STMICROELECTRONICS STEVAL

STEVAL-ILL021V1
LCD panels backlight demonstration board
based on the LED7707
Data brief
Features
■
■
■
Features boost section
– 4.5 V to 36 V input voltage range
– internal power MOSFET
– internal +5 V LDO for device supply
– up to 36 V output voltage
– constant frequency peak current-mode
control
– 250 kHz to 1 MHz adjustable switching
frequency
– external sync for multi-device application
– pulse-skip power saving mode at light load
– programmable soft-start
– programmable OVP protection
– single ceramic output capacitor
– non-latched thermal shutdown
Features backlight driver section
– six rows with 85 mA maximum current
capability (adjustable)
– up to 10 white LEDs per row
– rows disable option
– less than 10 µs minimum dimming time
– ±2.0% current matching between rows
– LED failure (open and short circuit)
detection
STEVAL-ILL021V1
The generators can be externally programmed to
sink up to 85 mA and can be dimmed via a PWM
signal (1% of minimum dimming duty cycle at
1kHz can be managed).
The device allows to detect and manage the open
and shorted LED faults and to let unused rows
floating.
Basic protections (output overvoltage, internal
MOSFET overcurrent and thermal shutdown) are
provided.
RoHS compliant
Description
This demonstration boards is based on the
LED7707 and implements a high efficiency
monolithic boost converter and six controlled
current generators (rows) specifically designed to
supply LEDs arrays used in the backlight of LCD
panels.
The device can manage an output voltage up to
36 V (i.e. ten white-LEDs per row).
May 2009
Doc ID 15677 Rev 1
For further information contact your local STMicroelectronics sales office.
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www.st.com
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Circuit schematic and PCB layout
1
STEVAL-ILL021V1
Circuit schematic and PCB layout
Figure 1.
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Figure 2.
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Top side component placement
Doc ID 15677 Rev 1
STEVAL-ILL021V1
Figure 3.
Circuit schematic and PCB layout
Bottom side
Doc ID 15677 Rev 1
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Revision history
2
STEVAL-ILL021V1
Revision history
Table 1.
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Document revision history
Date
Revision
06-May-2009
1
Changes
Initial release.
Doc ID 15677 Rev 1
STEVAL-ILL021V1
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