SIGNS
EW DE
N
D FOR
ARTS
MENDE LACEMENT P
OM
C
NOT RE ENDED REP
97672B
ECOMM L97671A or ISL
R
IS
6-Channel LED Driver with Phase Shift Control
ISL97676
The ISL97676 is an LED driver that drives 6 channels of LED current
for TFT-Display. The ISL97676 drives 6 channels of LED to support 78
LEDs from 4.5V to 26V or 48 LEDs from a boost supply of 2.7V to 26V
and a separate 5V bias supply on the ISL97676 VIN pin.
The ISL97676 compensates for non-uniformity of the forward voltage
drops in the LED strings with its 6 voltage controlled-current source
channels. Its headroom control monitors the highest LED forward
voltage string for output regulation, to minimize the voltage headroom
and power loss in the typical multi-string operation.
Intersil offers two PWM Dimming modes. In the first mode, the
ISL97676 digitizes the incoming PWM signal and provides 8-bit
dimming. The PWM frequency is set by a resistor providing dimming
frequency between 100Hz to 30kHz. The second mode offers direct
PWM mode without phase shift, where the dimming follows the input
PWM signal.
The ISL97676 features channel phase shift control to minimize the
input, output ripple characteristics and load transients as well as
spreading the light output to help eliminate or reduce the video and
audio noise interference from the backlight driver operation.
Features
• 6 Channels
• Channel Phase Shift PWM Dimming
• Direct PWM Dimming without Phase Shift
• 4.5V to 26V Input
• 45V Output Max
• Up to 30mA LED Current per Channel
• Drive up to 78 (3.2V/20mA each) LEDs
• Current Matching of ±1.5% from 1% ~ 100% Dimming
• Dynamic Headroom Control
• Protections
- String Open/Short Circuit, V
OUT
Short Circuit Overvoltage, and
Over-temperature Protections
- Optional Master Fault Protection
• Selectable 600kHz or 1.2MHz Switching Frequency
• 20 Ld QFN 4mmx4mm Package
Related Literature
• See
AN1568
“ISL97676IRZ-EVAL Quick Start Guide”
Applications
• Netbook Displays LED Backlighting
• Notebook Displays LED Backlighting
V
IN
* = 4.5~26V
V
OUT
= 45V*, 30mA PER STRING
ISL97676
17
FAULT
19
VIN
1
VDDIO
5
NC
2
EN
20
PWM
3
FSW/
SW
16
OVP
14
PGND
15
FB1
12
FB2
11
FB3
10
FB4
8
FB5
7
FB6
6
AGND
9
*For V
IN
> 6V
PhaseShift
18
COMP
RFPWM//
13
DirectPWM
4
ISET
FIGURE 1. TYPICAL APPLICATION CIRCUIT
September 14, 2011
FN7600.1
1
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
1-888-INTERSIL or 1-888-468-3774
|
Copyright Intersil Americas Inc. 2010, 2011. All Rights Reserved
Intersil (and design) is a trademark owned by Intersil Corporation or one of its subsidiaries.
All other trademarks mentioned are the property of their respective owners.
Block Diagram
VIN* = 4.5V~26V
OPTIONAL PFET
45V*/30mA PER STRING
78 (6X13) LEDS
10µH/3A
4.7µF/50V
FAULT
VIN
EN
REG
4.75V BIAS
FAULT
FET
DRV
SW
ISL97676
OVP
O/P SHORT
OVP
2
VDDIO
FSW/
PHASESHIFT
FSW
COMP
ISET
GND
PWM
FPWM/DIRECTPWM
FN7600.1
September 14, 2011
OSC &
RAMP
COMP
PHASE
SELECT
Σ
=0
IMAX
ILIMIT
LOGIC
FET
DRIVER
PGND
DETECT
GM
AMP
8-BIT
DAC
DYNAMIC
HEADROOM
CONTROL
FPO
HIGHEST VF
STRING
DETECT
OPEN CKT, SHORT CKT
DETECTS
ISL97676
FB1
FB2
FB6
VSET
+
-
REF OVP
REF VSC
+
-
1
TEMP
SENSOR
SHUTDOWN
REF
GEN
+
-
PHASE
SELECT
PHASE
SHIFT &
8-BIT
DIGITIZER
PWM
CONTROLLER
+
-
2
* V
IN
> = 6V
6
DIRECTPWM
DETECT
ISL97676
Pin Configuration
ISL97676
(20 LD QFN)
TOP VIEW
FAULT
17
COMP
PWM
VIN
SW
16
15
14
PAD
13
12
11
PGND
OVP
RFPWM/DirectPWM
FB1
FB2
10
FB3
20
VDDIO
EN
FSW/PhaseShift
ISET
NC
1
2
3
4
5
19
18
6
FB6
7
FB5
8
FB4
9
AGND
Pin Descriptions
(I = Input, O = Output, S = Supply)
PIN NAME
VDDIO
EN
FSW/PhaseShift
PIN NO.
1
2
3
TYPE
S
I
I
DESCRIPTION
Decouple with capacitor for internally generated supply rail.
Enable
FSW = 0 ~ 0.25 * VDDIO, Boost Switching Frequency = 1.2MHz with phase shift.
FSW = 0.25 * VDDIO ~ 0.5 * VDDIO, Boost Switching Frequency = 1.2MHz without phase shift.
FSW = 0.5 * VDDIO ~ 0.75 * VDDIO, Boost Switching Frequency = 600kHz without phase shift.
FSW = 0.75 * VDDIO ~ VDDIO, Boost Switching Frequency = 600kHz with phase shift.
Resistor connection for setting LED current (see Equation 3 for calculating the I
LED
peak).
No Connect.
Input 6 to current source, FB, and monitoring.
Input 5 to current source, FB, and monitoring.
Input 4 to current source, FB, and monitoring.
Analog Ground for precision circuits.
Input 3 to current source, FB, and monitoring.
Input 2 to current source, FB, and monitoring.
Input 1 to current source, FB, and monitoring.
External PWM dimming with frequency modulation or Direct PWM dimming without frequency
modulation.
When this pin is not biased and a resistor is connected to ground, the dimming frequency will be
set by the Setting Resistor.
When this pin is floating, the part enters Direct PWM mode such that the dimming follows the
input PWM signal without frequency modulation.
Overvoltage protection input.
Power ground (LX Power return).
Input to boost switch.
ISET
NC
FB6
FB5
FB4
AGND
FB3
FB2
FB1
RFPWM/DirectPWM
4
5
6
7
8
9
10
11
12
13
I
I
I
I
I
S
I
I
I
I
OVP
PGND
SW
14
15
16
I
S
O
3
FN7600.1
September 14, 2011
ISL97676
Pin Descriptions
(I = Input, O = Output, S = Supply)
(Continued)
PIN NAME
FAULT
COMP
VIN
PWM
PAD
PIN NO.
17
18
19
20
21
TYPE
O
I
S
I
I
DESCRIPTION
Gate drive signal for external fault MOSFET. This pin should be left floating when fault mosfet is
omitted in the application.
External compensation pin.
LED driver supply voltage.
PWM brightness control pin.
Connect EPAD to junction of AGND and PGND with adequate vias to form a star ground.
Ordering Information
PART NUMBER
(Notes 1, 2, 3)
ISL97676IRZ
NOTES:
1. Add “-T*” suffix for tape and reel. 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
ISL97676.
For more information on MSL please see techbrief
TB363.
PART
MARKING
976 76IRZ
TEMP RANGE
(°C)
-40 to +85
PACKAGE
(Pb-free)
20 Ld 4x4 QFN
PKG.
DWG. #
L20.4x4C
4
FN7600.1
September 14, 2011
ISL97676
Table of Contents
Absolute Maximum Ratings. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Thermal Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Operating Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Electrical Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Typical Performance Curves. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Theory of Operation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
PWM Boost Converter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
OVP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Enable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Power Sequence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Current Matching and Current Accuracy. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Dynamic Headroom Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Dimming Controls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Maximum DC Current Setting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
PWM Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Phase Shift Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
PWM Dimming Frequency Adjustment. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Direct PWM Dimming . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Switching Frequency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Inrush Control and Soft-Start . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Fault Protection and Monitoring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Short Circuit Protection (SCP) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Open Circuit Protection (OCP) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Overvoltage Protection (OVP) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Undervoltage Lockout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Master Fault Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Over-Temperature Protection (OTP) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Components Selections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Input Capacitor. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Inductor. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Output Capacitors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Channel Capacitor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Output Ripple . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Schottky Diode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
High Current Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Revision History . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Products . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Package Outline Drawing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
5
FN7600.1
September 14, 2011
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