LINEAR TECHNOLOGY LTC3206 Technical data

FEATURES

■

Step-Up/Direct-Connect Fractional Charge Pump
Provides Up to 92% Efficiency

■

Up to 400mA Continuous Output Current

■

Independent Current and Dimming Control for
1-6 LED MAIN, 1-4 LED SUB and RGB LED Displays

■

LED Currents Programmable Using 2-Wire I2C™
Serial Interface

■

1% LED Current Matching

■

Low Noise Constant Frequency Operation*

■

Minimal Component Count

■

Automatic Soft-Start Limits Inrush Current

■

16 Exponentially Spaced Dimming States Provides
128:1 Brightness Range for MAIN and SUB Displays

■

Up to 4096 Color Combinations for RGB Display

■

Low Operating Current: I

■

Tiny, Low Profile 24-Lead (4mm × 4mm × 0.75mm)

= 180µA

VIN

QFN Package

U

APPLICATIO S

■

Cellular Phones

■

Wireless PDAs

■

Multidisplay Handheld Devices

, LTC and LT are registered trademarks of Linear Technology Corporation.

I2C is a trademark of Philips Electronics N.V.
* U.S. Patent 6,411,531

LTC3206

I2C Multidisplay

LED Controller

U

DESCRIPTIO

The LTC®3206 is a highly integrated multidisplay LED con­troller. The part contains a high efficiency, low noise frac­tional step-up/direct-connect charge pump to provide
power for both main and sub white LED displays plus an
RGB color LED display. The LTC3206 requires only four
small ceramic capacitors plus two resistors to form a
complete 3-display LED power supply and current
controller.

Maximum currents for the main/sub displays and RGB
display are set independently. Current for each LED is
controlled with an internal current source. Dimming and
ON/OFF control for all displays is achieved via a 2-wire
serial interface. Two auxiliary LED pins can be individually
assigned to either the MAIN or SUB displays. 16 individual
dimming states exist for both the MAIN and SUB displays.
Each of the RED, GREEN and BLUE LEDs have 16 dimming
states as well, resulting in up to 4096 color combinations.

The LTC3206 charge pump optimizes efficiency based on
V

and LED forward voltage conditions. The part powers

IN

up in direct-connect mode and automatically switches to

1.5x step-up mode once any enabled LED current source
begins to enter dropout. Internal circuitry prevents inrush
current and excess input noise during start-up and mode
switching. The LTC3206 is available in a 24-lead (4mm ×
4mm) QFN package.

TYPICAL APPLICATIO

2.2µF 2.2µF

V

IN

2.7V TO

4.5V

I2C SERIAL
INTERFACE

V

IN

2.2µF 2.2µF

2

SERIAL PORT

I

RGB

LTC3206

CPO

MAIN1-4

AUX 1

SUB1-2

AUX 2

RGB

I

MS

4

2

3

U

MAIN DISPLAY SUB DISPLAY RGB ILLUMINATOR

RED GREEN BLUE

3206 TA01a

5-LED Main Display Efficiency

vs Input Voltage

100

90

80

) (%)

70

IN

/P

60

LED

50

40

30

EFFICIENCY (P

20

FIVE LEDs AT 15mA/LED

AT 15mA = 3.2V)

(TYP V

F

10

= 25°C

T

A

0

3.0

3.6

3.3
INPUT VOLTAGE (V)

3.9

4.2

3206 TA01b

3206f

1

LTC3206

24 23 22 21 20 19

7 8 9

TOP VIEW

25

UF PACKAGE

24-LEAD (4mm × 4mm) PLASTIC QFN

10 11 12

13

14

15

16

17

18

6

5

4

3

2

1

SUB1

SUB2

C2

–

C1

–

C1

+

C2

+

BLUE

GREEN

RED

V

IN

CPO

SGND

AUX2

AUX1

MAIN1

MAIN2

MAIN3

MAIN4

DV

CC

SDA

SCL

ENRGB/S

I

MS

I

RGB

ABSOLUTE AXI U RATI GS

(Note 1)

VIN, DVCC, CPO to GND............................... –0.3V to 6V

SDA, SCL, ENRGB/S ................. – 0.3V to (DV

I

(Continuous) (Note 4) ................................ 400mA

CPO

(Pulsed at 10% Duty Cycle) (Note 4)..................... 1A

I

MAIN1-4, ISUB1,2

(Pulsed at 10% Duty Cycle) (Note 4).............. 125mA

I

RED,GREEN,BLUE

(Pulsed at 10% Duty Cycle) (Note 4).............. 125mA

I

, I

MS

CPO Short-Circuit Duration ............................ Indefinite

Operating Temperature Range (Note 2) .. – 40°C to 85°C

Storage Temperature Range ................. –65°C to 125°C

ELECTRICAL CHARACTERISTICS

temperature range, otherwise specifications are at TA = 25°C. VIN = 3.6V, DVCC = 3V unless otherwise noted.

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

Input Power Supply

White LED Current (MAIN1-MAIN4, SUB1, SUB2, AUX1, AUX2)

RGB LED Current (RED, GREEN, BLUE)

Charge Pump (CPO)

2

WW

W

U

UUW

PACKAGE/ORDER I FOR ATIO

ORDER PART

+ 0.3V)

CC

, I

AUX 1, 2

(Note 4) ..................... 100mA

(Note 4) ..................................... 100mA

(Note 4) .................................................. 1mA

RGB

T

= 125°C, θJA = 37°C/W, θJC = 2°C/W

JMAX

EXPOSED PAD IS PGND (PIN 25)

MUST BE SOLDERED TO PCB

Consult LTC Marketing for parts specified with wider operating temperature ranges.

The ● denotes the specifications which apply over the full operating

VIN Operating Voltage ● 2.7 4.5 V

DVCC Operating Voltage ● 1.5 5.5 V

VIN Operating Current I

DVCC Operating Current Serial Port Idle 1 µA

VIN Shutdown Current 7.3 10 µA

DVCC Shutdown Current 1 µA

IMS Servo Voltage 25µA < IMS < 75µA 0.585 0.6 0.615 V

Full-Scale LED Current Ratio (I

LED/IMS

LED Dropout Voltage 1.5x Mode Switch Threshold, I

LED Brightness Range 0.78 100 %

LED Current Matching MAIN-MAIN, MAIN-AUX, SUB-SUB, SUB-AUX 1 %

I

Servo Voltage 25µA < I

RGB

LED Current Ratio (I

) RED, GREEN, BLUE Voltage = 1V 360 400 440 mA/mA

LED/IRGB

RGB LED Dropout Voltage 1.5x Mode Switch Threshold, I

RGB PWM (Duty Factor) Range 0/15 15/15 %

1x Mode Output Impedance 0.68 Ω

1.5x Mode Output Impedance VIN = 3V, V

I

CPO
CPO

= IMS = I
= IMS = I

= 0µA, Direct-Connect Mode 180 µA

RGB

= 0µA, 1.5x Step-Up Mode 3.9 mA

RGB

● 0.582 0.6 0.618 V

) MAIN1-MAIN4, SUB1, SUB2, AUX1, AUX2, Voltage = 1V ● 368 400 432 mA/mA

= 20mA 80 mV

LED

< 75µA 0.585 0.6 0.615 V

RGB

= 20mA 80 mV

LED

= 4.2V (Note 3) 1.90 Ω

CPO

● 0.582 0.6 0.618 V

NUMBER

LTC3206EUF

UF PART

MARKING

3206

3206f

LTC3206

ELECTRICAL CHARACTERISTICS

temperature range, otherwise specifications are at T

The ● denotes the specifications which apply over the full operating

= 25°C. VIN = 3.6V, DVCC = 3V unless otherwise noted.

A

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

CPO Regulation Voltage I

= 20mA, 1.5x Mode 4.75 V

CPO

CLK Frequency 0.68 0.96 1.36 MHz

SDA, SCL, ENRGB/S

V

IL

V

IH

I

IH

I

IL

V

OL

Low Level Input Voltage ● 0.3 • DV

High Level Input Voltage ● 0.7 • DV

Input Current SDA, SCL, ENRGB/S = DV

CC

CC

–1 1 µA

CC

Input Current SDA, SCL, ENRGB/S = 0V –1 1 µA

Digital Output Low (SDA) I

= 3mA ● 0.4 V

PULLUP

Timing Characteristics (Note 5)

t

SCL

t

BUF

t

HD, STA

t

SU, STA

t

SU, STD

t

HD, DAT(OUT)

t

HD, DAT(IN)

t

SU, DAT

t

LOW

t

HIGH

t

f

t

r

t

SP

Note 1: Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.

Note 2: The LTC3206E is guaranteed to meet performance specifications
from 0°C to 70°C. Specifications over the –40°C to 85°C operating
temperature range are assured by design, characterization and correlation

Clock Operating Frequency 400 kHz

Bus Free Time Between Stop and Start Condition 1.3 µs

Hold Time After (Repeated) Start Condition 0.6 µs

Repeated Start Condition Setup Time 0.6 µs

Stop Condition Setup Time 0.6 µs

Data Hold Time 225 900 ns

Input Data Hold Time 0 900 ns

Data Setup Time 100 ns

Clock Low Period 1.3 µs

Clock High Period 0.6 µs

Clock Data Fall Time 20 300 ns

Clock Data RiseTime 20 300 ns

Spike Suppression Time 50 ns

with statistical process controls.
Note 3: 1.5x mode output impedance is defined as (1.5VIN – V

CPO

)/I

OUT

.

Note 4: Based on long term current density limitations.
Note 5: All values are referenced to V

and V

IH

levels.

IL

V

V

UW

TYPICAL PERFOR A CE CHARACTERISTICS

I

LED

2.5mA/DIV

0mA

LED Pin Sink Current
vs LED Pin Voltage

100%

50%

25%

200mV/DIV 3206 G01 I

V

AT CURRENT SOURCE PIN

LED

AC COUPLED

(50mV/DIV)

AC COUPLED

(50mV/DIV)

Input and Output
Charge Pump Noise

CPO

V

IN

= 200mA 500ns/DIV 3206 G02

CPO

VIN = 3.6V

= C

= 1.6µF

C

IN

CPO

LED Pin Dropout Voltage
vs LED Pin Current

500

VIN = 3.6V

= 25°C

T

A

400

300

200

100

LED PIN DROPOUT VOLTAGE (mV)

0

10 30

20

50 90

60

40

LED CURRENT (mA)

70

80

100

3206 GO3

3206f

3

LTC3206

UW

TYPICAL PERFOR A CE CHARACTERISTICS

1.5x Mode Charge Pump Open­1x Mode Switch Resistance
vs Temperature

0.9
I

= 100mA

CPO

0.8

VIN = 3.6V

0.7

0.6

SWITCH RESISTANCE (Ω)

0.5
–40

–15

10

TEMPERATURE (°C)

V

IN

= 3.3V

VIN = 3.9V

35

60

85

3206 G04

Loop Output Resistance vs
Temperature (1.5V

2.50
VIN = 3V

= 4.2V

V

CPO

= C

= C

= C

FLY1

TEMPERATURE (°C)

OUTPUT RESISTANCE (Ω)

2.25

2.00

1.75

1.50

C

IN

CPO

–15 10 35 60

–40

FLY2

– V

IN

= 1.6µF

CPO

)/I

CPO

3206 G05

1.5x Mode CPO Voltage
vs Load Current

4.8

4.7

4.6

4.5

4.4

4.3

4.2

CPO VOLTAGE (V)

4.1

4.0

3.9

85

3.8
0

CIN = C

3.1V

VIN = 3V

100

LOAD CURRENT (mA)

200

CPO

3.2V

= C

3.3V

FLY1 CFLY2

3.6V

300

400

T

A

= 1.6µF

= 25°C

3.5V

3.4V

3206 G06

500

Oscillator Frequency
vs Supply Voltage

1100

1000

TA = –40°C

900

FREQUENCY (kHz)

800

700

2.7

3.0 3.3 3.6 3.9

TA = 25°C

VIN SUPPLY VOLTAGE (V)

1x Mode No Load Supply Current
vs Input Voltage

300

TA = 25°C

= I

= 0µA

I

MS

RGB

250

200

SUPPLY CURRENT (µA)

150

TA = 85°C

4.2 4.5

3206 G07

DVCC Shutdown Current
vs Input Voltage

0.5
VIN = 3.6V

0.4

TA = –40°C

3.0

TA = 25°C

3.3 3.6 3.9
DVCC VOLTAGE (V)

SHUTDOWN CURRENT (µA)

DV

0.3

0.2

CC

0.1

0

2.7

1.5x Mode Supply Current
vs I

(IIN – 1.5I

CPO

10

VIN = 3.6V

= 25°C

T

A

8

6

4

SUPPLY CURRENT (mA)

2

CPO

)

TA = 85°C

4.2 4.5

3206 G08

VIN Shutdown Current
vs Input Voltage

10

DVCC = 3V

8

TA = –40°C

6

4

SHUTDOWN CURRENT (µA)

IN

2

V

0

2.7

3.0

TA = 25°C

3.3 3.6 3.9

INPUT VOLTAGE (V)

LED Pin Voltage for Higher LED
Currents

120

VIN = 3.6V

= 25°C

T

A

100

80

60

40

LED CURRENT (mA)

20

IMS, I

IMS, I

IMS, I

IMS, I

IMS, I

TA = 85°C

= 250µA

RGB

= 200µA

RGB

= 150µA

RGB

= 100µA

RGB

= 50µA

RGB

4.2 4.5

3206 G09

4

100

2.7

3.0 3.3 3.6 3.9
INPUT VOLTAGE (V)

4.2 4.5

3206 G10

0

0

100 150 200

50

LOAD CURRENT (mA)

250 300

3206 G11

0

0

0.4 0.6 0.8

0.2
LED PIN VOLTAGE (V)

1.0

3206 G12

3206f

LTC3206

U

UU

PI FU CTIO S

SUB1, SUB2 (Pins 1, 2): Current Source Outputs for the
SUB Display White LEDs. The current for the SUB display
is controlled by the resistor on the I
SUB display can be set to exponentially increasing bright­ness levels from 0.78% to 100% of full-scale. See Table 1.

C1+, C1–, C2+, C2– (Pins 5, 4, 6, 3): Charge Pump Flying
Capacitor Pins. A 2.2µF X7R or X5R ceramic capacitor
should be connected from C1

+

to C2–.

C2

DV

(Pin 7): This pin sets the logic reference level of the

CC

SDA, SCL and ENRGB/S pins.

SDA (Pin 8): Input Data for the I2C Serial Port. Serial data
is shifted in one bit per clock to control the LTC3206 (see
Figures 3 and 4). The logic level for SDA is referenced to
DVCC.

SCL (Pin 9): Clock Input for the I2C Serial Port (see Figures
3 and 4). The logic level for SCL is referenced to DVCC.

ENRGB/S (Pin 10): This pin is used to enable and disable
either the RED, GREEN and BLUE current sources or the
SUB display depending on which is programmed to re­spond via the I2C port. Once ENRGB/S is brought high, the
LTC3206 illuminates the RGB or SUB display with the
color combination or intensity that was previously pro­grammed via the I2C port. The logic level for ENRGB/S is
referenced to DVCC.

IMS (Pin 11): This pin controls the maximum amount of
LED current in both the MAIN and SUB LED displays. The
IMS pin servos to 0.6V when there is a resistor to ground.
The full scale (100%) currents in the MAIN and SUB
display LEDs will be 400 times the current at the IMS pin.

I

(Pin 12): This pin controls the amount of LED current

RGB

at the RED, GREEN and BLUE LED pins. The I
servos to 0.6V when there is a resistor to ground. The
current in the RED, GREEN and BLUE LEDs will be 400
times the current at the I
scale.

+

pin when programmed to full

RGB

pin.The LEDs on the

MS

to C1– and another from

pin

RGB

CPO (Pin 14): Output of the Charge Pump. This output
should be used to power white, blue and “true” green
LEDs. Red LEDs can be powered from V
or X7R low impedance (ceramic) 2.2µF charge storage
capacitor is required on CPO.

VIN (Pin 15): Supply Voltage for the Charge Pump. The V
pin should be connected directly to the battery and by­passed with a 2.2µF X5R or X7R ceramic capacitor.

RED, GREEN, BLUE (Pins 16, 17, 18): Current Source
Outputs for the RGB Illuminator LEDs. The currents for the
RGB LEDs are controlled by the resistor on the I
The RGB LEDs can independently be set to any duty cycle
from 0/15 through 15/15 under software control giving a
total of 16 shades per LED and 4096 colors for the
illuminator. See Table 1. The RGB LEDs are modulated at
1/240 the speed of the charge pump oscillator (approxi­mately 4kHz).

MAIN1-MAIN4 (Pins 22, 21, 20, 19): Current Source
Outputs for the Main Display White LEDs. The current for
the main display is controlled by the resistor on the I
pin. The LEDs on the MAIN display can be set to 16
exponentially increasing brightness steps from 0.78% to
100% of full scale. See Table 1.

AUX1, AUX2 (Pins 23, 24): Current source outputs for the
auxiliary white LEDs. The auxiliary current sources can be
individually assigned to be either MAIN display or SUB
display LEDs via the I2C serial port. When either AUX1 and/
or AUX2 are assigned to the MAIN display they will have
the same power setting as the other MAIN LEDs. Likewise,
when either AUX1 and/or AUX2 are assigned to the SUB
display they will have the same power setting as the other
SUB LEDs. The currents for the AUX1 and AUX2 pins are
controlled by the resistor on the IMS pin.

PGND (Pin 25, Exposed Pad): Power Ground for the
Charge Pump. This pin should be connected directly to a
low impedance ground plane.

or CPO. An X5R

IN

pin.

RGB

IN

MS

SGND (Pin 13): Ground for the control logic. This pin
should be connected directly to a low impedance ground
plane.

3206f

5