ACE709G 0.85V Startup Voltage, Synchronous Step-Up Converter Description The ACE709G is a high efficiency synchronous step-up converter that can provide up to 3W of power to a boosted output from a low voltage source. Unlike most step-up converter, not only it starts up at a very low input voltage as low as 0.85V, it also incorporates circuits that disconnect the input from output, during shutdown, short-circuit, output current overloading, or other events when output is higher than the input. This eliminates the need for an external MOSFET and its control circuitry to disconnect the input from output, and provides robust output overload protection. The ACE709G starts up from a voltage as low as 0.85V making it ideal for applications with single-cell or two-cell alkaline, NiCd, and NiMh batteries. A switching frequency of 2MHz minimizes solution footprint by allowing the use of tiny and low profile inductors and ceramic capacitors. An internal synchronous MOSFET provides highest efficiency and with a current mode control that is internally compensated, external parts count is reduced to minimal. ACE709G is available in three output voltage options. They are 2.1V~ 5V. It is housed in a tiny SOT23-5 package Features Output Disconnect Short-circuit Protection 3W Output Power Output to Input Reversed Current Protection 0.85V Low Start-up Voltage VIN range from 0.6V to 4.5V Up to 96% Efficiency 40μA No load IQ and light load PFM Mode Internal Synchronous Rectifier Current Mode control Logic Control Shutdown and Thermal shutdown SOT23-5 Package Application USB OTG for MIDs, Smartphones Mobile back-up Battery Chargers Alkaline, NiCd, and NiMh batteries applications USB powered devices VER 1.1 1 ACE709G 0.85V Startup Voltage, Synchronous Step-Up Converter Absolute Maximum Ratings (Note: Exceeding these limits may damage the device. Exposure to absolute maximum rating conditions for long periods may affect device reliability.) Parameter Value SW Voltage -0.3V~5.5V All Other PIN Voltages -0.3V~5V SW to ground current Internally limited Operating Temperature Range -40℃~85℃ Storage Temperature Range -55℃~150℃ Thermal Resistance SOT23-5 ΘJA ΘJC 220 110 ℃/W Packaging Type SOT23-5 PIN # NAME DESCRIPTION 1 OUT Output pin. Bypass with a 22μF or larger ceramic capacitor closely 2 GND between this pin and GND Ground Pin 3 EN Enable pin for the IC. Drive this pin high to enable the part, low to disable. 4 IN Input Supply Voltage. Bypass with a 4.7μF ceramic capacitor to GND 5 SW Inductor Connection. Connect an inductor Between SW and the regulator output VER 1.1 2 ACE709G 0.85V Startup Voltage, Synchronous Step-Up Converter Ordering information ACE709G XX XX + H Halogen - free Pb - free BN : SOT23-5 Output Voltag:2.1V/2.5V/3.0V/ 3.3V……..5.0V Typical Application 22nF*Needed Vout=5v Efficiency Vs lOUT VOUT 5V lOUT(A) Block Diagram VER 1.1 3 ACE709G 0.85V Startup Voltage, Synchronous Step-Up Converter Electrical Characteristics (VIN = 1.8V, VOUT = 3.3V, unless otherwise specified. Typical values are at TA = 25℃.) Parameter Conditions Minimum Input Voltage Min Typ Max Units 0.6 0.6 4.5 V 0.85 1.1 V 5 V Startup Voltage IOUT=0A Output Voltage VIN=1.8 Quiescent Current at IN No Switching 40 Shutdown Supply Current at IN VEN=GND 0.5 5 μA Switching Frequency VIN<4.3V 2 2.4 MHz Maximum Duty Cycle 2.1 1.2 μA 90 % NMOS Switch On Resistance ISW =100mA 0.15 0.35 Ω PMOS Switch On Resistance ISW =100mA 0.15 0.35 Ω NMOS Switch Current Limit 1.2 Start-up Current Limit Output to Input Reverse Leakage Current SW Leakage Current VEN=GND, Measure at IN pin VOUT=5V,VSW=0 or 5V, VEN=GND 1.5 A 0.5 A 0.1 EN Input Current 0.1 EN Input Low Voltage EN Input High Voltage Thermal Shutdown 0.6 Rising, Hysteresis=10°C 5 μA 10 μA 1 μA 0.3 V V 165 ℃ VER 1.1 4 ACE709G 0.85V Startup Voltage, Synchronous Step-Up Converter Typical Characteristics (Typical values are at TA = 25℃ unless otherwise specified.) Efficiency Vs lOUT lOUT(A) Efficiency Vs lOUT lOUT(A) VOUT Vs VIN VIN (V) Efficiency Vs lOUT lOUT(A) Efficiency Vs VIN VIN (V) Maximum IOUT VS VIN VIN (V) VER 1.1 5 ACE709G 0.85V Startup Voltage, Synchronous Step-Up Converter Typical Characteristics (Typical values are at TA = 25℃ unless otherwise specified.) VOUT Vs lOUT No Load la Vs VIN lOUT(A) VIN(V) Frequency Vs VIN Heavy load Switching Waveform VIN=1.8V VOUT=3.3V lOUT=500mA VIN(V) Light load Switching Waveform VIN=1.8V VOUT=3.3V lOUT=10mA 100ms/div 500ns/div Short-Circuit Response VIN=3V VOUT=3.3V 200μs/div VER 1.1 6 ACE709G 0.85V Startup Voltage, Synchronous Step-Up Converter Typical Characteristics (Typical values are at TA = 25℃ unless otherwise specified.) Short-Circuit Recovery VIN=3V VOUT=3.3V 500ns/div Shut Down Waveform VIN=3.0V VOUT=3.3V lOUT=500mA 5ms/div Load Transient Response VIN=3V VOUT=3.3V lOUT=0.1A to 1A 1ms/div Star-Up Waveform VIN=3.0V VOUT=3.3V lOUT=500mA 5ms/div Load Transient Response VIN=3V VOUT=3.3V lOUT=0.1A to 0.5A 1ms/div Line Transient Response VOUT=3.3V lOUT =100mA VIN=1.2V to 3V 2ms/div VER 1.1 7 ACE709G 0.85V Startup Voltage, Synchronous Step-Up Converter FUNCTIONAL DECRIPTIONS Loop Operation The ACE709G is a wide input range, high-efficiency, DC-to-DC step-up switching regulator, capable of delivering up to 3W of output power, integrated with a 150mΩ high side MOSFET and 150 mΩ synchronous rectifier. 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. Light Load Operation Traditionally, a fixed 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. ACE709G 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. Short-Circuit Protection Unlike most step-up converters, the ACE709G allows for short circuits on the output. In the event of a short circuit, the device first turns off the NMOS when the sensed current reaches the current limit. After VOUT drops below VIN the device then enters a linear charge period with the current limited same as with the start-up period. In addition, the thermal shutdown circuits disable switching if the die temperature rises above 165°C. Down Mode (VIN>VOUT) Operation The ACE709G will continue to supply the output voltage even when the input voltage exceeds the output voltage. Since the PMOS no longer acts as a low-impedance switch in this mode, power dissipation increases within the IC to cause a sharp drop in efficiency. Limit the maximum output current to maintain an acceptable junction temperature VER 1.1 8 ACE709G 0.85V Startup Voltage, Synchronous Step-Up Converter 5V APPLICATIONS For ACE709G50, the 5V output voltage option, in order to maintain an acceptable peak voltage at SW, a small parallel capacitor snubber between SW and OUT is necessary, and an output cap of greater than 44μF is also required as shown in below figure. VER 1.1 9 ACE709G 0.85V Startup Voltage, Synchronous Step-Up Converter Packing Information VER 1.1 10 ACE709G 0.85V Startup Voltage, Synchronous Step-Up Converter 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 1.1 11