NCP4305DGEVB NCP4305 Synchronous Rectification Evaluation Board User's Manual www.onsemi.com Table 1. GENERAL PARAMETERS SMPS Type Supply Voltage Reverse Voltage Effective Resistance Flyback, QR 5−35 V 150 V 10 mW EVAL BOARD USER’S MANUAL Description This evaluation board user’s manual describes a high efficiency synchronous rectification evaluation board that can easily replace a secondary side rectification diode in an SMPS. The NCP4305 is used as synchronous rectification controller. The evaluation board has very few external components and illustrates how small and effective such a design can be. The NCP4305 features a very precise 0 mV turn-off comparator that supports even very low current flowing through the MOSFET even when very low RDSON synchronous MOSFETs is used. NCP4305 can be used in application working in CCM without external synchronization (it is optional) thanks to very low propagation delay and strong driver. Board has also assembled LLD circuit with components with value close to typical 65 kHz flyback application (adjust to used application is needed). Key Features • • • • • • • • • • Precise Turn-off Comparator Wide Input Voltage Range High Operation Frequency Strong MOSFET Driver High Efficiency Adjustable Minimum On and Off Times Light Load Detection Feature External Synchronization Capability for High Efficiency Operation in CCM Mode (Optional) Capable to Operate in Positive and Negative Branch Small size Figure 1. NCP4305 Evaluation Board © Semiconductor Components Industries, LLC, 2016 January, 2016 − Rev. 1 1 Publication Order Number: EVBUM2349/D NCP4305DGEVB Connection Diagram VCC A) B) Figure 2. Possible Connections in to Circuit The evaluation board can be connected in circuit where the rectification diode is in the positive or negative branch. When connection to a positive branch is used, it is necessary to use an external power supply (or auxiliary winding with rectification) to provide power to the evaluation board. VCC should be referenced to A1 or A2 points. Evaluation Board Schematic MIN_TOFF VCC DRV GND GND RG 0W IC1 2 3 RMIN_TON 15 kW RMIN_TOFF 22 kW RMIN_TOFFM NU GND RLLD1 39 kW DRV MIN_TOFF GND MIN_TON LLD CS TRIG/DIS NCP4305S08 RLLDD GND GND RLLD2 39 kW CLLD1 33 nF 4 VCC NU RLLD3 6.8 kW 7 GND M1 IRFS4115 6 RCS 0W 5 A1 CSNB 1.2 nF/200 V min C TRIG/DIS RMAX_TONM NU GND D4 BAS20 CLLD2 10 nF 8 RMAX_TON 1 kW 1 A2 RSNB2 NU C2 1 mF/35 V min RGD 10 kW C1 100 nF GND RSNB1 15 kW GND D1 BAS20 LLD1 LLD Figure 3. Schematic of the NCP4305 www.onsemi.com 2 NCP4305DGEVB LLD circuit consists of CLLD1, CLLD2, RLLD1, RLLD2, RLLD3 and D4. Purpose of circuit is to measure conduction duty cycle. When output power is low, conduction time is also low so voltage at CLLD1 is lower. Usually time constant of whole circuitry is low so voltage at LLD pin is smooth also in skip mode. The evaluation board was designed to support a minimal external component count implementation. C1 and C2 are decoupling capacitors. They should be placed as close as possible to the VCC and GND pins. Resistors RMIN_TON and RMIN_TOFF are used to set the protection interval when the synchronous MOSFET is turned on and off. Resistor RMIN_TOFFM is placed there to support a situation when an external circuit provides control for minimum off-time modulation. This is needed only in situations when the minimum off-time cannot be set across the whole range of power supply operation. Resistor RMAX_TON is for normal version only pull down for TRIG pin for Q version it is used to set maximum on-time (used for QR application) and RMAX_TONM is only protection resistor for normal version and for Q version it is only for max_ton modulation (if needed). A position for a gate resistor RG is provided in case there is a need to slow down the MOSFET switching process. The turn-off (and also the turn-on) threshold can be lowed when resistor RCS is used, but it is recommended to keep it zero. Components CSNB, RSNB1 and RSNB2 form a snubber circuit. Circuit Layout The PCB consists of a 2 layer FR4 board with 35 mm copper cladding. All components are surface mount and most of the components that may require adjustment are on the same side and use 1206 values for easy rework. Critical component such as blocking capacitors C1 and C2 have to be placed carefully near the IC. The synchronous driver path to the MOSFET was done with very low resistance and parasitic inductance to minimize emissions and minimize turn-on and turn-off times. The same is true for the CS pin. For the CS pin, a kelvin contact was done to be able to sense the voltage directly at the drain. Improper connection of the GND and CS connects can impact the turn-off process especially when a very low RDSON MOSFET is used. Figure 4. Top Layer Figure 5. Bottom Layer www.onsemi.com 3 NCP4305DGEVB Figure 6. Top Side Components Figure 7. Bottom Side Components www.onsemi.com 4 NCP4305DGEVB Figure 8. Evaluation Board Photo − Top Side Figure 9. Evaluation Board Photo − Bottom Side www.onsemi.com 5 NCP4305DGEVB Table 2. BILL OF MATERIALS FOR NCP4305 PUT-IN BOARD D2PAK (Note 1) Value Tolerance Footprint Manufacturer Manufacturer Part Number Substitution Allowed Ceramic Capacitor 100 nF 10% 1206 Kemet C1206X104K5RACTU Yes Ceramic Capacitor 1 mF/50 V 10% 1206 Kemet C1206X105K5RACTU Yes 1 Ceramic Capacitor 33 nF 10% 1206 Kemet C1206X333KBRACTU Yes CLLD2 1 Ceramic Capacitor 10 nF 10% 1206 Kemet C1206X103K5RACTU Yes CSNB 1 Ceramic Capacitor 1.2 nF/200 V 5% Through Hole TDK Corporation FK24C0G2E122J Yes D1, D4 2 Switching Diode, High Voltage BAS20HT1G − SOD−323 ON Semiconductor BAS20HT1G Yes IC1 (Note 2) 1 Secondary Side Synchronous Rectification Controller NCP4305D − SOIC−08 ON Semiconductor NCP4305DDR2G No M1 1 N-Channel Power MOSFET IRFS4415 − D2PAK International Rectifier IRFS4115TRLPBF Yes RCS, RG 2 Resistor SMD 0W 5% 1206 Yageo RC1206JR−070RL Yes RGD 1 Resistor SMD 10 kW 1% 1206 Yageo RC1206FR−0710KL Yes RLLD1, RLLD2 2 Resistor SMD 39 kW 1% 1206 Yageo RC1206FR−0739KL Yes RLLD3 1 Resistor SMD 6.8 kW 1% 1206 Yageo RC1206FR−076K8L Yes RLLDD, 3 Resistor SMD NU − 1206 − − Yes Parts Qty Description C1 1 C2 1 CLLD1 RMAX_TONM, RMIN_TOFFM RMAX_TON 1 Resistor SMD 1.0 kW 1% 1206 Yageo RC1206FR−071KL Yes RMIN_TOFF 1 Resistor SMD 22 kW 1% 1206 Yageo RC1206FR−0722KL Yes RMIN_TON 1 Resistor SMD 15 kW 1% 1206 Yageo RC1206FR−0715KL Yes RSNB1 1 Resistor 15 W 1% Through Hole Vishay BC Components MRS25000C1509FRP00 Yes RSNB2 1 Resistor NU − Through Hole − − Yes 1. 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