YB1313 1x/1.5x/2x Charge Pump for White LED Application Description Features The YB1313 charge pump is designed to drive up to 5 white LEDs with regulated constant current in back lit display application. The device can provide up to 25 mA per LED for a total of more than 125 mA. The input voltage ranges from 2.7V to 5.5V and is ideal for applications powered by a single LI-Ion or 3 to 4 NiCd, NiMH or Alkaline batteries. Input Range : 2.7V to 5.5V The 1MHz fix-frequency switching allows for tiny external components, and the regulation scheme is optimized to ensure low EMI and low input ripple. Internal soft-start circuitry effectively reduces the in-rush current. YB1313 also provides short circuit protection, over-temperature protection and over-voltage protection. In shutdown mode, the shutdown current is less than 1μA. YB1313 is available in a TQFN-16 3x3 package. Drives up to 5 LEDs at 25mA Each 1MHz Internal Oscillator Thermal Protection Shutdown Output Short-circuit Current Limit and Over-voltage Protection Under-Voltage Lockout With Hysteresis Automatic Soft-Start Reduces In-Rush Current Three Charge Pump Mode：1x/1.5x/2x 3mm x 3mm TQFN package Applications White LED Backlighting Handheld PCs and PDAs Mobile Phone Typical Application Circuit VIN = 2.7V To 5.5V VIN VOUT C1+ D1 C1- D2 2.2uF 0. 47 µF C2+ 0. 47 µF C2- YB 1313 EN1 D3 D4 D5 1 µF EN2 ISET GND PGND Figure 1. Typical application circuit YB1313 MRev.1.1 www.yobon.com.tw 1 YB1313 1x/1.5x/2x Charge Pump for White LED Application Pin Configuration 12 13 VIN 11 C2+ C1+ C1- C2- TQFN-16 3x3 Package 10 9 8 14 GND 7 15 EN1 PGND 6 16 5 4 D1 D2 D3 3 D4 2 ISET 1 D5 EN2 VOUT Figure 2. Pin configuration Pin Description Table 1 Pin Name Description 1 ISET Connect a RSET resistor between this pin and GND. RSET=10K, set ILED to 20 mA (Recommanded) 2 D5 Current sink output #5. If not used, connected to VIN or floating 3 D4 Current sink output #4. If not used, connected to VIN or floating 4 D3 Current sink output #3. If not used, connected to VIN or floating 5 D2 Current sink output #2. If not used, connected to VIN or floating 6 D1 Current sink output #1. If not used, connected to VIN or floating 7 PGND 8 VOUT Charge pump output 9 C2+ Flying capacitor 2 positive terminal. Connect a 0.47μF capacitor between C2+ and C2-. 10 C1+ Flying capacitor 1 positive terminal. Connect a 0.47μF capacitor between C1+ and C1- 11 C1- Flying capacitor 1 negative terminal 12 C2- Flying capacitor 2 negative terminal 13 VIN Input Voltage 14 GND Analog GND 15 EN1 Enable input1 16 EN2 Power GND Enable input2. EN1 and EN2 can be used for digital dimming with 4 steps from 0mA to the maximum current set with ISET. Ordering Information Table 2 Order Number YB1313QF33 YB1313 MRev.1.1 Package Type TQFN 3X3 Supplied as Package Marking 2500 units Tape & Reel 1313 www.yobon.com.tw 2 YB1313 1x/1.5x/2x Charge Pump for White LED Application Absolute Maximum Ratings Recommended Operating Conditions y Supply Voltage.................................................. 6.5V y Input Supply Voltage ........................ 2.7V to 5.5V y Output Voltage.................................................. 5.5V y Operating Temperature................. -40℃ to +85℃ y Output Short-Circuit Duration................Continuous y Junction Temperature Range ........................ +125℃ y Storage Temperature Range............-65℃ to +150℃ y Lead Temperature ......................................... +250℃ Electrical Characteristics Table 3 At TA=25℃, VIN=3.5V, SYMBOL CIN=1μF, C1=C2=0.47μF, COUT=2.2μF, EN1=EN2=VIN, unless otherwise noted. PARAMETER TEST CONDITIONS MIN TYP MAX UNIT 5.5 V SUPPLY VOLTAGE AND CURRENT VIN Input voltage range IQ Operating quiescent current ISD Shutdown current 2.7 1x 1.5x 800 μA 3 mA VIN = 3.5V, EN1 = EN2 = 0V 1 μA CHARGE PUMP STAGE VOUT Over-voltage limit LED unconnected, VIN=4.2V 5.5 FOSC Switching frequency ηCP Charge pump efficiency VIN = 3.5V, 1.5x mode 93 % Shutdown temperature Temperature rising 160 ℃ Recovery temperature Temperature falling 140 ℃ 0.6 0.8 V 1 MHz CURRENT SINKS k ILED to ISET current ratio EN1=EN2=1, RISET=10K ΔILED/ILED(min) Current matching between any two outputs2 VLED = 3.5V, TA = 25℃ ΔILED/ΔVIN Line regulation 2.7V < VIN < 4.3V VISET Reference voltage for current set 290 2.0 320 350 0.4 2.0 % 3.0 4.0 %/V EN1 = 1, EN2 = 0 200 mV EN1 = 0, EN2 = 1 400 mV EN1 = 1, EN2 = 1 600 620 640 mV ENABLE 1, ENABLE 2 V (UVLO) Under-Voltage Lockout Supply voltage falling UVLO hysteresis VIH EN1, EN2 Threshold high VIN = 5.5V VIL EN1, EN2 Threshold low VIN = 2.7V FPWM Frequency range at PWM EN1, EN2 shorted for PWM control YB1313 MRev.1.1 www.yobon.com.tw 2.3 V 100 mV 1.6 0 V 0.4 V 5 kHz 3 YB1313 1x/1.5x/2x Charge Pump for White LED Application Typical Characteristics VIN=3.6V, CIN=C1=C2=1μF, COUT=2.2μF, unless otherwise noted. 1.5X Mode Inrush Current 2/3 Load Efficiency vs. Supply Voltage (Full Load) 100 EN0/EN1 DC Coupled 5V/Div Efficiency (%) 90 80 VOUT DC Coupled 5V/Div 70 60 IIN DC Coupled 500mA/Div 50 40 30 2.7 2.9 3.1 3.3 3.5 3.7 3.9 4.1 4.3 Supply Voltage (V) Time=500μs/div 1.5X Mode Inrush Current Full Load 1.5X Mode, 2/3 Load EN0/EN1 DC Coupled 5V/Div VOUT DC Coupled 50mV/Div VOUT DC Coupled 5V/Div C2DC Coupled 2V/Div IIN DC Coupled 500mA/Div VDX DC Coupled 1V/Div Time=500μs/div Time=1μs/div 1.5X Mode, Full Load VOUT DC Coupled 50mV/Div C2DC Coupled 2V/Div VDX DC Coupled 1V/Div Time=1μs/div YB1313 MRev.1.1 www.yobon.com.tw 4 YB1313 1x/1.5x/2x Charge Pump for White LED Application Functional Block C1+ 10 C1- 11 C2+ 9 C2- 12 VIN 13 PGND VOUT 7 8 Current Sinks 1x/1.5x/2x Charge Pump + - Reference EN1 15 EN2 16 Control 2 D5 3 D4 4 D3 5 D2 6 D1 1 ISET Selmin 14 GND Figure 3. Block Diagram Functional Description The YB1313 uses a multi-mode fractional charge pump to generate a supply voltage and a precise sink circuitry to ensure a constant driving current for each LED. The charge pump operates in either 1x mode, 1.5x mode or 2x mode, depending on the input voltage and output current loading. The overall power consumption is best optimized by automatically switching among the 3 different operation mode. YB1313 MRev.1.1 The charge pump is possible to generate a total output current of more than 125 mA, more than 25 mA for each LED. But it is recommended to operate the device under total 125 mA. Connecting a RSET resistor of 10K ohm from pin ISET to ground generates around 20 mA LED output current and a RSET of 7.5K generates around 26 mA. www.yobon.com.tw 5 YB1313 1x/1.5x/2x Charge Pump for White LED Application Applications Information Soft-Start Circuitry The YB1313 includes soft-start circuitry to limit inrush current at turn-on. Once the input voltage is applied, the output capacitor is charged directly from the input with a ramped current source (with no charge-pump action) until the output voltage approaches the input voltage. Once this occurs, the charge pump determines if 1x, 1.5x, 2x mode is required. In the case of 1x mode, the soft-start is terminated and normal operation begins. In the case of 1.5x or 2x mode, soft-start operated until the lowest of LED1-LED4 reaches regulation. ENABLE (EN1, EN2) Table 4. Enable Levels The enable pins EN1 and EN2 are used to enable the device or set it into shutdown. The YB1313 is enabled if one of the enable pins is pulled higher than the enable trip point of 1.2V. The device starts up by going through the soft start routine as described in the section Soft Start. Pulling both pins to GND, after a delay, programs the device to shutdown. In shutdown, the charge pump, current sources, voltage reference, oscillator, and all other functions are turned off and the supply current is reduced to 0.1μA. EN1 and EN2 can also be used for dimming. The logic levels at EN1 and EN2 set the minimum voltage at the current mirrors and the voltage at the ISET pin to GND. This sets the current at the LEDs to be either the full current or a fraction of the full current. See Table 4 for further details. The maximum current through the LEDs is set by a resistor connected between YB1313 MRev.1.1 ISET and GND. EN1 and EN2 can also be used for PWM dimming. The PWM signal can either be applied to EN1 or EN2, or both inputs can be tied together and the PWM signal can be applied to both pins. Depending on the configuration, the current during PWM dimming is switched between 0 mA and its maximum (EN1 and EN2 connected to the PWM signal) or between 0 mA and 1/3 of the full LED current if EN2= 0 and EN1 is toggled. When EN1 = 0 and EN2 is toggled, the output current can be changed between 0 mA and 2/3 of the full range. Enable Level MODE LED Current EN2 EN1 0 0 Shutdown 0 0 1 VISET=200mV 1/3 1 0 VISET=400mV 2/3 1 1 VISET=620mV Full LED Current Setting The current of white LED connected to YB1313 can be set by RSET. Every current flows through the white LED is 320 times greater than the current of RSET. The white LED can be estimated by following equation: www.yobon.com.tw ⎛V I LED = 320 × ⎜⎜ ISET ⎝ RSET ⎞ ⎟⎟ ⎠ 6 YB1313 1x/1.5x/2x Charge Pump for White LED Application Thermal Protection The regulator has thermal shutdown circuitry that protects it from damage caused by high temperature conditions. The thermal protection circuitry shut down the device when the junction temperature reached approximately 160℃, allowing the device to cool. When the junction temperature cools to approximately 140℃, the device is automatically reenabled. Continuously running the regulator into thermal shutdown can degrade reliability. Undervoltage Lockout The undervoltage lockout circuit shuts down the device when the voltage at VIN drops below a typical threshold of 2.2V. The prevents damage to the devices. Termination of Unused Current Source Outputs If any outputs (D1 to D5) are not used, the LEDs pin should be connected to VDD or floating. Figure 4 shows the connection for 4LEDs application, D5 pin is connection to VDD directly. Power Efficiency The battery current and efficiency of the YB1313 are mostly dependent on the chare pump mode of operation. To get the best performance form the YB1313 it is better to use LEDs with consistently lower VF voltage. Lower VF will keep the charge pump in 1x mode longer and will uses less battery current, extending the run time of the battery. The power conversion efficiency of the YB1313 can be calculated by adding up the products of each LED current and voltage and dividing it by the product of the input voltage and current. With a fully charged battery where the input voltage is typically above the LED forward voltage, the charge pump operates in the 1x mode and efficiency is high. As the battery discharges, there is a point where the current sources no longer have enough voltage overhead to maintain a constant current regulation. At that point, the charge pump switches into the 1.5x mode. The conversion efficiency is lowest at the crossover. When in 1x mode the voltage conversion efficiency is defined as output power divided by input power: η= POUT VOUT × I OUT = ×100% PIN VIN × I IN I IN = I OUT + I Q η= Figure 4. Application for 4 LEDs. YB1313 MRev.1.1 POUT VOUT × I OUT = × 100% PIN VIN × ( I OUT + I Q ) When in 1.5x or 2x mode the voltage conversion efficiency is as output power divided by input power: www.yobon.com.tw 7 YB1313 1x/1.5x/2x Charge Pump for White LED Application η= POUT VOUT × I OUT = ×100% PIN VIN × I IN I IN = I OUT + I Q η= POUT VOUT × I OUT = ×100% PIN VIN × ( I OUT × Mode + I Q ) Mode = 1.5 or 2 And then LEDs efficiency is defined as LED forward voltage produces output current divided by input power: η= POUT VF × I OUT = × 100% PIN VIN × ( I OUT × Mode + I Q ) Capacitor Selection Ceramic capacitors such as X5R or X7R are recommended to be used with the YB1313. For the two flying capacitors C1 and C2, it is important to use low ESR capacitors to avoid unnecessary efficiency losses. Low ESR capacitors on VOUT reduce the ripple voltage on the supply of the current sources. Table 5 lists capacitor types that have been tested with the YB1313. Table 5. Recommended Capacitors and WLED Part Value Voltage C1608X5R1A105KT000E 1μF 10V C1608X7R1A105KT0S0N 1μF 10V C2012X7R1C225KT000N 2.2μF 16V 0805 ECJ1VB1A105K 1μF 10V 0603 ECJ2FB1A105K 1μF 10V ECJ2FB1A225K 2.2μF 16V LTW-193TS5 － － YB1313 MRev.1.1 Manufacturer Size Website 0603 TDK Panasonic 0805 0805 www.component.tdk.com www.panasonic.com 0805 Lite-On www.yobon.com.tw － www.liteon.com.tw 8 YB1313 1x/1.5x/2x Charge Pump for White LED Application Package Information Figure 5. YB1313 MRev.1.1 www.yobon.com.tw 9