an1668

Application Note 1668
ISL97684 LED Driver Evaluation Board User Manual
Introduction
• LED dimming frequency and duty cycle
The ISL97684 Evaluation Board provides a complete testing
platform for ISL97684, a four channel LED driver. Please refer
to the product datasheet for detailed information, including
pinout, pin function descriptions, electrical specifications and
applications related information.
1. As mentioned in Step #4, when the shunt on JP20 is
connected to the upper position and the FPWM/DPWM pin
is connected to VDC, the device enters direct PWM mode,
which means both the LED dimming frequency and the
duty cycle are synchronized with the external PWM signal
applied on the PWMI pin.
Instructions
2. When the shunt on JP20 is connected to the lower position,
the FPWM/DPWM pin is connected to a resistor. Under
such conditions, the LED dimming frequency of the chip is
programmed by the resistance connected on the
FPWM/DPWM pin per the following equation:
Please follow the steps described below to start your
evaluation.
1. Set Switch #1 and Switch #2 (SW1 and SW2) to position 3
(left side).
2. For the enable control jumper, JP1, set the shunt to the
“ON” position (right side) to connect the EN pin to VIN.
When the shunt is in the “OFF” position, it will disable the
chip by pulling the EN pin to ground.
3. Connect JP14 so the VIN pin is connected to PVIN.
7
FPWM ( Hz ) = 12.4 ×10 ⁄ R_FPWM ( Ω )
(EQ. 2)
The duty cycle is still modulated by the external PWM signal
applied on the PWMI pin. On board, a potentiometer R11
and a few other resistors are provided for easily adjusting
the LED dimming frequency under such configuration.
4. For JP20, connect the shunt to the upper position.
5. Connect WR and JP2-JP6.
6. Apply 1.5V~5.5V PWM signal between the PWMI pin and
AGND.
7. Apply 4V~26.5V between PVIN and PGND and the LEDs
should be lit. You may start the evaluation.
Note:
• In Step #1 above, the SW1, SW2 position can be adjusted to
different positions for different configurations. Details are
provided in the following:
TABLE 1.
SW1
POSITION
SW2
POSITION
1
1
LX switching frequency = 600kHz, PFM
CH1-CH4
3
3
LX switching frequency = 1MHz, PFM
CH1-CH4
3
1
LX switching frequency = 600kHz, No PFM
CH1-CH4
1
3
LX switching frequency = 1MHz, No PFM
CH1-CH4
DESCRIPTION
• The LED maximum DC current adjustment
For each channel, the maximum DC current is set by
resistance connected to the RSET pin. The current for each
channel can be calculated as follows:
I_LED(mA) = 402 ⁄ RSET 〈 kΩ〉
(EQ. 1)
On the board, a potentiometer R5 and a few other resistors
are provided for easily adjusting the LED maximum DC
current; please refer to the evaluation board schematic on
page 2 for more details.
December 13, 2011
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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. 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.
JP11
JP12
JP13
LED12
LED24
LED36
LED48
LED11
LED23
LED35
LED47
LED10
LED22
LED34
LED46
LED9
LED21
LED33
LED45
LED8
LED20
LED32
LED44
LED7
LED19
LED31
LED43
LED6
LED18
LED30
LED42
LED5
LED17
LED29
LED41
P8
D
R8
AGND
5k
P10
0
R5
1M
TP8
RSET
R7
PGND
R9
open
10k
R1
150k
100k
3
SW1
1
1
C15
8.2nF
U1
SW2
5
P4
PWMI
AGND
3
COMP
2
1
2
R2
VDC
C3
33PF
TP9
FSW/PHS
3
PGND
RSET
AGND
4
P9
2
P5
FSW/PHS
P6
AGND
R6
2
D
AGND
P7
TP6
16
CH4
PWMI
TP5
6
P3
EN
7
3
JP1
CH2
FPWN/DPWM
CH1
VDC
TP3
8
2
VIN
B
CH1
1nF/50V
27k
P2
R11
100k
0
VDC
TP7
JP19
F1
2A Fuse
12
10k
15uH
C12
1nF/50V
C11
LED4
C9
3.3nF/50V
LX
L1
357k
C10
TP1
C13
1nF/50V
R3
C4
1uF/16V
Open
C14
1nF/50V
VDC
R4
R13
JP14
11
R10
10
9
3
R12
PVIN P1
JP2: For measuring total output current
JP3-JP6: For measuring current on CH1-CH4 respectively
JP7-JP10, JP13-JP16: For easy configuration of 8x LED or 10x
LED per string
LX
JP20
When
SW1=SW2=1: Fsw=1.2MHz, WITH phase shift
SW1=SW2=3: Fsw=600KHz, WITH phase shift
SW1=1, SW2=3: Fsw=1.2MHz, WITHOUT phase shift
SW1=3, SW2=1: Fsw=600KHz, WITHOUT phase shift
13
CH2
OVP
1
C2
0.1uF/50V
EN can be connected in the following ways to
enable/disable the device:
(1) Connected it to VIN directly on JP1 to enable
(2) Connected it to GND directly on JP1 to disable
(3) Directly apply external voltage on P3(EN) to
enable/disable the device without putting shunt on JP1.
14
LED16
JP15
D1
LED28
LED40
100pF/50V
TP2
PMEG6030
LED3
JP16
LED15
JP17
LED27
JP18
B
LED39
VOUT
XAL6060-153MEB
C1
10uF/35V
C5
C6
4.7uF/50V 4.7uF/50V
nc
C7
nc
C8
LED2
LED14
JP7
2-layer board. Connect top layer PGND and bottom
layer AGND at one single point through the via on
the thermal pad under the chip.
JP2
LED26
JP8
LED38
JP9
JP10
LED1
LED13
LED25
LED37
JP3
JP4
JP5
JP6
I_OUT
A
A
Title
Size
B
Date:
File:
FIGURE 1. EVALUATION BOARD SCHEMATIC
Error : intersil.bmp file not found.
Number
ISL97684EVAL1Z
11-Oct-2011
Sheet of
C:\ISL97682_3_4\ISL97682EVAL1Z_RevA.ddb
Drawn By:
Revision
Rev. A
Application Note 1668
VIN
CH3
C
TP4
VDC
1
CH3
ISL97684
2
EN
PGND
C
15
CH4
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PCB Layout
3
Application Note 1668
FIGURE 2. TOP SILKSCREEN LAYER AND TOP LAYER
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(Continued)
PCB Layout
4
Application Note 1668
FIGURE 3. BOTTOM LAYER
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Application Note 1668
Bill of Materials
DESIGNATOR
PART TYPE
FOOTPRINT
PART MANUFACTURER/NUMBER
R1
150k
603
1% SMD Resistor
R2
100k
603
General purpose
R3
357k
603
R4
10k
603
R5
1M
VRES
R6
0
603
R7
Open
603
R8
5k
603
R9
10k
603
R10
0
603
R11
100k
VRES
R12
0
603
R13
Open
603
L1
15µH
CoilCraft (XAL6060-153MEB)
D1
PMEG6030
C1
10µF/35V
1210
General purpose C2
0.1µF/50V
603
Ceramic X5R/X7R capacitors
C3
33pF
603
C4
1µF/16V
603
C5
4.7µF/50V
1210
Murata, GRM32ER71H475KA88L
C6
4.7µF/50V
1210
C7
Place Holder
1210
Not Populated
C8
Place Holder
1210
C9
100pF/50V
603
General purpose C10
3.3nF/50V
603
Ceramic X5R/X7R capacitors
C11
1nF/50V
603
C12
1nF/50V
603
C13
1nF/50V
603
C14
1nF/50V
603
C15
8.2nF
603
F1
2A Fuse
1206
Bel Fuse Inc, C1Q 2
U1
QFN16 3MM
Intersil, ISL97682/3/4
JP2-JP19
JUMPER-2PIN
JUMPER-2PIN
FCI
WR
JUMPER-2PIN
JUMPER-2PIN
68000-236HLF-1x2
JP1
JUMPER-3PIN
JUMPER-3PIN
FCI
JP20
JUMPER-3PIN
JUMPER-3PIN
68000-236HLF-1x3
LED1-12 LED25-36
LED-SMT
LW_Y87C
TP1
LX
TEST POINT
Keystone Electronics
TP2
VOUT
TEST POINT
5010
5
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Application Note 1668
Bill of Materials (Continued)
DESIGNATOR
PART TYPE
FOOTPRINT
PART MANUFACTURER/NUMBER
TP3
CH1
TEST POINT
TP4
CH2
TEST POINT
TP5
CH3
TEST POINT
TP6
CH4
TEST POINT
TP7
VDC
TEST POINT
TP8
RSET
TEST POINT
TP9
FSW/PHS
TEST POINT
P5
AGND
TEST POINT
Keystone Electronics
P6
AGND
TEST POINT
5011
P9
PGND
TEST POINT
P1
PVIN
POWERPOST
Mill Max
P2
VIN
POWERPOST
3156-1-00-00-00-00-08-0
P3
EN
POWERPOST
P4
PWMI
POWERPOST
P7
AGND
POWERPOST
P8
AGND
POWERPOST
P10
PGND
POWERPOST
SW2
SPDT
SWITCH-SLIDE-SPDT
EAO
SW1
SPDT
SWITCH-SLIDE-SPDT
09.03201.02
Intersil Corporation reserves the right to make changes in circuit design, software and/or specifications at any time without notice. Accordingly, the reader is
cautioned to verify that the Application Note or Technical Brief is current before proceeding.
For information regarding Intersil Corporation and its products, see www.intersil.com
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