STEVAL-ILL021V1 STMicroelectronics, STEVAL-ILL021V1 Datasheet - Page 24

• 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

Operation description
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At the point marked as “1” in
across the current generator of the channel where the failed LED is connected increases by
an amount equal to the forward voltage of the faulty LED. Since the voltage across the
current generator is above the threshold (4 V), the device is turned off and the fault pin is set
low (point “2”). Note that, once a new dimming cycle starts (point “3”), the device waits the
masking time (approximately 100 μs) and then sets the FAULT pin low and turns off.
Figure 17. Shorted LED detection (MODE to GND)
Figure 17
masking time
masking time
1
1 1
one LED fails becoming a short-circuit. The voltage
3
3 3
2
2 2
LED7707