ALED7707 datasheet(21/36 Pages) STMICROELECTRONICS

21 / 36 page

DocID027854 Rev 2

21/36

ALED7707

Operation description

Figure 15. PWM dimming waveforms

5.3

Fault management

The main loop keeps the row having the lowest voltage drop regulated to about 700 mV. This

value slightly depends on the voltage across the remaining active rows. After the soft- start

sequence, all protections turn active and the voltage across the active current generators is

monitored to detect shorted LEDs.

5.3.1

FAULT pin

The FAULT pin is an open-collector output, (with 4 mA current capability) active low, which

gives information regarding faulty conditions eventually detected. This pin can be used

either to drive a status LED or to warn the host system.

The FAULT pin status is strictly related to the MODE pin setting (see Table 6 for details).

5.3.2

MODE pin

The MODE pin is a digital input and can be connected to AVCC or SGND in order to choose

the desired fault detection and management. The ALED7707 can manage a faulty condition

in two different ways, according to the application needs. Table 6 summarizes how the

device detects and handles the internal protections related to the boost section (overcurrent,

overtemperature and overvoltage) and to the current generators section (open and shorted

LEDs).

ALED7707 데이터시트(PDF) 21 Page - STMicroelectronics