Data Sheet 1.5MHz, 1A, STEP DOWN DC-DC CONVERTER General Description Features The AUR9713 is a high efficiency step-down DC-DC voltage converter. The chip operation is optimized using constant frequency, peak-current mode architecture with built-in synchronous power MOS switchers and internal compensators to reduce external part counts. It is automatically switching between the normal PWM mode and LDO mode to offer improved system power efficiency covering a wide range of loading conditions. • • • • • • • • • • • • The oscillator and timing capacitors are all built-in providing an internal switching frequency of 1.5MHz that allows the use only small surface mount inductors and capacitors for portable product implementations. Additional features included integrated Soft Start (SS), Under Voltage Lock OUT (UVLO). AUR9713 High Efficiency Buck Power Converter Low Quiescent Current Output Current: 1A Adjustable Output Voltage from 1V to 3.3V Wide Operating Voltage Range: 2.5V to 5.5V Built-in Power Switches for Synchronous Rectification with High Efficiency Feedback Voltage: 600mV 1.5MHz Constant Frequency Operation Automatic PWM/LDO Mode Switching Control Thermal Shutdown Protection Low Drop-out Operation at 100% Duty Cycle No Schottky Diode Required Applications • • • • The device is available in adjustable output voltage versions ranging from 1V to 3.3V, and is able to deliver up to 1A. Mobile Phone, Digital Camera and MP3 Player Headset, Radio and Other Hand-held Instrument Post DC-DC Voltage Regulation PDA and Notebook Computer The AUR9713 is available in TSOT-23-5 package. TSOT-23-5 Figure 1. Package Type of AUR9713 Mar. 2012 Rev. 1. 1 BCD Semiconductor Manufacturing Limited 1 Data Sheet 1.5MHz, 1A, STEP DOWN DC-DC CONVERTER AUR9713 Pin Configuration H Package (TSOT-23-5) EN 1 GND 2 LX 3 5 FB 4 VIN Figure 2. Pin Configuration of AUR9713 (Top View) Pin Description Pin Number Pin Name 1 EN 2 GND 3 LX This pin is the GND reference for the NMOS power stage. It must be connected to the system ground Connected to inductor 4 VIN Power supply input 5 FB Feedback voltage from the output Mar. 2012 Function Enable signal input, active high Rev. 1. 1 BCD Semiconductor Manufacturing Limited 2 Data Sheet 1.5MHz, 1A, STEP DOWN DC-DC CONVERTER AUR9713 Functional Block Diagram Figure 3. Functional Block Diagram of AUR9713 Ordering Information AUR9713 Package H: TSOT-23-5 G: Green Circuit Type A: Adjustable Output Package Temperature Range TSOT-23-5 -40 to 80°C Part Number AUR9713AGH Marking ID 9713AG Packing Type Tape & Reel BCD Semiconductor's Pb-free products, as designated with "G" in the part number, are RoHS compliant and green. Mar. 2012 Rev. 1. 1 BCD Semiconductor Manufacturing Limited 3 Data Sheet 1.5MHz, 1A, STEP DOWN DC-DC CONVERTER AUR9713 Absolute Maximum Ratings (Note 1) Parameter Symbol Value Unit Supply Input Voltage VIN 0 to 6.5 V Enable Input Voltage VEN -0.3 to VIN+0.3 V Output Voltage VOUT -0.3 to VIN+0.3 V Power Dissipation (On PCB, TA=30°C) PD 0.96 W Thermal Resistance (Junction to Ambient, Simulation) θJA 98.4 °C/W Thermal Resistance (Junction to Case, Simulation) θJC 35.2 °C/W Operating Junction Temperature TJ 160 °C Operating Temperature TO -40 to 85 °C Storage Temperature TS -55 to 150 °C ESD (Human Body Model) VHBM 2000 V ESD (Machine Model) VMM 200 V Note 1: Stresses greater than those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings 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. Recommended Operating Conditions Parameter Symbol Min Max Unit Supply Input Voltage VIN 2.5 5.5 V Junction Temperature Range TJ -20 125 °C Ambient Temperature Range TA -40 80 °C Mar. 2012 Rev. 1. 1 BCD Semiconductor Manufacturing Limited 4 Data Sheet 1.5MHz, 1A, STEP DOWN DC-DC CONVERTER AUR9713 Electrical Characteristics VIN=3.6V, VOUT=2.5V, VREF=0.6V, L=2.2µH, CIN=4.7µF, COUT=10µF, TA=25°C, IMAX=1A. Parameter Symbol Conditions Min Typ Max Unit Input Voltage Range VIN Shutdown Current Regulated1Feedback Voltage Regulated Output Voltage Accuracy Peak Inductor Current IOFF VEN=0 VFB For Adjustable Output Voltage Oscillator Frequency ∆VOUT/VOUT IPK fOSC 2.5 VIN=2.5V to 5.5V; IOUT=0 to 1A VIN=3V, VFB=0.5V or VOUT=90%, Duty Cycle＜35% VIN=3.6V 0.585 5.5 V 0.1 1 µA 0.6 0.615 V 3 % -3 1.5 1.2 1.5 A 1.8 MHz PMOSFET RON RON(P) VIN=3.6V, IOUT=200mA 0.28 Ω NMOSFET RON RON(N) VIN=2.5V, IOUT=200mA 0.38 Ω µA Quiescent Current IQ ILOAD=0mA, VFB=VREF+5% 100 LX Leakage Current ILX VIN=5V, VEN=0V, VLX=0V or 5V 0.01 Feedback Current IFB EN Leakage Current EN High-level Input Voltage EN Low-Level Input Voltage Under Voltage Lock Out IEN 0.01 VEN_H VIN=2.5V to 5.5V VEN_L VIN=2.5V to 5.5V Hysteresis Thermal Shutdown Mar. 2012 TSD Rev. 1. 1 0.1 µA 30 nA 0.1 µA 1.5 V 0.6 V 1.8 V 0.1 V 150 °C BCD Semiconductor Manufacturing Limited 5 Data Sheet 1.5MHz, 1A, STEP DOWN DC-DC CONVERTER AUR9713 Typical Performance Characteristics Figure 4. Efficiency vs. Output Current Figure 5. Efficiency vs. Load Current Figure 6. Efficiency vs. Load Current Mar. 2012 Figure 7. LDO Mode Efficiency vs. Load Current Rev. 1. 1 BCD Semiconductor Manufacturing Limited 6 Data Sheet 1.5MHz, 1A, STEP DOWN DC-DC CONVERTER AUR9713 Typical Performance Characteristics (Continued) Figure 9. UVLO Threshold vs. Temperature Figure 8. Output Voltage vs. Output Current Figure 10. Output Voltage vs. Temperature Mar. 2012 Figure 11. Frequency vs. Temperature Rev. 1. 1 BCD Semiconductor Manufacturing Limited 7 Data Sheet 1.5MHz, 1A, STEP DOWN DC-DC CONVERTER AUR9713 Typical Performance Characteristics (Continued) Figure 12. Frequency vs. Input Voltage Figure 13. Output Current Limit vs. Temperature VOUT 200mV/div VLX 2V/div VEN 2V/div Time Figure 14. Frequency vs. Input Voltage Mar. 2012 400ns/div Figure 15. Waveform of VIN=4.5V, VOUT=1.5V, L=2.2µH Rev. 1. 1 BCD Semiconductor Manufacturing Limited 8 Data Sheet 1.5MHz, 1A, STEP DOWN DC-DC CONVERTER AUR9713 Typical Performance Characteristics (Continued) VEN 2V/div VOUT 1V/div VLX 2V/div Time 200µs/div Figure 16. Soft Start Mar. 2012 Rev. 1. 1 BCD Semiconductor Manufacturing Limited 9 Data Sheet 1.5MHz, 1A, STEP DOWN DC-DC CONVERTER AUR9713 Application Information deviations do not much relieve. The selection of COUT is determined by the Effective Series Resistance (ESR) that is required to minimize output voltage ripple and load step transients, as well as the amount of bulk capacitor that is necessary to ensure that the control loop is stable. Loop stability can be also checked by viewing the load step transient response as described in the following section. The output ripple, △VOUT, is determined by: The basic AUR9713 application circuit is shown in Figure 18, external components selection is determined by the load current and is critical with the selection of inductor and capacitor values. 1. Inductor Selection For most applications, the value of inductor is chosen based on the required ripple current with the range of 2.2µH to 4.7µH. ∆VOUT ≤ ∆I L [ ESR + V 1 ∆I L = VOUT (1 − OUT ) f ×L VIN The output ripple is the highest at the maximum input voltage since △IL increases with input voltage. The largest ripple current occurs at the highest input voltage. Having a small ripple current reduces the ESR loss in the output capacitor and improves the efficiency. The highest efficiency is realized at low operating frequency with small ripple current. However, larger value inductors will be required. A reasonable starting point for ripple current setting is △IL=40%IMAX . For a maximum ripple current stays below a specified value, the inductor should be chosen according to the following equation: L =[ 3. Load Transient A switching regulator typically takes several cycles to respond to the load current step. When a load step occurs, VOUT immediately shifts by an amount equal to △ILOAD×ESR, where ESR is the effective series resistance of output capacitor. △ILOAD also begins to charge or discharge COUT generating a feedback error signal used by the regulator to return VOUT to its steady-state value. During the recovery time, VOUT can be monitored for overshoot or ringing that would indicate a stability problem. VOUT VOUT ][1 − ] f × ∆I L ( MAX ) VIN ( MAX ) 4. Output Voltage Setting The DC current rating of the inductor should be at least equal to the maximum output current plus half the highest ripple current to prevent inductor core saturation. For better efficiency, a lower DC-resistance inductor should be selected. The output voltage of AUR9713 can be adjusted by a resistive divider according to the following formula: VOUT = VREF × (1 + 2. Capacitor Selection I RMS = I OMAX VOUT R1 FB 1 2 AUR9713 R2 GND It indicates a maximum value at VIN=2VOUT, where IRMS=IOUT/2. This simple worse-case condition is commonly used for design because even significant Mar. 2012 R1 R ) = 0.6V × (1 + 1 ) R2 R2 The resistive divider senses the fraction of the output voltage as shown in Figure 17. The input capacitance, CIN, is needed to filter the trapezoidal current at the source of the top MOSFET. To prevent large ripple voltage, a low ESR input capacitor sized for the maximum RMS current must be used. The maximum RMS capacitor current is given by: [V (V − VOUT )] × OUT IN VIN 1 ] 8 × f × COUT Figure 17. Setting the Output Voltage Rev. 1. 1 BCD Semiconductor Manufacturing Limited 10 Data Sheet 1.5MHz, 1A, STEP DOWN DC-DC CONVERTER AUR9713 Application Information (Continued) 5. Efficiency Considerations a function of both PMOSFET RDS(ON) and NMOSFET The efficiency of switching regulator is equal to the output power divided by the input power times 100%. It is usually useful to analyze the individual losses to determine what is limiting efficiency and which change could produce the largest improvement. Efficiency can be expressed as: RDS(ON) resistance and the duty cycle (D): RSW = RDS (ON )P × D + RDS (ON ) N × (1 − D ) Therefore, to obtain the I2R losses, simply add RSW to RL and multiply the result by the square of the average output current. Efficiency=100%-L1-L2-….. Where L1, L2, etc. are the individual losses as a percentage of input power. Other losses including CIN and COUT ESR dissipative losses and inductor core losses generally account for less than 2 % of total additional loss. Although all dissipative elements in the regulator produce losses, two major sources usually account for most of the power losses: VIN quiescent current and I2R losses. The VIN quiescent current loss dominates the efficiency loss at very light load currents and the I2R loss dominates the efficiency loss at medium to heavy load currents. 6. Thermal Characteristics In most applications, the part does not dissipate much heat due to its high efficiency. However, in some conditions when the part is operating in high ambient temperature with high RDS(ON) resistance and high duty cycles, such as in LDO mode, the heat dissipated may exceed the maximum junction temperature. To avoid the part from exceeding maximum junction temperature, the user should do some thermal analysis. The maximum power dissipation depends on the layout of PCB, the thermal resistance of IC package, the rate of surrounding airflow and the temperature difference between junction and ambient. 5.1 The VIN quiescent current loss comprises two parts: the DC bias current as given in the electrical characteristics and the internal MOSFET switch gate charge currents. The gate charge current results from switching the gate capacitance of the internal power MOSFET switches. Each cycle the gate is switched from high to low, then to high again, and the packet of charge, dQ moves from VIN to ground. The resulting dQ/dt is the current out of VIN that is typically larger than the internal DC bias current. In continuous mode, 7. PCB Layout Considerations When laying out the printed circuit board, the following checklist should be used to optimize the performance of AUR9713. I GATE = f × (Q P + Q N ) Where QP and QN are the gate charge of power PMOSFET and NMOSFET switches. Both the DC bias current and gate charge losses are proportional to the VIN and this effect will be more serious at higher input voltages. 1) The power traces, including the GND trace, the LX trace and the VIN trace should be kept direct, short and wide. 2) Put the input capacitor as close as possible to the VIN and GND pins. 3) The FB pin should be connected directly to the feedback resistor divider. 4) Keep the switching node, LX, away from the sensitive FB pin and the node should be kept small area. 5.2 I2R losses are calculated from internal switch resistance, RSW and external inductor resistance RL. In continuous mode, the average output current flowing through the inductor is chopped between power PMOSFET switch and NMOSFET switch. Then, the series resistance looking into the LX pin is Mar. 2012 Rev. 1. 1 BCD Semiconductor Manufacturing Limited 11 Data Sheet 1.5MHz, 1A, STEP DOWN DC-DC CONVERTER AUR9713 Typical Application Note 3: VOUT = V REF × (1 + R1 ) ; R2 When R2=300kΩ to 60 kΩ, the IR2=2µA to 10µA, and R1×C1 should be in the range between 3×10-6 and 6×10-6 for component selection. Figure 18. Typical Application Circuit of AUR9713 Table 1. Component Guide VOUT(V) Mar. 2012 R1 (kΩ) R2 (kΩ) C1 (pF) L1 (µH) 3.3 450 100 13 2.2 2.5 320 100 18 2.2 1.8 200 100 30 2.2 1.2 100 100 56 2.2 1.0 66 100 91 2.2 Rev. 1. 1 BCD Semiconductor Manufacturing Limited 12 Data Sheet 1.5MHz, 1A, STEP DOWN DC-DC CONVERTER AUR9713 Mechanical Dimensions 5° Unit: mm(inch) GAUGE PLANE TSOT-23-5 4X7 ° Mar. 2012 Rev. 1. 1 BCD Semiconductor Manufacturing Limited 13 BCD Semiconductor Manufacturing Limited http://www.bcdsemi.com IMPORTANT NOTICE IMPORTANT NOTICE BCD Semiconductor BCD Semiconductor Manufacturing Manufacturing Limited Limited reserves reserves the the right right to to make make changes changes without without further further notice notice to to any any products products or or specifispecifications herein. cations herein. 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