ISL97519AIUZ

DATASHEET ISL97519A FN6683 Rev 3.00 February 16, 2012 600kHz/1.2MHz PWM Step-Up Regulator Features The ISL97519A is a high frequency, high efficiency step-up voltage regulator operated at constant frequency PWM mode. With an internal 2.0A, 200m MOSFET, it can deliver up to 1A output current at over 90% efficiency. Two selectable frequencies, 600kHz and 1.2MHz, allow trade offs between smaller components and faster transient response. An external compensation pin gives the user greater flexibility in setting frequency compensation allowing the use of low ESR Ceramic output capacitors. • >90% Efficiency • 2.0A, 200m Power MOSFET • 2.3V to 5.5V Input • 1.1*VIN up to 25V Output • 600kHz/1.2MHz Switching Frequency Selection • Adjustable Soft-Start When shut down, it draws 2.8V 2.0 A Shutdown Input Bias Current EN = 0V 0.01 rDS(ON) Switch ON-Resistance VDD = 2.7V, ILX = 1A 0.2 ILX-LEAK Switch Leakage Current VSW = 27V 0.01 VOUT/VIN Line Regulation 3V < VIN < 5.5V, VOUT = 12V 0.2 % VOUT/IOUT Load Regulation VIN = 3.3V, VOUT = 12V, IO = 30mA to 200mA 0.3 % FOSC1 Switching Frequency Accuracy FSEL = 0V 500 620 740 kHz FOSC2 Switching Frequency Accuracy FSEL = VDD 1000 1250 1500 kHz 0.5 V IEN VIL EN, FSEL Input Low Level VIH EN, FSEL Input High Level GM Error Amp Tranconductance VDD-ON 1.228 2.3 1.5 mA 0.5  3 1.5 I = 5µA VDD UVLO On Threshold µA µA V 70 130 150 1µ/ 1.95 2.1 2.25 V HYS VDD UVLO Hysteresis ISS Soft-Start Charge Current 2 3 4 µA Minimum Soft-Start Enable Voltage 40 65 150 mV 300 350 400 mA VSS-en ILIM-VSS-en OTP Current Limit Around SS Enable V Over-Temperature Protection 140 SS = 200mV 150 mV °C NOTE: 4. Parameters with MIN and/or MAX limits are 100% tested at +25°C, unless otherwise specified. Temperature limits established by characterization and are not production tested. FN6683 Rev 3.00 February 16, 2012 Page 3 of 9 ISL97519A Typical Performance Curves 95 92 90 90 88 EFFICIENCY (%) 85 EFFICIENCY (%) VIN = 3.3V, VO = 9V, fs = 620kHz VIN = 5V, VO = 12V, fs = 1.25 MHz 80 VIN = 5V, VO = 12V, fs = 620 kHz 75 VIN = 5V, VO = 9V, fs = 620 kHz 70 86 84 82 VIN = 3.3V, VO = 12V, fs = 620kHz VIN = 3.3V, VO = 12V, 80 fs = 1.25MHz 78 65 VIN = 5V, VO = 9V, fs = 1.25MHz 60 0 200 400 600 800 VIN = 3.3V, VO = 9V, fs = 1.25MHz 76 74 1000 0 100 200 FIGURE 1. BOOST EFFICIENCY vs IOUT 400 500 FIGURE 2. BOOST EFFICIENCY vs IOUT 0.7 0.9 0.8 VIN = 5V, VO = 12V, VIN = 5V, VO = 9V, fs = 1.25MHz fs = 1.25MHz 0.6 0.6 LOAD REGULATION (%) 0.7 LOAD REGULATION (%) 300 IOUT (mA) IOUT (mA) VIN = 5V, VO = 9V, fs = 620kHz 0.5 0.4 0.3 0.2 fs = 620kHz 200 400 fs = 1.25MHz 0.5 VIN = 3.3, VO = 9V, 0.4 fs = 620kHz 0.3 0.2 VIN = 3.3, VO = 12V, fs = 620kHz 0 0 0 VIN = 3.3V, VO = 9V, 0.1 VIN = 5V, VO = 12V, 0.1 VIN = 3.3V, VO = 12V, fs = 1.25MHz 600 800 1000 0 100 IOUT (mA) 200 300 400 IOUT (mA) FIGURE 3. LOAD REGULATION vs IOUT FIGURE 4. LOAD REGULATION vs IOUT 0.6 VO = 9V, IO = 80mA 0.5 VO = 12V IO = 50mA TO 300mA LINE REGULATION (%) fs = 1.25MHz 0.4 VO = 9V, IO = 100mA fs = 620kHz 0.3 VIN = 3.3V VO = 12V, IO = 80mA fs = 600kHz fs = 1.25MHz 0.2 0.1 0 -0.1 VO = 12V, IO = 80mA fs = 620kHz 2 3 4 VIN (V) 5 FIGURE 5. LINE REGULATION vs VIN FN6683 Rev 3.00 February 16, 2012 6 FIGURE 6. TRANSIENT RESPONSE Page 4 of 9 500 ISL97519A Typical Performance Curves (Continued) IO = 50mA to 300mA VO = 12V VIN = 3.3V fs = 1.2MHz FIGURE 7. TRANSIENT RESPONSE 1.0 FIGURE 8. SS DELAY AND LX DELAY DURING EN = VDD START- UP JEDEC JESD51-7 HIGH EFFECTIVE THERMAL CONDUCTIVITY TEST BOARD 870mW 0.8 0.7 M  SO JA = +1 P8 15 °C /W 0.6 0.5 0.4 0.6 POWER DISSIPATION (W) POWER DISSIPATION (W) 0.9 0.3 0.2 JEDEC JESD51-3 LOW EFFECTIVE THERMAL CONDUCTIVITY TEST BOARD 0.5 486mW 0.4  JA = 0.3 M SO +2 P 8 06 °C /W 0.2 0.1 0.1 0 0.0 0 25 50 75 85 100 125 0 Applications Information The ISL97519A is a high frequency, high efficiency boost regulator operated at constant frequency PWM mode. The boost converter stores energy from an input voltage source and delivers it to a higher output voltage. The input voltage range is 2.3V to 5.5V and output voltage range is 5V to 25V. The switching frequency is selectable between 600kHz and 1.2MHz allowing smaller inductors and faster transient response. An external compensation pin gives the user greater flexibility in setting output transient response and tighter load regulation. The converter soft-start characteristic can also be controlled by external CSS capacitor. The EN pin allows the user to completely shutdown the device. 75 85 100 125 FIGURE 10. PACKAGE POWER DISSIPATION vs AMBIENT TEMPERATURE boost converter operates in two cycles. During the first cycle, as shown in Figure 12, the internal power FET turns on and the Schottky diode is reverse biased and cuts off the current flow to the output. The output current is supplied from the output capacitor. The voltage across the inductor is VIN and the inductor current ramps up in a rate of VIN/L, L is the inductance. The inductance is magnetized and energy is stored in the inductor. The change in inductor current is shown in Equation 1: V IN I L1 = T1  -------L D T1 = ----------F SW Boost Converter Operations D = Duty Cycle Figure 11 shows a boost converter with all the key components. In steady state operating and continuous conduction mode where the inductor current is continuous, the I OUT V O = -------------  T 1 C OUT FN6683 Rev 3.00 February 16, 2012 50 AMBIENT TEMPERATURE (°C) AMBIENT TEMPERATURE (°C) FIGURE 9. PACKAGE POWER DISSIPATION vs AMBIENT TEMPERATURE 25 (EQ. 1) Page 5 of 9 ISL97519A During the second cycle, the power FET turns off and the Schottky diode is forward biased, (see Figure 13). The energy stored in the inductor is pumped to the output supplying output current and charging the output capacitor. The Schottky diode side of the inductor is clamped to a Schottky diode above the output voltage. So the voltage drop across the inductor is VIN - VOUT. The change in inductor current during the second cycle is shown in Equation 2: L D VIN VOUT CIN COUT ISL97519A IL IL2 V IN – V OUT I L = T2  ---------------------------L T2 VO 1–D T2 = ------------F SW (EQ. 2) For stable operation, the same amount of energy stored in the inductor must be taken out. The change in inductor current during the two cycles must be the same, as shown in Equation 3. I1 + I2 = 0 V IN 1 – D V IN – V OUT D -----------  ------- + -------------  ---------------------------- = 0 L F SW L F SW V OUT 1 ------------- = ------------1–D V IN (EQ. 3) FIGURE 13. BOOST CONVERTER - CYCLE 2, POWER SWITCH OPEN Output Voltage An external feedback resistor divider is required to divide the output voltage down to the nominal 1.24V reference voltage. The current drawn by the resistor network should be limited to maintain the overall converter efficiency. The maximum value of the resistor network is limited by the feedback input bias current and the potential for noise being coupled into the feedback pin. A resistor network less than 100k is recommended. The boost converter output voltage is determined by the relationship in Equation 4: R 1  V OUT = V FB   1 + ------- R 2  L (EQ. 4) The nominal VFB voltage is 1.24V. D VIN VOUT CIN COUT The inductor selection determines the output ripple voltage, transient response, output current capability, and efficiency. Its selection depends on the input voltage, output voltage, switching frequency, and maximum output current. For most applications, the inductance should be in the range of 2µH to 33µH. The inductor maximum DC current specification must be greater than the peak inductor current required by the regulator.The peak inductor current can be calculated in Equation 5: ISL97519A FIGURE 11. BOOST CONVERTER L VIN VOUT CIN Inductor Selection COUT I OUT  V OUT V IN   V OUT – V IN  I L  PEAK  = ------------------------------- + 1  2  ----------------------------------------------V IN L  V OUT  FREQ (EQ. 5) Output Capacitor ISL97519A IL IL1 T1 VO FIGURE 12. BOOST CONVERTER - CYCLE 1, POWER SWITCH CLOSE Low ESR capacitors should be used to minimized the output voltage ripple. Multi-layer ceramic capacitors (X5R and X7R) are preferred for the output capacitors because of their lower ESR and small packages. Tantalum capacitors with higher ESR can also be used. The output ripple can be calculated as shown in Equation 6: I OUT  D V O = ------------------------ + I OUT  ESR F SW  C O (EQ. 6) For noise sensitive application, a 0.1µF placed in parallel with the larger output capacitor is recommended to reduce the switching noise coupled from the LX switching node. FN6683 Rev 3.00 February 16, 2012 Page 6 of 9 ISL97519A Schottky Diode In selecting the Schottky diode, the reverse break down voltage, forward current and forward voltage drop must be considered for optimum converter performance. The diode must be rated to handle 2.0A, the current limit of the ISL97519A. The breakdown voltage must exceed the maximum output voltage. Low forward voltage drop, low leakage current, and fast reverse recovery will help the converter to achieve the maximum efficiency. Input Capacitor enough that it doesn't reach 0.6V before the output voltage reaches the final value. When the ISL97519A is disabled, the soft-start capacitor will be discharged to ground. Frequency Selection The ISL97519A switching frequency can be user selected to operate at either constant 620kHz or 1.25MHz. Connecting FSEL pin to ground sets the PWM switching frequency to 620kHz. When connecting FSEL high or VDD, the switching frequency is set to 1.25MHz. The value of the input capacitor depends the input and output voltages, the maximum output current, the inductor value and the noise allowed to put back on the input line. For most applications, a minimum 10µF is required. For applications that run close to the maximum output current limit, input capacitor in the range of 22µF to 47µF is recommended. Maximum Output Current The ISL97519A is powered from the VIN. A high frequency 0.1µF bypass capacitor is recommended to be close to the VIN pin to reduce supply line noise and ensure stable operation. The MOSFET current limit is nominally 2.0A and guaranteed 1.5A when VDD is greater than 2.8V. This restricts the maximum output current, IOMAX, based on Equation 8: Shutdown Control When the EN pin is pulled down, the ISL97519A is shutdown reducing the supply current to