LP5520 datasheet(15/46 Pages) TI1

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LP5520

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SNVS440B – MAY 2007 – REVISED MARCH 2016

Product Folder Links: LP5520

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Table 2. PWM Mode

<seq_mode1>

(BIT 7)

<seq_mode0>

(BIT 6)

MODE

Normal mode

Sequential mode with 2 PWM pulses per trigger

Sequential mode with 3 PWM pulses per trigger

Sequential mode with 4 PWM pulses per trigger

7.3.2.5 Current Control of the LEDs

The LP5520 has a separate 8-bit current control for each LED output. In manual mode the current for red LED is

controlled with the current_control_r (01H) register, the green LED is controlled with the current_control_g

(02H), and the blue LED with current_control_b (03H). Output current can be calculated with formula: current

(mA) = code × 0.235; for example, a 20-mA current is obtained with code 85 (55H).

In automatic and stand-alone modes the LED current values programmed in EEPROM are used, and the current

control registers have no effect. There are two ways to change the default current if needed. The defaults can be

changed permanently by programming new values to the EEPROM. The other option is to make a temporary

change by writing new current values in SRAM.

7.3.2.6 Output Enables

ROUT, GOUT, and BOUT output activity is controlled with 3 enable bits of the rgb_control (00H) register:

Table 3. Output Enable Bits

<en_b> (bit 2)

Blue LED output BOUT disabled

Blue LED output BOUT enabled

<en_g> (bit 1)

Green LED output GOUT disabled

Green LED output GOUT enabled

<en_r> (bit 0)

Red LED output ROUT disabled

Red LED output ROUT enabled

PWM control inputs PWMR, PWMG and PWMB can be used as external output enables in normal and automatic

mode. In the sequential mode these inputs are the trigger inputs for respective outputs.

7.3.2.7 Fade In and Fade Out

The LP5520 has an automatic fade in and out for the LED outputs. Fading makes the transitions smooth in on

and off switching or when brightness is changed. It is not applied for the changes caused by the compensation

algorithm. The fade can be turned on and off using the <en_fade> bit in the rgb_control (00H) register. The

fade time is constant 520 ms, and it does not depend on how big the brightness change is. The white balance is

maintained during fading. Fading is off in the stand-alone mode.

Table 4. Fade In and Fade Out With <en_fade> Bit

<en_fade>(bit 5)

Automatic fade disabled

Automatic fade enabled

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