Non Volatile

Memory

(NVM)

SRAM

Startup or

EE_PROG = 1

EEPROM

REGISTERS

Startup or

EE_UPDATE=1

+ EE_READ=1

Device

Control

Calculation

Unit

User

EPROM for

production

testing/trimming

Device Control

NVM Interface

EEPROM

registers

EE_UPDATE=0 + EE_READ=1

Controls

LP8543

SNVS604D – AUGUST 2009 – REVISED MARCH 2013

www.ti.com

EEPROM structure is described in the figure below. User has read and write access to SRAM part of the

PWM pin = low. To see whether the EEPROM can be accessed user can read <EE_READY> bit. ALS and

brightness coefficient curves (address A0h – Afh) and empty EEPROM cells (address B4h – BBh) have only

NVM and SRAM. Other EEPROM cells have also EEPROM registers. For the cells which have also EEPROM

registers, the changes made to SRAM does not take effect until update command is sent. This is done by setting

EE_UPDATE and EE_READ bits to 1. After an update, these bits must be set back to 0. For EEPROM bits

which do not have registers, changes take effect immediately.

At startup the values in NVM part of the EEPROM is loaded to SRAM and to EEPROM registers. User can also

load values from NVM to SRAM and EEPROM registers by writing EE_READ to 1.

To write SRAM values to NVM user needs to first erase EEPROM and the program it. This is done by first writing

EE_ERASE to 1 and then 0. At this point NVM is erased. To burn new values to NVM, user needs to write

EE_PROG to 1 and then 0. The LP8543 generates the needed erase and write voltage from boost output

voltage.

Figure 16. EEPROM Memory Control and Usage Principle

Boost Converter

Operation

The LP8543 boost DC/DC converter generates a 10…38V supply voltage for the LEDs from 5.5…22V input

voltage. The output voltage is controlled with a 5-bit register in 1V steps. The converter is a magnetic switching

PWM mode DC/DC converter with a current limit. The topology of the magnetic boost converter is called CPM

(current programmed mode) control, where the inductor current is measured and controlled with the feedback.

Switching frequency is selectable between 625 kHz and 1.25 MHz with EEPROM bit <BOOST_FREQ>. Boost is

enabled with <EN_BOOST> bit.

22

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