LP5521 datasheet(39/48 Pages) TI1

39 / 48 page

PWM value

127

255

Time (ms)

100

200

400

300

500

600

700

800

900 1000 1100

1200

R program:

ramp up to PWM value 128 in 200 ms

wait 200 ms

ramp down to PWM value 0 in 200 ms

wait 500 ms

1300 1400

1500 1600 1700

R program as binary code:

0000001101111111

0100110100000000

0000001111111111

0110000000000000

LP5521

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SNVS441H – JANUARY 2007 – REVISED MAY 2016

Product Folder Links: LP5521

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8.2.2.2 Detailed Design Procedures

Selecting input and output capacitors follows the same procedure as in the application with charge pump.

8.3 Initialization Setup

8.3.1 Program Load and Execution Example

1. Startup Device and Configure Device to SRAM Write Mode:

–

Supply e.g. 3.6 V to VDD

–

Supply e.g. 1.8 V to EN

–

Wait 1 ms (startup delay)

–

Generate 32 kHz clock to CLK_32K pin

–

Write to address 00H 0100 0000b (enable LP5521)

–

Wait 500

μs (startup delay)

–

Write to address 01H 0001 0000b (Configure R channel into "Load program to SRAM" mode)

2. Program Load to SRAM (see Figure 30):

–

Write to address 10H 0000 0011b (1st ramp command 8 MSB)

–

Write to address 11H 0111 1111b (1st ramp command 8 LSB)

–

Write to address 12H 0100 1101b (1st wait command 8 MSB)

–

Write to address 13H 0000 0000b (1st wait command 8 LSB)

–

Write to address 14H 0000 0011b (2nd ramp command 8 MSB)

–

Write to address 15H 1111 1111b (2nd ramp command 8 LSB)

–

Write to address 16H 0110 0000b (2nd wait command 8 MSB)

–

Write to address 17H 0000 0000b (2nd wait command 8 LSB)

3. Enable Powersave, charge pump automatic mode (1x / 1.5x) and use external 32 kHz clock:

–

Write to address 08H 0011 1000b

4. Run program:

–

Write to address 01H 0010 0000b (Configure LED controller operation mode to "Run program" in R

channel

–

Write to address 00H 0110 0000b (Configure program execution mode from "Hold" to "Run" in R channel

LP5521 will generate 1100 ms long LED pattern which will be repeated infinitely. LED pattern is illustrated in

Figure 30.

Figure 30. Sequence Diagram

8.3.2 Direct PWM Control Example

1. Start up device:

–

Supply, for example, 3.6 V to VDD

–

Supply, for example,1.8 V to EN

–

Wait 1 ms (start-up delay)

–

Write to address 00H 0100 0000b (enable LP5521)

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