SEMICONDUCTOR KAC3305DN TECHNICAL DATA Analog CMOS Integrated Circuits 700mA White LED Regulating Charge Pump for Camera Flashes and Movie Lights D F G 8 C A The KAC3305DN is charge pumps drive white LEDs, including camera strobes, with regulated current up to 700mA. The very low open-loop output resistance allows high flash brightness, even from a low battery input voltage. The adaptive 1 /2 regulating charge pump operation provides high efficiency while in movie mode or backlighting. Fast switching allows the use of tiny external components. The KAC3305DN use an external resistor to set the full-scale LED current. 5 1 4 E A B Top View H I Bottom View J Features Up to 700mA Output Drive Capability Side View Current Regulation for Flash 2.7V to 5.5V Supply voltage Range DIM A B C D E F G H I J MILLIMETERS _ 0.1 3.0 + _ 0.05 2.3+ _ 0.05 1.6 + 1.950 Ref _ 0.05 0.3 + _ 0.05 0.4 + 0.65 _ 0.05 0.75 + _ 0.008 0.203+ 0.0 ~ 0.05 PWM Dimming Control Soft-Start Limits Inrush current TDFN-8 Over Voltage Protection on Output Low Shutdown Current Thermal Shutdown Protection Applications White LED Flashes Strobes, and Movie Lights LCD Backlighting Camera Phones, Cell Phones, and Smart Phones, PDAs, Digital Cameras, and camcorders Generic Lighting Flash, and Strobo applications Typical operating Circuit Pin Configuration 1µF 2.7V to 5.5V CP VIN CN VOUT 4.7µF GND 2007. 8. 22 Revision No : 1 8 VOUT 1 TDFN-8 TOP VIEW CN EN2 KAC3305DN EN EN1 CP 10µF OFF ON Rs 4 FB VIN 5 GND FB 1/6 KAC3305DN Block Diagram VIN 6 CP CN 2 3 8 VOUT Charge Pump ( 1, 2) OSC (1MHz) Soft Start TSD OVP + REFERENCE EN1 1 7 FB CONTROL EN2 4 GND 5 Pin Descriptions 2007. 8. 22 Pin Name 1 EN1 2 CP Positive terminal of switched capacitor 3 CN Negative terminal of switched capacitor 4 EN2 Current and Shutdown Control Input 5 GND Ground. 6 VIN Power supply voltage Input 7 FB Feedback Input for the Current Control 8 VOUT Revision No : 1 Function Current and Shutdown Control Input Output of the charge pump 2/6 KAC3305DN Absolute Maximum Ratings Characteristics Input supply voltage Input pin Maximum Power Dissipation, ( Ta=25 ) Thermal Resistance Symbol Rating Units VIN -0.3 to +6.0 V EN1, EN2 -0.3 to (VIN +0.2) V PD 1.6 W 62.43 JA Operating Ambient Ta -40 to +85 Junction Temperature Range Tj 150 Storage Temperature Range Tstg -65 to +150 TLEAD 300 Lead Temperature /W Electrical Characteristics (VIN = 3.6V, CIN=10 F, C=1 F, COUT=4.7 F, Ta= 25 Parameter , unless otherwise noted.) Symbol Conditions Min Typ Max Units 2.7 - 5.5 V Input Supply voltage VIN Supply Current IIN no load - 1 2 mA ISHUT EN1=EN2=GND - - 1 A tsoft - 0.3 - ms VOVP - 5.3 - V Shutdown Supply Current Soft Start time OUT Overvoltage Protection FB Regulation Voltage (VOUT-VFB) VReg(FB) EN1=EN2=VIN 270 300 330 mV Maximum OUT Current IOUT VLED=3.8V 500 700 - mA - 1 - ROUT 1 mode Open Loop OUT Resistance 2 mode - 4.5 - - 5 - k - 1 - MHz OUT Internal Pulldown in Shutdown EN1=EN2=GND FOSC Switching Frequency EN Logic High Voltage VEN_IH VIN=2.7V to 5.5V 1.4 - - V EN Logic Low Voltage VEN_IL VIN=2.7V to 5.5V - - 0.4 V Logic Input Current IEN VEN=0V to 5.5V - - 1 A Thermal Shutdown Threshold TSD - 150 - 2007. 8. 22 Revision No : 1 3/6 KAC3305DN Application Information temperature drops back down below 110 , the part automatically recovers. Output Current The KAC3305DN is designed to deliver 200mA of continuos Setting the Output Current current and up to 700mA of pulsed current(about 500ms). The output regulation current is set by Rs by the equation : The charge pump switching frequency is approximately 1MHz, enabilng the use of small external flying capacitor. Rs=(VOUT-VFB)/IOUT Where I OUT is the output current and (V OUT-V FB) is the reference voltage. Mode Switching The resistor power obtained in the full current would be : The KAC3305DN has two modes of operation to control the output current : the 1 mode and 2 mode. When VIN is greater than V OUT, the KAC3305DN regulate the current P=(VOUT-VFB) IOUT 300 V 700 A=210 W For this application, the over 210mW resistor is recommended. through Rs. As VIN decreases and detects a dropout condition, the 2 charge pump starts boosting the output to maintain the regulation current. Capacitor Selection To reduce noise and ripple, it is recommended that low equivalent series resistance(ESR) ceramic capacitors be used Shutdown (EN1=EN2=Low) for both CIN and COUT. Tantalum and aluminum capacitors When voltage of the ENABLE pin goes under 0.4V, the are not recommended because of their high ESR. The flying KAC3305DN enter the shutdown mode. In shutdown mode, capacitors control the strength of the charge pump. In order to input current of IC go to zero and there are no current achieve the rated output current it is necessary to have at least between output capacitors and transfer capacitor. 1 F of actual capacitance. Ceramic capacitors with X5R or X7R temperature grade are Soft-Start recommended for most applications. To limit excessive inrush current at turn-on, the KAC3305DN employs built-in soft-start circuitry. When starting up with an Power Efficiency output voltage that is not near the input voltage, the output To calculate the power efficiency of a white LED driver chip, capacitor and flying capacitor are charged directly from the the LED power should be compared to the input power. The input until the output voltage approaches the input voltage. difference between these two numbers represents lost power Soft-start is achieved a period of approximately 300 s. If whether it is in the charge pump or the current sources. The detects a dropout condition, the KAC3305DN automatically power efficiency is given by switches to the 2 mode soft-start. = PLED/PIN=(VLED ILED)/(VIN 2 ILED) VLED/2 VIN Short protection Layout Considerations If output is shorted to ground, output current is limited until Due to its high switching frequency and the transient currents VOUT exceeds 2.3V. produced the KAC3305DN, careful board layout is necessary. The input and output capacitors should be located as close to Overvoltage Protection the VIN and VOUT as possible to obtain best bypassing. The The KAC3305DN has over voltage protection. If the output flying capacitor should be located as close to the CP and CN voltage rises above the 5.3V threshold, the over voltage as possible. Connect the exposed pad to GND directly under protection shuts off all of the output switches to prevent the the IC and allow sufficient copper area for cooling output voltage from rising further. Thermal Protection When the temperature of the KAC3305DN rises above 150 , the over temperature protection circuitry turns off the output switches to prevent damage to the device. If the 2007. 8. 22 Revision No : 1 4/6 KAC3305DN Start Up [IOUT =700mV] Input and Output Ripples in 1 Mode EN VOUT : 2V/div VIN : 100mV/div IOUT : 200mA/div VOUT : 100mV/div 40µS/div 1µS/div, AC Coupled Input and Output Ripples in 2 [IOUT=200mA] Mode Input and Output Ripples in 2 [IOUT=700mA] VIN : 100mV/div VIN : 100mV/div VOUT : 100mV/div VOUT : 100mV/div 1µS/div, AC Coupled 1µS/div, AC Coupled LED Current vs. Temperature [IOUT=200mA] Efficiency vs. Supply Voltage [IOUT = 700mA] 210 80 208 Efficiency (%) LED CURRENT (mA) 90 70 VLED = 4.3V 60 50 40 30 VLED = 3.5V 20 3.1 3.5 3.9 4.3 4.7 VIN (V) 2007. 8. 22 206 204 202 200 198 196 194 192 10 0 2.7 Mode Revision No : 1 5.1 5.5 190 -40 -15 10 35 60 85 TEMPERATURE ( C ) 5/6 KAC3305DN LED Current vs. Supply Voltage [IOUT=700mA] Reference Voltage vs. Temperature REFERENCE VOLTAGE (mV) 800 700 IOUT (mV) 600 VLED=3.5V 500 VLED=4.3V 400 300 200 100 3.1 3.5 4.3 4.7 5.1 5.5 299 297 -15 10 35 60 TEMPERATURE ( C ) Battery Current vs. Supply Voltage [IOUT=700mA] LED Current vs. RS 800 1400 700 LED CURRENT (mA) 1600 VLED=3.5V 1000 VLED=4.3V 800 600 400 200 85 600 500 400 300 200 100 0 0 2.7 3.1 3.5 3.9 4.3 4.7 VIN (V) 2007. 8. 22 301 VIN (V) 1200 IIN (mV) 3.9 303 295 -40 0 2.7 305 Revision No : 1 5.1 5.5 0.0 0.5 1.0 1.5 2.0 2.5 3.0 RS (Ω) 6/6