 Rev 4.00
August 27, 2013
Page 2 of 12
ISL97634
Pin Configuration
ISL97634
(8 LD TDFN)
TOP VIEW
GND 1
VIN 2
PWM/EN 3
NC 4
THERMAL
PAD
8 LX
7 VOUT
6 FBSW
5 FB
Pin Descriptions
PIN NUMBER
1
2
3
4
5
6
7
8
PIN NAME
GND
VIN
PWM/EN
NC
FB
FBSW
VOUT
LX
PAD
Ground Pin. Connect to local ground.
Input Supply Pin. Connect to the input supply voltage, the inductor and the input supply decoupling capacitor.
PWM or Enable Pin. Connect external PWM signal allows pulse width modulation current operation. Enable
signal allows peak current operation or disable signal shuts down the device.
No Connect
Feedback Pin. Connect the sense resistor between FB and ground. The cathode of bottom LED can also be
connected at this pin if the output current is not to be PWMed.
FB Disconnect Switch. Connect to the cathode of the bottom LED if the output current to be PWMed.
Output Pin. Connect to the anode of the top LED and the output filter capacitor.
Switching Pin. Connect to inductor.
Connect to ground plane on the PCB to maximize thermal performance.
DESCRIPTION
Ordering Information
PART NUMBER
(Notes 1, 2, 3)
ISL97634IRT14Z-T
ISL97634IRT14Z-TK
ISL97634IRT18Z-T
ISL97634IRT18Z-TK
ISL97634IRT26Z-T
ISL97634IRT26Z-TK
NOTES:
1. Please refer to
TB347
for details on reel specifications
2. These Intersil Pb-free plastic packaged products employ special Pb-free material sets, molding compounds/die attach materials, and 100% matte
tin plate plus anneal (e3 termination finish, which is RoHS compliant and compatible with both SnPb and Pb-free soldering operations). Intersil
Pb-free products are MSL classified at Pb-free peak reflow temperatures that meet or exceed the Pb-free requirements of IPC/JEDEC J STD-020.
3. For Moisture Sensitivity Level (MSL), please see device information page for
ISL97634.
For more information on MSL please see tech brief
TB363.
ELE
ELE
ELF
ELF
ELG
ELG
PART
MARKING
OVP OPTIONS
(V)
14
14
18
18
26
26
TEMP RANGE
(°C)
-40 to +85
-40 to +85
-40 to +85
-40 to +85
-40 to +85
-40 to +85
PACKAGE
Tape and Reel
(Pb-free)
8 Ld 2x3 TDFN
8 Ld 2x3 TDFN
8 Ld 2x3 TDFN
8 Ld 2x3 TDFN
8 Ld 2x3 TDFN
8 Ld 2x3 TDFN
PKG.
DWG. #
L8.2x3A
L8.2x3A
L8.2x3A
L8.2x3A
L8.2x3A
L8.2x3A
FN6264 Rev 4.00
August 27, 2013
Page 3 of 12
ISL97634
Absolute Maximum Ratings
(T
A
= +25°C)
Input Voltage
(
V
IN)
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3V to 6V
LX Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3V to 28V
FBSW Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3V to 28V
All Other Pins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3V to 6V
Thermal Information
Thermal Resistance
JA
(°C/W)
JC
(°C/W)
8 Ld TDFN Package (Notes 4, 5). . . . . . . . .
77
12
Maximum Junction Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . .+125°C
Storage Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . .-65°C to +150°C
Pb-Free Reflow Profile . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . see link below
http://www.intersil.com/pbfree/Pb-FreeReflow.asp
Operating Conditions
Temperature Range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -40°C to +85°C
CAUTION: Do not operate at or near the maximum ratings listed for extended periods of time. Exposure to such conditions may adversely impact product
reliability and result in failures not covered by warranty.
IMPORTANT NOTE: All parameters having Min/Max specifications are guaranteed over temperature of -40°C to +85°C unless otherwise stated. Typ values are
for information purposes only at TJ = TC = TA = +25°C.
NOTES:
4.
JA
is measured in free air with the component mounted on a high effective thermal conductivity test board with “direct attach” features. See Tech
Brief
TB379.
5. For
JC
, the “case temp” location is the center of the exposed metal pad on the package underside.
Electrical Specifications
PARAMETER
V
IN
I
IN
V
IN
= V
PWM/EN
= 3V. Boldface limits apply over the operating temperature range, -40°C to +85°C.
CONDITION
MIN
(Note 6)
2.4
PWM/EN = 3V, enabled, not switching
PWM/EN = 0V, disabled
0.8
TYP
MAX
(Note 6) UNIT
5.5
1.5
1
1,300
90
400
ILX = 100mA
VLX = 28V
90
VFB = 95mV
10
IDIODE = 100mA, T
A
= +25°C
ISL97634IRT14Z
ISL97634IRT18Z
ISL97634IRT26Z
600
14
18
26
28
0.6
1.5
1.5
200
850
1,450
95
470
900
0.01
95
1
100
1
1,600
V
mA
µA
kHz
%
mA
mΩ
µA
mV
µA
Ω
mV
V
V
V
V
V
µs
µs
DESCRIPTION
Supply Voltage
Supply Current
f
SW
DMAX
I
LIM
R
SW(LX)
ILEAK
VFB
IFB
R
SW(FBSW)
V
DIODE
OVP
Switching Frequency
Maximum Switching Duty Cycle
LX Current
LX Switch ON-Resistance
LX Switch Leakage Current
Feedback Voltage
FB Pin Bias Current
FBSW Switch ON-Resistance
Schottky Diode Forward Voltage
Overvoltage Protection
VIL
VIH
PWM_on
EN_delay
Logic Low Voltage of PWM/EN
Logic High Voltage of PWM/EN
Minimum PWM On-Time
EN to Vout Delay
NOTE:
6. Parameters with MIN and/or MAX limits are 100% tested at +25°C, unless otherwise specified. Temperature limits established by characterization
and are not production tested.
FN6264 Rev 4.00
August 27, 2013
Page 4 of 12
ISL97634
Typical Performance Curves
90
85
80
EFFICIENCY (%)
75
70
65
60
55
50
0
20
4 LEDs, 10µH
I q (mA)
3 LEDs, 10µH
3 LEDs, 22µH
7 LEDs, 22µH
ILED_peak = 25mA
V
IN
= 4V
RSET = 4
f
PWM
= 1kHz
40
60
80
PWM DUTY CYCLE (%)
100
7 LEDs, 10µH
0.6
0.4
0.2
0.0
-0.2
1.0
0.8
0
1
2
3
V
IN
(V)
4
5
6
FIGURE 2. EFFICIENCY vs PWM DUTY CYCLE
FIGURE 3. QUIESCENT CURRENT vs V
IN
(PWM/EN = HI)
20.08
19.76
19.74
20.04
19.72
I
O
(mA)
19.70
19.68
19.66
19.64
I
O
(mA)
20.00
19.96
19.92
0
5
10
15
V
OUT
(V)
20
25
30
19.62
2.5
3.0
3.5
4.0
V
IN
(V)
4.5
5.0
5.5
FIGURE 4. LOAD REGULATION (V
IN
= 4V)
FIGURE 5. LINE REGULATION
100
90
80
FB VOLTAGE (mV)
70
60
50
40
30
20
10
0
0
20
40
32kHz
60
80
100
120
ILED
20kHz
PWM/EN
7 LEDs
V
IN
= 4V
RSET = 4
L = 10µH
V
OUT
1kHz
LX
V
IN
= 4V
R
1
= 4
L
1
= 22µH
DUTY CYCLE (%)
FIGURE 6. DIMMNG LINEARITY (FB VOLTAGE) vs DUTY CYCLE
FIGURE 7. PWM DIMMING AT 1kHz, D = 1%
FN6264 Rev 4.00
August 27, 2013
Page 5 of 12
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