EN_RGB

RGB_PWM

RGB max

current reg

XSW

RGB total current

0A

Max current

Pre-flash

Flash

Pre-flash current value

Max current value

EN_RGB

XSW

RGB_PWM

EN_EXT_X_PWM

EN_PWM_PIN

GPIO[0]/PWM

RGB total current

0A

Max current

Pre-flash

Flash

LP5526

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SNVS431C – FEBRUARY 2006 – REVISED JULY 2009

Figure 7. Using External PWM Control for Flash

2. Controlling RGB Max Current Register Values

In this case pre-flash brightness is adjusted by adjusting the current values in the RGB max current register.

•

Enable RGB functions and disable PWM mode (EN_RGB = 1, RGB_PWM = 0)

•

Enable RGB constant current mode (CC_SW = 0)

•

Write pre-flash values for each output to RGB max current register (e.g. 00b for 25% of maximum current)

•

Start pre-flash by switching on the LEDs (RSW = 1, GSW = 1, BSW = 1). Pre-flash brightness can be

adjusted also by setting on only one or two LEDs during the pre-flash

•

Start flash by writing each output maximum current values to RGB max current register

•

Stop flash by switching off the LEDs (RSW = 0, GSW = 0, BSW = 0)

Figure 8. Controlling RGB Max Current Values to Introduce Flash

When RLED, GLED and BLED are connected together as in Typical Application 1, flash current can be adjusted

with 8.33% step in constant current mode by changing RGB max current register values as seen on following

table. Note that 0% means that appropriate output is turned off by setting RSW, GSW or BSW bit to 0.

Total current [%]

0

0

25

8.33

0

0

50

16.67

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