FP6715S6CTR

FP6715 fitipower integrated technology lnc. 85T 5V, 2.5A, 550KHz High Efficiency Low Ripple Synchronous Step-Up Converter Description Features The FP6715 is a high efficiency, fixed frequency 550KHz, current mode PWM boost DC/DC converter which could operate battery such as input voltage down to 2.5V. The converter output voltage can be adjusted to a maximum of 5.25V by an external resistor divider. Besides the converter includes a 0.08Ω N-channel MOSFET switch and 0.12Ω P-channel synchronous rectifier. So no external Schottky diode is required and could get better efficiency near 93%.           The converter is based on a fixed frequency, current mode, pulse-width-modulation PWM controller that goes automatically into PSM mode at light load.      When converter operation into discontinuous mode, the internal anti-ringing switch will reduce interference and radiated electromagnetic energy. The FP6715 is available in a space-saving SOT-23-6 package for portable application. High Efficiency up to 93% Low RDS(ON) Integrated Power MOSFET NMOS 80mΩ / PMOS120mΩ Wide Input Voltage Range: 2.5V to 5.5V Fixed 550KHz Switching Frequency Low-Power Mode for Light Load Conditions ±2.0% Voltage Reference Accuracy PMOS Current Limit for Short Circuit Protection Low Quiescent Current Output Ripple under 200mV. (Scope Full Bandwidth) Fast Transient Response Built-In Soft Start Function Over-Temperature Protection with Auto Recovery Output Overvoltage Protection Space-Saving SOT-23-6 Package Applications     Portable Power Bank Wireless Equipment Handheld Instrument GPS Receiver Pin Assignments Ordering Information S6 Package (SOT-23-6) FP6715□□□ TR: Tape/Reel VIN OUT EN 6 5 C: Green 4 (Marking) 1 2 Package Type S6: SOT-23-6 3 LX GND FB Figure 1. Pin Assignment of FP6715 FP6715-Preliminary 0.1-MAY-2013 SOT-23-6 Marking Part Number Product Code FP6715S6CTR D6G 1 FP6715 fitipower integrated technology lnc. 85T Typical Application Circuit L1 VIN VOUT 5V/1A 10μH 2.5V to 5.5V C1 10μF C2 0.1μF 6 2 4 VIN LX FP6715 GND OUT FB EN 1 C4, C6 0.1μF C3, C5 22μF R1 525K 5 3 R2 100K ON OFF Figure 2. Typical Application Circuit Functional Pin Description Pin Name Pin No. Pin Function EN 4 Logic Controlled Shutdown Input. GND 2 Ground Pin. LX 1 Power Switching Connection. VIN 6 Power Supply Input Pin. OUT 5 Output of the Synchronous Rectifier. FB 3 Voltage Feedback Input Pin. FP6715-Preliminary 0.1-MAY-2013 Connect LX to the inductor and output rectifier. 2 FP6715 fitipower integrated technology lnc. 85T Block Diagram VIN LX PMOS OUT ANTI-RING EN On/Off Control NMOS Body-Diode Switch OSC PWM Control Logic OVP UVLO Anti-Reverse Comparator Isense/Current Limit Slope Comp. PFM Control COMP Error Amp OTP FB Bandgap Reference VIN GND Figure 3. Block Diagram of FP6715 FP6715-Preliminary 0.1-MAY-2013 3 fitipower integrated technology lnc. FP6715 85T Absolute Maximum Ratings (Note 1) ● Supply Voltage VIN --------------------------------------------------------------------------------------------- -0.3V to +6.5V ● LX Voltage VLX -------------------------------------------------------------------------------------------------- -0.3V to +6.5V ● All Other Pins Voltage ----------------------------------------------------------------------------------------- -0.3V to +6.5V ● Maximum Junction Temperature (TJ) --------------------------------------------------------------------- +150°C ● Storage Temperature (TS) ----------------------------------------------------------------------------------- -65°C to +150°C ● Lead Temperature (Soldering, 10sec.) ------------------------------------------------------------------- +260°C ● Package Thermal Resistance (θJA) SOT-23-6 ---------------------------------------------------------------------------------------------- +250°C/W ● Package Thermal Resistance (θJC) SOT-23-6 ---------------------------------------------------------------------------------------------- +130°C/W Note 1：Stresses beyond this listed under “Absolute Maximum Ratings" may cause permanent damage to the device. Recommended Operating Conditions ● Supply Voltage VIN --------------------------------------------------------------------------------------------- +2.5V to +5.5V ● Output Voltage Range ---------------------------------------------------------------------------------------- up to +5.25V ● Operation Temperature Range ------------------------------------------------------------------------------ -40°C to +85°C FP6715-Preliminary 0.1-MAY-2013 4 FP6715 fitipower integrated technology lnc. 85T Electrical Characteristics (VIN=3.3V, TA=25°C, unless otherwise specified.) Parameter VIN Input Supply Voltage Symbol Conditions VIN Min Typ 2.5 Max Unit 5.5 V Input UVLO Threshold VIN Rising 1.85 V Under Voltage Lockout Threshold Hysteresis VIN Falling 0.2 V VIN Supply Current (Switching) VIN=3.3V, VFB=0.8V Measure VIN 300 VIN Supply Current (No switching) VFB=1V Feedback Voltage VFB 2.5V≦VIN≦5.5V 0.784 0.8 500 μA 25 μA 0.816 V High-Side PMOSFET RDS(ON) 120 mΩ Low-Side NMOSFET RDS(ON) 80 mΩ High-Side MOSFET Leakage Current ILX(leak) Low-Side MOSFET Leakage Current Oscillation Frequency VLX=5.5V, VOUT=0V 10 μA VLX=5.5V 10 μA 650 KHz FOSC 450 550 Switch Current Limit VIN=3.3V Short Circuit Trip Point Monitored FB voltage 0.3 V Short Circuit Current Limit VIN = 3.3V 50 mA 90 % Maximum Duty Cycle DMAX VIN=3.3V Line Regulation VIN=2.5V to 5.5V, IOUT=100mA Load Regulation IOUT=0A to 1A 2.5 85 1 OVP Threshold Voltage on OUT Pin OVP Threshold Hysteresis Internal Soft-Start Time VEN (L) EN Input High Voltage VEN (H) EN Input Current IEN % 6 V 500 mV Thermal Shutdown Threshold (Note 2) TSD 1.4 VIN=3.3V % 0.5 1 EN Input Low Voltage Thermal Shutdown Hysteresis A 3 ms 0.4 V V 2 μA 150 °C 30 °C Note 2：Not production tested. FP6715-Preliminary 0.1-MAY-2013 5 fitipower integrated technology lnc. FP6715 85T Application Information Controller Circuit Device Enable The device is based on a current-mode control topology and uses a constant frequency pulse-width modulator to regulate the output voltage. The controller limits the current through the power switch on a pulse by pulse basis. The current sensing circuit is integrated in the device; therefore, no additional components are required. Due to the nature of the boost converter topology used here, the peak switch current is the same as the peak inductor current, which will be limited by the integrated current limiting circuits under normal operating conditions. The device will be shut down when EN is set to GND. In this mode, the regulator stops switching, all internal control circuitry including the low-battery comparator will be switched off, and the load will be disconnected from the input (as described in above synchronous rectifier section). This also means that the output voltage may drop below the input voltage during shutdown. The device is put into operation when EN is set high. During start-up of the converter, the duty cycle is limited in order to avoid high peak currents drawn from the battery. The limit is set internally by the current limit circuit. Synchronous Rectifier The device integrates an N-channel and a Pchannel MOSFET transistor to realize a synchronous rectifier. There is no additional Schottky diode required. Because the device uses a integrated low RDS(ON) PMOS switch for rectification, the power conversion efficiency reaches 93%. A special circuit is applied to disconnect the load from the input during shutdown of the converter. In conventional synchronous rectifier circuits, the backgate diode of the high-side PMOS is forward biased in shutdown and allows current flowing from the battery to the output. This device, however, uses a special circuit to disconnect the backgate diode of the high-side PMOS and so, disconnects the output circuitry from the source when the regulator is not enabled (EN=low). PSM Mode The FP6715 is designed for high efficiency over wide output current range. Even at light load, the efficiency stays high because the switching losses of the converter are minimized by effectively reducing the switching frequency. The controller will enter a power saving mode if certain conditions are met. In this mode, the controller only switches on the transistor if the output voltage trips below a set threshold voltage. It ramps up the output voltage with one or several pulses, and goes again into PSM mode once the output voltage exceeds a set threshold voltage. FP6715-Preliminary 0.1-MAY-2013 Anti-Ringing Switch The device integrates a circuit which removes the ringing that typically appears on the SW node when the converter enters the discontinuous current mode. In this case, the current through the inductor ramps to zero and the integrated PMOS switch turns off to prevent a reverse current from the output capacitors back to the battery. Due to remaining energy that is stored in parasitic components of the semiconductors and the inductor, a ringing on the SW pin is induced. The integrated anti-ringing switch clamps this voltage internally to VIN; therefore, dampens this ringing. Adjustable Output Voltage The accuracy of the output voltage is determined by the accuracy of the internal voltage reference, the controller topology, and the accuracy of the external resistor. The reference voltage has an accuracy of ± 2%. The controller switches between fixed frequency and PSM mode, depending on load current. The tolerance of the resistors in the feedback divider determines the total system accuracy. Design Procedure The FP6715 boost converter family is intended for systems that are powered by a single-cell Ion battery with a typical terminal voltage between 3V to 4.2V. 6 FP6715 fitipower integrated technology lnc. 85T Application Information (Continued) (1) Programming the Output Voltage The output voltage of the FP6715 can be adjusted with an external resistor divider. The typical value of the voltage on the FB pin is 800mV in fixed frequency operation. The maximum allowed value for the output voltage is 5.5V. The current through the resistive divider should be about 100 times greater than the current into the FB pin. The typical current into the FB pin is 0.01µA, and the voltage across R2 is typically 800mV. Based on those two values, the recommended value for R2 is in the range of 800kΩ in order to set the divider current at 1µA. From that, the value of resistor R1, depending on the needed output voltage (VO), can be calculated using Equation 1. R1 R2 O T F -1 800kΩ O T 800m -1 …..(1) (2) Inductor Selection A boost converter normally requires two main passive components for storing energy during the conversion. A boost inductor is required and a storage capacitor at the output. To select the boost inductor, it is recommended to keep the possible peak inductor current below the current limit threshold of the power switch in the chosen configuration. The second parameter for choosing the inductor is the desired current ripple in the inductor. Normally, it is advisable to work with a ripple of less than 20% of the average inductor current. A smaller ripple reduces the magnetic hysteresis losses in the inductor, as well as output voltage ripple and EMI. But in the same way, regulation time at load changes rises. In addition, a larger inductor increases the total system cost. With those parameters, it is possible to calculate the value for the inductor by using Equation 2. N O T- N O T (3) Capacitor Selection The major parameter necessary to define the output capacitor is the maximum allowed output voltage ripple of the converter. This ripple is determined by two parameters of the capacitor, the capacitance and the ESR. It is possible to calculate the minimum capacitance needed for the defined ripple, supposing that the ESR is zero, by using Equation 3. MN O T O TO T N …..(3) Parameter f is the switching frequency and △V is the maximum allowed ripple. The total ripple is larger due to the ESR of the output capacitor. This additional component of the ripple can be calculated using Equation 4. ESR O T RESR …..(4) The total ripple is the sum of the ripple caused by the capacitance and the ripple caused by the ESR of the capacitor. It is possible to improve the design by enlarging the capacitor or using smaller capacitors in parallel to reduce the ESR or by using better capacitors with lower ESR, like ceramics. Tradeoffs must be made between performance and costs of the converter circuit. A 10µF input capacitor is recommended to improve transient behavior of the regulator. A ceramic or tantalum capacitor with a 100nF in parallel placed close to the IC is recommended. …..(2) Parameter is the switching requency and Δ L is the ripple current in the inductor, i.e, 20% x IL. With this calculated value and currents, it is possible to choose a suitable inductor. Care must be taken that load transients and losses in the circuit can lead to higher currents. Also, the losses in the inductor caused by magnetic hysteresis losses and copper losses are a major parameter for total circuit efficiency. FP6715-Preliminary 0.1-MAY-2013 7 fitipower integrated technology lnc. FP6715 85T Application Information (Continued) Layout Considerations As for all switching power supplies, the layout is an important step in the design, especially at high peak currents and high switching frequencies. If the layout is not carefully done, the regulator could show stability problems as well as EMI problems. Therefore, use wide and short traces for the main current path as indicated in bold in Figure 4. The input capacitor, output capacitor and the inductor should be placed as close to the IC as possible. Use a common ground node as shown in Figure 4 to minimize the effects of ground noise. The feedback divider should be placed as close to the IC as possible. VOUT VIN 5 4 C6 6 C4 C2 C1 C3 GND GND L1 LX 1 2 C5 3 R2 R1 Figure 4. Layout Diagram FP6715-Preliminary 0.1-MAY-2013 8 FP6715 fitipower integrated technology lnc. 85T Outline Information SOT-23-6 Package (Unit: mm) SYMBOLS UNIT DIMENSION IN MILLIMETER MIN MAX A 0.90 1.45 A1 0.00 0.15 A2 0.90 1.30 B 0.30 0.50 D 2.80 3.00 E 2.60 3.00 E1 1.50 1.70 e 0.90 1.00 e1 1.80 2.00 L 0.30 0.60 Note：Followed From JEDEC MO-178-C. Carrier Dimensions Life Support Policy Fitipower’s products are not authorized or use as critical components in li e support devices or other medical systems . FP6715-Preliminary 0.1-MAY-2013 9