LP5521 datasheet(40/48 Pages) TI1

40 / 48 page

TRIG

SDA

SCL

ADDR

SEL0

INT

ADDR

SEL1

CFLY

CLK

32K

GND

VDD

GND

CFLY

VOUT

CFLY

GPO

MicroVias

Vias to GND plane

To LEDs

Control signals

Top Layer

Inner Layer

LP5521

SNVS441H – JANUARY 2007 – REVISED MAY 2016

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Product Folder Links: LP5521

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Initialization Setup (continued)

–

Wait 500 µs (start-up delay)

2. Enable charge pump 1.5x mode and use internal clock:

–

Write to address 08H 0001 0001b

3. Direct PWM control:

–

Write to address 01H 0011 1111b (Configure R, G and B channels into "Direct PWM control mode")

4. Write PWM values:

–

Write to address 02H 1000 0000b (R driver PWM 50% duty cycle)

–

Write to address 03H 1100 0000b (G driver PWM 75% duty cycle)

–

Write to address 04H 1111 1111b (B driver PWM 100% duty cycle)

LEDs are turned on after the PWM values are written. Changes to the PWM value registers are reflected

immediately to the LED brightness. Default LED current (17.5 mA) is used for LED outputs, if no other values are

written.

9 Power Supply Recommendations

The device is designed to operate from an input voltage supply range between 2.7 V and 5.5V. In a typical

application this is from single Li-ion battery cell. This input supply must be well regulated and able to withstand

maximum input current and maintain stable voltage without voltage drop even at load transition condition (start-

up or rapid brightness change). The resistance of the input supply rail must be low enough that the input current

transient does not cause drop below a 2.7-V level in the LP5521 supply voltage.

10 Layout

10.1 Layout Guidelines

Place capacitors as close to the LP5521 device as possible to minimize the current loops. Figure 31 shows an

example of LP5521 PCB layout and component placement.

10.2 Layout Example

Figure 31. Example of Typical Layout

LP5521 Datasheet(PDF) 40 Page - Texas Instruments

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