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LTC3220/LTC3220-1

32201fc

TYPICAL APPLICATION

FEATURES

APPLICATIONS

DESCRIPTION

360mA Universal

18-Channel LED Driver

The LTC3220/LTC3220-1 are highly integrated multi-display

LED drivers. These parts contain a high efﬁ ciency, low noise

charge pump to provide power to up to eighteen universal

LED current sources. The LTC3220/LTC3220-1 require

only ﬁ ve small ceramic capacitors to form a complete

LED power supply and current controller.

The LED currents are set by an internal precision cur-

rent reference. Independent dimming, on/off, blinking

and gradation control for all universal current sources

is achieved via the I

C serial interface. 6-bit linear DACs

are available to adjust brightness levels independently for

each universal LED current source.

The LTC3220/LTC3220-1 charge pump optimizes efﬁ ciency

based on the voltage across the LED current sources. The

part 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

parts into 1.5x mode and a subsequent dropout switches

the LTC3220/LTC3220-1 into 2x mode. The parts reset to

1x mode whenever a data bit is updated via the I

C port.

Eighteen 20mA 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

C Interface

Low Noise Multi-Mode Charge Pump (1x, 1.5x, 2x)

Provides Up to 91% Efﬁ ciency

Slew Limited Switching Reduces Conducted and

Radiated Noise (EMI)

Up to 360mA Total Output Current

Internal Current Reference

Single Reset Pin for Asynchronous Shutdown and

Reset of All Data Registers

Two I

C Addresses Are Available (LTC3220: 0011100,

LTC3220-1: 0011101)

Automatic or Forced Mode Switching

Internal Soft-Start Limits Inrush Current

Short-Circuit/Thermal Protection

4mm × 4mm Ultrathin (0.55mm) 28-Lead QFN

Package

Video Phones with QVGA+ Displays

Keypad Lighting

General/Miscellaneous Lighting

L, 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.

RESET

0.1μF

C1P

SCL/SDA

2.2μF

CPO

ULED1-18

C1M

GND

C2P

LTC3220

LTC3220-1

C2M

4.7μF

RGB1

3220 TA01

RST

RGB2 RGB3 RGB4 MAIN

6-LED Main, 4 RGB LEDs

Summary of content (20 pages)

PAGE 1
LTC3220/LTC3220-1 360mA Universal 18-Channel LED Driver FEATURES DESCRIPTION n The LTC3220/LTC3220-1 are highly integrated multi-display LED drivers. These parts contain a high efﬁciency, low noise charge pump to provide power to up to eighteen universal LED current sources. The LTC3220/LTC3220-1 require only ﬁve small ceramic capacitors to form a complete LED power supply and current controller.
PAGE 2
LTC3220/LTC3220-1 ABSOLUTE MAXIMUM RATINGS PIN CONFIGURATION (Notes 1, 4) C2M C1M VIN RST C2P C1P CPO TOP VIEW 28 27 26 25 24 23 22 ULED1 1 21 ULED18 ULED2 2 20 ULED17 ULED3 3 19 ULED16 ULED4 4 18 ULED15 29 ULED5 5 17 ULED14 ULED6 6 16 ULED13 ULED7 7 ULED11 ULED10 SDA SCL DVCC 9 10 11 12 13 14 ULED9 15 ULED12 8 ULED8 VIN, DVCC, CPO to GND ................................ –0.3V to 6V ULED1-ULED18 to GND ............................... –0.3V to 6V SDA, SCL, RST.................
PAGE 3
LTC3220/LTC3220-1 ELECTRICAL CHARACTERISTICS The l denotes the speciﬁcations which apply over the full operating temperature range, otherwise speciﬁcations are at TA = 25°C. VIN = 3.6V, DVCC = 3V, RST = high, C1 = C2 = C3 = 2.2μF, C4 = 4.7μF, unless otherwise noted.
PAGE 4
LTC3220/LTC3220-1 ELECTRICAL CHARACTERISTICS The l denotes the speciﬁcations which apply over the full operating temperature range, otherwise speciﬁcations are at TA = 25°C. VIN = 3.6V, DVCC = 3V, RST = high, C1 = C2 = C3 = 2.2μF, C4 = 4.7μF, unless otherwise noted.
PAGE 5
LTC3220/LTC3220-1 TYPICAL PERFORMANCE CHARACTERISTICS 1.5x Mode Charge Pump Open-Loop Output Resistance vs Temperature 1x Mode Switch Resistance vs Temperature 0.65 VIN = 3.6V 0.60 0.55 VIN = 3.9V 0.50 0.45 0.40 0.35 4.3 4.6 3.6V 4.1 3.9 3.5 3.3 3.1 2.9 4.9 5.2 4.7 5.1 4.5 5.0 4.3 4.9 3.9 3.5 3.6 800 2.9 –40 –25 –10 5 20 35 50 65 80 95 110 125 TEMPERATURE (°C) 4.2 3V 3.0 60 120 180 240 ICPO (mA) 300 770 760 TA = 85°C 730 2.9 360 TA = 125°C 3.55 4.2 4.
PAGE 6
LTC3220/LTC3220-1 TYPICAL PERFORMANCE CHARACTERISTICS 2x Mode VIN Current vs ICPO (IVIN – 2ICPO) 16 14 14 12 VIN CURRENT (mA) VIN CURRENT (mA) 12 10 8 6 ULED Pin Current vs ULED Pin Voltage 25 ULED PIN CURRENT (mA) 1.5x Mode VIN Current vs ICPO (IVIN – 1.5ICPO) TA = 25°C unless otherwise noted. 10 8 6 4 4 20 15 10 5 2 2 0 0 60 120 240 180 ICPO (mA) 0 300 360 0 60 120 240 180 ICPO (mA) 300 3220 G13 360 0 0 0.1 0.05 0.15 ULED PIN VOLTAGE (V) 3220 G14 0.
PAGE 7
LTC3220/LTC3220-1 PIN FUNCTIONS SDA (Pin 12): Input Data for the Serial Port. Serial data is shifted in one bit per clock cycle to control the LTC3220/ LTC3220-1. The logic level is referenced to DVCC. RST (Pin 25): Active Low Reset Input. RST Resets all internal registers and forces LTC3220/LTC3220-1 into shutdown mode. C1P, C2P, C1M, C2M (Pins 27, 26, 23, 22): Charge Pump Flying Capacitor Pins. A 2.2μF X7R or X5R ceramic capacitor should be connected from C1P to C1M and C2P to C2M.
PAGE 8
LTC3220/LTC3220-1 OPERATION Power Management Soft-Start The LTC3220/LTC3220-1 use a switched capacitor charge pump to boost CPO as much as 2 times the input voltage up to 5.1V. The part starts up in 1x mode. In this mode, VIN is connected directly to CPO. This mode provides maximum efﬁciency and minimum noise. The LTC3220/ LTC3220-1 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
LTC3220/LTC3220-1 OPERATION If the LED forward voltage is 3.8V and the current sources require 100mV, the advantage voltage for 1.5x mode is 3.1V • 1.5 – 3.8V – 0.1V or 750mV. Notice that if the input voltage is raised to 3.2V, the advantage voltage jumps to 900mV, a 20% improvement in available strength. From Figure 1, for 1.5x mode the available current is given by: IOUT = 1.
PAGE 10
LTC3220/LTC3220-1 OPERATION Blinking Each universal output (ULED1 to ULED18) can be set to blink with an on time of 0.156 seconds, or 0.625 seconds and a period of 1.25 seconds, or 2.5 seconds via the I2C port. The blinking rate is selected via REG19 and ULED outputs are selected via REG1 to REG18. Blinking and gradation rates are independent. Please refer to Application Note 115 for detailed information and examples on programming blinking.
PAGE 11
LTC3220/LTC3220-1 OPERATION sub-address register is then written to, followed by the data register. Each data register has a sub-address. After the data register has been written a load pulse is created after the stop bit. The load pulse transfers all of the data held in the data registers to the DAC registers. The stop bit can be delayed until all of the data master registers have been written. At this point the LED current will be changed to the new settings.
PAGE 12
LTC3220/LTC3220-1 OPERATION Sub-Address Byte MSB LSB 7 6 5 4 3 2 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 1 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Register Function 0 REG0 COMMAND 1 REG1 ULED1 0 REG2 ULED2 1 REG3 ULED3 0 0 REG4 ULED4 1 0 1 REG5 ULED5 1 1 0 REG6 ULED6 0 1 1 1 REG7 ULED7 1 0 0 0 REG8 ULED8 1 0 0 1 REG9 ULED9 0 0 0 0 1 0 1 0 REG10 ULED10 0
PAGE 13
LTC3220/LTC3220-1 OPERATION Data Bytes REG1 to REG18, Universal LED 6-bit linear DAC data with blink/gradation.
PAGE 14
LTC3220/LTC3220-1 OPERATION Bus Speed Acknowledge The I2C port is designed to be operated at speeds 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. The acknowledge signal is used for handshaking between the master and the slave.
PAGE 15
LTC3220/LTC3220-1 OPERATION Bus Write Operation The master initiates communication with the LTC3220/ LTC3220-1 with a START condition and a 7-bit address followed by the write bit R/W = 0. If the address matches that of the LTC3220/LTC3220-1, the LTC3220/LTC3220-1 return an acknowledge. The master should then deliver the most signiﬁcant sub-address byte for the data register to be written. Again the LTC3220/LTC3220-1 acknowledge and then the data is delivered starting with the most signiﬁcant bit.
PAGE 16
LTC3220/LTC3220-1 APPLICATIONS INFORMATION VIN, CPO Capacitor Selection The style and value of the capacitors used with the LTC3220/ LTC3220-1 determine several important parameters such as regulator control loop stability, output ripple, charge pump strength and minimum start-up time. To reduce noise and ripple, it is recommended that low equivalent series resistance (ESR) ceramic capacitors are used for both CVIN and CCPO. Tantalum and aluminum capacitors are not recommended due to high ESR.
PAGE 17
LTC3220/LTC3220-1 APPLICATIONS INFORMATION 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 LTC3220/LTC3220-1. Ceramic capacitors should always be used for the ﬂying capacitors. The ﬂying capacitors control the strength of the charge pump. In order to achieve the rated output current it is necessary to have at least 1.6μF of capacitance for each of the ﬂying capacitors.
PAGE 18
LTC3220/LTC3220-1 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 PLED VLED •ILED VLED = = PIN VIN •IIN VIN ηIDEAL = (4) The efﬁciency of the LTC3220/LTC3220-1 depends upon the mode in which it is operating.
PAGE 19
LTC3220/LTC3220-1 PACKAGE DESCRIPTION PF Package 28-Lead UTQFN (4mm × 4mm) (Reference LTC DWG # 05-08-1759 Rev Ø) 0.70 ±0.05 2.64 ± 0.05 2.40 REF 4.50 ± 0.05 3.10 ± 0.05 2.64 ± 0.05 PACKAGE OUTLINE 0.20 ±0.05 0.40 BSC RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS APPLY SOLDER MASK TO AREAS THAT ARE NOT SOLDERED 4.00 ± 0.10 BOTTOM VIEW—EXPOSED PAD 0.55 ± 0.05 R = 0.05 TYP R = 0.10 TYP 27 28 0.40 ± 0.5 PIN 1 TOP MARK (NOTE 6) 1 2.64 ± 0.10 4.00 ± 0.10 PIN 1 NOTCH R = 0.20 TYP OR 0.
PAGE 20
LTC3220/LTC3220-1 TYPICAL APPLICATION Cellular Phone Multi-Display LED Controller with Auxiliary Current Source Output 2.2μF VIN 2.2μF C1P C1M C2P C2M VIN CPO 2.2μF LTC3220 LTC3220-1 DVCC DVCC CAM MAIN RGB BLINKING STATUS INDICATORS GPO 1, 2, 3 VIN 60mA 4.7μF 18 100k GPO4 ULED1-18 3220 TA02 0.1μF I2C SCL/SDA RST GND RELATED PARTS PART NUMBER DESCRIPTION COMMENTS LTC3205 250mA, 1MHz, Multi-Display LED Controller VIN: 2.8V to 4.5V, VOUT(MAX) = 5.