Reference Design RD-402

Transcription

1 Reference Design RD Fairchild Motion SPM 5 SuperFET Series This reference design supports designs using Fairchild s Motion SPM 5 SuperFET series of products. It should be used in conjunction with the SPM 5 SuperFET series datasheets and Fairchild s technical support team. Please visit Fairchild s website at Application Home Appliance (Refrigerator) Fairchild Devices FSB50660SF, FSB50660SFT, FSB50760SF, FSB50760SFT Input Voltage Range Typical Power Rating Topology 300~400 V DC 150 W~200 W 3-Phase Inverter Key Features 600 V R DS(ON) =530 mω / 700 mω (Max.) 3-Phase SuperFET Inverter Bridge, including High Voltage Integrated Circuit (HVIC) 3 Divided Negative DC-Link Terminals for Inverter Current-Sensing Application HVIC for Gate Driving and Under-Voltage Lockout (UVLO) Protection Optimized for Low Electromagnetic Interference Embedded Bootstrap Diode in Package Integrated Temperature-Sensing Function (Linear Voltage Output by Temperature) in HVIC Isolation Voltage Rating of 1500 V RMS for 1 Minute 2013 Fairchild Semiconductor Corporation 1 RD_402 / FSB50760SF Rev

2 2. Schematics Inrush current limit Circuitry AC Power Bridge Rectifier 5V SMPS Part (FPS, Green FPS) Regulator 5V or 3.3V Operating Commend from Upper Controller MCU / BLDC Controller VPN VCC GND VIN(H) VIN(L) Reference Design For Motion SPM 5 SuperFET Series 5V V2 SPM5 15V VCC COM VIN(H) VIN(L) 5V VREF OTP LPF VTS VTS 5V VB HVIC SCP VREF FO NU IDC NV P P NW N U V W W U U V Compressor V W VSP VU, VV, VW (Phase Voltage Sensing) Figure 1. Block Diagram of Compressor Driver for Refrigerator 2013 Fairchild Semiconductor Corporation 2 RD_402 / FSB50760SF Rev

3 (12) V U (13) V V (14) V W R16 990K 1/2W C R17 900K 1/2W R18 990K 1/2W R19 10K 1/8W R20 10K 1/8W R21 10K 1/8W C C (1) UH (4) UL R1 100R 1/8W R2 100R 1/8W C1 C2 1 C3 1 ZD1 1N4747A (1) COM (2) VB(U) (3) VCC(U) (4) IN(UH) (5) IN(UL) (6) NC (7) VB(V) Motion SPM 5 SuperFET Series (17) P VCC VB HIN HO (18) U, VS(U) LIN VS COM LO (19) NU P U (2) VH (5) VL R4 100R 1/8W R6 100R 1/8W C4 C5 C6 1 (8) VCC(V) (9) IN(VH) (10) IN(VL) (11) VTSU (12) VB(W) VCC HIN LIN COM VTSU VB HO VS LO (20) NV (21) V, VS(V) V C20 630V (3) WH (6) WL R3 100R 1/8W R5 100R 1/8W C7 C8 C9 (13) VCC(W) (14) IN(WH) (15) IN(WL) (16) NC VCC HIN LIN COM VB HO VS LO (22) NW (23) W, VS(W) W (15) I DC R R 1W N (7) F O (8) V TS 1 R7 10K 1/8W R8 4.3K 1% OP1 LM393 R9 1.5K 1/8W F R11 10K 1/8W OP2 LM393 R12 3.6K 1/8W F R15 2.0K 1/8W (9) V DD (10) V CC (11) GND C10 220uF/35V C11 C C13 C14 R10 C15 1.1K 1/8W F C16 C17 C18 C19 R13 1K 1/8W F C20 C21 Figure 2. Schematic of Reference Design for 3-Phase Inverter Key Parameter Design 2013 Fairchild Semiconductor Corporation 3 RD_402 / FSB50760SF Rev

4 3. Key Parameter Design 3.1. Selection of Bootstrap Capacitance (CBS) The bootstrap capacitor can be calculated by: C BS I Leak t = V BS where: Δt = maximum on pulse width of high-side MOSFET; ΔV BS = the allowable discharge voltage of the C BS (voltage ripple); and I Leak = maximum discharge current of the C BS. (1) Normally, I Leak consist of the following items: Gate charge for turning the high-side MOSFET turn on Quiescent current to the high-side circuit in the HVIC Level-shift charge required by level-shifters in HVIC Leakage current in the bootstrap diode C BS capacitor leakage current (ignored for non-electrolytic capacitors) Bootstrap diode reverse recovery charge Practically, 1 ma of I Leak is recommended (operating V BS supply current). Calculation example of C BS : I Leak t ma 2.6ms CBS _ min = = = V 0.2V BS 1 6 where: I Leak = 1 ma (recommended value); ΔV BS = 0.2 V (depends on system); Δt= 2.6 ms (depends on system); More than 2~3 times 20~30 μf standard nominal capacitance 22 μf. (2) 2013 Fairchild Semiconductor Corporation 4 RD_402 / FSB50760SF Rev

5 3.2. Initial Charging Sequence for Bootstrap Capacitor Figure 3 is built-in bootstrap diode I F -V F characteristic in FSB50760SF. The built-in bootstrap diodes of the Motion SPM 5 SuperFET series have equivalent resistance characteristic by special I F -V F characteristics. Therefore, circuit engineers only need external bootstrap capacitor for bootstrap circuit. Figure 3. I-V Characteristic of Built-In Bootstrap Diode The bootstrap capacitors should be fully charged for the supply voltage of HVIC by the turn-on low-side MOSFET and the gate voltage of the high-side MOSFET; otherwise, the high-side MOSFET is operated in high-dissipation mode. For one bootstrap capacitor (C BS ), when charged initial charging current (I BS ) flows through low-side MOSFET and I BS is approximately 1.0 A. Figure 4 is bootstrap capacitor charging waveform and Figure 5 is bootstrap capacitor charging time by bootstrap capacitor value (t charge at V BS =12.0 V). To charge three bootstrap capacitors at the same time; theoretically, the maximum initial charging current is around 3.0 A. In this case, this I BS could be lead to a SCP (OCP) error. Therefore, charge bootstrap capacitors individually, as shown in Figure 6. Figure 4. Bootstrap Capacitor Charging Time and Maximum Current (I BS,MAX) by Capacitance 2013 Fairchild Semiconductor Corporation 5 RD_402 / FSB50760SF Rev

6 V IN(L) : 5.0V/div V CC : 5.0V/div V BS : 5.0V/div I BS : 0.2A/div Figure 5. Time : 500μs/div Waveform of Bootstrap Capacitor Charge (V CC=15 V, C BS=47 μf, f SW=5.0 khz, T J=25 C) V DC V CC V IN(UL) V IN(VL) V IN(WL) Bootstrap capacitor charging(u phase) Bootstrap capacitor charging(v phase) Bootstrap capacitor charging(w phase) Bootstrap capacitor charging period System operating periode Figure 6. Recommended Initial Bootstrap Capacitors Charging Sequence 2013 Fairchild Semiconductor Corporation 6 RD_402 / FSB50760SF Rev

7 3.3. Selection of Shunt Resistor The value of shunt resistor is calculated by the following equations. Maximum Short Circuit (SC) current trip level (depend on user selection): I SC(max)=1.5 x I D (rated current) (3) SC trip reference voltage (depend on user selection): Shunt resistance: V SC = min.0.45 V, typ.0.5 V, max.0.55 V (Tolerance 10%, depends on system) (4) I SC(max) = V SC(max) / R SHUNT(min) R SHUNT(min) = V SC(max) / I SC(max) (5) If the deviation of shunt resistor is limited below ±5%: R SHUNT(typ) = R SHUNT(min) / 0.95, R SHUNT(max) = R SHUNT(typ) x 1.05 (6) Actual SC trip current level becomes: I SC(typ) = V SC(typ) / R SHUNT(typ), I SC(min)= V SC(min) / R SHUNT(max) (7) The power rating of shunt resistor is calculated by the following equation: P SHUNT = (I 2 rms x R SHUNT x Margin) / Derating Ratio (8) where: I rms = Maximum load current of inverter; R SHUNT = Shunt resistor typical value at T C =25 C; Derating Ratio of shunt resistor at T SHUNT =100 C (from datasheet of shunt resistor); and Safety margin (determined by customer). Value of Shunt Resistor Calculation Examples Calculation Conditions: DUT: FSB50760SF, Tolerance of R SHUNT : ±5% SC trip reference voltage: V SC(min)=0.45 V, V SC(typ)=0.50 V, V SC(max)=0.55 V where: I SC(max) : 1.5 x I C = 1.5 x 1.5 = 2.25 A R SHUNT(min) : V SC(max) / I SC(max) = 0.55 V / 2.25 A = 0.24 Ω R SHUNT(typ) : R SHUNT(min) / 0.95 = 0.24 Ω / 0.95 = 0.26 Ω R SHUNT(max) : R SHUNT(typ) x 1.05 = 0.26 Ω x 1.05 = 0.27 Ω I SC(min) : V SC(min) / R SHUNT(max) = 0.45 V / 0.27 Ω = 1.67 A I SC(typ) : V SC(typ) / R SHUNT(typ) = 0.5 V / 0.26 Ω = 1.94 A Power Rating of Shunt Resistor Calculation Example Calculation Conditions: Maximum load current of inverter (I rms ): 1.0 A rms Shunt resistor value at T C =25 o C (R SHUNT ): 0.27 Ω Derating ratio of shunt resistor at T SHUNT =100 o C: 70% Safety margin: 20% P SHUNT (I 2 rms x R SHUNT x Margin) / Derating Ratio)=(0.8 2 x 0.27 x 1.2) / 0.7=0.46 W (Therefore, recommended power rating of shunt resistor is 1.0 W) Fairchild Semiconductor Corporation 7 RD_402 / FSB50760SF Rev

8 3.4. Design of Short-Circuit Current Protection (SCP) Circuit Figure 7 and Figure 8 are typical application circuits for SCP function. Figure 7 (using MCU), needs external comparator circuits. Figure 8 (using BLDC controller, such as FCM8531 with an OCP function), needs no external circuits. MCU Interrupt Port R1 10K Comparator R2 9.1K 1% R15 2.0K 1/8W Motion SPM 5 SuperFET Product NU, NV, NW C1 R3 1.0K 1% C2 C3 R R 1W Figure 7. Short-Circuit Current Protection (SCP) Circuit Using MCU BLDC Controller (FCM8531) IA, IB, IC R15 2.0K 1/8W Motion SPM 5 SuperFET Product NU, NV, NW C3 333 R R 1W Figure 8. Short-Circuit Current Protection (SCP) Circuit Using BLDC Controller 3.5. Design of Over-Temperature Protection (OTP) Circuit Figure 9 is V-T curve of built-in Temperature Sensing (TS) function in the HVIC of FSB50760SF. For detail information of V-T table, refer to related application note. Figure 9. V-T Curve of Temperature-Sensing (TS) Function in HVIC of FSB50760SF 2013 Fairchild Semiconductor Corporation 8 RD_402 / FSB50760SF Rev

9 Figure 10 is typical application circuit for temperature-sensing function. In this reference design, the set level is 100 C (V TS =2.23 V), reset level is 80 C (V TS =1.85 V), and hysteresis temperature is 20 C (see Figure 11). If using an Analog-to-Digital Conversion (ADC) port, only a capacitor between the VTS pin and GND is required (see Figure 12). MCU R7 10K R8 4.3K 1% R9 1.5K 1% Motion SPM 5 SuperFET Product I/O Port Comparator V TS C14 R10 1.1K 1% C16 C17 Figure 10. Examples of Temperature-Sensing Circuit Using I/O Port in MCU 5V V COMP Set Voltage: V TS=2.23V(T HVIC=100 ) Hysteresis voltage: ΔV TS=0.39V(T HVIC=20 ) Reset Voltage: V TS=1.85V(T HVIC=80 ) V TS 0V Figure 11. Timing Chart of Temperature-Sensing Circuit MCU / BLDC Controller (FCM8531) ADC Pin Motion SPM 5 SuperFET Product V TS C17 Figure 12. Examples of Temperature-Sensing Circuit Using ADC Port in MCU or BLDC Controller 2013 Fairchild Semiconductor Corporation 9 RD_402 / FSB50760SF Rev

10 4. Print Circuit Board (PCB) Layout Guidance C2 C2 C2 Top layer P N VCC VFO VIN(W) VTS VIN(V) VIN(U) Bottom layer R5 R5 R5 C6 C1 C1 C1 The capacitor between VCC and COM & zener diode should be placed to SPM as close as possible C3 U V W It is recommended to connect control GND and power GND at only a point.(not copper pattern and don t make a loop in GND pattern) And this wiring should be as short as possible The main electrolytic capacitor should be placed to snubber capacitor as close as possible Wiring between NU, NV, NW and shunt resistor should be as short as possible Place snubber capacitor between P and N and closely to terminals The VIN RC filter should be placed to SPM as close as possible Comparator Circuit for SCP C5 C5 C5 FSB50760SF R1 Capacitor should be locate closely to terminal Figure 13. PCB Layout Guidance 2013 Fairchild Semiconductor Corporation 10 RD_402 / FSB50760SF Rev

11 5. Related Resources FSB50660SF Motion SPM 5 SuperFET Series FSB50660SFT Motion SPM 5 SuperFET Series FSB50660SFS Motion SPM 5 SuperFET Series FSB50760SF Motion SPM 5 SuperFET Series FSB50760SFT Motion SPM 5 SuperFET Series FSB50760SFS Motion SPM 5 SuperFET Series AN-9082 Motion SPM 5 Series Thermal Performance Information by Contact Pressure FCM8531 MCU Embedded and Configurable 3-Phase PMSM / BLDC Motor Controller Fairchild Reference Designs at Reference Design Disclaimer Fairchild Semiconductor Corporation ( Fairchild ) provides these reference design services as a benefit to our customers. Fairchild has made a good faith attempt to build for the specifications provided or needed by the customer. Fairchild provides this product as is and without recourse and MAKES NO WARRANTY, EXPRESSED, IMPLIED OR OTHERWISE, INCLUDING ANY WARRANTY OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. Customer agrees to do its own testing of any Fairchild reference designs in order to ensure design meets the customer needs. Neither Fairchild nor Customer shall be liable for incidental or consequential damages, including but not limited to, the cost of labor, requalifications, rework charges, delay, lost profits, or loss of goodwill arising out of the sale, installation or use of any Fairchild product. Subject to the limitations herein, Fairchild will defend any suit or proceeding brought against Customer if it is based on a claim that any product furnished hereunder constitutes an infringement of any intellectual property rights. Fairchild must be notified promptly in writing and given full and complete authority, information and assistance (at Fairchild s expense) for defense of the suit. Fairchild will pay damages and costs therein awarded against Customer but shall not be responsible for any compromise made without its consent. In no event shall Fairchild s liability for all damages and costs (including the costs of the defense by Fairchild) exceed the contractual value of the products or services that are the subject of the lawsuit. In providing such defense, or in the event that such product is held to constitute infringement and the use of the product is enjoined, Fairchild, in its discretion, shall procure the right to continue using such product, or modify it so that it becomes noninfringing, or remove it and grant Customer a credit for the depreciated value thereof. Fairchild s indemnity does not extend to claims of infringement arising from Fairchild s compliance with Customer s design, specifications and/or instructions, or the use of any product in combination with other products or in connection with a manufacturing or other process. The foregoing remedy is exclusive and constitutes Fairchild s sole obligation for any claim of intellectual property infringement and Fairchild makes no warranty that products sold hereunder will not infringe any intellectual property rights. All solutions, designs, schematics, drawings, boards or other information provided by Fairchild to Customer are confidential and provided for Customer s own use. Customer may not share any Fairchild materials with other semiconductor suppliers Fairchild Semiconductor Corporation 11 RD_402 / FSB50760SF Rev