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| Solved by SP7611A, SP7612A, SP7614A TM 2-4 Channel Low Dropout Linear LED Driver N/C VLED1 CTRL FEATURES LED Drivers for parallel connected LEDs No EMI, no switching noise Integrated current matching PWM and Analog brightness control Enable/Shutdown control Shutdown current < 0.01A Tiny, RoHS Compliant Lead-Free Packages: SC-70, 2x2 TDFN 3 2 1 SP7614A 6 Pin SC70 4 GND 5 VLED2 6 ON/OFF Pin outs for SP7611A and SP7612A on page 3 Part # SP7611A SP7612A SP7614A Channels 4 3 2 Maximum Steady State Current per LED 40mA 40mA 80mA APPLICATIONS Ultra low cost Handsets PDA, DSC, MP3 players Handheld Computers LCD Display Modules Keyboard Backlight LCD Backlight DESCRIPTION The SP761X driver family provides a simple solution for a matched current source for any color LED. The current in the LEDs can be programmed by an external resistor. The SP7611A is capable of driving four LEDs, while the SP7612A can drive three LEDs. The SP7614A is designed to drive two high current LEDs. LED1 should always be connected to an LED and never left open in order to have the other LEDs driven with a matched current to LED1. The SP7612A and SP7614A feature Enable pins for flexible on/off control and PWM dimming. SP7612A/4A has extremely low (0.01uA typical) shutdown current, prolonging the battery life and giving the longest standby period possible in today's modern design. SP761X driver family is available in a small footprint 6-pin SC-70 package as well as the 6-pin 2x2 TDFN. TYPICAL APPLICATION SCHEMATIC VIN I SET VCONTROL RSET LED1 CTRL SP7614A ENABLE GND LED2 (R) (R) Apr20-07 RevS SP7611A/7612A/7614A Low Dropout Linear LED driver Page 1 2007 Sipex Corporation ABSOLUTE MAXIMUM RATINGS These are stress ratings only and functional operation of the device at these ratings or any other above those indicated in the operation sections of the specifications below is not implied. Exposure to absolute maximum rating conditions for extended periods of time may affect reliability. VLED1, VLED2, VLED3, VLED4 and ENABLE Voltage to GND............................................................................... -0.3V to 6V CTRL Voltage to GND . ..................................................................................................................................... .-0.5V Output Current (IOUT) (SP7611A and 7612A)....................................................................................................... 40mA Output Current (IOUT) (SP7614A)........................................................................................................................ 80mA Power Dissipation per Package - 6-pin SC-70 at TA =85 C.............................................................................. 190mW Junction Temperature ...................................................................................................................................... +150 C Storage Temperature.......................................................................................................................... -55 to +150 C C ESD Level........................................................................................................................................................................................................ 4kV HBM ESD Level........................................................................................................................................................................................................ 1kV CDM ELECTRICAL SPECIFICATIONS Specifications are at TA=25 VIN = 3.3 to 5.5, ENABLE =VIN, denotes the specifications which apply C, over the full operating temperature range, unless otherwise specified. PARAMETER LED Cathode Voltage (VLED) Ambient Temperature Output Current Multiplication Ratio in Saturation (Note1) Output Current Multiplication Ratio (Gain) (Note1) LED to LED Current Matching Current in OFF Mode Min. ENABLE ""ON Voltage" (Note 2) Max. ENABLE ""OFF Voltage" (Note 2) -40 SP7611A SP7612A SP7614A SP7611A SP7612A SP7614A 365 730 -3 SP7612A SP7614A SP7612A SP7614A 435 870 0.8 0.01 3 0.5 505 1010 3 1 % A V V A A A A 140 20 200 PART # MIN TYP MAX 5.5 85 260 UNITS V C CONDITIONS See graph for LED Current vs. Cathode Voltage ISET = 100A VLED = 300mV ISET = 100A VLED = 150mV ISET = 25A VLED = 0.5V ISET = 100A VLED = 300mV VENABLE = 0.0V ISET = 150A Note 1: Output current Multiplication Ratio (ILED/ISET) is not linear. For actual ratio and ILED please refer to typical performance characteristics on pages 4 through 7. Note 2: ENABLE "ON" is VON/OFF where ILED1 > 20mA @ VLED1 = 0.3V. ENABLE "OFF" is V where I < 1A @ V > 0.3V. Apr20-07 RevS SP7611A/7612A/7614A Low Dropout Linear LED driver Page 2 2007 Sipex Corporation PIN DESCRIPTION SC70 Package Pin # 1 2 3 4 5 6 6 SP7611A CTRL LED2 LED1 GND LED4 LED3 Pin Name SP7612A CTRL LED2 LED1 GND LED3 ENABLE SP7614A CTRL LED1 NC GND LED2 ENABLE DESCRIPTION Set s L E D C urren t Con nect t o C ath od e of Con nect t o C ath od e of Groun d Con nect t o C ath od e of Con nect t o C ath od e of C h i p ON/ OFF/ D i s a b l e LED LED LED LED 2X2 TDFN Package Pin # 1 2 3 3 4 5 6 SP7611A LED2 CTRL LED3 LED 4 GND LED 1 Pin Name SP7612A LED2 CTRL ENABLE LED 3 GND LED 1 SP7614A NC CTRL ENABLE LED 2 GND LED 1 DESCRIPTION Con nect t o C ath od e of Set s L E D Cu rren t Con nect t o C ath od e of C h i p ON/ OFF/ D i s a b l e Con nect t o C ath od e of GROUND Con nect t o C ath od e of LED LED LED LED PINOUTS LED2 CTRL LED3 1 2 3 SP7611A 2x2 6 Pin TDFN 6 5 4 LED1 GND LED4 LED2 CTRL ENABLE 1 2 3 SP7612A 2x2 6 Pin TDFN 6 5 4 LED1 GND LED3 NC CTRL ENABLE 1 2 3 SP7614A 2x2 6 Pin TDFN 6 5 4 LED1 GND LED2 Apr20-07 RevS SP7611A/7612A/7614A Low Dropout Linear LED driver Page 3 2007 Sipex Corporation SP7611A/12A TYPICAL PERFORMANCE CHARACTERISTICS Apr20-07 RevS SP7611A/7612A/7614A Low Dropout Linear LED driver Page 4 2007 Sipex Corporation SP7611A/12A TYPICAL PERFORMANCE CHARACTERISTICS Apr20-07 RevS SP7611A/7612A/7614A Low Dropout Linear LED driver Page 5 2007 Sipex Corporation SP7614A TYPICAL PERFORMANCE CHARACTERISTICS Apr20-07 RevS SP7611A/7612A/7614A Low Dropout Linear LED driver Page 6 2007 Sipex Corporation SP7614A TYPICAL PERFORMANCE CHARACTERISTICS SP7614A ILED vs. Set Resistor and Cathode Voltage Vcontrol =3V Set Resistor in k Apr20-07 RevS SP7611A/7612A/7614A Low Dropout Linear LED driver Page 7 2007 Sipex Corporation APPLICATION INFORMATION Setting the LED Current The LED current is controlled by ICONTROL and RSET according to the following formula: ILED = Gain X (VCONTROL - VCTRL) / RSET Gain depends on mode of operation VCONTROL is the voltage going into RSET VCTRL is the voltage at the pin of the device The voltage VCTRL can be determined using the ISET vs Control voltage graph located in the typical performance characteristics section. As an example, to set the LED current for an SP761x the procedure is: Take the LED current and divide it by the Gain to get ISET = ILED / Gain. Look up the VCTRL pin voltage using ISET on the graph "Ctrl Current vs. Control Voltage". Once VCTRL is known, use the following formula to find RSET. The gain is not linear, the LED current vs. Cathode voltage graph needs to be used to determine gain. Typically, the gain is ~870 for SP7614A and ~435 for SP7611A/12A when the part is operating in the linear region. RSET = (VCONTROL - VCTRL) / ISET RSET Example For an SP7614A with VCONTROL of 3V and LED current of 20mA. ISET = 20mA/870 (870 is the typical gain in linear operation) = 22uA. Using the graph on page 5 in the typical performance section, the VCTRL voltage on the control pin will be about 1.1V, then RSET will be determined by: RSET = (3V - 1.1V) / 22uA RSET = 86K PWM FUNCTION The LED's brightness can also be adjusted by driving either the ENABLE or the CTRL pin with a PWM signal. The driving signal frequency should be greater than 100Hz to avoid flickering, increasing to more than 1MHz, if necessary. Temperature Considerations LEDs are very sensitive to temperature. In most cases the maximum allowed junction temperature is 100C. The case of overtemperature due to power dissipation is de-scribed by the following: TJ = TA + JA x I x VF where TJ is the LED junction temperature, TA is the ambient temperature, JA is the junction to ambient thermal resistance, I is the LED current and VF is the LED forward voltage. When the temperature rises and the cathode voltage increases, SP761X reduces the current through LEDs. Refer to "LED Current vs. LED Cathode Voltage" graph under the Typical Performance Characteristics section. Efficiency The system efficiency, defined as the ratio between the LED's power and the input supplied power can be calculated as follows: Efficiency = (VIN - VCATHODE) / VIN The lower the VCATHODE , the higher the system efficiency. Efficiency can be further improved using a higher VIN with more LEDs as shown in example 3. The SP761X driver's low dropout architecture can significantly improve the efficiency compared to using simple ballast resistors. Application Information The ultra-low voltage drop across the SP761X series of LED drivers allows the devices to drive white, blue, and other color LEDs in a wide range of input voltages. The driver can be used in many Apr20-07 RevS SP7611A/7612A/7614A Low Dropout Linear LED driver Page 8 2007 Sipex Corporation APPLICATION INFORMATION applications. Any of the SP761X series of LED drivers can be used in the applications presented in this document, due to their similar operation. Example 1: Drive low VF white or blue LEDs directly from single cell Li-Ion When using white or blue low VF LEDs, and utilizing the driver's low voltage drop, only 3.4V VIN is needed for the full 20mA LED current. At 3.1V, there is still 5mA of typical current available for the LEDs. The single cell Li-Ion battery is utilized in many applications like cell phones or digital still cameras. In most cases, the Li-Ion battery voltage level only goes down to 3.0V, and not down to the full discharge level (2.7V) before requesting the charger. VDROP < 0.3V. This is the dropout voltage for the SP7611A. - VF = 3.1V. Low VF white LED forward voltage drop - VIN (at 20mA) needs to be greater than (VDROP+VF) 3.1V+.3V= 3.4V Key Advantages 1) No boost circuit needed for the LCD or keyboard backlight. 2) Drivers directly connected to a Li-Ion battery. 3) No EMI, no switching noise, no boost converter efficiency loss, 1 capacitor, and no inductor. Example 2: Drive high VF white or blue LEDs from existing bus ~ 4.0V to 5.5V High VF LEDs have a forward voltage drop in the range of 3.2V to 4.0V. In order to drive these LEDs with the maximum current of 20mA, enabling maximum brightness usually requires a boost circuit for a single cell Li-Ion power supply. The SP761X series is capable of driving high VF white or blue LEDs with its ultra-low dropout feature. The VIN needs to be only 300mV higher than the highest VF in the circuit. - VDROP < 0.3V. Dropout voltage of the SP7611A - VF (at 20mA) < 3.3V to 4.0V (High VF) - VIN (at 20mA) = VDROP + VF = 3.6V to 4.3V - VIN (at 5mA typical) ~ 3.3V Where VIN = Existing bus = 3.3V to 4.3V Key Advantages 1) No boost circuit needed for the LCD or keyboard backlight. 2) Drivers utilize existing bus. 3) Ultra-low voltage drop provides the full 20mA LED current at the lowest possible voltage level. Example 3: Drive white, blue, red, amber LED string In a boost circuit, or existing voltage bus, the SP761X series of LED drivers can be used to drive a whole string of LEDs and achieve flexible brightness control - whether using analog or PWM. VDROP = 0.3V. Dropout voltage of the SP7611A - VIN_MIN = N x VF + VDROP - VIN_MIN = N x VF + 0.3V Where VIN_MIN = Existing bus, boost Voltage `N' number of LEDs Per Branch VF = Forward voltage of the LED Key Advantages 1) No need for current matching resistors and discrete transistors for brightness control. Apr20-07 RevS SP7611A/7612A/7614A Low Dropout Linear LED driver Page 9 2007 Sipex Corporation APPLICATION INFORMATION LED Brightness Control The SP761X LED Drivers feature analog and PWM controls to give designers flexible brightness control. To determine the value of RSET , use the "ISET vs. VCRTL" graph under the Typical Performance Characteristics. 1. SP761X/A - Analog using VCONTROL Set VCONTROL and RSET for LED current SETTING THE LED CURRENT - page 8 - PWM - Vcontrol -Amplitude of PWM signal sets maximum LED current -Pulse width controls current between 0 and maximum LED Set current PWM using Enable - Set VCONTROL and RSET for LED current SETTING THE LED CURRENT - page 6 ENABLE = PWM -Amplitude has no effect on current -Pulse width controls current between 0 and maximum LED set current Apr20-07 RevS SP7611A/7612A/7614A Low Dropout Linear LED driver Page 10 2007 Sipex Corporation BLOCK DIAGRAMS Apr20-07 RevS SP7611A/7612A/7614A Low Dropout Linear LED driver Page 11 2007 Sipex Corporation PACKAGE: 6 PIN SC-70 Apr20-07 RevS SP7611A/7612A/7614A Low Dropout Linear LED driver Page 12 2007 Sipex Corporation PACKAGE: 6 PIN 2x2TDFN Apr20-07 RevS SP7611A/7612A/7614A Low Dropout Linear LED driver Page 13 2007 Sipex Corporation ORDERING INFORMATION Part Number SP7611AEC6-L SP7611AEC6-L/TR SP7611AER6-L SP7611AER6-L/TR SP7612AEC6-L SP7612AEC6-L/TR SP7612AER6-L SP7612AER6-L/TR SP7614AEC6-L SP7614AEC6-L/TR SP7614AER6-L SP7614AER6-L/TR SP7611AEC6 SP7611AEC6/TR SP7612AEC6 SP7612AEC6/TR SP7614AEC6 SP7614AEC6/TR Temperature Range -40 to +85C C -40 to +85C C -40 to +85C C -40 to +85C C -40 to +85C C -40 to +85C C -40 to +85C C -40 to +85C C -40 to +85C C -40 to +85C C -40 to +85C C -40 to +85C C -40 to +85C C -40 to +85C C -40 to +85C C -40 to +85C C -40 to +85C C -40 to +85C C Package 6 Pin SC70 6 Pin SC70 6 Pin 2x2 TDFN 6 Pin 2x2 TDFN 6 Pin SC70 6 Pin SC70 6 Pin 2x2 TDFN 6 Pin 2x2 TDFN 6 Pin SC70 6 Pin SC70 6 Pin 2x2 TDFN 6 Pin 2x2 TDFN 6 Pin SC70 6 Pin SC70 6 Pin SC70 6 Pin SC70 6 Pin SC70 6 Pin SC70 RoHS Pack Type Canister Tape & Reel Canister Tape & Reel Canister Tape & Reel Canister Tape & Reel Canister Tape & Reel Canister Tape & Reel Canister Tape & Reel Canister Tape & Reel Canister Tape & Reel Pack Quantity Status Active Active Active Active Active Active Active Active Active Active Active Active EOL EOL EOL EOL EOL EOL Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Any 3000 Any 3000 Any 3000 Any 3000 Any 3000 Any 3000 Any 3000 Any 3000 Any 3000 For further assistance: Email: WWW Support page: Sipex Application Notes: Sipexsupport@sipex.com http://www.sipex.com/content.aspx?p=support http://www.sipex.com/applicationNotes.aspx Solved by Sipex Corporation Headquarters and Sales Office 233 South Hillview Drive Milpitas, CA95035 tel: (408) 934-7500 FAX: (408) 935-7600 TM Sipex Corporation reserves the right to make changes to any products described herein. Sipex does not assume any liability arising out of the application or use of any product or circuit described herein; neither does it convey any license under its patent rights nor the rights of others. Apr20-07 RevS SP7611A/7612A/7614A Low Dropout Linear LED driver Page 14 2007 Sipex Corporation |
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