OUT

FB

GND_BOOST

ENABLE

WLED1

C

VDD1

C

VDDA

RT

RT

Voltage

Reference

Oscillator

Li-Ion Battery

or Charger

Boost Converter

Micro-

controller

Micro-

Wire or

I2C

interface

Control

Logic

L

e

v

e

l

S

h

i

f

t

D1

8-Bit IDAC

D

D

A

A

RGB_EN

8-Bit IDAC

WLED2

WLED3

WLED4

GND_WLED

WLED5

WLED6

Thermal

Shutdown

PWM

RGB

LOGIC

POR

GND_RGB

GND1

GND2

GND_T

SCL

DO

DI

CS

RGB_EN

NRST

ROUT

GOUT

BOUT

RGB

RROUT

120 mA

max per LED

0 - 25 mA

X

= 250 mA

L1

C

OUT

A

v

e

r

a

g

e

C

VREF

LDO

2.8V / 1mA

8-bit

ADC

AIN

AREF

Optical

sensor

MW_SEL

10 PH

10 PF

10 PF

1 PF

1 PF

82k

1 PF

C

VDDIO

R

AMB

1 PF

100 nF

0 - 25 mA

Main Display Backlight

Sub Display Backlight

RGOUT

RBOUT

V

4.1 - 5.3V

RGB_EN

RGB_EN

V

REF

V

DD1

V

DD2

C

VDD2

C

IN

V

DDA

V

DDIO

100k

RDO

V

IN

LP3936

SNVS259D – NOVEMBER 2003 – REVISED MAY 2013

www.ti.com

BLOCK DIAGRAM

Modes of Operation

RESET: In the RESET mode all the internal registers are reset to the default values. Boost output register is set

to 4.55V (register 0Dh = 07h), ext_pwm is enabled for color outputs (register 2Bh = 1Ch), EN_BOOST bit

is high (register 0Bh bit 5) and all other registers are set to 00h. Reset is entered always if input NRST is

LOW or internal Power On Reset is active.

STANDBY: The STANDBY mode is entered if the register bit NSTBY is LOW and Reset is not active. This is the

low power consumption mode, when all circuit functions are disabled. Registers can be written in this

mode and the control bits are effective immediately after start up.

etc.). To ensure the correct oscillator initialization, a 10 ms delay is generated by the internal state-

machine. Thermal shutdown (THSD) disables the chip operation and Startup mode is entered until no

thermal shutdown event is present.

BOOST STARTUP: Soft start for boost output is generated in the BOOST STARTUP mode. In this mode the

boost output is raised in PFM mode during the 10 ms delay generated by the state-machine. The Boost

startup is entered from Internal Startup Sequence if EN_BOOST is HIGH or from Normal mode when

EN_BOOST is written HIGH. During Boost Startup all LEDs are turned off to reduce the loading.

6

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