ACE721A Technology 1.2MHz, 800mA SYNCHRONOUS DC-DC BUCK CONVERTER Description The ACE721A is a 1.2MHz fixed frequency, current mode, PWM synchronous buck (step-down) DC-DC converter, capable of driving a 800mA load with high efficiency, excellent line and load regulation. The device integrates a main switch and a synchronous switch without an external Schottky diode. It is ideal for powering portable equipment that runs from a single Li-ion battery. A standard series of inductors are available from several different manufactures optimized for use with the ACE721A. This feature greatly simplifies the design of switch-mode power supplies. This IC is available in SOT-23-5 packages. Features • • • • • • • • • • High Efficiency: up to 95% Output Current: 800mA Input Voltage Range: 2.5V to 5.5V Fixed 1.2MHz Frequency Current Mode Control 100% Duty Cycle in Dropout Built-in Short Circuit Protection Built-in Thermal Shutdown Function Built-in Current Limit Function Shutdown Current: <1μA Application • • • • GPS WiFi Card Portable Media Player Digital Still and Video Cameras Absolute Maximum Ratings Parameter Symbol Value Unit Input Voltage VIN -0.3 to 6 V Feedback Voltage VFB -0.3 to VIN+0.3 V EN Pin Voltage VEN -0.3 to VIN+0.3 V SW Pin Voltage VSW -0.3 to VIN+0.3 V Thermal Resistance θJA Operating Junction Temperature TJ 125 ℃ Storage Temperature TSTG -65 to 150 ℃ SOT-23-5 250 ℃/W VER 1.3 1 ACE721A Technology 1.2MHz, 800mA SYNCHRONOUS DC-DC BUCK CONVERTER Note 1: Stresses greater than those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress rating only, and functional operation of the device at these or any other conditions beyond those indicated under “Recommended Operating Conditions” is not implied. Exposure to “Absolute Maximum Ratings” for extended periods may affect device reliability. Packaging Type 5 1 4 2 3 Pin SOT-23-5 1 EN 2 GND 3 SW 4 VIN 5 FB Ordering information Selection Guide ACE721A XX XX + H Halogen - free Pb - free BN : SOT-23-5 ADJ: Adjustable Voltage Functional Block Diagram VER 1.3 2 ACE721A Technology 1.2MHz, 800mA SYNCHRONOUS DC-DC BUCK CONVERTER Recommended Work Conditions Item Min Typ Max Unit Input Voltage (VIN) 2.5 5.5 V Maximum Output Current (IOUT(MAX)) 800 mA Operating Ambient Temperature (TA) -40 85 ℃ Electrical Characteristics VIN=VEN=3.6V, TA=25℃, unless otherwise specified. Specifications with boldface type apply over full operating temperature range from -40 to 85℃ Parameter Symbol Conditions Supply Current ICC Shutdown Supply Current Typ. Max. Unit VFB=0.55V 400 600 μA ISHDN VEN=0V, VIN=5.5V 0.01 1 μA Under Voltage Lockout Threshold VUVLO Rising edge 2.27 V Under Voltage Lockout Hysteresis VHUVLO 200 mV Feedback Bias Current IFB VFB=0.65V -50 0.5 50 nA Feedback Voltage VFB IOUT=100mA 0.588 / 0.582 0.600 0.612 / 0.618 V VIN=2.5V, VOUT=0.9V 800 VIN=3.6V, VOUT=1.2V 800 VIN=4.6V, VOUT=3.3V 800 VFB=0.55V 0.85 1.15 0.8 1.2 Maximum Output Current IOUT(MAX) Switch Current Limit ILIM Oscillator Frequency fOSC EN Pin Threshold Min. mA VENL A 1.4 MHz 0.6 1.5 VENH V IH VEN=3.6V -0.1 0.1 IL VEN=0V -0.1 0.1 Internal PFET On Resistance RDSONP ISW=100mA 0.44 Ω Internal NFET On Resistance RDSONN ISW=-100mA 0.29 Ω Maximum Duty Cycle DMAX VFB=0.55V 100 % Soft-start Time TSS VEN=0V to VIN IOUT=50mA 220 μS Thermal Shutdown Threshold TOTSD 160 ℃ Thermal Shutdown Hysteresis THYS 30 ℃ EN Pin Input Leakage Current VER 1.3 μA 3 ACE721A Technology 1.2MHz, 800mA SYNCHRONOUS DC-DC BUCK CONVERTER Typical Application Circuit Vin 2.5V to 5.5V 150K 300K R2 R1 EN FB VIN SW ACE721A-ADJ GND L 10uH Vout 1.8V Cin Cout 10uF 10uF 800mA Typical Performance Characteristics L=10μH, COUT=10μF, TA=25℃, unless otherwise noted. Input Voltage (V) Figure 1. Frequency vs. Input Voltage Temperature (℃) Figure 3. Current Limit vs. Temperature Temperature (℃) Figure 2. Supply Current vs. Temperature Output Current (mA) Figure 4. Output Voltage vs. Output Current VER 1.3 4 ACE721A Technology 400ns/div Figure 5. Light Load Operation (VIN=3.6V, VOUT=1.8V, IOUT=0mA) 200μs/div Figure 7. Load Transient (VIN=3.6V, VOUT=1.8V, IOUT=0mA to 800mA) 10μs/div Figure 9. Short Circuit Protection (VIN=3.6V, VOUT=1.8V, no load) 1.2MHz, 800mA SYNCHRONOUS DC-DC BUCK CONVERTER 400ns/div Figure 6. Heavy Load Operation (VIN=3.6V, VOUT=1.8V, IOUT=800mA) 400μs/div Figure 8. Start up from Shutdown (VIN=3.6V, VOUT=1.8V, RLOAD=2.5Ω) 40μs/div Figure 10. Short Circuit Recovery (VIN=3.6V, VOUT=1.8V, no load) VER 1.3 5 ACE721A Technology 1.2MHz, 800mA SYNCHRONOUS DC-DC BUCK CONVERTER Output Current (mA) Figure 11. Efficiency vs. Output Current Output Current (mA) Figure 12. Efficiency vs Output Current Temperature (℃) Figure 13. Normalized Feedback Voltage vs. Temperature VER 1.3 6 ACE721A Technology 1.2MHz, 800mA SYNCHRONOUS DC-DC BUCK CONVERTER Packing Information SOT-23-5 VER 1.3 7 ACE721A Technology 1.2MHz, 800mA SYNCHRONOUS DC-DC BUCK 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 1.3 8