LP55281TLSLASHNOPB datasheet(15/42 Pages) TI2

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0.2

0.4

0.6

0.8

1. 0

1. 2

1.4

TIME( 200Ps/DIV)

4.0

4.2

4.4

4.6

4.8

5.0

5.2

5.4

Control= 00 :)):00

VIN = 6V

I LOAD = 50 mA

LP55281

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SNVS458D – JUNE 2007 – REVISED OCTOBER 2016

Product Folder Links: LP55281

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7.3 Feature Description

7.3.1 Magnetic Boost DC-DC Converter

7.3.1.1 Boost Standby Mode

User can stop the boost converter operation by writing the Enables register bit EN_BOOST low. When

EN_BOOST is written high, the converter starts for 10 ms in PFM mode and then goes to PWM mode.

7.3.1.2 Boost Output Voltage Control

User can control the Boost output voltage by boost output 8-bit register.

BOOST OUTPUT [7:0] Register 0Fh

BOOST OUTPUT VOLTAGE (TYPICAL)

Bin

Hex

0000 0000

4 V

0000 0001

4.25 V

0000 0011

4.4 V

0000 0111

4.55 V

0000 1111

4.7 V

0001 1111

4.85 V

0011 1111

5 V (default)

0111 1111

5.15 V

1111 1111

5.3 V

Figure 11. Boost Output Voltage Control

7.3.1.3 Boost Frequency Control

FRQ_SEL[2:0]

FREQUENCY

1XX

2 MHz

01X

1.67 MHz

001

1 MHz

7.3.2 Functionality of RGB LED Outputs (R1-4, G1-4, B1-4)

The LP55281 device has 4 sets of RGB/color LED outputs. Each set has 3 outputs, which can be controlled

individually with a 6-bit PWM control register. The pulsed current level for each LED output is set with a single

external resistor RRGB and a 2-bit coarse adjustment bit for each LED output (see Table 1 and Table 2).

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