LP5526TL/NOPB National Semiconductor, LP5526TL/NOPB Datasheet - Page 13

• Manufacturer Part Number: LP5526TL/NOPB
• Description: IC LED DRVR WT/RGB BCKLT 25-USMD
• Manufacturer: National Semiconductor
• Series: PowerWise®r
• Type: Backlight, White LED, RGB (I²C Interface)r

Specifications of LP5526TL/NOPB

• Constant Current: Yes
• Topology: PWM, Step-Up (Boost)
• Number Of Outputs: 5
• Internal Driver: Yes
• Type - Primary: Backlight, Light Management Unit (LMU)
• Type - Secondary: RGB, White LED
• Frequency: 1MHz
• Voltage - Supply: 3 V ~ 5.5 V
• Voltage - Output: 8 V ~ 20 V
• Mounting Type: Surface Mount
• Package / Case: 25-MicroSMD
• Operating Temperature: -30°C ~ 85°C
• Current - Output / Channel: 150mA
• Internal Switch(s): Yes
• Efficiency: 88%
• For Use With: LP5526TLEV - BOARD EVAL LP5526 LMU LED DRIVER
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: LP5526TLTR

Maximum current for each LED output is adjusted with the
RGB max current register in following way:
External ballast resistors are not needed in this mode. The
maximum current for all RGB LED drivers is set with R
The equation for calculating the maximum current is:
where
I
stant current mode)
1.23V = reference voltage
100 = internal current mirror multiplier
R
50Ω = Internal resistor in the I
MAX
RGB
IR[1:0], IG[1:0], IB[1:0]
= maximum RGB current in any RGB output (during con-
= resistor value in Ohms
00
01
10
11
I
MAX
= 100 × 1.23V / (R
RGB
Maximum current / output
input
RGB
0.25 x I
0.50 x I
0.75 x I
1.00 x I
+ 50 Ω)
MAX
MAX
MAX
MAX
RGB
.
13
Table with example resistance values and corresponding out-
put currents:
Note that the LED output requires a minimum saturation volt-
age in order to act as a true constant current sink. The
saturation voltage minimum is typically 230mV defined with
10% current drop. If the LED output voltage drops below
230mV, then the current will decrease significantly.
3. EXTERNAL PWM CONTROL
The GPIO[0]/PWM pin can be used to control the RGB output
brightness or set RGB leds on/off. PWM function for the pin
is selected by writing EN_PWM_PIN high in GPIO control
register (address 06H). Note, that EN_RGB bit must be set
high. Each LED output can be enabled with RSW, GSW and
BSW bits. EN_EXT_R_PWM, EN_EXT_G_PWM and
EN_EXT_B_PWM bits are used to select, which LED outputs
are controlled with the external PWM input. Note that polarity
of external PWM control is active high i.e. when pin is in high
state, then LED output is enabled. If RGB_PWM is set low,
then each selected LED output is controlled directly with ex-
ternal PWM input. If RGB_PWM is set high, then internal
PWM control is modulated by the external PWM input. In latter
case, internal PWM control is passed to LED when external
PWM input is high.
RGB resistor R
2.4
2.7
3.0
3.3
3.6
3.9
4.3
4.7
5.1
5.6
6.2
RGB
(kΩ)
Maximum current / output I
(mA)
50.2
44.7
40.3
36.7
33.7
31.1
28.3
25.9
23.9
21.8
19.7
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MAX