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LTC3219

3219fa

TYPICAL APPLICATION

FEATURES

APPLICATIONS

DESCRIPTION

250mA Universal

Nine Channel LED Driver

The LTC

3219 is a highly integrated multidisplay LED

driver. The device contains a high efﬁ ciency, low noise

charge pump to provide power to nine universal LED

current sources. The LTC3219 requires only ﬁ ve small

ceramic capacitors to form a complete LED power supply

and current controller.

The maximum display currents are set by an internal pre-

cision current reference. Independent dimming, On/Off,

blinking and gradation control for all current sources is

achieved via the I

C serial interface. 6-bit linear DACs are

available for adjusting brightness levels for each universal

LED current source.

The LTC3219 charge pump optimizes efﬁ ciency based on

the voltage across the LED current sources. The device

powers up in 1x mode and will automatically switch to

boost mode whenever any enabled LED current source

begins to enter dropout. The ﬁ rst dropout switches the

IC into 1.5x mode and a subsequent dropout switches

the LTC3219 into 2x mode. The part resets to 1x mode

whenever a data register is updated via the I

C port.

■

Multimode Charge Pump Provides Up to 91%

Efﬁ ciency

■

Slew Limited Switching Reduces Conducted and

Radiated Noise (EMI)

■

Up to 250mA Total Output Current

■

Nine 28mA Universal Current Sources with 64-Step

Linear Brightness Control

■

Independent On/Off, Brightness Level, Blinking and

Gradation Control for Each Current Source Using

2-Wire I

Interface

■

Internal Current Reference

■

Conﬁ gurable ENU Pin for Asynchronous LED On/Off

Control

■

Low Noise Charge Pump Operates in 1x, 1.5x or 2x

Mode for Optimal Efﬁ ciency*

■

Automatic or Forced Mode Switching

■

Internal Soft-Start Limits Inrush Current

■

Short-Circuit/Thermal Protection

■

3mm × 3mm 20-Lead QFN Plastic Package

■

Video Phones with QVGA+ Displays

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

All other trademarks are the property of their respective owners.

*Protected by U.S. Patents, including 6411531.

1μF

C1P C1M

GND

1μF

C2P

LTC3219

C2M

CPO

ULED1-9

3219 TA01a

BAT

MAIN SUB RGB

SCL/SDA

2.2μF

0.1μF

2.2μF

ENABLE DISABLE

ENU

4-LED Main, 2-LED Sub and RGB

Summary of content (20 pages)

PAGE 1
LTC3219 250mA Universal Nine Channel LED Driver FEATURES ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ DESCRIPTION Multimode Charge Pump Provides Up to 91% Efﬁciency Slew Limited Switching Reduces Conducted and Radiated Noise (EMI) Up to 250mA Total Output Current Nine 28mA Universal Current Sources with 64-Step Linear Brightness Control Independent On/Off, Brightness Level, Blinking and Gradation Control for Each Current Source Using 2-Wire I2CTM Interface Internal Current Reference Conﬁgurable ENU Pin for Asynchronous
PAGE 2
LTC3219 ABSOLUTE MAXIMUM RATINGS PIN CONFIGURATION (Notes 1, 4) VBAT, DVCC, CPO ........................................... –0.3V to 6V ULED1-ULED9 ............................................. –0.3V to 6V SDA, SCL, ENU ...........................–0.3V to (DVCC + 0.3V) ICPO (Note 2) .......................................................250mA CPO Short-Circuit Duration .............................. Indeﬁnite Operating Temperature Range (Note 3).... –40°C to 85°C Storage Temperature Range................
PAGE 3
LTC3219 ELECTRICAL CHARACTERISTICS The ● denotes the speciﬁcations which apply over the full operating temperature range, otherwise speciﬁcations are at TA = 25°C. VBAT = 3.6V, DVCC = 3V, ENU = Hi, C1/C4 = 2.2μF, C2, C3 = 1μF, unless otherwise noted. PARAMETER CONDITIONS Gradation Period REG11, D1 and D2 MIN TYP MAX 0.325 UNITS IOUT = 1mA, Single Output Enabled 10 s s s s s s mV 1 Ω 1.5x Mode Output Impedance VBAT = 3V, VCPO = 4.2V (Notes 5, 7) 5.
PAGE 4
LTC3219 TYPICAL PERFORMANCE CHARACTERISTICS Mode Switch Dropout Times 1.5x Mode CPO Ripple 2x Mode CPO Ripple VBAT = 3.6V ICPO = 100mA CCPO = 2.2μF VBAT = 3.6V VCPO 1V/DIV TA = 25°C unless otherwise noted. VCPO 20mV/DIV AC COUPLED 2x 1.5x VBAT = 3.6V ICPO = 100mA CCPO = 2.2μF VCPO 20mV/DIV AC COUPLED 1x 3219 G02 500ns/DIV 3219 G01 SWITCH RESISTANCE (Ω) 1.15 1x Mode Switch Resistance vs Temperature 6.50 ICPO = 100mA 1.10 OPEN-LOOP OUTPUT RESISTANCE (Ω) 1.20 VBAT = 3.3V 1.05 VBAT = 3.
PAGE 5
LTC3219 TYPICAL PERFORMANCE CHARACTERISTICS 7.5 VBAT Shutdown Current vs VBAT Voltage 425 TA = 25°C unless otherwise noted. 1x Mode No Load VBAT Current vs VBAT Voltage 415 TA = –40°C VBAT CURRENT (μA) VBAT SHUTDOWN CURRENT (μA) 420 6.5 5.5 TA = 25°C TA = 85°C 4.5 3.5 410 405 400 395 390 385 2.5 380 1.5 2.9 3.3 4.9 4.1 4.5 3.7 VBAT VOLTAGE (V) 375 2.7 3.0 3.3 3.6 3.9 4.2 4.5 4.8 5.1 5.4 VBAT VOLTAGE (V) 5.3 3219 G11 3219 G10 10 ULED Pin Current vs ULED Pin Voltage VBAT = 3.
PAGE 6
LTC3219 PIN FUNCTIONS CPO (Pin 1): Output of the Charge Pump Used to Power all LEDs. A 2.2μF X5R or X7R ceramic capacitor should be connected to ground. ULED1-ULED9 (Pins 2 to 6, Pins 11 to 14): Current Source Outputs for Driving LEDs. The LED current can be set from 0mA to 28mA in 64 steps via software control and internal 6-bit linear DAC. Each output can be disabled by setting the associated data register REG1-REG9 to 0. ULED1-ULED9 can also be used as I2C controlled open-drain outputs.
PAGE 7
LTC3219 BLOCK DIAGRAM 20 C1P 17 C1M 19 16 C2P C2M GND 850kHz OSCILLATOR CPO CHARGE PUMP 18 + – U1 U3 + U4 – U5 9 10 1 VBAT U2 7 15 DVCC 1.
PAGE 8
LTC3219 OPERATION Power Management Charge Pump Strength The LTC3219 uses a switched capacitor charge pump to boost CPO to as much as 2 times the input voltage up to 5.04V. The part starts up in 1x mode. In this mode VBAT is connected directly to CPO. This mode provides maximum efﬁciency and minimum noise. The LTC3219 will remain in 1x mode until an LED current source drops out. Dropout occurs when a current source voltage becomes too low for the programmed current to be supplied.
PAGE 9
LTC3219 OPERATION Mode Switching Blinking The LTC3219 will automatically switch from 1x mode to 1.5x mode and subsequently to 2x mode whenever a dropout condition is detected at an LED pin. Dropout occurs when an active current source voltage becomes too low for the programmed current to be supplied. The mode change will not occur unless dropout has existed for approximately 400μs. This delay will allow the LEDs to warm up and achieve the ﬁnal LED forward voltage value.
PAGE 10
LTC3219 OPERATION To use the ENU pin, the I2C port must ﬁrst be conﬁgured to select the desired LED outputs. When ENU is high, the selected displays will be enabled as per the REG10 and REG11 settings. When ENU is Low the selected displays will be off. If no other displays are programmed to be enabled, the chip will be in shutdown. Gradation can also be pre-programmed for control by the ENU pin. The registers are written as required per the gradation description and the UP bit is ignored.
PAGE 11
LTC3219 OPERATION I2C Interface The LTC3219 is a receive-only (slave) device. The LTC3219 communicates with a host (master) using the standard I2C 2-wire interface. The Timing Diagram (Figure 2) shows the timing relationship of the signals on the bus. The two bus lines, SDA and SCL, must be high when the bus is not in use. External pull-up resistors or current sources, such as the LTC1694 SMBus accelerator, are required on these lines.
PAGE 12
LTC3219 OPERATION Sub-Address Byte MSB LSB 7 6 5 4 3 2 1 0 Register Function X X X X 0 0 0 0 REG0 COMMAND X X X X 0 0 0 1 REG1 ULED1 X X X X 0 0 1 0 REG2 ULED2 X X X X 0 0 1 1 REG3 ULED3 X X X X 0 1 0 0 REG4 ULED4 X X X X 0 1 0 1 REG5 ULED5 X X X X 0 1 1 0 REG6 ULED6 X X X X 0 1 1 1 REG7 ULED7 X X X X 1 0 0 0 REG8 ULED8 X X X X 1 0 0 1 REG9 ULED9 X X X X 1 0 1 0 REG10 ENU X X X X 1
PAGE 13
LTC3219 OPERATION Data Bytes REG1 to REG9, Universal LED 6-bit linear DAC data with blink/gradation.
PAGE 14
LTC3219 OPERATION Bus Speed The I2C port is designed to be operated at speeds of up to 400kHz. It has built-in timing delays to ensure correct operation when addressed from an I2C compliant master device. It also contains input ﬁlters designed to suppress glitches should the bus become corrupted. Start and Stop Conditions A bus-master signals the beginning of a communication to a slave device by transmitting a Start condition.
PAGE 15
LTC3219 OPERATION to any Stop that appears on the bus with only one exception, independent of the number of Repeat-Start’s that have occurred. If a Repeat-Start is given and the LTC3219 successfully acknowledges its address and ﬁrst byte, it will not respond to a Stop until all bytes of the new data have been received and acknowledged. Quick Write Registers REG1 to REG9 can be written in parallel by setting Bit 1 of REG 0 high.
PAGE 16
LTC3219 APPLICATIONS INFORMATION VBAT LTC3219 GND 3219 F04 Figure 4. 10nH Inductor Used for Input Noise Reduction (Approximately 1cm of Board Trace) Flying Capacitor Selection Warning: Polarized capacitors such as tantalum or aluminum should never be used for the ﬂying capacitors since their voltage can reverse upon start-up of the LTC3219. Ceramic capacitors should always be used for the ﬂying capacitors. The ﬂying capacitors control the strength of the charge pump.
PAGE 17
LTC3219 APPLICATIONS INFORMATION Power Efﬁciency To calculate the power efﬁciency (η) of an LED driver chip, the LED power should be compared to the input power. The difference between these two numbers represents lost power whether it is in the charge pump or the current sources. Stated mathematically, the power efﬁciency is given by: η= PLED PIN (4) The efﬁciency of the LTC3219 depends upon the mode in which it is operating.
PAGE 18
LTC3219 TYPICAL APPLICATIONS Three RGB LED Groups C3 1μF C2 1μF RGB1 C1P C1M C2P C2M VBAT C1 2.2μF I2C DVCC 2 VBAT CPO C5 0.1μF RGB3 C4 2.2μF LTC3219 9 ULED1-9 SCL/SDA RGB2 3219 TA03 DVCC ENU GND PWM 5-LED Main, 4 General Purpose Open-Drain Outputs C2 1μF C3 1μF MAIN C1P C1M C2P C2M VBAT C1 2.2μF I2C DVCC ENABLE DISABLE 2 C5 0.1μF VBAT CPO C4 2.
PAGE 19
LTC3219 PACKAGE DESCRIPTION UD Package 20-Lead Plastic QFN (3mm × 3mm) (Reference LTC DWG # 05-08-1720 Rev A) 0.70 p 0.05 3.50 p 0.05 (4 SIDES) 1.65 p 0.05 2.10 p 0.05 PACKAGE OUTLINE 0.20 p 0.05 0.40 BSC RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS APPLY SOLDER MASK TO AREAS THAT ARE NOT SOLDERED 3.00 p 0.10 (4 SIDES) BOTTOM VIEW—EXPOSED PAD R = 0.115 TYP 0.75 p 0.05 R = 0.05 TYP PIN 1 TOP MARK (NOTE 6) PIN 1 NOTCH R = 0.20 TYP OR 0.25 s 45° CHAMFER 19 20 0.40 p 0.10 1 2 1.65 ± 0.
PAGE 20
LTC3219 TYPICAL APPLICATION 3-LED Main, 1-LED Sub and 5-LED Camera C2 1μF C3 1μF MAIN C1P C1M C2P C2M VBAT C1 2.2μF I 2C DVCC ENABLE DISABLE 2 C5 0.1μF CPO VBAT ULED1-3 3 3219 TA02 ULED4 DVCC ULED5-9 CAM C4 2.2μF LTC3219 SCL/SDA SUB 5 ENU GND RELATED PARTS PART NUMBER DESCRIPTION COMMENTS LTC3205 250mA, 1MHz, Multi-Display LED Controller VIN: 2.8V to 4.5V, VOUT(MAX) = 5.5V, IQ = 50μA, ISD < 1μA, QFN Package LTC3206 400mA, 800kHz, Multi-Display LED Controller VIN: 2.8V to 4.