CAT3626

CAT3626 6-Channel LED Driver with I2C Interface FEATURES Drives 6 LED channels Independent current on 3 pairs of LEDs I2C serial interface programming Adjustable current to 32mA in 0.5mA step Power efficiency up to 91% Fractional pump 1x/1.5x Low noise input ripple Fixed High Frequency Operation 1MHz “Zero” Current Shutdown Mode Soft start and current limiting Short circuit protection Thermal shutdown protection PRODUCT DESCRIPTION The CAT3626 is a high efficiency 1x/1.5x fractional charge pump with programmable dimming current in six LED channels. To ensure uniform brightness in LCD backlight applications, each LED channel delivers an accurate regulated current. Low noise and input ripple is achieved by operating at a constant switching frequency of 1MHz which allows the use of small external ceramic capacitors. The 1x/1.5x fractional charge pump supports a wide range of input voltages from 3V to 5.5V with efficiency up to 91%, and is ideal for Li-Ion battery powered devices. The LED channels are configured into three independent pairs, each containing 2 matched channels. Each pair can be separately programmed from zero to 32mA, in 0.5mA resolution steps, using the I2C serial interface. Any individual channel can be disabled while others remain active. When the enable input (EN) is low, the device is in shutdown mode drawing zero current. The device is available in a 16-lead thin QFN package with a max height of 0.8mm. APPLICATION RGB LEDs LCD and keypad Backlighting Cellular Phones, PDAs Digital Cameras ORDERING INFORMATION Quantity Package per Reel Marking CAT3626HS4-T2 Thin QFN-16 2000 C626 CAT3626HV4-T2 Thin QFN-16 2000 G626 Green* Note *: Matte Tin Lead Finish Part Number Package PIN CONFIGURATION TYPICAL APPLICATION CIRCUIT QFN 16-lead 4x4mm (Top View) 2 I C is a trademark of Philips Electronics N.V. © 2006 Catalyst Semiconductor, Inc. 1 Doc. No. 3022 Rev. A Characteristics subject to change without notice CAT3626 ABSOLUTE MAXIMUM RATINGS Parameter VIN, LEDxx voltage VOUT, C1±, C2± voltage EN, SDA, SCL voltage Storage Temperature Range Junction Temperature Range Lead Temperature Rating 6 7 VIN + 0.7V -65 to +160 -40 to +125 300 Unit V V V ºC ºC ºC RECOMMENDED OPERATING CONDITIONS Parameter VIN Ambient Temperature Range LED forward voltage ILED per LED pin Range 3 to 5.5 -40 to +85 Up to 4.2 0 to 32 Unit V ºC V mA Typical application circuit with external components are shown on page 1. ELECTRICAL OPERATING CHARACTERISTICS VIN = 3.6V, EN = High, ambient temperature of 25ºC (over recommended operating conditions unless specified otherwise) Symbol Parameter IQ IQSHDN ILED ILED-ACC ILED-DEV ROUT FOSC ISC_MAX IIN_MAX IEN VHI VLO TSD THYS VUVLO Quiescent Current Shutdown Current LED Current Range with 6 LEDs LED Current Accuracy LED Channel Matching Output Resistance (open loop) Charge Pump Frequency Output short circuit Current Limit Input Current Limit EN Pin - Input Leakage - Logic High Level - Logic Low Level Thermal Shutdown Thermal Hysteresis Undervoltage lock out (UVLO) threshold Conditions 1x mode, all LEDs Off 1x mode, all LEDs On 1.5x mode, all LEDs Off VEN = 0V 1mA ≤ ILED ≤ 31mA (ILED - ILEDAVG) / ILEDAVG 1x mode, IOUT = 120mA 1.5x mode, IOUT = 120mA 0.8 VOUT < 0.5V 1x mode, VOUT > 1V -1 1.3 165 20 2 Min Typ 0.5 2.2 3.5 0 ±3 ±3 0.5 2.8 1 60 300 1.3 Max Unit mA mA mA µA mA % % Ω Ω MHz mA mA µA V V ºC ºC V 0 1 32 1 0.4 Doc. No. 5014 Rev. A 2 © 2006 Catalyst Semiconductor, Inc. Characteristics subject to change without notice CAT3626 A.C. CHARACTERISTICS For 3V ≤ VIN ≤ 5.5V, over full ambient temperature range -40 to +125°C (over recommended operating conditions unless specified otherwise). Symbol fSCL tAA tBUF tHD:STA tLOW tHIGH tSU:STA tHD:DAT tSU:DAT tR tF tSU:STO tDH Parameter Clock Frequency SCL Low to SDA Data Out and ACK Out Bus Free Time Before a New Transmission Can Start Start Condition Hold Time Clock Low Period Clock High Period Start Condition Setup Time (For a Repeated Condition) Data In Hold Time Data In Setup Time SDA and SCL Rise Time SDA and SCL Fall Time Stop Condition Setup Time Data Out Hold Time Min Typ Max 400 0.9 Unit kHz µs µs µs µs µs µs ns ns µs ns µs ns 1.2 0.6 1.2 0.6 0.6 0 100 0.3 300 0.6 50 Figure 1. I2C Bus Timing Characteristics © 2006 Catalyst Semiconductor, Inc. Characteristics subject to change without notice 3 Doc. No. 5014 Rev. A CAT3626 TYPICAL CHARACTERISTICS VIN = 3.6V, IOUT = 90mA (6 LEDs at 15mA), EN = VIN, CIN = C1 = C2 = COUT = 1µF, TAMB = 25ºC, unless otherwise specified. Efficiency vs. Input Voltage (6 LEDs) 100 90 EFFICIENCY [%] EFFICIENCY [%] Efficiency vs. Total LED Current (6 LEDs) 100 90 80 70 60 50 40 VIN = 3.2V (1.5x mode) VIN = 4V (1x mode) 1x Mode 15mA per LED 80 70 60 50 40 4.2 4.0 3.8 3.6 3.4 3.2 3.0 INPUT VOLTAGE [V] 20mA per LED 1.5x Mode 0 50 100 150 200 TOTAL LED CURRENT [mA] Quiescent Current vs. Input Voltage (1x Mode) QUIESCENT CURRENT [mA] 0.8 0.6 0.4 6 LEDs OFF 0.2 0 3.0 3.2 3.4 3.6 3.8 4.0 4.2 INPUT VOLTAGE [V] Quiescent Current vs. Temperature (1x Mode) QUIESCENT CURRENT [mA]. 0.8 0.6 0.4 0.2 6 LEDs OFF 0.0 -40 0 40 80 TEMPERATURE [°C] 120 Quiescent Current vs. Input Voltage (1.5x Mode) QUIESCENT CURRENT [mA]. 5 4 3 2 1 0 3.0 3.2 3.4 3.6 3.8 4.0 INPUT VOLTAGE [V] 4.2 6 LEDs OFF Quiescent Current vs. Temperature (1.5x Mode) QUIESCENT CURRENT [mA]. 5 4 3 2 1 6 LEDs OFF 0 -40 0 40 80 TEMPERATURE [°C] 120 Doc. No. 5014 Rev. A 4 © 2006 Catalyst Semiconductor, Inc. Characteristics subject to change without notice CAT3626 TYPICAL CHARACTERISTICS VIN = 3.6V, IOUT = 90mA (6 LEDs at 15mA), EN = VIN, CIN = C1 = C2 = COUT = 1µF, TAMB = 25ºC, unless otherwise specified. LED Current Change vs. Input Voltage 5.0 4.0 3.0 2.0 1.0 0.0 -1.0 -2.0 -3.0 -4.0 -5.0 3.0 LED CURRENT CHANGE [%] 4.2 LED CURRENT CHANGE [%] LED Current Change vs. Temperature 5.0 4.0 3.0 2.0 1.0 0.0 -1.0 -2.0 -3.0 -4.0 -5.0 -40 -20 0 20 40 60 TEMPERATURE [°C] 80 1x Mode 1.5x Mode 3.2 3.4 3.6 3.8 4.0 INPUT VOLTAGE [V] Oscillator Frequency vs. Input Voltage 1.3 FREQUENCY [MHz] . 1.2 1.1 1.0 0.9 0.8 0.7 3.0 3.2 3.4 3.6 3.8 INPUT VOLTAGE [V] 4.0 Oscillator Frequency vs. Temperature CLOCK FREQUENCY [MHz] . 1.3 1.2 1.1 1.0 0.9 0.8 0.7 -40 0 40 80 TEMPERATURE [°C] 120 Output Resistance vs. Input Voltage (1x Mode) 1.0 OUTPUT RESISTANCE [Ω] . Output Resistance vs. Input Voltage(1.5x Mode) 4.0 OUTPUT RESISTANCE [Ω] . 3.5 3.0 2.5 2.0 1.5 1.0 3.0 3.2 3.4 3.6 3.8 4.0 INPUT VOLTAGE [V] 4.2 0.8 0.6 0.4 0.2 0.0 3.0 3.2 3.4 3.6 3.8 4.0 INPUT VOLTAGE [V] 4.2 © 2006 Catalyst Semiconductor, Inc. Characteristics subject to change without notice 5 Doc. No. 5014 Rev. A CAT3626 TYPICAL CHARACTERISTICS VIN = 3.6V, IOUT = 90mA (6 LEDs at 15mA), EN = VIN, CIN = C1 = C2 = COUT = 1µF, TAMB = 25ºC, unless otherwise specified. Power Up with 6 LEDs at 15mA (1x Mode) Power Up with 6 LEDs at 15mA (1.5x Mode) Enable Power Down (1x Mode) Enable Power Down (1.5x Mode) Switching Waveforms in 1.5x Mode Operating Waveforms in 1x Mode Doc. No. 5014 Rev. A 6 © 2006 Catalyst Semiconductor, Inc. Characteristics subject to change without notice CAT3626 TYPICAL CHARACTERISTICS VIN = 3.6V, IOUT = 90mA (6 LEDs at 15mA), EN = VIN, CIN = C1 = C2 = COUT = 1µF, TAMB = 25ºC, unless otherwise specified. Line Transient Response in 1x mode 4.0 OUTPUT VOLTAGE [V] 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0.0 0 100 200 300 OUTPUT CURRENT [mA] 400 1x Mode Foldback Current Limit © 2006 Catalyst Semiconductor, Inc. Characteristics subject to change without notice 7 Doc. No. 5014 Rev. A CAT3626 PIN DESCRIPTIONS Pin # 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 Name LEDA1 SDA SCL EN VOUT VIN C1C1+ C2C2+ GND LEDC2 LEDC1 LEDB2 LEDB1 LEDA2 TAB Function Cathode terminal of LED A1 I2C Serial data input/output I2C Serial clock input Enable input Charge pump output connected to the LED anodes Supply voltage Bucket capacitor 1 terminal Bucket capacitor 1 terminal Bucket capacitor 2 terminal Bucket capacitor 2 terminal Ground reference Cathode terminal of LED C2 Cathode terminal of LED C1 Cathode terminal of LED B2 Cathode terminal of LED B1 Cathode terminal of LED A2 Connect to Ground on PCB PIN FUNCTION VIN is the supply pin for the charge pump. A small 1µF ceramic bypass capacitor is required between the VIN pin and ground near the device. The operating input voltage range is from 2.2V to 5.5V. Whenever the input supply falls below the undervoltage threshold (2V), all LEDs channels will be automatically disabled. EN is the enable logic input for the driver. Guaranteed levels of logic high and logic low are set at 1.3V and 0.4V respectively. When EN is initially taken high, the device becomes enabled and all LED currents remain at 0mA. To place the device into zero current shutdown mode, the EN pin must be held low. SDA is the I2C serial data line. This is a bidirectional line allowing data to be written into and read from the four registers in the driver. Registers RegA/B/C set the LED current in each pair of channels, while RegEn sets the On/Off state independently of each channel. SCL is the I2C serial clock input. VOUT is the charge pump output that is connected to the LED anodes. A small 1µF ceramic bypass capacitor is required between the VOUT pin and ground near the device. GND is the ground reference for the charge pump. The pin must be connected to the ground plane on the PCB. C1+, C1- are connected to each side of the 1µF ceramic bucket capacitor C1. C2+, C2- are connected to each side of the 1µF ceramic bucket capacitor C2. LEDxx provide the internally regulated current to the six LED cathodes. These pins enter a high-impedance zero-current state whenever the device is placed in shutdown mode. In applications using less than six LEDs, the unused channels should be disabled through the RegEn register. TAB is the exposed pad underneath the package. For best thermal performance, the tab should be soldered to the PCB and connected to the ground plane. Doc. No. 5014 Rev. A 8 © 2006 Catalyst Semiconductor, Inc. Characteristics subject to change without notice CAT3626 BLOCK DIAGRAM Figure 2. CAT3626 Functional Block Diagram BASIC OPERATION At power-up, the CAT3626 starts operating in 1x mode where the output will be approximately equal to the input supply voltage (less any internal voltage losses). If the output voltage is sufficient to regulate all LEDs currents the device remains in 1x operating mode. If the input voltage is insufficient or falls to a level where the regulated currents cannot be maintained, the device automatically switches (after a fixed time of 400µs) into 1.5x mode. In 1.5x mode, the output is approximately equal to 1.5 times the input supply voltage (less any internal voltage losses). The above sequence is repeated each and every time the chip is either powered-up or taken out of shutdown (via EN pin), or the RegEn register is accessed by write cycle. LED CURRENT SETTING The LED current setting is programmed via the I2C serial interface and is stored in four 8-bit registers RegA, RegB, RegC and RegEn as follows: RegA stores the LED current for group A (LEDA1 and LEDA2 channels), RegB stores the LED current for group B (LEDB1 and LEDB2 channels), RegC stores the LED current for group C (LEDC1 and LEDC2 channels), RegEn selects the on/off state of each of the 6 LED channels. At each write access to RegEn, the driver automatically reconfigures to the mode (1x or 1.5x) that provides the highest efficiency. © 2006 Catalyst Semiconductor, Inc. Characteristics subject to change without notice 9 Doc. No. 5014 Rev. A CAT3626 Table 1. Register address and data configuration Register name RegA RegB RegC RegEn Notes: X = not used 1 = logic high 0 = logic low Register Address 0 1 2 3 Bit 7 X X X X Bit 6 X X X X Bit 5 Bit pattern Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 See Table 2 for values LEDC2 On = 1 Off = 0 LEDC1 On = 1 Off = 0 LEDB2 On = 1 Off = 0 LEDB1 On = 1 Off = 0 LEDA2 On = 1 Off = 0 LEDA1 On = 1 Off = 0 The table 2 lists the various LED currents with the associated RegA, RegB, and RegC register values Table 2. LED Current Selection and Register Value LED current (mA) 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0 8.5 9.0 9.5 10.0 10.5 11.0 11.5 12.0 12.5 13.0 13.5 14.0 14.5 15.0 15.5 16.0 D7 X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X D6 X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X D5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 D4 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 D3 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 D2 0 0 0 0 1 1 1 1 0 0 0 0 1 1 1 1 0 0 0 0 1 1 1 1 0 0 0 0 1 1 1 1 D1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 D0 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 Dec 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 LED current (mA) 16.5 17.0 17.5 18.0 18.5 19.0 19.5 20.0 20.5 21.0 21.5 22.0 22.5 23.0 23.5 24.0 24.5 25.0 25.5 26.0 26.5 27.0 27.5 28.0 28.5 29.0 29.5 30.0 30.5 31.0 31.5 32.0 D7 X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X D6 X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X D5 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 D4 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 D3 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 D2 0 0 0 0 1 1 1 1 0 0 0 0 1 1 1 1 0 0 0 0 1 1 1 1 0 0 0 0 1 1 1 1 D1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 D0 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 Dec 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 Notes: X = not used Doc. No. 5014 Rev. A 10 © 2006 Catalyst Semiconductor, Inc. Characteristics subject to change without notice CAT3626 I2C INTERFACE The LED driver is interfaced through a 2-wire serial I2C-bus in order to control the state and the current in each of the six LED channels. The SDA and SCL lines comply with the I2C electrical specification and should be terminated with pull-up resistors. When the bus is not used, both lines are high. The device supports the maximum bus speed of 400 kbit/s. The serial bit sequence is shown below for read and write operations into the registers. Read and write Read operation: S Slave address W A Register address A S Slave address R A Data A* P instructions are initiated by the master controller/CPU and acknowledged by the slave LED driver. The I2C address of the driver is internally fixed to the binary value 1100110. The protocol requires that the start bit and the device address are both repeated. For further details on the I2C protocol, please refer to the I2C-Bus Specification, document number 9398 393 40011, from Philips Semiconductors. Write operation: S Slave address W A Register address A Data A P S: Start condition R, W: Read bit (1), Write bit (0) A: Acknowledge sent by the slave LED driver (SDA high) A*: Not Acknowledge sent by the master microcontroller (SDA low) P: Stop condition Slave address: Device address 7 bits (MSB first, slave address is 1100110). Register address: Device register address 8 bits Data: Data to read or write 8 bits Write Instruction Sequence © 2006 Catalyst Semiconductor, Inc. Characteristics subject to change without notice 11 Doc. No. 5014 Rev. A CAT3626 Write Instruction Example setting 20mA current in LEDB1 and LEDB2 I2C Bus Protocol TYPICAL APPLICATION The CAT3626 is ideal for driving RGB (red green blue) LEDs with common anode configuration. The individual LED currents associated with the red, green and blue LEDs are programmable independently through the I2C interface, allowing to generate an accurate color mixing. Dimming while maintaining the same color can be done by reprogramming the RegEn register on and off with the appropriate duty cycle (PWM mode). RGB LED Doc. No. 5014 Rev. A 12 © 2006 Catalyst Semiconductor, Inc. Characteristics subject to change without notice CAT3626 PACKAGE DRAWING AND DIMENSIONS Thin QFN 16-Lead 4mm x 4m © 2006 Catalyst Semiconductor, Inc. Characteristics subject to change without notice 13 Doc. No. 5014 Rev. A REVISION HISTORY Date 03/20/2006 Rev. A Reason Initial Issue Copyrights, Trademarks and Patents Trademarks and registered trademarks of Catalyst Semiconductor include each of the following: DPP ™ AE2 ™ Catalyst Semiconductor has been issued U.S. and foreign patents and has patent applications pending that protect its products. CATALYST SEMICONDUCTOR MAKES NO WARRANTY, REPRESENTATION OR GUARANTEE, EXPRESS OR IMPLIED, REGARDING THE SUITABILITY OF ITS PRODUCTS FOR ANY PARTICULAR PURPOSE, NOR THAT THE USE OF ITS PRODUCTS WILL NOT INFRINGE ITS INTELLECTUAL PROPERTY RIGHTS OR THE RIGHTS OF THIRD PARTIES WITH RESPECT TO ANY PARTICULAR USE OR APPLICATION AND SPECIFICALLY DISCLAIMS ANY AND ALL LIABILITY ARISING OUT OF ANY SUCH USE OR APPLICATION, INCLUDING BUT NOT LIMITED TO, CONSEQUENTIAL OR INCIDENTAL DAMAGES. Catalyst Semiconductor products are not designed, intended, or authorized for use as components in systems intended for surgical implant into the body, or other applications intended to support or sustain life, or for any other application in which the failure of the Catalyst Semiconductor product could create a situation where personal injury or death may occur. Catalyst Semiconductor reserves the right to make changes to or discontinue any product or service described herein without notice. Products with data sheets labeled "Advance Information" or "Preliminary" and other products described herein may not be in production or offered for sale. Catalyst Semiconductor advises customers to obtain the current version of the relevant product information before placing orders. Circuit diagrams illustrate typical semiconductor applications and may not be complete. Catalyst Semiconductor, Inc. Corporate Headquarters 1250 Borregas Avenue Sunnyvale, CA 94089 Phone: 408.542.1000 Fax: 408.542.1200 www.catsemi.com Document No: 5014 Revision: A Issue date: 03/20/2006