ACE721B 1.3A 1.4MHz Synchronous Step-Down Converter Description The ACE721B series are a high efficiency monolithic synchronous buck regulator using a constant frequency, current mode architecture. The device is available in an adjustable version. Supply current during operation is only 40μA and drops to ≤ 1μA in shutdown. The 2.5V to 5.5V input voltage range makes the ACE721B ideally suited for single Li-Ion battery-powered applications. 100% duty cycle provides low dropout operation, extending battery life in portable systems. Automatic Burst Mode operation increases efficiency at light loads, further extending battery life. Switching frequency is internally set at 1.4MHz, allowing the use of small surface mount inductors and capacitors. The internal synchronous switch increases efficiency and eliminates the need for an external Schottky diode. Low output voltages are easily supported with the 0.6V feedback reference voltage. Features High Efficiency: Up to 95% Very Low Quiescent Current: 40μA 1.3A Output Current 2.5V to 5.5V Input Voltage Range 1.4MHz Constant Frequency Operation No Schottky Diode Required Low Dropout Operation: 100% Duty Cycle 0.6V Reference Allows Low Output Voltages Shutdown Mode Draws < 1μA Supply Current Current Mode Operation for Excellent Line and Load Transient Response Over temperature Protected Application Mobile Phones Personal Information Appliances Wireless and DSL Modems Digital Still Cameras MP3 Players Portable Instruments VER 1.2 1 ACE721B 1.3A 1.4MHz Synchronous Step-Down Converter Absolute Maximum Ratings Parameter Symbol Value Unit Supply Voltage VIN -0.3 to 6 V EN, VFB Voltages VEN -0.3 to VIN V SW Voltage VSW -0.3 to VIN+0.3 V Peak SW Sink and Source Current IPK 3 A Power Dissipation TA=25℃ PD 0.606 W Operation Temperature TOPR -40 to 85 ℃ Storage Temperature Range TSTG -65 to 150 ℃ Packaging Type DFN2*2-6L (TOP VIEW) DFN2*2-6L Description 1 GND 2 EN 3 VIN 4 SW 5 GND 6 FB/VOUT 7 EP Function Ground pin Chip Enable Pin. Drive EN above 1.5V to turn on the part. Drive RUN below 0.3V to turn it off. Do not leave RUN floating. Supply input pin. Power Switch Output. It is the switch node connection to Inductor.This pin connects to the drains of the internal P-ch and N-ch MOSFET switches. Ground pin Adjustable version feedback input. Connect FB to the center point of the external resistor divider. The feedback threshold voltage is 0.6V. Power Ground exposed pad, Must be connected to bare copper ground plane VER 1.2 2 ACE721B 1.3A 1.4MHz Synchronous Step-Down Converter Ordering information ACE721B XX XX + H Halogen - free Pb - free MN : DFN2*2-6L ADJ: Adjustable Voltage/1.2V/1.5V/1.8V Functional Block Diagram VER 1.2 3 ACE721B 1.3A 1.4MHz Synchronous Step-Down Converter Electrical Characteristics VIN=3.6V, TA=25℃, VOUT=1.8V, L=2.2µH, COUT=10µF, unless otherwise specified. Symbol Parameter Conditions VIN Input Voltage Range Min Typ 2.5 Max Unit 5.5 V Input DC Supply Current IS PWM Mode Vout = 90%, Iload=0mA PFM Mode Vout = 105%, Iload=0mA Shutdown Mode VRUN = 0V, VIN=4.2V TA = 25°C TA = 0°C ≤ TA ≤ 85°C TA = -40°C ≤TA ≤ 85°C VFB Regulated Feedback Voltage ΔVOUT Reference Voltage Line Regulation VLOADREG Output Voltage Load Regulation VVOLTAGEREG Output Voltage Accuracy FOSC Oscillation Frequency RPFET On Resistance of PMOS Vout=0V ISW=100mA RNFET On Resistance of NMOS IPK Peak Current Limit VIH * VIN =2.5V to 5.5V VIN = 2.5V to 5.5V, Iout=10mA to 1300mA Iout=10mA to 1300mA EN Leakage Current ILSW SW Leakage Current 300 75 1.0 0.6 0.6 0.6 0.612 0.613 0.615 0.1 -3 Vout=100% µA V %/V 3 %Vo ut 0.2 %/A 1.4 300 MHz KHz 150 200 mΩ ISW=-100mA 120 180 mΩ VIN = 3V, Vout=90% 2.6 EN Threshold IEN 0.588 0.586 0.585 150 35 0.1 0.3 VRUN=0V,VIN=Vsw=5V A 1 1.5 V ±0.01 ±1 µA ±0.01 ±1 µA *:If need to use the EN pin close output, please make sure the EN level is lower than 0.3V. Typical Application Circuit ACE721B VER 1.2 4 ACE721B 1.3A 1.4MHz Synchronous Step-Down Converter With R2 = 300kΩ to 60kΩ so the IR2 = 2μA to 10μA, and (R1 x C1) should be in the range between 3x10-6 and 6x10-6 for component selection. PCB Layout Checklist When laying out the printed circuit board, the following checklist should be used to ensure proper operation of the ACE721B. Check the following in your layout: 1. The power traces, consisting of the GND trace, the SW trace and the V IN trace should be kept short, direct and wide. 2. Does the VFB pin connect directly to the feedback resistors, The resistive divider R1/R2 must be connected between the ( + ) plate of COUT and ground. 3. Does the ( + ) plate of CIN connect to VIN as closely as possible, This capacitor provides the AC current to the internal power MOSFETS. 4. Keep the switching node, SW, away from the sensitive VFB node. 5. Keep the ( – ) plates of CIN and COUT as close as possible. Typical Performance Characteristics VER 1.2 5 ACE721B 1.3A 1.4MHz Synchronous Step-Down Converter Typical Performance Characteristics VER 1.2 6 ACE721B 1.3A 1.4MHz Synchronous Step-Down Converter Packing Information DFN2*2-6L VER 1.2 7 ACE721B 1.3A 1.4MHz Synchronous Step-Down 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 1.2 8