XC8113B

XenCreator XC8113B High-Efficiency,3A, 18V, 500KHz Synchronous,Step-Down Converter FEATURES GENERAL DESCRIPTION The XC8113B is a high-frequency, synchronous, rectified, step-down, switch-mode converter with internal power MOSFETs. It offers a very compact solution to achieve a 3A continuous output current over a wide input supply range, with excellent load and line regulation. The XC8113B has synchronous-mode operation for higher efficiency over the output current-load range. Current-mode operation provides fast transient response and eases loop stabilization. Protection features include over-current protection and thermal shutdown. The XC8113Brequires a minimal number of readily available, standard external components and is available in a spacesaving TSOT23-6L package. ● 3.6 Vto 18V input voltage ● Output adjustable from 0.8V to 15V ● Output current up to 3A ● Integrated 110mΩ/58mΩ power MOSFET switches ● Shutdown current 3μA typical ● Efficiency up to 95% ● Fixed frequency 500KHz ● Internal soft start ● Over current protection and Hiccup ● Over temperature protection ● RoHS Compliant and 100% Lead (Pb) Free APPLICATIONS ● Digital Set-top Box (STB) ● Tablet Personal Computer (Pad) ● Flat-Panel Television and Monitors ● Digital Video Recorder (DVR) ● Portable Media Player (PMP) ● General Purposes TYPICAL APPLICATIONS XC8113B XC8113B v.1.00 - 1- www.xencreator.com XenCreator XC8113B PACKAGE/ORDER INFORMATION Order Part Num ber XC811 3B Packa ge SOT23-6L FUNCTIONAL PIN DESCRIPTION PIN NAME TYPE FUNC TION DESCR IPTIONS 1 BOOT I High-Side Gate Drive Boost Input. BOOT supplies the drive for the highside N-Channel MOSFET switch. Connect a 0.1μF or greater capacitor from SW to BOOT to power the high side switch. 2 GND I Ground. 3 FB I/O 4 EN G 5 IN I/O 6 SW XC8113B v.1.00 I Feedback Input. FB senses the output voltage to regulate that voltage. Drive FB with a resistive voltage divider from the output voltage. The feedback threshold is 0.6V. Enable Input. EN is a digital input that turns the regulator on or off. Drive EN high to turn on the regulator, drive it low to turn it off. Pull up with 100kΩ resistor for automatic startup. Power Input. IN supplies the power to the IC, as well as the step-down converter switches. Drive IN with a 4.75V to 18V power source. Bypass IN to GND with a suitably large capacitor to eliminate noise on the input to the IC. Power Switching Output. SW is the switching node that supplies power to the output. Connect the output LC filter from SW to the output load. Note that a capacitor is required from SW to BOOT to power the high-side switch. - 2- www.xencreator.com XenCreator XC8113B Function Block Diagram XC811 3B ABSOLUTE MAXIMUM RATINGS PARAMETER ABSOLUTE MAXIMUM RATINGS UNIT VIN -0.3 to 20 V VSW -0.3 to VIN+0.3 V VSW -0.3 to VSW+6 V VBOOT -0.3 to 6 V Continuous Power Dissipation(TA =+25℃) 1.25 W Junction Temperature 150 °C Lead Temperature 260 °C -65 to 150 °C Thermal Resistance θJA 100 °C /W Thermal Resistance θJC 55 °C /W All Other Pins Storage Temperature XC8113B v.1.00 - 3- www.xencreator.com XenCreator XC8113B RECOMMENDED OPERATING CONDITIONS PARAMETER RECOMMENDED UNIT Supply Voltage VIN 3 . 6 to 18 V 0 .6 to VIN-3V Output Voltage VOUT V -40 to 125 Operating Junction Temp.(TJ) °C ELECTRICAL CHARACTERISTICS (TA = +25°C, VIN = +12V, unless otherwise noted.) PARAMETER SYMBOL Supply Voltage VIN VOUT Output Voltage Shutdown Supply Current MIN MAX UNIT 3.6 18 V 0.8 15 V 6 µA VEN = 0V Supply Current Feedback Voltage TEST CONDITIO NS 3 4.75V ≤ VIN ≤ 18V 0.588 High-Side Switch-On Resistance * Low-side Switch-On Resistance * V AEA 1000 V/V RDS(ON)1 RDS(ON)2 110 58 mΩ mΩ VEN = 0V, VSW = 0V, TA = +125°C Upper Switch Current Limit Minimum Duty Cycle Lower Switch Current Limit From Drain to Source Oscillation Frequency FOSC1 Short Circuit Oscillation Maximum Duty Cycle FOSC2 DMAX VFB = 0V VFB = 0.5V VEN Falling VEN Rising VIN Rising Soft-Start Period Thermal Shutdown * XC8113B v.1.00 0.612 V High-Side Switch Leakage Current Minimum On Time * EN Falling Threshold Voltage EN Rising Threshold Voltage Input Under Voltage Lockout Threshold Input Under Voltage Lockout Threshold Hysteresis 0.6 0.88 Feedback Over-voltage Threshold Error Amplifier Voltage Gain * mA 0.7 VEN = 2.0V, VFB = 1V VFB TYP - 4- 10 3.7 µA 4.3 A 0 A 600 KHz 400 500 100 125 90 KHz % 120 1.22 1.32 3.75 ns V V V 200 mV 1 150 ms °C www.xencreator.com XenCreator XC8113B TYPICAL PERFORMANCE CHARACTERISTICS VIN = 12V, VO = 3.3V, L1 = 4.7μH, C1 = 10μF, C2 = 22μF x 2, TA = +25°C, unless otherwise noted. Start UP & Inrush Current 12V→3.3V (Load 1A) Shut Down (Iout 1A→Shut down) Vout Vout VEN VEN ISW ISW Output Ripple (12V => 3.3V, Load=2A) Output Ripple (12V => 3.3V, Load=1A) Vout Vout ISW ISW Dynamic Load (Iload=0.2A_1.2AVout=3.3V) Output Ripple (12V => 3.3V, Load=0A) Vout Vout ISW ISW Short Circuit Protection Vout ISW XC8113B v.1.00 - 5- www.xencreator.com XenCreator XC8113B TYPICAL PERFORMANCE CHARACTERISTICS Efficiency XC8113B v.1.00 Efficiency - 6- www.xencreator.com XenCreator XC8113B Overview The XC8113B is a synchronous rectified, current-mode, step-down regulator. It regulates input voltages from 4.7V to 18V down to an output voltage as low as 0.8V, and supplies up to 3A of load current.The XC8113B uses current-mode control to regulate the output voltage. The output voltage is measured at FB through a resistive voltage divider and amplified through the internal transconductance error amplifier. The converter uses internal N-Channel MOSFET switches to step-down the input voltage to the regulated output voltage. Since the high side MOSFET requires a gate voltage greater than the input voltage, a boost capacitor connected between SW and BOOT is needed to drive the high side gate. The boost capacitor is charged from the internal 5V rail when SW is low.When the XC8113B FB pin exceeds 10% of the nominal regulation voltage of 0.8V, the over voltage comparator is tripped, forcing the high-side switch off. : Setting the Output Voltage Inductor Selection The external resistor divider sets the output voltage.The feedback resistor R1 also sets the feedback-loop bandwidth through the internal compensation capacitor (see the Typical Application circuit). Choose R1 around 10kΩ, and R2 by: The inductor is required to supply constant current to the output load while being driven by the swi tched input voltage. A larger value inductor will re sult in less ripple current that will result in lower out put ripple voltage. However, the larger value inductor will have a larger physical size, higher series resistance, and/or lower saturation current. A good rule for determining the inductance to use is to allow the peak-to-peak ripple current in the indu ctor to be approximately 30% of the maximum switch current limit. Also, make sure that the peak inductor current is below the maximum switch current limit. The inductance value can be calculated by: Use a network below for when V OUT is low L = [ VOUT / (fS × ΔIL) ] × (1 − VOUT/VIN) Figure 1: Network. Where VOUT is the output voltage, VIN is the input voltage, fS is the switching frequency, and ΔIL is the peak-to-peak inductor ripple current. Choose an inductor that will not saturate under the maximum inductor peak current. The peak inductor current can be calculated by: Table 1 lists the recommended T-type resistors value for common output voltages. VOUT (V) R1 (KΩ) R2 (KΩ) Rt(KΩ) COUT (μF) 1.05 1.2 1.8 2.5 3.3 20.5 30.1 40.2 40.2 40.2 82 60.4 32.4 19.1 13 82 82 56 33 33 44 44 44 44 44 5 40.2 7.68 33 44 ILP = I LOAD + [ VOUT / (2 × fS × L) ] × (1 − VOUT/VIN) Where ILOAD is the load current.The choice of which style inductor to use mainly depends on the price vs.size requirements and any EMI requirements. Table 1: Resistor selection for common output voltages. Rt is used to set control loop’s bandwidth, which is proportional to the relation by R1, R2, RT:1/[(Rt+15k)*(1+R1/R2)+R1] So Increase RT & Decrease R1&R2 value(keeping R1/R2 ratio), the bandwidth can be kept the same(the relation value need to be the same) XC8113B v.1.00 - 7- www.xencreator.com XenCreator XC8113B Input Capacitor Selection The input current to the step-down converter is discontinuous, therefore a capacitor is required to supply the AC current to the step-down converter while maintaining the DC input voltage. Use low ESR capacitors for the best performance. Ceramic capacitors are preferred, but tantalum or low-ESR electrolytic capacitors may also suffice. Choose X5R or X7R dielectrics when using ceramic capacitors. Since the input capacitor (C1) absorbs the input switching current it requires an adequate ripple current rating. The RMS current in the input capacitor can be estimated by: IC1 = I LOAD × [ (VOUT/VIN) × (1 − VOUT/VIN) ] 1/2 The worst-case condition occurs at VIN = 2VOUT, where IC1 = ILOAD /2. For simplification, choose the input capacitor whose RMS current rating greater than half of the maximum load current. The input capacitor can be electrolytic, tantalum or ceramic. When using electrolytic or tantalum capacitors, a small, high quality ceramic capacitor, i.e. 0.1μF, should be placed as close to the IC as possible. When using ceramic capacitors, make sure that they have enough capacitance to provide sufficient charge to prevent excessive voltage ripple at input. The input voltage ripple for low ESR capacitors can be estimated by: ΔVIN = [ ILOAD/(C1 × fS) ] × (VOUT/VIN) × (1 − VOUT/VIN) Where C1 is the input capacitance value. Optional Schottky Diode Selection During the transition between high-side switch and low-side switch, the body diode of the low-side power MOSFET conducts the inductor current. The forward voltage of this body diode is high. An optional Schottky diode may be paralleled between the SW pin and GND pin to improve overall efficiency. Table 2 lists example Schottky diodes and their Manufacturers. Part Number B130 Voltage and Current Rating 30V, 1A Diodes Inc. SK13 MBRS130 30V, 1A 30V, 1A Diodes Inc. International Rectifier Vendor Table 2: Diode selection guide. Output Capacitor Selection The output capacitor is required to maintain the DC output voltage. Ceramic, tantalum, or low ESR electrolytic capacitors are recommended. Low ESR capacitors are preferred to keep the output voltage ripple low. The output voltage ripple can be estimated by: ΔVOUT = [ VOUT/(fS × L) ] × (1 − VOUT/VIN)× [ RESR + 1 / (8 × fS × C2) ] Where C2 is the output capacitance value and RESR is the equivalent series resistance (ESR) value of the output capacitor.In the case of ceramic capacitors, the impedance at the switching frequency is dominated by the capacitance. The output voltage ripple is mainly caused by the capacitance. For simplification, the output voltage ripple can be estimated by: ΔVOUT = [ VOUT/(8 × fS2 × L × C2) ] × (1 − VOUT/VIN) In the case of tantalum or electrolytic capacitors, the ESR dominates the impedance at the switching frequency. For simplification, the output ripple can be approximated to: ΔVOUT = [ VOUT/(fS × L) ] × (1 − VOUT/VIN) × RESR The characteristics of the output capacitor also affect the stability of the regulation system. The XC8113B can be optimized for a wide range of capacitance and ESR values. XC8113B v.1.00 - 8- www.xencreator.com XenCreator XC8113B External Bootstrap Diode Selection An external bootstrap diode may enhance the efficiency of the regulator, the applicable conditions of external BOOT diode are: ● VOUT = 5V or 3.3V; and ● Duty cycle is high: D = VOUT/VIN > 65% XC8113B XC8113B Figure 2: Add optional external bootstrap Figure 3: Add a Schottky diode to promote efficiency diode to enhance efficiency. when VIN ≤ 6V. In these cases, an external BOOT diode is recommended from the output of the voltage regulator to BOOT pin, as shown in Figure 2. The recommended external BOOT diode is IN4148, and the BOOT capacitor is 0.1 ~ 1μF. When VIN ≤ 6V, for the purpose of promote the efficiency,it can add an external Schottky diode between IN and BOOT pins, as shown in Figure 3. PC BOARD LAYOUT PCB layout is very important to achieve stable operation. Please follow the guidelines below. 1) Keep the path of switching current short and minimize the loop area formed by Input capacitor, high-side MOSFET and low-side MOSFET. 2) Bypass ceramic capacitors are suggested to be put close to the VIN Pin. 3) Ensure all feedback connections are short and direct. Place the feedback resistors and compensation components as close to the chip as possible. 4) Rout SW away from sensitive analog areas such as FB. 5) Connect IN, SW, and especially GND respectively to a large copper area to cool the chip to improve thermal performance and long-term reliability. 6) Make sure Vcc capacitor (C6) as close to the IC as possible. BOM of XC8113B Please refer to the Typical Application Circuit. Item Reference Part 1 C1 10μF 2 C5 100nF 3 C7 0.1μF 4 R4 100K Vout = 5.0V Vout = 3.3V Vout = 2.5V Vout = 1.8V Vout = 1.2V L1 6.8μH 6.8μH 4.7μH 3.3μH 2.2μH R1 40.2K 40.2K 40.2K 40.2K 20.5K R2 7.68K 13K 19.1K 32.4K 41.2K C2 22μF×2 22μF×2 22μF×2 22μF×2 22μF×2 Table 4: BOM selection table II. Table 3: BOM selection table I. XC8113B v.1.00 0 - 9- www.xencreator.com XenCreator XC8113B PACKAGE SOT23-6L D C B e A b H A1 L Symbol A A1 B b C D e H L XC8113B v.1.00 Dimensions in mm Min Max 0.700 0.900 0.000 0.100 1.600 1.700 0.350 0.500 2.650 2.950 2.820 3.020 0.950 BSC 0.080 0.200 0.300 0.600 - 10 - Dimensions in Inch Min Max 0.028 0.035 0.000 0.004 0.063 0.067 0.014 0.020 0.104 0.116 0.111 0.119 0.037 BSC 0.003 0.008 0.012 0.024 www.xencreator.com