LED7708 datasheet(8/53 Pages) STMICROELECTRONICS

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Pin function

LED7708

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Doc ID 022698 Rev 1

XOVF

Internal DAC overflow I/O. Used for extended output voltage regulation and fault

management in multi-device applications. It is used to inform slave devices that the

maximum output voltage has been reached. A 100 k pull-up resistor to LD03 is required.

XMSK

Fault detection masking I/O. This signal is used for extended output voltage regulation &

fault management in multi-device applications. It is used to avoid incorrect fault detection

by forcing slave devices to ignore LED-short detection during output voltage steering. A

100 k pull-up resistor to LD03 is required.

FSW

Switching frequency selection / synchronization input. Used to set the desired switching

frequency of the boost controller. Also used as synchronization input.

SYNC

Boost converter synchronization output. The buffered switching clock signal is provided at

this pin to eventually synchronize other SMPS in the host system.

FOSC

Dimming oscillator frequency. A resistor to ground sets the frequency of the internal

grayscale clock dimming oscillator. If set high, the internal dimming oscillator is disabled

and the GSCK pin becomes the clock input (see GSCK pin).

CLIM

Boost section current limit setting. A resistor between this pin and SGND sets the boost

converter current limit.

SLOPE

Slope compensation setting. A resistor between this pin and SGND is required to set the

proper amount of slope compensation to avoid sub-harmonic instability.

COMP

Transconductance amplifier output. Connect a simple RC series between this pin and

SGND to properly compensate the loop-gain of the boost converter.

ISETH

Output current setting (on). Connect a resistor between this pin and SGND to set the

current sunk by each channel during the on-phase of the dimming.

ISETL

Output current setting (off). Connect a resistor between this pin and SGND to set the

current sunk by each channel during the off-phase of the dimming (LED biasing). Connect

to LDO3 to disable the bias current.

SGND

Signal ground. Common return for signals and settings.

AGND

Analog Ground. Common return for the current generators (channels).

CH1

Driver output (channel) #1.

CH2

Driver output (channel) #2.

CH3

Driver output (channel) #3.

CH4

Driver output (channel) #4.

CH5

Driver output (channel) #5.

CH6

Driver output (channel) #6.

CH7

Driver output (channel) #7.

CH8

Driver output (channel) #8.

CH9

Driver output (channel) #9.

CH10

Driver output (channel) #10.

CH11

Driver output (channel) #11.

CH12

Driver output (channel) #12.

CH13

Driver output (channel) #13.

Table 2.

Pin description (continued)

Function

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