DATASHEET
ISL97687
4-Channel LED Driver with Phase Shift Control and 10-Bit Dimming Resolution
The
ISL97687
is a PWM controlled LED driver that supports
4 channels of LED current, for Monitor and TV LCD backlight
applications. It is capable of driving 160mA per channel from a
9V to 32V input supply, with current sources rated up to 75V
absolute maximum.
The ISL97687’s current sources achieve typical current
matching to ±1%, while dynamically maintaining the
minimum required V
OUT
necessary for regulation. This adaptive
scheme compensates for the non-uniformity of forward
voltage variance in the LED strings.
The ISL97687 can decode both an incoming PWM signal and
an analog input voltage, for DC-to-PWM dimming applications.
Modes include direct PWM and several modes where the PWM
frequency is synthesized on chip at 10-bit resolution. This can
be either free running, or synchronized with the frame rate to
give both a frequency and a phase lock, minimizing panel to
panel variation and display flicker. Phase shift is supported,
reducing flicker and audio noise, as is multiplication of the
incoming decoded analog and PWM values.
The ISL97687 has an advanced dynamic headroom control
function, which monitors the highest LED forward voltage
string, and regulates the output to the correct level to minimize
power loss. This proprietary regulation scheme also allows for
extremely linear PWM dimming from 0.02% to 100%. The LED
current can also be switched between two current levels, giving
support for 3D applications. The ISL97687 incorporates
extensive protections of string open and short circuit
detections, OVP, and OTP.
FN7714
Rev.3.00
Sep 13, 2017
Features
• 4x160mA, 75V rated channels with integrated channel
regulation FETs
• Channels can be ganged for high current
- 2x350mA
- 1x700mA
• 9V~32V input voltage
• Dimming modes:
- Direct PWM dimming from 100Hz~30kHz
- PWM dimming with adjustable output frequency
- 10-bit dimming resolution
- V
SYNC
function to synchronize PWM signal to frame
rate
- Phase shift
- Analog to PWM dimming with 8-bit resolution
• 2 selectable current levels for 3D applications
• Current matching of ±1%
• Integrated fault protection features such as string open
circuit protection, string short circuit protection, overvoltage
protection, and over-temperature protection
• 28 Ld 5mmx5mm TQFN and 28 Ld 300mil SOIC Packages
Available
Applications
• Monitor/TV LED Backlighting
• General/Industrial/Automotive Lighting
Related Literature
• For a full list of related documents, visit our website
•
ISL97687
product page
VIN: 9V~32V
FUSE
D1
VIN
VDC
VLOGIC
EN
STV
EN_VSYNC
EN_ADIM
PWMI
ACTL
EN_PS
CSEL
ISET1
ISET2
OSC
PWM_SET/PLL
CH1
CH2
CH3
CH4
SLEW
GD
CS
PGND
COMP
OVP
R
SENSE
Q1
160mA MAX PER STRING
110
100
CHANNEL CURRENT (mA)
90
80
70
60
50
40
30
20
10
0
0
20
40
60
80
100
I_CH1
I_CH4
I_CH2
I_CH3
DIMMING DUTY CYCLE (%)
FIGURE 1. ISL97687 APPLICATION DIAGRAM
FIGURE 2. PWM DIMMING LINEARITY
Block Diagram
FN7714 Rev.3.00
Sep 13, 2017
Page 1 of 24
ISL97687
V
IN
: 9V~32V
FUSE
160mA MAX PER STRING
VIN
REG1
ANALOG BIAS
REG2
DIGITAL
BIAS
F
SW
EN
SLEW
GD
CS
VDC
VLOGIC
OSC
O/P SHORT
OVP
FAULT/STATUS
REGISTER
OVP
OVP
OSC &
RAMP
COMP
=0
I
MAX
ILIMIT
LOGIC
FET
DRIVERS
COMP
GM
AMP
FAULT/STATUS
CONTROL
HIGHEST VF STRING
DETECT
VSET
+
-
OPEN CKT, SHORT CKT
DETECTS
CH1
CH4
1
2
3
TEMP
SENSOR
+
-
ISET1
ISET2
CSEL
REF
GEN
REF_OVP
REF_VSC
GND
+
-
4
PWMI
EN_PS
STV
EN_VSYNC
SERIAL
INTERFACE
LED
DIMMING
CONTROLLER
PLL
ANALOG
INTERFACE
OSC
ACTL
EN_ADIM
PWM_SET/PLL
FIGURE 3. ISL97687 BLOCK DIAGRAM
FN7714 Rev.3.00
Sep 13, 2017
Page 2 of 24
ISL97687
Pin Configurations
ISL97687
(28 LD 5x5 TQFN)
TOP VIEW
PGND
PGND
CSEL
CH1
CH2
CH3
CH4
CH2
CH1
21
20
19
THERMAL*
PAD
18
17
16
15
8
VIN
9
EN
10
AGND
11
GD
12
SLEW
13
CS
14
PGND
ACTL
OSC
ISET2
ISET1
COMP
OVP
PWM_SET/PLL
PGND
CSEL
PWMI
STV
EN_ADIM
EN_PS
VLOGIC
1
2
3
4
5
6
7
8
9
ISL97687
(28 LD SOIC)
TOP VIEW
28
27
26
25
24
23
22
21
20
19
18
17
16
15
CH3
CH4
PGND
ACTL
OSC
ISET2
ISET1
COMP
OVP
PWM_SET/PLL
PGND
CS
SLEW
GD
28
PWMI
STV
EN_ADIM
EN_PS
VLOGIC
EN_VSYNC
VDC
1
2
3
4
5
6
7
27
26
25
24
23
22
EN_VSYNC 10
VDC 11
VIN 12
EN 13
AGND 14
*EXPOSED THERMAL PAD
Pin Descriptions
TQFN
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
SOIC
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
PIN NAME PIN TYPE
PWMI
STV
EN_ADIM
EN_PS
VLOGIC
EN_VSYNC
VDC
VIN
EN
AGND
GD
SLEW
CS
PGND
PWM_SET/
PLL
OVP
COMP
I
I
I
I
S
I
S
S
I
S
O
I
I
S
I
PWM Brightness Control Input pin.
Start Vertical Frame signal; used in VSYNC mode.
Enable Analog Dimming
Enable Phase Shift
Internal 2.5V Digital Bias Regulator. Needs Decoupling Capacitor added to ground.
Frame synchronization enable. Ties high to VDC for enable V
SYNC
function. PWM_SET/PLL also
needs to be configured with an RC network. Pin can be tied to VDC or VLOGIC to enable function.
Internal 5V Analog Bias Regulator. Needs Decoupling Capacitor added to ground.
Main Power Input. Range: 9V to 32V.
LED Driver Enable. Whole chip will shut down when low.
Analog Ground
External Boost FET gate control
Boost Regulation Switching Slew Rate control.
External Boost FET current sense input.
Boost FET gate driver power ground and ground reference for CS pin.
For direct PWM mode, tie this pin high to VDC. For other non-VSYNC modes, connect to a resistor
to set the dimming frequency. If the VSYNC function is enabled, connect this pin to the PLL loop
filter network.
Overvoltage Protection Input as well as Output Voltage feedback pin.
Boost compensation
PIN DESCRIPTION
16
17
20
21
I
I
FN7714 Rev.3.00
Sep 13, 2017
Page 3 of 24
ISL97687
Pin Descriptions
(Continued)
TQFN
18
19
20
21
22
23
24
25
26
27
28
SOIC
22
23
24
25
26
27
28
1
2
3
4
PIN NAME PIN TYPE
ISET1
ISET2
OSC
ACTL
PGND
CH4
CH3
CH2
CH1
PGND
CSEL
I
I
I
I
S
I
I
I
I
S
I
PIN DESCRIPTION
Resistor connection for setting LED current. 28.7kΩ = 100mA.
Resistor connection for setting LED current. 28.7kΩ = 100mA.
Boost switching frequency adjustment.
Analog dimming input (input range is 0.3V to 3V).
Power Ground return for LED current.
LED PWM Driver
LED PWM Driver
LED PWM Driver
LED PWM Driver
Power Ground return for LED current.
ISET Resistor Selection Pin.
CSEL = 0 : ISET 1 resistor sets LED current
CSEL = 1 : ISET 2 resistor sets LED current
Ordering Information
PART NUMBER
(Notes
3, 4)
ISL97687IRTZ (Note
1)
ISL976787IBZ (Note
2)
ISL97687IRTZ-LEVALZ
ISL97687IRTZ-HEVALZ
ISL97687IBZEV1Z
NOTES:
1. Add “-T” suffix for 6k unit tape and reel option. Refer to
TB347
for details on reel specifications.
2. Add “-T” suffix for 1k unit tape and reel option. Refer to
TB347
for details on reel specifications.
3. 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.
4. For Moisture Sensitivity Level (MSL), see product information page for
ISL97687.
For more information on MSL, refer to
TB363.
PART
MARKING
ISL9768 7IRTZ
ISL97687IBZ
PACKAGE
(RoHS Compliant)
28 Ld 5x5 TQFN
28 Ld SOIC (300mil)
L28.5x5B
M28.3
PKG.
DWG. #
Evaluation Board (12 LEDs populated in each channel)
Evaluation Board (22 LEDs populated in each channel)
Evaluation Board (None of LEDs on the evaluation board)
FN7714 Rev.3.00
Sep 13, 2017
Page 4 of 24
ISL97687
Table of Contents
Absolute Maximum Ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Thermal Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Operating Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Electrical Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Typical Performance Curves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Theory of Operation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
PWM Boost Converter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
OVP and V
OUT
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Current Matching and Current Accuracy. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Dynamic Headroom Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Dimming Controls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
LED DC Current Setting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
PWM Dimming Frequency Adjustment. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Phase Shift Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
V
OUT
Control when LEDs are Off. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Switching Frequency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5V and 2.4V Low Dropout Regulators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Soft-Start and Boost Current Limit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Fault Protection and Monitoring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Short Circuit Protection (SCP) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Open Circuit Protection (OCP) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Undervoltage Lock-out . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Over-Temperature Protection (OTP) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Shutdown . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Component Selections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Input Capacitor. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Inductor. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Output Capacitors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Channel Capacitor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Schottky Diode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
High Current Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
PCB Layout Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Two Layers PCB Layout with TQFN Package . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
General Power PAD Design Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
One Layer PCB Layout with SOIC Package. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
11
11
11
11
11
11
11
13
13
13
14
14
14
14
14
15
15
15
15
16
16
17
17
17
17
17
18
18
18
18
Equivalent Circuit Diagrams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Revision History. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
About Intersil . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Package Outline Drawings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
FN7714 Rev.3.00
Sep 13, 2017
Page 5 of 24
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