LP8553

SNVS701B – SEPTEMBER 2011 – REVISED JANUARY 2014

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Output Diode

A Schottky diode should be used for the output diode. Peak repetitive current should be greater than inductor

peak current (2.5A) to ensure reliable operation. Average current rating should be greater than the maximum

output current. Schottky diodes with a low forward drop and fast switching speeds are ideal for increasing

efficiency in portable applications. Choose a reverse breakdown voltage of the Schottky diode significantly larger

(~60V) than the output voltage. Do not use ordinary rectifier diodes, since slow switching speeds and long

recovery times cause the efficiency and the load regulation to suffer.

Resistors for Setting the LED Current and PWM Frequency

See Table 3 on how to select values for these resistors

Filter Component Values

Optimal components for 60 Hz VSYNC frequency and 4 Hz cut-off frequency of the low-pass filter are shown in the

Typical Application diagrams and in the figure below. If 2 Hz cut-off frequency i.e. slower response time is

desired, filter components are: C1 = 1 μF, C2 = 10 μF and R = 47 kΩ. If different VSYNC frequency or response

time is desired, please contact TI representative for guidance.

Table 2. Register Map

ADDR

REGISTER

D7

D6

D5

D4

D3

D2

D1

D0

DEFAULT

00H

Brightness

BRT[7:0]

0000 0000

Control

01H

Device Control

BRT_MODE[1:0]

BL_CTL

0000 0000

02H

Fault

OPEN

SHORT

2_CHANN 1_CHANN

BL_FAULT

OCP

TSD

UVLO

0000 0000

ELS

EL

03H

ID

PANEL

MFG[3:0]

REV[2:0]

1111 1100

04H

Direct Control

OUT[4:1]

0000 0000

05H

Temp MSB

TEMP[10:3]

0000 0000

06H

Temp LSB

TEMP[2:0]

0000 0000

72H

EEPROM_con EE_READ

EE_INIT

EE_PROG

EE_READ 0000 0000

trol

Y

Table 3. EEPROM Memory Map

ADDR

REGISTER

D7

D6

D5

D4

D3

D2

D1

D0

A0H

eeprom addr 0

CURRENT[7:0]

A1H

eeprom addr 1

BOOST_FREQ[1:0]

EN_PWM

TEMP_LIM[1:0]

SLOPE[2:0]

_&_I_CTR

L

A2H

eeprom addr 2

ADAPTIVE_SPEED[1:0]

ADV_SLO

MODE_25/

EN_ADAPT

EN_BOOS

BOOST_IM

I_SLOPE[

PE

50%_SEL

T

AX

1]

A3H

eeprom addr 3

UVLO[1:0]

EN_PSP

PWM_FREQ[4:0]

WM

A4H

eeprom addr 4

PWM_RESOLUTION[1:

EN_I_RE

LED_FAUL

I_SLOPE[0]

DRV_HEADR[2:0]

0]

S

T_THR

A5H

eeprom addr 5

EN_VSY

DITHER[1:0]

VBOOST[4:0]

NC

A6H

eeprom addr 6

PLL[12:5]

A7H

eeprom addr 7

PLL[4:0]

EN_F_RES

HYSTERESIS[1:0]

26

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