lp5526tlx National Semiconductor Corporation, lp5526tlx Datasheet - Page 13

• Manufacturer Part Number: lp5526tlx
• Description: Lighting Management Unit With High Voltage Boost Converter With Up To 150ma Serial Flash Led Driver
• Manufacturer: National Semiconductor Corporation

Functionality of Color LED Outputs (RLED, GLED, BLED)
Overlapping Mode
In overlapping mode the brightness is controlled using PWM
duty cycle based control method as the following figure
shows.
Since RGB outputs are on simuneltaneously, the maximum
load peak current is:
Non-Overlapping Mode
The timing diagram shows the splitted R, G and B and
brightness control effect to splitted parts. Full brightness is
used in the diagram. If for example
frame is still 50µs, but all LED outputs’ ON time is 50%
shorter and at the last 25µs all LED outputs are OFF.
The non-overlapping mode has 16 programmed colors (dif-
ferent R, G and B ratio -
B are split in to non-overlapping slots the output current
through the RGB LED can be calculated with following equa-
tion:
where
C = Color [%] (see table of color control)
B = Brightness [%] (see table of brightness control)
I
MAX
= I(RLED)
I
AVG
=(C
MAX
R
>
xI
+ I(GLED)
different color). Since the R, G and
R
+C
G
xI
G
+C
1
⁄
MAX
2
brightness is used, the
B
xI
+ I(BLED)
B
)xB
MAX
Non-Overlapping Mode
Overlapping Mode
13
2. LED ON/OFF CONTROL WITH RGB CONTROL
REGISTER
Each LED output can be set ON by writing the corresponding
bit high in the Control register (00H). RSW controls RLED,
GSW controls GLED and BSW controls BLED output. Note
that EN_RGB bit must be high and RGB_PWM bit low. In this
mode, the RGB register (01H) does not have any effect.
CC_SW bit in Control register defines the LED output mode.
(Continued)
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