EUP3651 4-Channel, 1X/1.5X Charge Pump White LED Driver DESCRIPTION FEATURES The EUP3651 is a high efficiency charge pump white LED driver. It supports 4 white LEDs with regulated constant current for uniform intensity. The EUP3651 maintains the highest efficiency by utilizing a 1.5X fractional charge pump and low dropout current regulators. A low external parts count (two 1uF flying capacitors and two small 1uF capacitors at VIN and VOUT) makes the EUP3651 ideally suited for small battery-powered applications. The EN logic input is used to enable, disable, and set current with a 16-step linear scale.The LED current can be configured between 5mA and 25mA. If EN is kept low for more than 1.5ms, the EUP3651 enters shutdown mode. The EUP3651 is available in a 12-pin 3mm x 3mm TDFN package. z z z z z z z z z z z 1X/1.5X Mode for Ultra-High Efficiency Up to 25mA Output Current for Each Channel 2.7V to 5.5V Input Voltage 1MHz Fixed Switching Frequency Single-Wire Serial Pulse Interface to Set LED Current with 16-step Linear scale Soft Start Function Built-In Short-Circuit Protection Built-in Thermal Protection IQ<1uA in Shutdown TDFN-12 Package RoHS Compliant and 100% Lead (Pb)-Free APPLICATIONS z z z z Typical Application Circuit Figure 1. DS3651 Ver1.0 Feb. 2008 1 Mobile phone Small LCD Backlighting Programmable Current Sinks White Photo Flash for Digital Cameras EUP3651 Block Diagram Figure 2. DS3651 Ver1.0 Feb. 2008 2 EUP3651 Pin Configurations Package Type Pin Configurations TDFN-12 Pin Description PIN NAME 1 LED4 2 EN Device enable (active high) and 1 wire control input 3 C1P Bucket capacitor 1, positive terminal 4 C1N Bucket capacitor 1, negative terminal 5 VOUT Charge pump output, connect to LED anodes 6 C2P Bucket capacitor 2, positive terminal 7 C2N Bucket capacitor 2, negative terminal 8 VIN Charge pump input, connect to battery or supply 9 GND Ground 10 LED1 LED1 cathode terminal 11 LED2 LED2 cathode terminal 12 LED3 LED3 cathode terminal EP TAB Connect to GND on the PCB DS3651 Ver1.0 Feb. 2008 DESCRIPTION LED4 cathode terminal 3 EUP3651 Ordering Information Order Number Package Type Marking Operating Temperature range EUP3651JIR1 TDFN-12 xxxxx P3651 -40 °C to 85°C EUP3651 □ □ □ □ Lead Free Code 1: Lead Free 0: Lead Packing R: Tape & Reel Operating temperature range I: Industry Standard Package Type J: TDFN DS3651 Ver1.0 Feb. 2008 4 EUP3651 Absolute Maximum Ratings Input Voltage (VIN) ----------------------------------------------------------- -0.3V to +6V EN/SET to GND Voltage (VEN/SET) ---------------------------------- -0.3V to VIN +0.3V Maximum DC Output Current (IOUT) ----------------------------------------------- 150mA Operating Junction Temperature Range (TJ) ------------------------------- -40°C to +150°C Maximum Soldering Temperature (at leads, 10 sec) ------------------------------300°C Operating Ratings Maximum Power Dissipation (PD) ------------------------------------------------------- 2W Operating Temperature (θJA) --------------------------------------------------------- 50°C/W Electrical Characteristics (Over recommended operating conditions unless specified otherwise) VIN = 3.6V, EN = High, TAMB = 25℃. EUP3651 Symbol Parameter Conditions Min Typ Max VIN Operating Voltage 3 5.5 1X mode, no load IQ Quiescent Current ISD Shutdown Current VEN = 0V LED Current Accuracy EN Falling Edges = 1 ILED-ERR ILED-LED-ERR LED Channel Matching 1.5X mode, no load Any two channel mismatch Output Resistance (open loop) FOSC Charge Pump Frequency 1.5X mode Output short Circuit Current Limit VOUT < 0.5V 1.5X mode, IOUT = 100mA 0.75 V 0.65 1 mA 2 2.5 mA 1 µA 27.5 mA 3 % 25 -3 1X mode, IOUT = 100mA ROUT ISC 22.5 Units 1.75 Ω 4 Ω 1 1.25 MHz 250 mA VHYS 1.5X to 1X Transition Hysteresis 400 mV TDLY Transition Filter Delay 500 µs TSD Thermal Shutdown 160 ℃ THYS Thermal Hysteresis 20 ℃ IEN EN Input Leakage -1 VHI EN Logic High Level 1.6 VLO EN Logic Low Level TSETUP 1 µA V 0.4 V EN setup from shutdown 10 TLO EN program low time 0.5 100 µs THI EN program high time 0.5 100 µs TOFF EN low time to shutdown 1.5 EN Delay to DATA 500 TDATADLY DS3651 Ver1.0 Feb. 2008 5 µs ms 1000 µs EUP3651 Typical Operating Characteristics Shutdown Current vs. Temperature 2.40 0.5 2.20 0.4 Shutdown Current (uA) Quiescent Current (mA) Quiescent Current vs. Temperature 2.00 1.80 1.60 0.3 0.2 0.1 0.0 -40 -20 0 20 40 60 80 -40 -20 0 Temperature (℃ ) 1200 1.10 1100 Frequency (kHz) Normalized LED Current 1.20 1.00 0.90 60 80 1000 900 0.80 800 -40 -20 0 20 40 60 80 Temperature (℃ ) -40 0 20 40 Temperature (℃) Quiescent Current vs. Input Voltage Frequency vs. Input Voltage 2.50 -20 60 80 1200 -40℃ -40℃ 25℃ 2.00 25℃ 85℃ 1100 Frequency (kHz) Quiescent Current (mA) 40 Frequency vs. Temperature Normalized LED Current vs. Temperature 85℃ 1.50 1.00 1000 900 800 700 0.50 2.7 3.2 3.7 4.2 4.7 2.7 5.2 Ver1.0 Feb. 2008 3 3.3 3.6 Input Voltage (V) Input Voltage (V) DS3651 20 Temperature (℃ ) 6 3.9 EUP3651 Efficiency vs. Load Current Efficiency vs. Input Voltage 90 100 85 80 Efficiency (%) Efficiency (%) 90 80 70 75 70 65 60 60 VIN=3.6V 55 VIN=4V Load Currnet=40mA 50 50 20.00 30.00 40.00 50.00 60.00 70.00 3 80.00 3.2 Load Current (mA) 3.6 3.8 4 4.2 Efficiency vs. Input Voltage 90 90 85 85 80 80 Efficiency (%) Efficiency (%) Efficiency vs. Input Voltage 75 70 65 75 70 65 60 60 55 55 Load Currnet=60mA Load Currnet=80mA 50 50 3 DS3651 3.4 Input Voltage (V) 3.2 3.4 3.6 3.8 4 3 4.2 3.2 3.4 3.6 3.8 Input Voltage (V) Input Voltage (V) Enable Transient Response Shutdown Timeout EN EN VOUT VOUT VLED VLED IIN IIN Ver1.0 Feb. 2008 7 4 4.2 EUP3651 40mA Load at VIN=3V 80mA Load at VIN=3V VIN VIN VOUT VOUT VLED VLED 40mA Load at VIN=3.6V DS3651 80mA Load at VIN=3.6V VIN VIN VOUT VOUT VLED VLED Ver1.0 Feb. 2008 8 EUP3651 The LED current vs. EN series pulses edges as the Figure 4. LED Current vs. Pulse Edges Basic Operation At power-up, the EUP3651 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 LED 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 into 1.5X mode (after a fixed delay time of about 500µs). In 1.5X mode, the output voltage is approximately equal to 1.5 times the input supply voltage (less any internal voltage losses). If the device detects a sufficient input voltage is present to drive all LED currents in 1X mode, it will change automatically back to 1X mode. 25 LED Current (mA) 20 15 10 5 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 EN Pulse Falling Edges Figure 4. LED Current vs. Single Wire Series Pulse Falling Edges Unused LED Channels The EN Serial Pulses Interface The current of the four LED channels can be configured by the EN logic input. By pulsing this signal with a specific protocol, the internal registers can be written into and then configure LEDs with the desired current. The EN serial pulses timing diagram see Figure 3. For applications with 3 LEDs or less, unused LEDs can be disabled by connecting the LED pin directly to VOUT, as shown on Figure 5. If LED pin voltage is within 1V of VOUT, then the channel is switched off and a 8µA test current is placed in the channel to sense when the channel moves below VOUT – 1V. Figure 3. EN Timing Diagram z z z z z DS3651 The device requires a minimum 10us delay TSETUP to ensure the initialization of the internal logic at power-up. TLO and THI must be between within 500ns to 100us. Once the final rising edge of DATA1 pulses transfer completed, the user must wait for more than 500us before transferring another DATA2 pulse falling edge. To power-down the device, the EN input should be kept low for a duration TOFF of 1.5ms or more. To power-down the device, the EN input should be kept low for a duration TOFF of 1.5ms or more. When power-down, all registers data are lost and reset to default value. Ver1.0 Feb. 2008 Figure 5. 3 LEDs Application Protection Mode If an LED is disconnected, the output voltage VOUT automatically limits at about 5.8V. This is to prevent the output pin from exceeding its absolute maximum rating. If the die temperature exceeds 160°C the driver will enter a thermal protection shutdown mode. When the device temperature drops by about 20°C the device will resume normal operation. LED Selection LEDs with forward voltages (VF) ranging from 1.3V to 4V may be used with the EUP3651. Selecting LEDs with lower VF is recommended in order to improve the efficiency by keeping the driver in 1X mode longer as the battery voltage decreases. For example, if a white LED with a VF of 3.3V is selected over one with VF of 3.5V, the EUP3651 will stay in 1X mode for lower supply voltage of 0.2V. This helps improve the efficiency and extends battery life. 9 EUP3651 Layout Consideration Due to the switching frequency and high transient current of EUP3651, careful consideration of PCB layout is necessary. The CIN should be connected as close to the IC as possible. The ground of CIN and COUT should be placed as close as possible. To achieve the best performance of EUP3651, minimize the distance between every two components and also minimize every connection length with a maximum trace width. Make sure each device connects to immediate ground plane. A copper area matching the TDFN exposed pad (TAB) must be connected to the ground plane underneath. The use of multiple via improves the package heat dissipation. External Component The driver requires two external 1µF ceramic capacitors for decoupling input, output, and for the charge pump. Both capacitors type X5R and X7R are recommended for the LED driver application. In charge pump modes, the input current ripple is kept very low by design and an input bypass capacitor of 1µF is sufficient. In 1X mode, the device operates in linear mode and does not introduce switching noise back onto the supply. Applications Examples I. Use the EUP3651 to drive four LEDs for one panel backlighting. II. Use the EUP3651 to drive 3 LEDs for one panel backlighting. The unused channel should be connected to VOUT. DS3651 Ver1.0 Feb. 2008 10 EUP3651 Packaging Information TDFN-12 SYMBOLS A A1 b E D D1 E1 e L DS3651 Ver1.0 Feb. 2008 MILLIMETERS MIN. MAX. 0.70 0.80 0.00 0.05 0.18 0.30 2.90 3.10 2.90 3.10 2.40 1.70 0.45 0.30 0.50 11 INCHES MIN. 0.028 0.000 0.007 0.114 0.114 MAX. 0.031 0.002 0.012 0.122 0.122 0.094 0.067 0.018 0.012 0.020