LP8543

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SNVS604D – AUGUST 2009 – REVISED MARCH 2013

Table 5. PWM Frequencies with Phase Shift Disabled (continued)

PWM_MODE = 0

PWM_MODE = 1

PWM_FREQ[2:0] +

PWM Frequency (Hz)

Output Frequency (Hz)

PSPWM_FREQ[1:0]

11101

19531

4808

11110

19531

9766

11111

19531

19531

Device Thermal Regulation

LP8543 has an internal temperature sensor which can be used to measure the junction temperature of the

device and protect the device from overheating. During thermal regulation, LED PWM is reduced by 4% of full

scale per °C whenever the temperature threshold is reached. I.e., with 100% PWM value the PWM goes to 0%

25°C above threshold temperature. With lower PWM start value 0% is reached earlier. Temperature regulation is

enabled automatically when the chip is enabled. 11-bit temperature value can be read from Temp MSB and

Temp LSB registers, MSB should be read first. Temperature limit can be programmed in EEPROM as shown in

the following table.

Table 6. Over Temperature Limit Settings

TEMP_LIM[1:0]

Over Temperature Limit (ºC)

00

100

01

110

10

120

11

130

Figure 15. Internal Temperature Sensor Readings

EEPROM

EEPROM memory stores various parameters for chip control. The 256 bit EEPROM memory is organized as 32

x 8 bits. The EEPROM structure consists of a SRAM front end and the Non-volatile memory (NVM). SRAM data

can be read and written through the serial interface. To erase and write NVM, separate commands need to be

sent. Erase and Write voltages are generated on-chip, no other voltages than normal input voltage are required.

A complete EEPROM memory map is shown in the chapter LP8543 EEPROM Memory Map.

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