ACE716 40V Backlight LED Driver with PWM Direct Dimming Description The ACE716 is a high efficiency current‐mode asynchronous, 40V boost converter for LED backlight driving. Its input voltage ranges from 2.5V to 4.5V and it provides an adjustable constant current output decided by the Rset connected to ACE716’s FB pin. The LED brightness can also be controlled by a PWM signal directly set to CE pin, making dimming control very simple. The ACE716’s switching frequency is set to 600KHz, and it will automatically switch between PFM and PWM mode based on the load current, thus to enhance the converter efficiency at light load as well as heavy load. ACE716 consists of many protection blocks such as UVLO, output voltage over voltage protection, and thermal protection to keep the chip and load safe under unexpected environment. Features Adjustable Output Voltage, Vfb=0.2V Output voltage 40V, driving up to 12 LED string Range of operation input voltage: 2.5 – 4.5V Output Overvoltage Protection @40V CE pin PWM direct dimming function Line regulation: 0.1%/V (typ.) Load regulation: 10mV (typ.) High efficiency, up to 90% in driving 10 LEDs Environment Temperature: ‐20℃~85℃ Application Smartphone 7” MID Portable DVD TFT LCD bias Portable LED lighting or torch Other application need high voltage Absolute Maximum Ratings Parameter Max Input voltage 5.5V Package Thermal Resistance DFN2*2-6L (ΘJC) 20℃/W DFN2*2-6L (ΘJA) 140℃/W Operating Junction Temperature (TJ) 125℃ Ambient Temperature (TA) -20℃ to 85℃ ESD (HBM) >2000V Storage Temperature (Ts) -40℃ to 150℃ Output Voltage (SW pin) 40V Power Dissipation (SOT-23-6) 400mW Note: Exceed these limits to damage to the device. Exposure to absolute maximum rating conditions may affect device reliability. VER 1.3 1 ACE716 40V Backlight LED Driver with PWM Direct Dimming Typical Application and PIN OUT ACE716 Packaging Type DFN2*2-6L SOT-23-6 6 1 DFN2*2-6L SOT-23-6 Description 5 2 4 3 Function 1 3 FB 2 1 Comp 3 2 GND Ground 4 6 SW 5 5 CE 6 4 VIN Power switching node to connect inductor Chip enable, but a PWM signal with various duty cycle can directly sent to CE pin to achieve the backlight dimming Power input, 1uf input capacitor is recommended Feedback input with reference voltage set to 0.2V Compensation pin, to connect a 220nF capacitor to make loop stable VER 1.3 2 ACE716 40V Backlight LED Driver with PWM Direct Dimming Ordering Information ACE716 XX + H Halogen - free Pb - free KN : DFN2*2-6L GM : SOT-23-6 Efficiency for Driving 10LEDs Recommended work conditions Parameter Value Input Voltage Range 2.5~4.5V Operating Junction Temperature (TJ) -20℃~125℃ VER 1.3 3 ACE716 40V Backlight LED Driver with PWM Direct Dimming Block Diagram Electrical Characteristics (TA=25℃) Parameter Symbol Conditions Input Voltage Range VIN Feedback Voltage Vref Vin=3.6V, Vce=Vin UVLO Voltage VUVLO Vin H -->L,Iout=0.5A Feedback Leakage current Ifb Quiescent Current Iq Line Regulation Min Typ 2.5 0.19 0.2 Max Units 4.5 V 0.21 V 2.5 V 0.1 0.4 uA Active, Vfb=1V, No Switching 0.6 1 mA Shutdown, Vin=3.6V 1 5 uA LnReg Vin=2.5V to 4.5V 0.1 Switching Frequency Fsoc Vin=Vce=3.6V Low side Switch Rdson RdsonH Isw=200mA Peak Inductor Current Limit llimit Vin=3.6V, Vout=32V 0.8 Toff CE High to low 2.5 CE pin pulse width to shutdown CE PWM dimming frequency Output Over-Voltage Protection Protection Over Temperature Protection Fpwm_CE Vovp Vce=3.6V TSD Hystersis=40℃ Ce High Threshold Vceh CE Low Threshold Vcel 450 %/V 600 750 KHz 300 500 mohm 1 1.4 A ms 10 50 KHz 40 42 V 150 ℃ 1 1.5 3 V 0.3 V VER 1.3 4 ACE716 40V Backlight LED Driver with PWM Direct Dimming Typical Performance Characteristics (Vin=3.6V, L=22uH, Cin=1uF, Cout=1uF, TA=25℃, unless otherwise stated) VER 1.3 5 ACE716 40V Backlight LED Driver with PWM Direct Dimming Typical Performance Characteristics (Vin=3.6V, L=22uH, Cin=1uF, Cout=1uF, TA=25℃, unless otherwise stated) Functional Descriptions Loop Operation The ACE716 is a high voltage, high‐efficiency, DC‐to‐DC step‐up LED driver, capable of driving up to 10 LEDs. It integrates with a 300mΩ MOSFET, with external schottky diode. It uses a PWM current‐mode control scheme. An error amplifier integrates error between the FB signal and the internal reference voltage. The output of the integrator is then compared to the sum of a current‐sense signal and the slope compensation ramp. This operation generates a PWM signal that modulates the duty cycle of the power MOSFETs to achieve regulation for output voltage. Current Limit There is a cycle‐by‐cycle current limit on the high‐side MOSFET of 1A(typ). When the current flowing out of SW exceeds this limit, the low‐side MOSFET turns off and the external schottky diode rectifier turns on. Unlike the traditional method of current limiting by limiting the voltage at the external compensation node, which usually has large variation due to duty cycle variance, this type of peak current limiting scheme provides a relatively more accurate limit for output current, thereby lowering the requirements for system design. Light Load Operation Traditionally, a fixed current mode constant frequency PWM DC‐DC regulator always switches even when the output load is small. When energy is shuffling back and forth through the power MOSFETs, power is lost due to the finite RDSONs of the MOSFETs and parasitic capacitances. At light load, this loss is prominent and efficiency is therefore very low. ACE716 employs a proprietary control scheme that improves efficiency in this situation by enabling the device into a power save mode during light load, thereby extending the range of high efficiency operation. Pwm Brightness Dimming Control at CE Pin When CE pin is forced a PWM signal with frequency higher than 5KHz, the chip is in dimming mode. The internal circuit changes the feedback voltage according to the duty cycle of the PWM signal. The feedback voltage (Vfb) is simply defined as below: Vfb=200mV x Duty Cycle (%) To shut down the chip, one has to make the CE signal low, and keep its low state for more than 2.5ms. VER 1.3 6 ACE716 40V Backlight LED Driver with PWM Direct Dimming Packing Information DFN2*2-6L VER 1.3 7 ACE716 40V Backlight LED Driver with PWM Direct Dimming Packing Information SOT-23-6 VER 1.3 8 ACE716 40V Backlight LED Driver with PWM Direct Dimming Notes ACE does not assume any responsibility for use as critical components in life support devices or systems without the express written approval of the president and general counsel of ACE Electronics Co., LTD. As sued herein: 1. Life support devices or systems are devices or systems which, (a) are intended for surgical implant into the body, or (b) support or sustain life, and shoes failure to perform when properly used in accordance with instructions for use provided in the labeling, can be reasonably expected to result in a significant injury to the user. 2. A critical component is any component of a life support device or system whose failure to perform can be reasonably expected to cause the failure of the life support device or system, or to affect its safety or effectiveness. ACE Technology Co., LTD. http://www.ace-ele.com/ VER 1.3 9