Intersil ISL97682IRTZEVALZ User Manual

ISL97682 LED Driver Evaluation Board User Manual
Introduction
The ISL97682IRTZEVALZ Evaluation Board provides a
complete testing platform for the ISL97682, a two channel
LED driver. Please refer to the product datasheet (ISL97682,
FN7689) for detailed information including pinout, pin function
description, electrical specifications, applications related
information, etc.
Instructions
Please follow the steps described below to start your
evaluation.
1. For both switch #1 and #2 (SW1 and SW2 shown on the
board), set them to position 3 (left side).
2. For enable control jumper JP1, put the shunt to the "ON"
position (right side) to connect EN pin to VIN. When the
shunt is set to 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.
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 PWMI pin and
AGND.
7. Apply 4V~26.5V between PVIN and PGND and the LEDs
should be lit, and you can start the evaluation.
NOTE: In step #1 above, the SW1, SW2 position can be adjusted to
different positions for different configurations, see Table 1 for details.
TABLE 1.
SW1 SW2
POSITION POSITION
1 1 LX switching frequency = 600kHz, PFM
CH1 and CH3
3 3 LX switching frequency = 1MHz, PFM
CH1 and CH3
3 1 LX switching frequency = 600kHz, No PFM
CH1 and CH3
1 3 LX switching frequency = 1MHz, No PFM
CH1 and CH3
• The LED maximum DC current adjustment.
For each channel, the maximum DC current is set by
resistance connected to RSET pin. The current for each
channel can be calculated as shown in Equation 1:
402
( )
I_LED mA
--------------------------- -
=
( )
RSET kΩ
On the board, a potentiometer R5 and a few other resistors
are provided for easily adjust the LED maximum DC current.
October 11, 2011
AN1662.0
DESCRIPTION
(EQ. 1)
1
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
1-888-INTERSIL or 1-888-468-3774
Application Note 1662
Please refer to the "ISL97682IRTZEVALZ Evaluation Board
Schematic" on page 2 for more details.
• LED dimming frequency and duty cycle.
- As mentioned in step #4 above, when the shunt on JP20
is connected to the upper position, 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.
- 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 as per Equation 2:
( )
FPWM Hz 12.4
=
The duty cycle is still modulated by the external PWM
signal applied on PWMI pin. On board, potentiometer R11
and a few other resistors are provided for easily adjusting
the LED dimming frequency under such a configuration.
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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.
7
10
•
-----------------------------------
R_FPWM Ω ( )
(EQ. 2)