YB1303 Low Dropout LED Driver Description Features The YB1303 provides a simple solution for driving three channels of any color LEDs with current matching ability. The ultra low dropout LED driver features higher peak efficiency and very low shutdown current. The LED current can be adjusted by an external resistor or the control voltage. The YB1303 can work independently or combine with any boost converters which need to have current matching function for LED drivers. The YB1303 is available in 6-pin tiny SC70-6 package. LED Drivers for Parallel Connected LEDs Only One External Resistor is Needed PWM and Analog Brightness Control No EMI and Switching Noise Power Saving Shutdown Mode (<0.1μA) Small Footprint SC70-6 Package Applications LCD Display Modules Keyboard Backlight PDA, DSC, MP3 players LED Displays Handheld Computers Cell Phones Typical Application Circuit Figure 1: Typical Application Circuit YB1303 Rev.1.0 www.yobon.com.tw 1 YB1303 Low Dropout LED Driver Pin Configuration CTR 1 6 EN LED2 2 5 LED3 LED1 3 4 GND SC70-6 Figure 2: Pin Configuration Pin Assignment &Description Table 1 Pin Name Description 1 CTR Connect this pin with a resistor to set the LED current. 2 LED2 Connect this pin to LED cathode. 3 LED1 Connect this pin to LED cathode. 4 GND Ground pin. 5 LED3 Connect this pin to LED cathode. 6 EN Connect this pin to logic high to enable this chip, logic low to disable this chip. Ordering Information Table 2 Order Number Package Type Supplied As Package Marking YB1303SC76A SC70-6 3000 Units Tape & Reel Please contact sales representative YB1303 Rev.1.0 www.yobon.com.tw 2 YB1303 Low Dropout LED Driver Absolute Maximum Ratings Recommended Operating Conditions LED1, LED2, LED3 to GND ........ -0.3V to 6V EN to GND.................................. -0.3V to 6V CTR to GND ............................... -0.3V to 3V Power Dissipation by SC70-6 TA=85℃........133mW Junction Temperature Range...............150℃ Storage Temperature Range .....-55℃ to 150℃ Lead Temperature................................250℃ ESD HBM .......................................... 1.5KV ESD CDM ...........................................750V LED Cathode Voltage ................. 0.3V to1V Operating Temperature.........-40℃ to 85℃ Electrical Characteristics Table 3 (VIN=3.3 to 5.5V, VEN=3V, TA=25°C, unless otherwise noted. VF is LED forward voltage.) Description Symbol LED Cathode Voltage VCATHODE Output Current Multiplication Factor Test Conditions ISET = 100μA, VLED = 300mV MIN TYP MAX Units 0.3 0.5 1 V 140 200 260 1 Shutdown Current ISD VEN = 0V 0.1 LED Current ILED ISET = 100μA 20 -3 LED to LED Current Matching Efficiency η VIN =3.3V, (VIN – VCATHODE) / VIN SHDN Logic Low Level VIL ILED < 1μA SHDN Logic High Level VIH ISET = 100μA YB1303 Rev.1.0 www.yobon.com.tw mA +3 90 % % 0.5 3 μA V V 3 YB1303 Low Dropout LED Driver Typical Performance Characteristics VIN=3.3 to 5.5V, VEN=3V, TA=25°C, unless otherwise noted. VF is LED forward voltage. LED Current vs. LED Cathode Voltage Iset vs. Control Voltage (Vcontrol=3V, VEN=3V) (RSET=17.4k, Vcathode=0.3V) 22 160 20 140 LED Current (mA) 120 100 Iset (uA) Rset=17.4k Iset=100uA 18 80 60 40 16 14 12 10 8 6 4 20 2 0 0.00 0 0.0 0.5 1.0 1.5 2.0 Vcontrol (V) 2.5 3.0 3.5 4.0 0.20 0.40 0.60 1.00 1.20 1.40 1.60 1.80 2.00 2.20 Cathode Voltage (V) LED Current vs. Enable Voltage LED Current vs. Rset (Vcontrol=3V, Vcathode=0.3V, Rset=17.4k) (VEN=3V, Vcontrol=3V) 22 45 20 40 18 35 LED Current (mA) 16 LED Current (mA) 0.80 14 12 10 8 6 30 Vcathode=0.3 25 Vcathode=0.5 Vcathode=1 20 15 10 4 5 2 0 0 0 1 2 3 VEN Voltage (V) 4 5 Control Voltage Transient Response YB1303 Rev.1.0 6 0 10 20 30 40 Rset (kOhms) 50 60 70 80 Enable Voltage Transient Response www.yobon.com.tw 4 YB1303 Low Dropout LED Driver Application Information voltage. The lower the VLED voltage, the higher the system efficiency. The system efficiency can be calculated as follows: Analog Dimming Control Table Table 4 VEN=3V, VCONTROL=3V ILED (mA) 5 10 15 20 25 RSET (kΩ) 75 34 24 17.4 13 Efficiency = (VIN-VCATHODE) / VIN Thermal Considerations At any given ambient temperature, the maximum package power dissipation can be determined by the following equation: Table 5 VEN=3V, RSET=17.4k ILED (mA) 5 10 15 20 25 PD(MAX) = [TJ(MAX)-TA] / θJA VCONTROL (V) 1.5 2.1 2.5 3 3.6 Setting the LED Current The LED current can be set by the control voltage and the RSET resistor from the following equation. Constraints for the YB1303 are maximum junction temperature TJ(MAX)=125 ℃ , and package thermal resistance, θJA=300℃/W. The maximum total LED current for YB1303 depends on package power dissipation and the LED cathode voltage at TJ(MAX). At 85℃, PD(MAX)=133mW. At TA = 25℃, PD(MAX)=333mW. The maximum current is calculated by the following equation: ILED=200×(VCONTROL-VCTR)/RSET The suggested values and relations between VCONTROL and RSET can also be found in the diagram of typical characteristics and table 4 and table5. The LED brightness can be controlled by either the above equation or applying a PWM signal to the EN pin. The driving signal frequency should be greater than 100Hz to avoid flickering, and increased to more than 1MHz if necessary. Efficiency Considerations The YB1303 featured low drop out can achieve excellent efficiency performance. The efficiency is mainly dominated by VLED YB1303 Rev.1.0 ILED < (PD(MAX) / VLED(MAX)) For example, if ILED = 60mA, and TA = 85℃, VLED(MAX) = 2.2V. If the ambient temperature were to increase, the internal die temperature would increase, and the device would be damaged. Application Examples The ultra-low voltage drop across the YB1303 allows the devices to drive white, blue and any color LEDs in a wide range of input voltages. The driver can be used in many applications presented in this document, due to their similar operation. www.yobon.com.tw 5 YB1303 Low Dropout LED Driver Example 1: Drive low VF white or blue LEDs directly from single cell Li-Ion battery Example 2: Drive high VF white or blue LEDs from exiting bus from 4.0V to 6V When using white or blue low VF LEDs, and utilizing the driver’s low voltage drop, only 3.4V in VIN is needed for the full 20mA LED current. At 3.2V, there is still 5mA typical current available for the LEDs. The single cell Li-Ion battery is utilized in many applications like cell-phones and digital still cameras. In most cases, the Li-Ion battery voltage level only goes down to 3V, and not down to the full discharged level (2.7V) before requesting the charger. High VF white or blue LEDs have forward voltage drop in the range of 3.2V to 4.0V. To drive these LEDs with the maximum current of 20mA for maximum brightness, usually requires a boost circuit for a single cell Li-Ion voltage range. In some cases, there is already a voltage bus in the system, which can be utilized. Due to the ultra-low voltage drop of the YB1303 to drive high VF white or blue LEDs, the VIN needs to be only 300mV higher than the highest VF in the circuit. -VDROP < 0.3V -VF (@20mA) < 3.1V (Low VF) -VIN (@20mA) = -VDROP+VF=3.4V -VDROP < 0.3V -VF (@20mA) < 3.3V to 4.0V (High VF) -VIN (@5mA typical) ~3.1V Where VIN = Single cell Li-Ion Voltage Key advantages: y No boost circuit needed for the LCD or keyboard backlight. y Drivers directly connected to a Li-Ion battery. y No EMI, no switching noise, no boost efficiency lost, no capacitor and no inductor. YB1303 Rev.1.0 -VIN (@20mA) = -VDROP+VF=3.6V to 4.3V -VIN (@5mA typical) ~3.3V Where VIN = Existing bus = 3.3V to 4.3V Key advantages: y No boost circuit needed for the LCD or keyboard backlight. y Driver utilizes the existing bus. y Ultra-low voltage drop provides the full 20mA LED current at the lowest possible voltage level. www.yobon.com.tw 6 YB1303 Low Dropout LED Driver Example 3: Drive white, blue, red, amber LEDs string Assuming boost circuit, or existing voltage bus, the YB1303 can be used to drive a whole string of LEDs and flexible brightness control – whether using analog or PWM (Notes). LED Brightness Control The YB1303 LED drivers feature analog and PWM controls to give designers flexible brightness control. These control methods can be applied to the circuit in two different ways which provide flexible solution. To determine the value of RSET, use the “ISET vs. VCTR” graph under the “typical characteristics” section. Scenario 1 - Analog -VDROP < 0.3V -VIN_MIN = N×VF + VDROP - VIN_MAX = N×VF + 6V -VIN (@5mA typical) ~3.3V Where VIN = Existing Bus / Boost Voltage Key advantages: y No need for current matching resistors and discrete transistor for brightness control. Set VCONTROL and RSET for LED current ILED=200×(VCONTROL-VCTR)/RSET Scenario 2 – PWM - 1 ILED=200×(VCONTROL-VCTR)/RSET VCONTROL = PWM y Amplitude sets maximum LED current y Pulse width controls between 0 and maximum Notes: Scenario 3 – PWM - 2 1. Whether using analog or PWM signal, please ILED ~ 200×ISET notice to avoid from exceeding the absolute maximum rating claimed in this document. 2. EN must be turned on prior to VIN (delivered by boost circuit or existing bus) and avoid from VIN > 6V when EN is off. YB1303 Rev.1.0 VEN = PWM y Amplitude has no effect on current y Pulse width controls between 0 and maximum www.yobon.com.tw 7 YB1303 Low Dropout LED Driver Package Information (SC70-6) NOTICE: y The information described herein is subject to change without notice. y Yobon does not assume any responsibility for use of any circuitry or applications described herein, nor does it convey any patent license. YB1303 Rev.1.0 www.yobon.com.tw 8