FP5102/FP5102A 1 Channel Synchronous PWM Controller General Description The FP5102 / A is a DC-DC synchronous buck converter controller IC. It comprises high, low side NMOS gate drivers, boot diode, internal soft start, and over current protection circuit. With +2V to +12V VIN supply voltage, it is suitable for a wide range of applications. Features Operates from +5V to +12V Vcc Supply Voltage Feedback Reference Voltage: 0.8V (±2%) Fixed Frequency Oscillator: 300 / 600KHz Peak Output Driving Capability: 500mA Internal Soft Start Function High-Gain Voltage Mode PWM Control Over Current Protection by detecting Low-side MOS Voltage Drop Package: SOP8 / SOP8 (EP) Applications Graphic Card Telecom and Datacom Applications High Power DC-DC Regulators Typical Application Circuit VIN+2V TO +12V VCC+5V TO +12V VCC COMP BOOT UGATE PSC FP5102 / A VOUT SW FB LGATE GND This datasheet contains new product information. Feeling Technology reserves the rights to modify the product specification without notice. No liability is assumed as a result of the use of this product. No rights under any patent accompany the sales of the product. Rev. 0.63 Website: http://www.feeling-tech.com.tw 1/21 FP5102 / FP5102A Function Block Diagram This datasheet contains new product information. Feeling Technology reserves the rights to modify the product specification without notice. No liability is assumed as a result of the use of this product. No rights under any patent accompany the sales of the product. Rev. 0.63 Website: http://www.feeling-tech.com.tw 2/21 FP5102 / FP5102A Pin Descriptions SOP-8L Name No. I/O Description BOOT 1 P UGATE 2 O High Side Gate Driver Output GND 3 P Ground LGATE 4 O Low Side Gate Driver Output VCC 5 P IC Power Supply FB 6 I Error Amplifier Inverting Input COMP 7 O Error Amplifier Output SW 8 I Switch Signal Input Boosted Power Supply Pin for High Side MOS Gate Driving SOP-8L (EP) 5102 9Fa86L This datasheet contains new product information. Feeling Technology reserves the rights to modify the product specification without notice. No liability is assumed as a result of the use of this product. No rights under any patent accompany the sales of the product. Rev. 0.63 Website: http://www.feeling-tech.com.tw 3/21 FP5102 / FP5102A Marking Information SOP-8L (EP) & SOP-8L Halogen Free: Halogen free product indicator Lot Number: Wafer lot number’s last two digits For Example: 132386TB 86 Internal ID: Internal Identification Code Per-Half Month: Production period indicated in half month time unit For Example: January → A (Front Half Month), B (Last Half Month) February → C (Front Half Month), D (Last Half Month) Year: Production year’s last digit This datasheet contains new product information. Feeling Technology reserves the rights to modify the product specification without notice. No liability is assumed as a result of the use of this product. No rights under any patent accompany the sales of the product. Rev. 0.63 Website: http://www.feeling-tech.com.tw 4/21 FP5102 / FP5102A Ordering Information Part Number FP5102DR-LF FP5102XR-LF FP5102ADR-LF FP5102AXR-LF OSC Freq. Operating Temperature 300KHz -40°C ~ +85 C 600KHz -40°C ~ +85°C Package MOQ Description SOP-8L 2500EA Tape & Reel SOP-8L (EP) 2500EA Tape & Reel SOP-8L 2500EA Tape & Reel SOP-8L (EP) 2500EA Tape & Reel Absolute Maximum Ratings Parameter Symbol Power Supply Voltage VCC BOOT Supply Voltage VBOOT Conditions Min. Typ. -0.6 BOOT to SW (VBOOT-VSW) SW Voltage Max. Unit +15 V +30 V +15 V +15 V VSW -0.6 UGATE Voltage VUGATE VSW -0.3 LGATE Voltage VLGATE -0.6 VCC + 0.3 V -0.6 6 V SOP-8L 0.5 W SOP-8L (EP) 1.3 W FB, COMP Voltage Allowable Power Dissipation Thermal Resistance (Junction to Ambient) Thermal Resistance (Junction to Case) θJA θJC VBOOT + 0.3 V SOP-8L +120 °C / W SOP-8L (EP) +50 °C / W SOP-8L +20 °C / W SOP-8L (EP) +10 °C / W SOP8 (EP) Lead Temperature +260 (soldering, 10sec) °C This datasheet contains new product information. Feeling Technology reserves the rights to modify the product specification without notice. No liability is assumed as a result of the use of this product. No rights under any patent accompany the sales of the product. Rev. 0.63 Website: http://www.feeling-tech.com.tw 5/21 FP5102 / FP5102A IR Re-flow Soldering Curve Note: 1. Suggest IR Re-flow Soldering Profile Condition Recommended Operating Conditions Parameter Symbol Supply Voltage Conditions VCC Min. Typ. Max. Unit 4.3 5 13.2 V Operating Temperature -40 +85 °C Operating Junction Temperature -40 +125 °C DC Electrical Characteristics (VCC= 12V, TA=25°C, unless otherwise specified) Parameter Symbol Conditions Min. Typ. Max. Unit Input Supply Current Standby Current ISHUTDOWN VCOMP=0V Supply Current ISUPPLY UGATE and LGATE open 640 µA 5 mA Enable / Disable UVLO Threshold Voltage VUVLO 3.9 4.1 4.3 V Hysteresis Voltage VHYS 0.3 0.35 0.4 V FP5102 250 300 350 KHz FP5102A 500 600 700 KHz Oscillator Oscillation Frequency Ramp Amplitude f ΔVOSC 1.5 VP-P This datasheet contains new product information. Feeling Technology reserves the rights to modify the product specification without notice. No liability is assumed as a result of the use of this product. No rights under any patent accompany the sales of the product. Rev. 0.63 Website: http://www.feeling-tech.com.tw 6/21 FP5102 / FP5102A DC Electrical Characteristics (Cont.) Parameter Symbol Conditions Min. Typ. Max. Unit 0.784 0.8 0.816 V 5 20 mV Reference Reference Voltage VFB VFB Change with Voltage VFB Change with Temperature ΔVFB VCC=10.8V to 13.2V ΔVFB / ΔT TA = -40°C to 85°C 1 % Error Amplifier Unity Gain Bandwidth Product BW 15 MHz Open Loop DC Gain AVO 88 dB 300 mA Gate Drivers VBOOT ﹣VSW=12V Upper Gate Source Current IUGASR Upper Gate Source Resistance RUGSR Upper Gate Sink Resistance RUGSN Lower Gate Source Current ILGSR VCC=12V, VLGATE =6V Lower Gate Source Resistance RLGSR VCC=12V, VCC ﹣VLGATE=1V 4 6 Ω Lower Gate Sink Resistance RLGSN VCC=12V, VLGATE=1V 2 4 Ω VBOOT ﹣VUGATE=6V VBOOT ﹣VSW=12V VBOOT ﹣VUGATE=1V VBOOT ﹣VSW=12V VUGATE ﹣VSW=1V 7 10 Ω 4 8 Ω 500 mA Protection FB Under Voltage Protection VFBUV 0.3 0.4 0.5 V Over Current Threshold VOC -210 -250 -290 mV Soft-Start Interval TSS 2 3.2 4.2 ms This datasheet contains new product information. Feeling Technology reserves the rights to modify the product specification without notice. No liability is assumed as a result of the use of this product. No rights under any patent accompany the sales of the product. Rev. 0.63 Website: http://www.feeling-tech.com.tw 7/21 FP5102 / FP5102A TYPICAL CHATACTERISTICS UGATE Rising Time UGATE Falling Time CH1:UGATE CH2:LGATE CH3:SW CH1:UGATE Load Transient Response CH3:Vout CH2:LGATE CH3:SW Power On then Trigger OCP CH4:IL CH1:UGATE CH4:IL OCP then Power On Power On then Shorted CH1:UGATE CH4:IL CH1:UGATE CH4:IL This datasheet contains new product information. Feeling Technology reserves the rights to modify the product specification without notice. No liability is assumed as a result of the use of this product. No rights under any patent accompany the sales of the product. Rev. 0.63 Website: http://www.feeling-tech.com.tw 8/21 FP5102 / FP5102A Shorted then Power On Power ON CH1:UGATE CH4:IL CH1:Vin CH2:HGATE CH3:Vout CH4:IL Power OFF CH1:Vin CH2:HGATE CH3:Vout CH4:IL This datasheet contains new product information. Feeling Technology reserves the rights to modify the product specification without notice. No liability is assumed as a result of the use of this product. No rights under any patent accompany the sales of the product. Rev. 0.63 Website: http://www.feeling-tech.com.tw 9/21 FP5102 / FP5102A Function Description Power On Reset The FP5102 / A automatically initializes upon input power VCC. The Power-On Reset (POR) function continually monitors the bias voltage at the VCC pin. The POR threshold level is typically 4.1V at VCC rising. VIN Detection After POR is outstripped, the FP5102 / A continuously generates a 10kHz pulse train with 1μs pulse width to turn on the upper MOSFET for detecting the existence of VIN. FP5102 / A keeps monitoring SW pin voltage during the detection period. When the SW voltage crosses 1.5V two times, VIN existence is recognized and the FP5102 / A initiates its soft start cycle as described in next section. Soft Start After the existence of VIN is detected, the soft-start (SS) begins automatically. The feedback voltage (VFB) is clamped by internal linear ramping up SS voltage during this period, causing PWM pulse width increasing slowly and thus inducing little surge current. The maximum load current is available after the soft-start cycle is completed. Soft-start completes when SS voltage exceeds internal reference voltage (0.8V), the time duration is about 3.2ms. Over Current Protection The FP5102 / A senses the current flowing through lower MOSFET for over current protection (OCP) by sensing the SW pin voltage as shown in the Functional Block Diagram. A 30μA current source flows through the internal resistor 21.6kΩ to SW pin causing 0.65V voltage drop across the resistor. OCP is triggered if the voltage at SW pin (drop of lower MOSFET VDS) is lower than -0.25V when low side MOSFET conducting. Accordingly inductor current threshold for OCP is a function of conducting resistance of lower MOSFET RDS (ON) as : IOCSET 0.25 V R DS( ON) If MOSFET with RDS (ON) = 10mΩ is used, the OCP threshold current is about 25A. Once OCP is triggered, the FP5102 / A enters hiccup mode and re-soft starts again. The FP5102 / A shuts down after OCP hiccups twice. To prevent the over current protection occurs in the normal operating load range, the drift of all This datasheet contains new product information. Feeling Technology reserves the rights to modify the product specification without notice. No liability is assumed as a result of the use of this product. No rights under any patent accompany the sales of the product. Rev. 0.63 Website: http://www.feeling-tech.com.tw 10/21 FP5102 / FP5102A parameters in the above equation should be considered. -The RDS (ON) of MOSFET varies with temperature and gate to source voltage, the user should determine the maximum RDS(ON) in manufacturer’s datasheet. -The parasitic series resistance in PCB’s trace must be considered and added to RDS (ON) in the above equation. -The minimum IOCSET (=-0.21V/RDS (ON)) should be considered over the above equation. Note that the IOCSET is the current flow through the low side MOSFET. IOCSET must be greater than maximum output current add the half of inductor ripple current. That is, IOCSET IO(MAX ) IL(MAX ) 2 LGATE>425ns LGATE=425ns LGATE<425ns LGATE<<425ns To avoid the gate transition noise and ringing on the SW pin, the actual monitoring of the bottom-side MOSFET's on-resistance starts 200ns (nominal) after the LGATE rising edge. The This datasheet contains new product information. Feeling Technology reserves the rights to modify the product specification without notice. No liability is assumed as a result of the use of this product. No rights under any patent accompany the sales of the product. Rev. 0.63 Website: http://www.feeling-tech.com.tw 11/21 FP5102 / FP5102A monitoring ends when the LGATE goes low. The OCP can be detected anywhere within the above window. If the regulator is running at high UGATE duty cycles (around 75% for 600kHz or 87% for 300kHz operation), then the LGATE pulse width may be not wide enough for the OCP to properly sample the VSW. For those cases, if the LGATE is too narrow (or not there at all) for 3 consecutive pulses, then the third pulse will be stretched and/or inserted to the 425ns minimum width. This allows for OCP monitoring every three pulses under this kind of condition. This can introduce a small pulse-width error on the output voltage, which will be corrected on the next pulse; and the output ripple voltage will have an unusual 3-clock pattern, which may look like jitter. This datasheet contains new product information. Feeling Technology reserves the rights to modify the product specification without notice. No liability is assumed as a result of the use of this product. No rights under any patent accompany the sales of the product. Rev. 0.63 Website: http://www.feeling-tech.com.tw 12/21 FP5102 / FP5102A Application Information Frequency Compensation The FP5102 / A is a voltage-mode controller for a synchronous-rectified buck converter. Figure 1 highlights the voltage-mode control loop for a synchronous-rectified buck converter. The output voltage (VOUT) is regulated to the reference voltage level. The error amplifier (ERROR AMP) output (VCOMP) is compared with the oscillator (OSC) triangular wave to provide a pulse-width modulated (PWM) wave with an amplitude of VIN at the SW node. The PWM wave is smoothed by the output LC filter (LOUT and COUT). The modulator transfer function is the small-signal transfer function of VOUT / VCOMP. This function is dominated by a DC gain and the output filter (LOUT and COUT), with a double-pole break frequency at FLC and a zero at FESR. The DC gain of the modulator is the input voltage (VIN) divided by the peak-to-peak oscillator voltage (ΔVOSC). The following equations define the modulator break frequencies as a function of the output LC filter: FLC 1 2 L OUT C OUT The ESR zero is contributed by the ESR associated with the output capacitance. Note that this requires the output capacitor should have enough ESR to satisfy stability requirements. The ESR zero of the output capacitor is expressed as following: FESR 1 2 C OUT ESR This datasheet contains new product information. Feeling Technology reserves the rights to modify the product specification without notice. No liability is assumed as a result of the use of this product. No rights under any patent accompany the sales of the product. Rev. 0.63 Website: http://www.feeling-tech.com.tw 13/21 FP5102 / FP5102A VIN DRIVER OSC PWM COMPARATOR ΔVOSC LOUT _ + DRIVER VOUT COUT ESR ZFB Vcomp _ + ERROR ZIN AMP Vref DETAILED COMPENSATION COMPONENTS C2 VOUT ZFB C1 R2 ZIN R3 C3 R1 COMP _ FB + Vref Figure 1 Voltage-mode Buck Converter Compensation Design The compensation network consists of the error amplifier (internal to the FP5102 / A) and the impedance networks ZIN and ZFB. The goal of the compensation network is to provide a closed-loop transfer function with the highest 0dB crossing frequency (F0dB) and adequate phase margin. Phase margin is the difference between the closed loop phase at F0dB and 180 degrees. The equations below relate the compensation network’s poles, zeros, and gain to the components (R1, R2, R3, C1, C2, and C3), shown in Figure 1. FZ1 FP1 1 2R 2C2 1 CC 2R2 ( 1 2 ) C1 C2 This datasheet contains new product information. Feeling Technology reserves the rights to modify the product specification without notice. No liability is assumed as a result of the use of this product. No rights under any patent accompany the sales of the product. Rev. 0.63 Website: http://www.feeling-tech.com.tw 14/21 FP5102 / FP5102A FZ2 1 2C 3 (R 1 R 3 ) FP2 1 2R 3 C 3 Use the following steps to locate the poles and zeros of the compensation network. 1. Pick gain (R2/R1) for the desired converter bandwidth. Choose a value for R1, usually between 1K and 10K. Select the desired zero crossover frequency FO : (1/ 5 ~ 1/ 10) FS FESR Use the following equation to calculate R2: R2 VOSC FO R1 VIN FLC 2. Place the first zero below the filter’s double pole (~75% FLC). FZ1 0.75 FLC Calculate the C2 by the equation: C2 1 2 R 2 FLC 0.75 3. Place the first pole at the ESR zero. FP1 FESR Calculate the C1 by the equation: C1 C2 2 R 2 C2 FESR 1 4. Place the second zero at filter’s double pole. 5. Place the second pole at half the switching frequency. FP2 0.5 FS FZ 2 FLC Combine above two equations will get the following component equations R3 C3 R1 FS 1 2 FLC 1 R3 FS 6. Check the gain against the error amplifier’s open loop gain. 7. Estimate phase margin. Repeat if necessary. This datasheet contains new product information. Feeling Technology reserves the rights to modify the product specification without notice. No liability is assumed as a result of the use of this product. No rights under any patent accompany the sales of the product. Rev. 0.63 Website: http://www.feeling-tech.com.tw 15/21 FP5102 / FP5102A Figure 2 shows an asymptotic plot of the DC-DC converter’s gain vs. frequency. The actual modulator gain has a high gain peak due to the high Q factor of the output filter and is not shown in Figure 2. Using the above guidelines should give a compensation gain similar to the red curve plotted. The open-loop error amplifier gain bounds the compensation gain. Check the compensation gain at FP2 with the capabilities of the error amplifier. The closed-loop gain is constructed on the graph of Figure 2 by adding the modulator gain (in dB) to the compensation gain (in dB). This is equivalent to multiply the modulator transfer function by the compensation transfer function and plotting the gain. The compensation gain uses external impedance networks ZFB and ZIN to provide a stable high bandwidth overall loop. A stable control loop has a gain crossing with a –20dB/decade slope and a phase margin GAIN (dB) greater than 45°. Include worst-case component variations when determining phase margin. Figure 2. Asymptotic Bode Plot of Converter Gain This datasheet contains new product information. Feeling Technology reserves the rights to modify the product specification without notice. No liability is assumed as a result of the use of this product. No rights under any patent accompany the sales of the product. Rev. 0.63 Website: http://www.feeling-tech.com.tw 16/21 FP5102 / FP5102A Component Selection Input capacitor Selection The voltage rating at maximum ambient temperature should be 1.25 to 1.5 times the maximum input voltage. More conservative approaches can bring the voltage rating up to 2 times the maximum input voltage. High frequency decoupling, which is highly recommended, is implemented through the use of ceramic capacitors in parallel with the bulk capacitor filtering. In switch mode, the input current is discontinuous in a buck converter. The source current of the high-side MOSFET is a square wave. To prevent large voltage transients, a low ESR input capacitor sized for the maximum RMS current must be used. The RMS value of input capacitor current can be calculated by: IRMS IO _ MAX VO VIN V 1 O VIN It can be seen that when VO is half of VIN, CIN is under the worst current stress. The worst current stress on CIN is IO_MAX/2. Inductor Selection The value of the inductor is selected based on the desired ripple current. Large inductance gives low inductor ripple current and small inductance result in high ripple current. However, the larger value inductor has a larger physical size, higher series resistance, and/or lower saturation current. In experience, the value is to allow the peak-to-peak ripple current in the inductor to be 10%~20% maximum load current. The inductance value can be calculated by: L ( VIN VO ) VO ( VIN VO ) VO f IL VIN f 2 (10% ~ 20%)IO VIN The inductor ripple current can be calculated by: IL VO V 1 O f L VIN Choose an inductor that does not saturate under the worst-case load conditions even at the highest operating temperature. (The load current plus half the peak-to-peak inductor ripple current). The peak Inductor current is: IL _ PEAK IO IL 2 This datasheet contains new product information. Feeling Technology reserves the rights to modify the product specification without notice. No liability is assumed as a result of the use of this product. No rights under any patent accompany the sales of the product. Rev. 0.63 Website: http://www.feeling-tech.com.tw 17/21 FP5102 / FP5102A MOSFET Selection There are three major aspects of power loss that are associated with the MOSFET. These are conduction losses, switching losses, and gate drive power losses. PD(MOSFET ) Pconduction Pswitching Pgate 2 PD(HIigh _ MOSFET ) IO R DS( ON) D 1 VIN IO ( t r t f ) f s Q Gate VGS f s 2 2 PD(HIigh _ MOSFET ) IO R DS( ON) (1 D) 1 Vf IO ( t r t f ) f s Q Gate VGS f s 2 VIN = Input Voltage for Vf = Lower side turn on VDS IO = Output Current D = Duty Cycle tr = MOSFET rising time tf fs = MOSFET rising time = Switching Frequency Q Gate = MOSFET gate charge VGS = MOSFET gate voltage Output Capacitor Selection The output capacitor is required to maintain the DC output voltage. Low ESR capacitors are preferred to keep the output voltage ripple low. In a buck converter circuit, output ripple voltage is determined by inductor value, switching frequency, output capacitor value and ESR. The output ripple is determined by: 1 VO IL ESR COUT 8 f C OUT Where f = operating frequency, COUT= output capacitance and ΔIL = ripple current in the inductor. For a fixed output voltage, the output ripple is highest at maximum input voltage since ΔIL increases with input voltage. The most commonly used choice for output bulk capacitors is aluminum electrolytic capacitors because of their low cost and low ESR. Due to the capacitor ESR varies with frequency, user should consider the ESR value rated at the PWM frequency. The output capacitance should also include a number of small capacitance value ceramic capacitors placed as close as possible to the chip; 0.1μF and 0.01μF are recommended values. This datasheet contains new product information. Feeling Technology reserves the rights to modify the product specification without notice. No liability is assumed as a result of the use of this product. No rights under any patent accompany the sales of the product. Rev. 0.63 Website: http://www.feeling-tech.com.tw 18/21 FP5102 / FP5102A PC Board Layout Checklist The switching power converter layout is critical to achieve low power losses, clean waveforms, and stable operation. It needs careful attention. Following are specific recommendations for good board layout: 1. Keep the high current traces and load connections as short as possible. 2. Use thick copper plated PCB whenever possible to achieve higher efficiency. 3. Keep the loop area between the SW node, low-side MOSFET, Inductor, and the output capacitor as small as possible. 4. Route high DV / Dt signals, such as SW node, away from the error amplifier input/output pins. Keep both the high DV / Dt signals and the error amplifier input/output signals as short as possible. 5. Place VCC ceramic decoupling capacitors very close to VCC pin. 6. All input signals are referenced with respect to GND pin. Dedicate large copper area of the PCB for a GND plane. 7. Minimize GND loops in the layout to avoid EMI-related issues. 8. Use wide traces for the lower gate drive to keep the drive impedances low. 9. Use wide land areas with appropriate thermal vias to effectively remove heat from the MOSFETs. 10. Preserve the snubber circuit to minimize high frequency ringing at SW node for EMI issues. This datasheet contains new product information. Feeling Technology reserves the rights to modify the product specification without notice. No liability is assumed as a result of the use of this product. No rights under any patent accompany the sales of the product. Rev. 0.63 Website: http://www.feeling-tech.com.tw 19/21 FP5102 / FP5102A Package Outline SOP-8L UNIT: mm Symbols Min. (mm) Max. (mm) A 1.346 1.752 A1 0.101 0.254 A2 1.498 D 4.800 4.978 E 3.810 3.987 H 5.791 6.197 L 0.406 1.270 θ° 0° 8° Note: 1. Package dimensions are in compliance with JEDEC outline: MS-012 AA. 2. Dimension “D” does not include molding flash, protrusions or gate burrs. 3. Dimension “E” does not include inter-lead flash or protrusions. This datasheet contains new product information. Feeling Technology reserves the rights to modify the product specification without notice. No liability is assumed as a result of the use of this product. No rights under any patent accompany the sales of the product. Rev. 0.63 Website: http://www.feeling-tech.com.tw 20/21 FP5102 / FP5102A SOP-8L (EP) UNIT: mm Symbols Min. (mm) Max. (mm) A 1.346 1.752 A1 0.050 0.152 A2 1.498 D 4.800 4.978 E 3.810 3.987 H 5.791 6.197 L 0.406 1.270 θ° 0° 8° Min. (mm) Max. (mm) Exposed PAD Dimensions: Symbols E1 2.184 REF D1 2.971 REF Note: 1. Package dimensions are in compliance with JEDEC outline: MS-012 AA. 2. Dimension ”D” does not include molding flash, protrusions or gate burrs. 3. Dimension “E” does not include inter-lead flash or protrusions. This datasheet contains new product information. Feeling Technology reserves the rights to modify the product specification without notice. No liability is assumed as a result of the use of this product. No rights under any patent accompany the sales of the product. Rev. 0.63 Website: http://www.feeling-tech.com.tw 21/21