LP3954 datasheet(13/58 Pages) TI2

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100

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3.6

3.8

4.0

4.2

4.4

4.6

4.8

5.0

5.2

OUTPUT CURRENT (mA)

VIN = 3V

f = 2 MHz

L - TDK VLF0410 4.7 PH

CIN = COUT = 10 PF

LOAD CURRENT (mA)

Autoload ON

Autoload OFF

LP3954

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SNVS340D – JUNE 2005 – REVISED MARCH 2013

Vin = 3.6V, Vout = 5.0V if not otherwise stated

Output Voltage vs Load Current

Efficiency At Low Load vs Autoload

Figure 12.

Figure 13.

Functionality of Color LED Outputs (R1, G1, B1; R2, G2, B2)

LP3954 has 2 sets of RGB/color LED outputs. Both sets have 3 outputs and the sets can be controlled in 4

different ways:

1. Command based pattern generator control (internal PWM)

2. Audio synchronization control

3. Direct ON/OFF control

4. External PWM control

By using command based pattern generator user can program any kind of color effect patterns. LED intensity,

blinking cycles and slopes are independently controlled with 8 16-bit commands. Also real time commands are

possible as well as loops and step by step control. If analog audio is available on system, the user can use

audio synchronization for synchronizing LED blinking to the music. The different modes together with the

various sub modes generate very colorful and interesting lighting effects. Direct ON/OFF control is mainly for

switching on and off LEDs. External PWM control is for applications where external PWM signal is available

and required to control the color LEDs. PWM signal can be connected to any color LED separately as shown

later.

COLOR LED CONTROL MODE SELECTION

The RGB_SEL[1:0] bits in the Enables register (08H) control the output modes for RGB1 (R1, G1, B1) and RGB2

(R2, G2, B2) outputs. The following table shows the RGB_SEL functionality.

Command Based Pattern Generator

RGB_SEL[1:0]

Audio Sync Connected To

Connected To

none

RGB1 & RGB2

RGB1

RGB2

RGB1

RGB1 & RGB2

none

RGB Control register (00H) has control bits for direct on/off control of all color LEDs. Note that the LEDs have

to be turned on in order to control them with audio synchronization or pattern generator.

The external PWM signal controls any LED depending on the control register setup. The controls are in the Ext.

PWM Control register (address 07H) except the FLASH control in HC_Flash (10H) register as follows:

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