FR9701 fitipower integrated technology lnc. 23V, 2A, 600KHz Asynchronous Step-Down DC/DC Converter Features Description The FR9701 is a monolithic step-down switch mode converter with a built-in power MOSFET. It achieves 2A output current over a wide input supply range with excellent load and line regulation. Current mode operation provides fast transient response and eases loop stabilization. Fault condition protection includes cycle-by-cycle current limiting and over temperature protection. The FR9701 requires a minimum number of available standard external components. The FR9701 is available in TSOT23-6 and SOT23-6 packages. 2A Output Current 180mΩ Internal Power MOSFET Switch Stable with Low ESR Output Ceramic Capacitors Up to 92% Efficiency Fixed 600KHz Frequency Current Mode Operation Over-Temperature Protection with Hiccup-Mode Cycle-by-Cycle Over Current Protection Wide 4.5V to 23V Operating Input Range Output Adjustable from 0.805V to 15V 10uA Shutdown Current Available in TSOT23-6 and SOT23-6 Packages Pin Assignment TOP VIEW BS 1 6 SW GND 2 5 VIN FB 3 4 EN Applications Distributed Power Systems Battery Charger OLPC, Netbook Pre-Regulator for Linear Regulators WLED Drivers Ordering Information FR9701□□□ TR: Tape / Reel G: Green Package Type S6: SOT-23-6 FR9701-1.0-DEC-2009 1 FR9701 fitipower integrated technology lnc. Absolute Maximum Ratings (Note 1) Supply Voltage VIN.....................................................................................25V VSW...................................................................................–0.3V to VIN + 0.3V VBS....................................................................................................Vsw + 6V All Other Pins..............................................................................–0.3V to +6V Junction Temperature............................................................................150°C Lead Temperature .................................................................................260°C Storage Temperature ...........................................................–65°C to +150°C Recommended Operating Conditions (Note 2) Input Supply Voltage VIN……………………………………………...4.5V ~ 23V Output Voltage VOUT………………………..…..........................0.805V ~ 15V Ambient Temperature TA……………….......................................-40°C ~ 8 5°C Thermal Characteristics TSOT23-6 θJA…………………………………………….………………220°C /W TSOT23-6 θJC……………………………..………………….………..…110°C /W SOT23-6 θJA………………………………………………………………220°C /W SOT23-6 θJC………………………………………………………………110°C /W Note 1: Stresses exceed those ratings may damage the device. Note 2: If out of its operation conditions, the device is not guaranteed to function. Electrical Characteristic ( VIN = 12V, TA = 25℃, unless otherwise specified ) Parameter Feedback Voltage Switch-On Resistance (*) Switch Leakage Current Limit (*) Test Conditions Min Typ Max Unit 4.5V ≤ VIN ≤ 23V 0.785 0.805 180 0.825 V mΩ µA A VEN = 0V, VSW = 0V 3 Oscillator Frequency Fold-back Frequency Maximum Duty Cycle Minimum On-Time (*) FR9701-1.0-DEC-2009 10 480 VFB = 0V 600 720 KHz 120 85 KHz % 100 ns 2 FR9701 fitipower integrated technology lnc. Electrical Characteristic (continued) ( VIN = 12V, TA = 25℃, unless otherwise specified ) Parameter Test Conditions Min Typ Max Unit Under Voltage Lockout Threshold Rising Under Voltage Lockout Threshold Hysteresis EN Input Low Voltage 4.1 4.4 4.7 V EN Input High Voltage 1.2 250 mV 0.4 V V µA VEN = 2V 2.0 VEN = 0V 0.1 Supply Current (Shutdown) VEN = 0V 10 µA Supply Current (Quiescent) VEN = 2V, VFB = 1V 1.8 mA 150 °C EN Input Current Over-Temperature Protection Threshold (*) *: Guaranteed by design Block Diagram Figure 1 FR9701-1.0-DEC-2009 FR9701 Functional Block Diagram 3 FR9701 fitipower integrated technology lnc. Function Pin Description Pin NO. Pin Name Pin Description Bootstrap. A 22nF capacitor is connected between SW and BS pins to drive the power switch’s gate above the supply voltage. Ground. This pin is the voltage reference for the regulated output voltage. For this reason care must be taken in its layout. Feedback. An external resistor divider from the output to GND, tapped to the FB pin sets the output voltage. 1 BS 2 GND 3 FB 4 EN On/Off Control Input. Pull EN above 1.2V and below 5V to turn the device on. 5 VIN Power Supply Input. Drive 4.5V to 23V voltage to this pin to power on this chip. Connecting a 10uF ceramic bypass capacitor between VIN and GND to eliminate noise. 6 SW Switch Output. Connect this pin to the switching end of the inductor. Typical Application Circuit FR9701 Figure 2 FR9701-1.0-DEC-2009 Output 3.3V Application Circuit 4 FR9701 fitipower integrated technology lnc. Typical Operating Characteristics VIN = 12V, VOUT = 3.3V, C1 = 10uF, C2 = 47uF, L1 = 4.7uH, TA = +25℃ ℃, unless otherwise noted. Efficiency vs. Loading (VIN = 5V) 100% 100% 90% 90% 80% 80% 70% 70% 60% 60% Efficiency Efficiency Efficiency vs. Loading (VIN = 12V) 50% 40% 50% 40% 30% 30% 20% 20% VOUT = 3.3V VOUT = 5V VOUT = 1.2V 10% VOUT = 3.3V VOUT = 1.8V VOUT = 1.2V 10% 0% 0% 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 0 2 0.2 0.4 0.6 0.8 Load current (A) Feedback Voltage vs. Case Temperature 0.82 1.2 1.4 1.6 1.8 2 Switching Frequency vs. Case Temperature IOUT = 0.5A 650 0.818 IOUT = 0.5A Switching Frequency (KHz) 640 0.816 Feedback Voltage (V) 1 Load current (A) 0.814 0.812 0.81 0.808 0.806 0.804 0.802 630 620 610 600 590 580 570 560 0.8 550 -40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90 100 -40 -30 -20 Case Temperature ( ℃ ) 0 10 20 30 40 50 60 70 80 90 100 Case Temperature (℃ ) DC Ripple Waveform DC Ripple Waveform IOUT = 2A IOUT = 0.1A VIN 50mV/div. VIN 200mV/div. VOUT 10mV/div. IL 1A/div. VOUT 10mV/div. IL 1A/div. VSW 5V/div. VSW 5V/div. 1us/div. FR9701-1.0-DEC-2009 -10 1us/div. 5 FR9701 fitipower integrated technology lnc. Typical Operating Characteristics (continued) VIN = 12V, VOUT = 3.3V, C1 = 10uF, C2 = 47uF, L1 = 4.7uH, TA = +25℃ ℃, unless otherwise noted. Startup Through Enable Waveform Startup Through Enable Waveform IOUT = 2A IOUT = 0.1A VEN 5V/div. VEN 5V/div. VOUT 1V/div. VOUT 1V/div. IL 1A/div. 40us/div. VSW 10V/div. IL 1A/div. VSW 10V/div. 80us/div. 80us/div. Shutdown Through Enable Waveform Shutdown Through Enable Waveform IOUT = 2A IOUT = 0.1A VEN 5V/div. VEN 5V/div. VOUT 1V/div. VOUT 1V/div. IL 1A/div. IL 1A/div. VSW 10V/div. VSW 10V/div. 1ms/div. 80us/div. Short Circuit Recovery Waveform Short Circuit Test Waveform VOUT 1V/div. VOUT 1V/div. IL 1A/div. IL 1A/div. 40us/div. FR9701-1.0-DEC-2009 20us/div. 6 fitipower integrated technology lnc. FR9701 Typical Operating Characteristics (continued) VIN = 12V, VOUT = 3.3V, C1 = 10uF, C2 = 47uF, L1 = 4.7uH, TA = +25℃ ℃, unless otherwise noted. Load Transient Waveform IOUT = 100mA to 2A step VOUT 200mV/div. IL 1A/div. 400us/div. FR9701-1.0-DEC-2009 7 FR9701 fitipower integrated technology lnc. Application Information Setting EN Automatic Startup Voltage FR9701 Th e external resistor divider is used to set the EN automatic startup voltage: R4 = 5V ≈ 71.5KΩ 12V-5V 100KΩ Table 1 shows a list of resistor selection for common input voltages: Table 1—Resistor Selection for Common Input Voltages VIN R3 R4 5V 100KΩ NC 12V 100KΩ 71.5KΩ 16V 100KΩ 45.3KΩ Setting Output Voltage The external resistor divider is used to set the output voltage. FR9701 feedback resistors are unconcerned of compensation and provide an easy way to program output voltage. Table 2 shows a list of resistor selection for common output voltages: VOUT = 0.805 × 1+ FR9701-1.0-DEC-2009 R1 V R2 5V 43KΩ 8.2KΩ 3.3V 30.9KΩ 10KΩ 2.5V 21KΩ 10KΩ 1.8V 12.4KΩ 10KΩ 1.2V 4.99KΩ 10KΩ Selecting the Inductor VEN VIN-VEN R3 For example, VIN = 12V, R3 = 100KΩ, thus R4 resistor value is: R4 = Table 2—Resistor Selection for Common Output Voltages R1 R2 VOUT A 4.7µH inductor with a DC current rating of at least 25% percent higher than the maximum load current is recommended for most applications. For highest efficiency, the inductor’s DC resistance should be less than 200mΩ. For most designs, the required inductance value can be derived from the following equation. ∆I=0.3 × IL(MAX) VOUT L ≥ ( VIN-VOUT ) × FSW × ∆I × VIN Where ∆I is the inductor ripple current. Choose the inductor ripple current to be 30% of the maximum load current. The maximum inductor peak current is calculated from: IL(MAX) = ILOAD + ∆IL 2 Under light load conditions below 100mA, a larger inductance is recommended for improved efficiency. Selecting the Input Capacitor The input capacitor reduces the surge current drawn from the input supply and the switching noise from the device. The input capacitor impedance at the switching frequency should be less than the input source impedance to prevent 8 FR9701 fitipower integrated technology lnc. high frequency switching current from passing through the input. Ceramic capacitors with X5R or X7R dielectrics are highly recommended because of their low ESR and small temperature coefficients. For most applications, a 10µF capacitor is sufficient. 1. Place the input capacitors, output capacitors as close to the device as possible. Trace to these capacitors should be as short and wide as possible to minimize parasitic inductance and resistance. 2. Place VIN bypass capacitors close to the VIN Selecting the Output Capacitor pin. The output capacitor keeps the output voltage ripple small and a 47uF ceramic capacitor with X5R or X7R dielectrics is recommended for its low ESR characteristics. 3. Place feedback resistors close to the FB pin. 4. Keep the sensitive signal FB away from the switching signal SW. External Bootstrap Diode An external bootstrap diode is recommended if the input voltage is less than 5V or if there is a 5V system rail available. This diode helps improve the efficiency. Low cost diodes, such as 1N4148 are suitable for this application. D2 1N4148 VIN 5V BS VIN FR9701 TA2158 C3 Figure 3 SW Recommended Layout Diagram Rectifier Diode Use a Schottky diode as the rectifier to conduct current when the high-side power MOSFET is off. The Schottky diode must have current rating higher than the maximum output current and the reverse voltage rating higher than the maximum input voltage. PCB Layout Recommendation The device’s performance and stability is dramatically affected by PCB layout. It is recommended to follow these general guidelines show below: FR9701-1.0-DEC-2009 9 FR9701 fitipower integrated technology lnc. Package Information SOT23-6 D 5 4 1 2 3 R c L2 e e1 ( TOP VIEW ) GAUGE PLANE L E E1 L1 θ 6 ( FRONT VIEW ) A A2 θ2 UNIT: MM A1 y b 4×θ 1 ( SIDE VIEW ) 1.2 2.6 SYMBOLS MIN NOM MAX A 1.05 ---- 1.35 A1 0.05 ---- 0.15 A2 1.00 1.10 1.20 b 0.30 ---- 0.50 c 0.08 ---- 0.20 D 2.80 2.90 3.00 E 2.60 2.80 3.00 E1 1.50 1.60 1.70 e 0.95 BSC e1 1.90 BSC L 0.35 L1 0.95 ( PCB FOOTPRINT ) 0.55 0.60 REF L2 0.6 0.45 0.25 BSC y ---- ---- 0.10 R 0.10 ---- ---- 0˚ ---- 8˚ θ θ1 θ2 7˚ NOM 5˚ NOM NOTES: 1. JEDEC OUTLINE: MO-178C 2. DIMENSION “D” DOES NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS.MOLD FLASH, PROTRUSIONS OR GATE BURRS SHALL NOT EXCEED .10mm PER SIDE. 3. DIMENSION “E1” DOES NOT INCLUDE INTER-LEAD FLASH, OR PROTRUSIONS. INTER-LEAD FLASH OR PROTRUSIONS SHALL NOT EXCEED .15mm PER SIDE FR9701-1.0-DEC-2009 10 FR9701 fitipower integrated technology lnc. Carrier Tape & Reel Dimensions SOT23-6 9.20±0.10 76.2(3.0 INCHES)NOMINAL INSIDE CORE DIAMETER 0.048±0.005 HEAT SEALABLE ADHESIVE THIS SIDE Φ1.5+0.1/-0.0 4.00 Φ1.00 MIN 2.00±.05 4.00 0.25±.05 1.75 ± .10 B B A 3.50 ± .05 R 0.3 MAX Bo 8.0 +0.3/-0.1 A R 0.3 TYP Ko Ao SECTION A - A SECTION B - B 0.20 MAX. Ao = 3.15 Bo = 3.20 NOTES: Ko = 1.40 +0.10/-0 1. DIM IN MM. 2. 10 SPROCKET HOLE PITCH CUMULATIVE TOLERANCE ±0.2. 3. POCKET POSITION RELATIVE TO SPROCKET HOLE MEASURED AS TRUE POSITION OF POCKET, NOT POCKET HOLE. Life Support Policy Fitipower’s products are not authorized for use as critical components in life support devices or other medical systems. FR9701-1.0-DEC-2009 11