LED7706 datasheet(23/31 Pages) STMICROELECTRONICS

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LED7706

Backlight driver section

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Backlight driver section

7.1

Current generators

The LED7706 is a LEDs driver with six channels (rows); each row is able to drive multiple

LEDs in series (max. 40 V) and to sink up to 30 mA maximum current, allowing to manage

different kinds of LEDs.

The LEDs current can be set by connecting an external resistor (RRILIM ) between the RILIM

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 16

Where KR = 987 V.

The maximum current mismatch between the rows is ± 2 % @ Irowx = 20 mA.

Due to the spread of the LEDs’ forward voltage, the total drop across the LED’s strings will

be different. The device will manage the unconnected rows according to the MODE pin

setting (see Table 7).

The LED7706 allows parallelizing different rows if required by the application. If the

maximum current provided by a single row (30 mA) is not enough for the load, two or more

current generators can be connected together, as shown in Figure 14. The connection

between rows in parallel must be done as close as possible to the device in order to

minimize parasitic inductance.

Figure 14.

rows parallelization for higher current

RILIM

ROWx

ROW1

ROW2

ROW3

ROW4

ROW5

ROW6

LDO5

BILIM

RILIM

SGND

VIN

COMP

High Current WLEDs

Enable

Dimming

Fault

LED7706

Sync Output

Faults Management Selection

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