LP5526TL datasheet(18/33 Pages) NSC

18 / 33 page

Functionality of Color LED

Outputs (RLED, GLED, BLED)

(Continued)

FLASH SAFETY TIMER FUNCTION

Flash safety function can be used to prevent damages due

to possible overheating when flash or RGB LEDs have been

stuck on because of software or user error. Safety function

has two operation modes:

Disabling selected RGB drivers when no writing has

been done to the RGB max current register (address

02H) for 1 second

Disabling selected RGB drivers if the external flash trig-

ger pulse is longer than 1 second

Flash safety function can be individually enabled for all RGB

LED drivers (EN_SAFETY_R, EN_SAFETY_G, EN_SAFE-

TY_B). The safety function operation mode depends on the

state of EN_FLASH bit.

EN_FLASH = 0: Safety counter starts counting when at

least one of the EN_SAFETY_X bits is enabled. Safety

counter can be cleared by executing an I

2C read or write

sequence to address 02H. If safety counter reaches one

second, the LEDs which have the safety function en-

abled, are switched off. Also the read-only bit SAFETY-

_SET is set high.

EN_FLASH = 1: Safety counter starts counting when the

external flash trigger pulse starts (GPIO[0]/PWM goes

high) and stops counting when flash pulse stops

(GPIO[0]/PWM goes low). If flash pulse is longer than

one second, the LEDs which have the safety function

enabled, are switched off. Also the read-only bit SAFE-

TY_SET is set high.

In both cases (EN_FLASH = 0/1) after one second is

reached and the LEDs which safety bit has been enabled are

switched off, the LED state can be restored by disabling the

safety function of the corresponding LED. Counter can be

cleared only by disabling all safety bits (EN_SAFETY_R = 0,

EN_SAFETY_G = 0, EN_SAFETY_B = 0), I

2C read or write

sequence to address 02H does not clear the counter when

safety function has been activated.

RGB LEDs Driver Performance Characteristics

Symbol

Parameter

Condition

Min

Typ

Max Units

LEAKAGE

RLED, GLED, BLED pin leakage current

µA

MAX(RGB)

Maximum recommended sink current

CC mode

SW mode

Accuracy @ 50mA

CC mode

12.5

Current mirror ratio

CC mode

1:100

RGB current matching error

RGB set to 50mA, CC mode

Switch resistance

SW mode

3.2

Ω

RGB

RGB internal PMW switching frequency

Accuracy same as internal clock

frequency accuracy

kHz

SAT

Saturation voltage (current drop 10%)

+25oC, I

RGB set to 50mA

-30oC

+85oC

230

350

300

430

Note: RGB current should be limited as follows:

constant current mode – limited by external RRGB resistor

switch mode – limited by external ballast resistors

Output Current vs Pin Voltage (CC Mode)

Output Current vs R

RGB (CC Mode)

20179705

20179706

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