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AS3820

16-Channel White LED Controller for LCD Backlight

Rev. 1.1

Datasheet

www.dialog-semiconductor.com

12 of 52

05-Feb-2019

8.1.4 Open LED Detection

If open led detection is enabled a broken LED-string is detected during PWM=1. If a LED-string is broken and the

feedback function is enabled, the “idac_fbx_counter” will count up in order to increase the power supply output volt-

age. After the “idac_fbx_counter” has reached its maximum value, a debounce counter is started. In order to run the

debounce counter, the corresponding PWM-signal has to be high for more than 150μs. After the debounce couter has

counted up for 32ms, the corresponding “OPENLED_x” bit is set and the output xFAULT = “0”.

Figure 8.2 : Open LED Detection

8.1.5 Short LED Detection

Short LED detection is implemented in two different ways:

1. With a built-in self-test (Short-BIST) circuit.

2. With two comparator inputs for monitoring external voltages (Short-COMP).

The external voltage is divided by an external resistor and an internal current source. The output of the comparators

only takes effect if all selected PWM-signals are “1” for a minimum time of “Tshortmin“ at the same time. The selection

of Short1 or Short2 Group is done by “fb_ON_x” and “fb_sel_X”.

AS3820 bảng dữ liệu(PDF) 12 Page - Dialog Semiconductor