LED7707 datasheet(30/48 Pages) STMICROELECTRONICS

Part #	LED7707

Description	6-rows 85 mA LEDs driver with boost regulator for LCD panels backlight

PDF	48 Pages

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Manufacturer	STMICROELECTRONICS [STMicroelectronics]

Direct Link	http://www.st.com

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30 / 48 page

Application information

LED7707

30/48

Equation 22

where nROWs is the number of active rows, ΔVf,LEDs is the spread of the LEDs forward

voltage and nLEDs is the number of LEDs per row.

LDO losses, due to the dissipation of the 5 V linear regulator:

Equation 23

The LED7707 is housed in a 24 leads 4x4-VFQFPN package with exposed pad that allows

good thermal performance. However it is also important to design properly the

demonstration board layout in order to assure correct heat dissipation.

Figure 20

shows a picture of the LED7707 application demonstration board taken using an

infrared camera. The chip temperature, in those application conditions, is kept below 50 °C.

Figure 20.

Demonstration board thermographic analysis

(

)

(

)

DIM

LEDs

IFB

ROWs

ROW

GEN

⋅

−

⋅

(

)

LDO

⋅

−

64°C

50°C

VIN = 12V

IROW = 60mA

VOUT = 30V

FSW = 660kHz

DDIM = 100%

Tamb = 25°C

64°C

50°C

VIN = 12V

IROW = 60mA

VOUT = 30V

FSW = 660kHz

DDIM = 100%

Tamb = 25°C

LED7707 Datasheet(PDF) 30 Page - STMicroelectronics

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