STEVAL-ILL021V1 STMicroelectronics, STEVAL-ILL021V1 Datasheet - Page 19

• Manufacturer Part Number: STEVAL-ILL021V1
• Description: BOARD EVAL LCD BACKLIGHT LED7707
• Manufacturer: STMicroelectronics

Specifications of STEVAL-ILL021V1

• Design Resources: STEVAL-ILL021V1 Bill of Material STEVAL-ILL021V1 Schematic
• Current - Output / Channel: 85mA
• Outputs And Type: 6, Non-Isolated
• Voltage - Output: 36 V
• Features: Dimmable, Extra 5V Output
• Voltage - Input: 4.5 ~ 36 V
• Utilized Ic / Part: LED7707
• Description/function: LCD backlight demonstration board
• Operating Voltage: 4.5 V to 36 V
• Product: Display Modules
• Core Chip: LED7707
• No. Of Outputs: 1
• Output Voltage: 36V
• Dimming Control Type: PWM
• Mcu Supported Families: LED7707
• Lead Free Status / RoHS Status: Lead free by exemption / RoHS compliant by exemption
• For Use With/related Products: LED7707
• Other names: 497-10044

LED7707
5.2
5.2.1
Backlight driver section
Current generators
The LED7707 is a LEDs driver with six channels (rows); each row is able to drive multiple
LEDs in series (max. 36 V) and to sink up to 85 mA maximum current, allowing to manage
different kinds of LEDs.
The LEDs current can be set by connecting an external resistor (R
pin and ground. The voltage across the RILIM pin is internally set to 1.23 V and the rows
current is proportional to the RILIM current according to the following equation:
Equation 9
Where K
The graph in
choose the correct value of the resistor to set the desired row current.
Figure 13. Row current vs R
The maximum current mismatch between the rows is ± 2 % @ I
The LED7707 allows parallelism different rows if required by the application. If the maximum
current provided by a single row (85 mA) is not enough for the load, two or more current
generators can be connected together, as shown in
generators stable, the row current should be higher than 40 mA.The connection between
channels in parallel must be done as close as possible to the device in order to minimize
parasitic inductance.
R
= 1850 V.
Figure 13
better shows the relationship between I
RILIM
I
ROWx
=
R
K
RILIM
R
Figure 14
. To keep the parallelism
ROW
rowx
RILIM
and R
Operation description
= 60 mA.
) between the RILIM
RILIM
and helps to
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