For Non-Isolated Off-Line PWM Controllers with Integrated Power MOSFET STR5A460 Series Data Sheet Description Package The STR5A460 Series is power ICs for switching power supplies, incorporating a MOSFET and a current mode PWM controller IC for non-isolated buck converter and inverting-converter. The low standby power is accomplished by the automatic switching between the PWM operation in normal operation and the burst-oscillation under light load conditions. The product achieves high cost-performance power supply systems with few external components. DIP8 FB 1 8 S/GND VCC 2 7 S/GND 6 S/GND S/GND D/ST 4 5 VCC 1 8 S/GND FB 2 7 S/GND 6 S/GND 5 S/GND SOIC8 Features ● ● ● ● ● ● ● ● ● ● ● Buck Converter Inverting Converter Auto Standby Function Operation Normal Operation : PWM Mode Light Load Operation : Green Mode Standby : Burst Oscillation Mode Build-in Startup Function (reducing power consumption at standby operation, shortening the startup time) Current Mode Type PWM Control Build-in Error Amplifier for Phase Compensation Random Switching Function Leading Edge Blanking Function Soft Start Function Protections Overload Protection (OLP): Auto-restart Overvoltage Protection (OVP): Auto-restart Thermal Shutdown with hysteresis (TSD): Auto-restart D/ST Not to scale STR5A460 Series ● Electrical Characteristics fOSC(AVG) = 60 kHz VD/ST = 700V (max.) Products STR5A464D STR5A464S FB S/GND VCC S/GND 2 8 C4 R1 13.6 Ω 0.41 A Package DIP8 SOIC8 Input Voltage D/ST Input ≥ 40 V Voltage Output Voltage > 11 V > – 27.5 V Range* < 27.5 V < – 11 V *Add zener diode or transistor (dropper) to VCC pin when target output voltage is high. D2 STR5A400D 1 IDLIM (typ.) Buck Inverting Converter Converter AC 85 V to AC 265 V R3 R2 RDS(ON) (max.) Recommended Operating Condition Typical Application (Buck Convertor, DIP8) D1 4 C3 7 6 S/GND VOUT L1 DR1 5 4 D/ST S/GND (+) L2 VAC C1 C2 D3 C5 R4 DR2 (-) TC_STR5A400_1_R2 Applications ● White goods ● Auxiliary power supply (lighting equipment with microcomputer, etc.) ● Power supply for motor control (actuator, etc.) ● Telecommunication equipment (convertible from 48VDC to 15VDC) ● Other Switchung mode power supply, SMPS STR5A460-DSE Rev.2.2 SANKEN ELECTRIC CO.,LTD. Nov. 11, 2015 http://www.sanken-ele.co.jp/en © SANKEN ELECTRIC CO.,LTD. 2013 1 STR5A460 Series CONTENTS Description ------------------------------------------------------------------------------------------------------ 1 CONTENTS ---------------------------------------------------------------------------------------------------- 2 1. Absolute Maximum Ratings----------------------------------------------------------------------------- 3 2. Electrical Characteristics -------------------------------------------------------------------------------- 3 3. Performance Curves -------------------------------------------------------------------------------------- 5 4. Block Diagram --------------------------------------------------------------------------------------------- 6 5. Pin Configuration Definitions --------------------------------------------------------------------------- 6 6. Typical Application --------------------------------------------------------------------------------------- 7 7. External Dimensions and Marking Diagram -------------------------------------------------------- 8 7.1 DIP8 ---------------------------------------------------------------------------------------------------- 8 7.2 SOIC8-------------------------------------------------------------------------------------------------- 9 8. Operational Description ------------------------------------------------------------------------------- 10 8.1 Startup Operation of IC ------------------------------------------------------------------------- 10 8.2 Undervoltage Lockout (UVLO) ---------------------------------------------------------------- 10 8.3 Power Supply Startup and Soft Start Function --------------------------------------------- 10 8.4 Constant Voltage (CV) Control----------------------------------------------------------------- 11 8.4.1 Buck Converter Operation ---------------------------------------------------------------- 12 8.4.2 Inverting Converter Operation ----------------------------------------------------------- 13 8.5 Leading Edge Blanking Function -------------------------------------------------------------- 14 8.6 Random Switching Function -------------------------------------------------------------------- 14 8.7 Auto Standby Function--------------------------------------------------------------------------- 14 8.8 Overload Protection (OLP)---------------------------------------------------------------------- 14 8.9 Overvoltage Protection (OVP) ------------------------------------------------------------------ 15 8.10 Thermal Shutdown (TSD) ----------------------------------------------------------------------- 15 9. Design Notes ---------------------------------------------------------------------------------------------- 16 9.1 External Components ---------------------------------------------------------------------------- 16 9.1.1 Input and Output Electrolytic Capacitor ----------------------------------------------- 16 9.1.2 Inductor --------------------------------------------------------------------------------------- 16 9.1.3 VCC Pin Peripheral Circuit --------------------------------------------------------------- 16 9.1.4 FB Pin Peripheral Circuit ----------------------------------------------------------------- 16 9.1.5 Freewheeling diode -------------------------------------------------------------------------- 17 9.1.6 Bleeder resistance --------------------------------------------------------------------------- 17 9.2 D/ST Pin --------------------------------------------------------------------------------------------- 17 9.3 Output Inductor Value Setting ----------------------------------------------------------------- 18 9.3.1 Buck Converter ------------------------------------------------------------------------------ 19 9.3.2 Inverting Converter ------------------------------------------------------------------------- 22 9.4 PCB Trace Layout -------------------------------------------------------------------------------- 25 10. Pattern Layout Example (DIP8)---------------------------------------------------------------------- 27 10.1 Buck Converter ------------------------------------------------------------------------------------ 27 10.2 Inverting Converter ------------------------------------------------------------------------------- 28 11. Reference Design of Power Supply ------------------------------------------------------------------ 29 11.1 Buck Converter ------------------------------------------------------------------------------------ 29 11.2 Inverting Converter ------------------------------------------------------------------------------- 30 IMPORTANT NOTES ------------------------------------------------------------------------------------- 31 STR5A460-DSE Rev.2.2 SANKEN ELECTRIC CO.,LTD. Nov. 11, 2015 http://www.sanken-ele.co.jp/en © SANKEN ELECTRIC CO.,LTD. 2013 2 STR5A460 Series 1. Absolute Maximum Ratings ● The polarity value for current specifies a sink as "+," and a source as "−," referencing the IC. ● Unless otherwise specified, TA = 25 °C, all S/GND pins (5 pin to 8pin) are shorted. ● The pin number of SOIC8 package products is shown in bracket. Parameter Symbol FB Pin Voltage VFB VCC Pin Voltage VCC D/ST Pin Voltage VD/ST Drain Peak Current(1) IDP Maximum Switching Current IDMAX MOSFET Power Dissipation PD1 Test Conditions Pins 1–5 (2 – 5) 2–5 (1 – 5) 4–5 Single pulse, Within 500 ns pulse 4–5 Negative: Within 2 μs pulse width 4–5 (2) Rating Units − 0.3 to 7 V − 0.3 to 32 V − 0.3 to 700 V 1.7 A − 0.2 to 0.97 − 0.2 to 0.91 1.55 – 5A464D 5A464S 5A464D W 1.51 5A464S TOP – − 40 to 125 °C Storage Temperature Tstg – − 40 to 125 °C Junction Temperature Tj – 150 °C (2) 2. 5A464D 5A464S A Operating Ambient Temperature (1) Notes Refer to MOS FET Ta-PD curve. When embedding this hybrid IC onto the printed circuit board (cupper area in a 15mm×15mm) Electrical Characteristics ● The polarity value for current specifies a sink as "+," and a source as "−," referencing the IC. ● Unless otherwise specified, TA = 25 °C, all S/GND pins (5 pin to 8pin) are shorted. ● The pin number of SOIC8 package products is shown in bracket. Parameter Symbol Test Conditions Pins Min. Typ. Max. Units 13.6 15.0 16.6 V 7.3 8.0 8.7 V – – 2.0 mA 19 29 39 V − 2.7 − 1.5 − 0.5 mA 4–5 53 60 67 kHz Notes Power Supply Startup Operation Operation Start Voltage VCC(ON) Operation Stop Voltage VCC(OFF) Circuit Current in Operation ICC(ON) VCC = 12 V 2–5 (1 – 5) 2–5 (1 – 5) 2–5 (1 – 5) 4–5 2–5 (1 – 5) Startup Circuit Operation Voltage VSTARTUP VCC = 13.5 V Startup Current ISTARTUP VCC = 13.5 V VD/ST = 100 V PWM Operation Average PWM Switching Frequency Switching Frequency Modulation Deviation fOSC(AVG) VFB= 2.44 V Δf 4–5 – 2.8 – kHz Feedback Reference Voltage VFB(REF) 1–5 (2 – 5) 2.44 2.50 2.56 V STR5A460-DSE Rev.2.2 SANKEN ELECTRIC CO.,LTD. Nov. 11, 2015 http://www.sanken-ele.co.jp/en © SANKEN ELECTRIC CO.,LTD. 2013 3 STR5A460 Series Parameter Symbol Test Conditions Pins Min. Typ. Max. Units − 2.4 − 0.8 − μA – – 2.5 μs Feedback Current(1) IFB(OP) Minimum Sampling Time tFBMS 1–5 (2 – 5) 1–5 (2 – 5) Standby Drain Current IDSTB 4–5 – 50 – mA Standby Operation Cycle TSTBOP 4–5 530 740 940 μs Maximum ON Duty DMAX 4–5 50 57 64 % tBW – – 230 – ns IDLIM 4–5 0.37 0.41 0.45 A 27.5 29.3 31.3 V – 72 – ms 4–5 3.5 5.2 6.8 ms Tj(TSD) – 135 – – °C Tj(TSDHYS) – – 70 – °C Tj = 125 °C VD/ST = 584 V 4–5 – – 50 µA ID = 41 mA 4–5 – 11.0 13.6 Ω tf 4–5 – – 250 ns θj-C – – – 15 – – 16 VFB = 2.3 V Notes 5A464D 5A464S Protection Leading Edge Blanking Time(1) Drain Current Limit OVP Threshold Voltage OLP Delay Time at Startup Standby Blanking Time at Startup Thermal Shutdown Operating Temperature(1) Thermal Shutdown Hysteresis(1) VCC(OVP) tOLP tSTB(INH) VFB= 0 V VFB= 2.6 V 2–5 (1 – 5) 4–5 5A464D 5A464S 5A464D 5A464S Power MOSFET Drain Leakage Current(1) On Resistance Switching Time IDSS RDS(ON) 5A464D 5A464S Thermal Characteristics Thermal Resistance Junction to Case(1)(2) (1) (2) 5A464D °C/W 5A464S Design assurance Case temperature (TC) measured at the center of the case top surface STR5A460-DSE Rev.2.2 SANKEN ELECTRIC CO.,LTD. Nov. 11, 2015 http://www.sanken-ele.co.jp/en © SANKEN ELECTRIC CO.,LTD. 2013 4 STR5A460 Series 3. Performance Curves ● STR5A464D Ambient Temperature versus Power Dissipation Curve 1.00 0.75 0.50 0.25 1 θj-c (°C /W) Power Dissipation, PD (W) 1.25 10 Transient Thermal Resistance PD_STR5A464D_R1 PD = 1.55 W 1.50 0.00 0 25 50 75 100 125 TR_STR5A464D_R1 Transient Thermal Resistance Curve 1.75 0.1 0.01 150 1μ 10μ Ambient Temperature, TA (°C ) 100μ 1m 10m 100m 10m 100m Time (s) ● STR5A464S Ambient Temperature versus Power Dissipation Curve 1.00 0.75 0.50 0.25 0.00 θj-c (°C /W) 1 0.1 0.01 0 25 50 75 100 125 150 TR_STR5A464S_R1 Power Dissipation, PD (W) 1.25 10 Transient Thermal Resistance PD = 1.51 W 1.50 Transient Thermal Resistance Curve PD_STR5A464S_R1 1.75 1μ 10μ Ambient Temperature, TA (°C ) STR5A460-DSE Rev.2.2 SANKEN ELECTRIC CO.,LTD. Nov. 11, 2015 http://www.sanken-ele.co.jp/en © SANKEN ELECTRIC CO.,LTD. 2013 100μ 1m Time (s) 5 STR5A460 Series 4. Block Diagram ● The pin number of SOIC8 package products is shown in bracket. 2 (1) VCC STARTUP D/ST 4 UVLO OVP REG PROTECTION TSD DRV PWM OSC S Q R OCP 1 (2) FB S/H E/A VFB(REF) Feedback Control LEB S/GND 5, 6, 7, 8 BD_STR5A400_R2 5. Pin Configuration Definitions ● DIP8 FB 1 VCC 2 D/ST 4 Pin Name 8 S/GND 1 FB 7 S/GND 2 VCC 6 S/GND 3 – 5 S/GND 4 D/ST 5~8 S/GND Pin Name 1 VCC 2 FB 3 – 4 D/ST 5~8 S/GND Descriptions Constant voltage control signal input Power supply voltage input for control part and Overvoltage Protection (OVP) signal input (Pin removed) MOSFET drain and startup current input MOSFET source and ground ● SOIC8 VCC 1 8 S/GND FB 2 7 S/GND 6 S/GND 5 S/GND D/ST 4 Descriptions Power supply voltage input for control part and Overvoltage Protection (OVP) signal input Constant voltage control signal input (Pin removed) MOSFET drain and startup current input MOSFET source and ground STR5A460-DSE Rev.2.2 SANKEN ELECTRIC CO.,LTD. Nov. 11, 2015 http://www.sanken-ele.co.jp/en © SANKEN ELECTRIC CO.,LTD. 2013 6 STR5A460 Series 6. Typical Application Figure 6-1 and Figure 6-2 are the example circuits of DIP8 products. In order to enhance the heat dissipation, the wide pattern layout of S pin (5 through 8 pin) is recommended. When the target output voltage ｜VOUT｜is higher than 27.5 V, zener diode DZ1 is connected to D1 in serial as shown in Figure 6-3. The output voltage should be in the range of equation (1) or (2) according to the configuration, where VZ is the zener voltage. Buck converter: (1) Inverting converter: (2) D1 FB S/GND VCC S/GND 2 R3 R2 STR5A400D 1 D2 8 7 R1 C4 C3 6 S/GND L2 L1 DR1 D/ST C1 VOUT 5 4 S/GND (+) C5 C2 R4 D3 VAC DR2 (-) TC_STR5A400D_2_R2 Figure 6-1 Buck converter D1 FB S/GND VCC S/GND 2 R3 R2 STR5A400D 1 D2 8 7 R1 C4 C3 NC 6 S/GND L1 DR1 D/ST C1 D3 5 4 VOUT (-) S/GND C5 C2 VAC R4 L2 DR2 (+) TC_STR5A400D_3_R2 Figure 6-2 Inverting converter D1 DZ1 D2 (+) VCC 2 C4 S C3 5,6,7,8 STR5A400D TC_STR5A400D_4_R2 Figure 6-3 Absolute value of target output voltage |VOUT| is high STR5A460-DSE Rev.2.2 SANKEN ELECTRIC CO.,LTD. Nov. 11, 2015 http://www.sanken-ele.co.jp/en © SANKEN ELECTRIC CO.,LTD. 2013 7 STR5A460 Series 7. 7.1 External Dimensions and Marking Diagram DIP8 ● External Dimensions NOTES: 1) Units: mm (inch) 2) Control dimension is in inches. (values in mm are for reference) 3) Pb-free. Device composition compliant with the RoHS directive ● Marking Diagram DIP8 8 5A46×D Part Number SKYMD 1 Lot Number Y = Last Digit of Year (0-9) M = Month (1-9,O,N or D) D = Period of days (1 to 3) 1 : 1st to 10th 2 : 11th to 20th 3 : 21st to 31st Sanken Control Number STR5A460-DSE Rev.2.2 SANKEN ELECTRIC CO.,LTD. Nov. 11, 2015 http://www.sanken-ele.co.jp/en © SANKEN ELECTRIC CO.,LTD. 2013 8 STR5A460 Series 7.2 SOIC8 ● External Dimensions NOTES: 1) Units: mm 2) Control dimension is in inches. (values in mm are for reference) 3) Pb-free. Device composition compliant with the RoHS directive Land Pattern Example (not to scale) 1.6 (0.063) 3.8 (0.15) 1.27 (0.0500) 0.61 (0.024) Unit: mm (inch) ● Marking Diagram SOIC8 8 5A46×S Part Number SKYMD 1 Lot Number Y = Last Digit of Year (0-9) M = Month (1-9,O,N or D) D = Period of days (1 to 3) 1 : 1st to 10th 2 : 11th to 20th 3 : 21st to 31st Sanken Control Number STR5A460-DSE Rev.2.2 SANKEN ELECTRIC CO.,LTD. Nov. 11, 2015 http://www.sanken-ele.co.jp/en © SANKEN ELECTRIC CO.,LTD. 2013 9 STR5A460 Series 8. Operational Description All of the parameter values used in these descriptions are typical values, unless they are specified as minimum or maximum. With regard to current direction, "+" indicates sink current (toward the IC) and "–" indicates source current (from the IC). The reference ground of the value of voltage is S/GND pin in this section. In Section 8, the pin number of SOIC8 package products in the circuits is shown in bracket. 8.1 Figure 8-1 shows the circuit around VCC pin. ISTRTUP Startup D1 D2 STARTUP Normal Operation Contro1 VCC 2(1) C3 C4 S/GND L2 5~8 Undervoltage Lockout (UVLO) Figure 8-2 shows the relationship of VCC pin voltage and circuit current ICC. When VCC pin voltage increases to VCC(ON) = 15.0 V, the control circuit starts switching operation and the circuit current ICC increases. When VCC pin voltage decreases to VCC(OFF) = 8.0 V, the control circuit stops operation by Undervoltage Lockout (UVLO) circuit, and reverts to the state before startup. VOUT (＋) 4 D/ST (4) 8.2 Startup Operation of IC U1 stored in the inductor, L2. When the MOSFET turns off, C4 is charged by the inductor current through D1 and D2. In normal operation, the voltage between VCC pin and S/GND pin is calculated as follows, where VFD1, VFD2 and VFD3 are the forward voltage of D1, D2 and D3 respectively: Circuit current, ICC VIN D3 C5 R4 Stop (－) Start C2 Figure 8-1 VCC pin peripheral circuit in buck converter The IC incorporates the startup circuit. The circuit is connected to D/ST pin. When D/ST pin voltage reaches to Startup Circuit Operation Voltage V STARTUP = 29 V, the startup circuit starts operation. During the startup process, the constant current, ISTARTUP = − 1.5 mA, charges C4 at VCC pin. When VCC pin voltage increases to VCC(ON) = 15.0 V, the control circuit starts switching operation. After switching operation begins, the startup circuit turns off automatically so that its current consumption becomes zero. The approximate startup time tSTART is calculated as follows: (3) where, tSTART is startup time of IC (s), VCC(INT) is initial voltage on VCC pin (V). Figure 8-1 shows the current path in normal operation. During the on state of internal MOSFET, the energy is VCC（OFF） VCC pin VCC（ON） voltage Figure 8-2 Relationship between VCC pin voltage and ICC 8.3 Power Supply Startup and Soft Start Function The IC has the Soft Start Function. This function reduces the voltage and the current stress of MOSFET and freewheel diode. Figure 8-3 shows the startup waveforms. Since the voltage of internal comparator is low at startup, the IC is in no load condition. The IC has the Standby Blanking Time at Startup, tSTB(INH), that inhibits the burst oscillation mode so that the soft start is operated after the IC starts. The IC activates the soft start circuitry during the startup period. Soft start time is fixed (about 5.2 ms). During the soft start period, the over current threshold is increased step-wisely (7 steps). The IC does switching operation by the frequency responding to FB pin voltage STR5A460-DSE Rev.2.2 SANKEN ELECTRIC CO.,LTD. Nov. 11, 2015 http://www.sanken-ele.co.jp/en © SANKEN ELECTRIC CO.,LTD. 2013 10 STR5A460 Series until the output becomes setting voltage. The tLIM is the period until FB pin voltage reaches 1.6 V after the IC starts. When tLIM is tOLP of 72 ms and more, the IC stops switching operation. Thus, it is necessary to adjust the value of output electrolytic capacitor, C5 so that the tLIM is less than tOLP. If VCC pin voltage reaches VCC(OFF) and a startup failure occurs as shown in Figure 8-4, increase the C4 value or decrease the C5 value. Since the larger capacitance causes the longer startup time of IC, it is necessary to check and adjust the startup process based on actual operation in the application. Since the Leading Edge Blanking Function (refer to Section 8.5) is deactivated during the soft start period, there is the case that ON time is less than the leading edge blanking time, tBW = 230 ns. 8.4 Constant Voltage (CV) Control The IC achieves the constant voltage (CV) control of the power supply output by using the peak-current-mode control method, which enhances the response speed and provides the stable operation. The IC controls the peak value of the voltage of build-in sense resistor (VROCP) to be close to target voltage (VSC), comparing VROCP with VSC by internal FB comparator. The IC sampless the FB pin voltage at the sampling point that is tFBFS = 2.5 μs (max.) after the power MOSFET turns off, by pulse-by-pulse. Feedback Control circuit receives the target voltage, VSC, reversed FB pin voltage by an error amplifier (refer to Figure 8-5 and Figure 8-6). U1 Feedback Control FB comp Startup of IC VCC pin voltage VSC R2 R3 E/A + - 1(2) S/H FB Normal opertion Startup of SMPS tSTART R1 PWM Control VCC(ON) VCC(OFF) + ROCP 4 L2 VOUT (＋) 5~8 S/GND D/ST tSTB(INH) Time C3 VROCP ION D3 C2 R1 C5 (－) Soft start period approximately 5.2 ms (fixed) D/ST pin current, ID Figure 8-5 FB pin peripheral circuit in buck converter Time FB pin voltage VFB(REF) tLIM < tOLP - VSC + VROCP FB comparator Voltage on both side of ROCP 1.6V Time Drain current, ION Figure 8-3 Startup waveforms VCC pin voltage Figure 8-6 Drain current ID and FB comparator in steady operation Startup success IC starts operation Target operating voltage VCC(ON) Increase with rising of output voltage VCC(OFF) Startup failure Time Startup time of IC, tSTART Figure 8-4 VCC pin voltage during startup period ● Light Load Conditions The FB pin voltage increases with the increase of the output voltage when the output load becomes light. Accordingly, the output voltage of internal error amplifier (target voltage VSC) decreases. As a result, the peak value of VROCP is controlled to be lower so that the peak of the drain current decreases. This control prevents the output voltage from increasing. ● Heavy Load Conditions The control circuit performs reverse operations to the former. The target voltage VSC of internal comparator STR5A460-DSE Rev.2.2 SANKEN ELECTRIC CO.,LTD. Nov. 11, 2015 http://www.sanken-ele.co.jp/en © SANKEN ELECTRIC CO.,LTD. 2013 11 STR5A460 Series 8.4.1 Buck Converter Operation Figure 8-7 shows the output current path in the buck converter. Figure 8-8 shows the operational waveforms. In this case, the operation range satisfies the Equation (5), (6), (7), and (8) back electromotive force in the inductor, L2 and D3 turns on. Then the energy stored in L2 during the PWM on-time flows through the IOFF path shown in Figure 8-7. After the Average PWM Switching Cycle, 1 / fOSC(AVG), the internal power MOSFET turns-on again, and the PWM on-time period repeats as shown in Figure 8-8 U1 VCC 2(1) Contro1 becomes higher and the peak drain current increases. This control prevents the output voltage from decreasing. (5) D2 D1 FB 1(2) C3 C4 VROCP 4 S/GND VL (6) C2 VOUT (＋) L2 5~8 D/ST VIN IL ROCP ION (MOSFET ON) D3 IOFF (MOSFET OFF) R4 C5 (7) (8) where, VIN is C2 voltage, VOUT is output voltage, DMAX is maximum ON Duty, VRON is on voltage of internal MOSFET, VSTARTUP (max.) is maximum value of Startup Circuit Operation Voltage, VCC(OFF) (max.) is maximum value of Operation Stop Voltage, VCC(OVP) (min.) is minimum value of OVP Threshold Voltage, VFD1 is forward voltage of D1, VFD2 is forward voltage of D2, and VFD3 is forward voltage of D3. (－) Figure 8-7 Output current flow in the buck converter VL ON VIN-VRON-VOUT 0 t -(VOUT-VFD3) IL t ION t IOFF t In the buck converter, the current control of internal PWM is described in the following. 1) PWM On-Time Period At startup or during normal operation before the current reaches the target level, internal power MOSFET turns on and the current flows through the ION path shown in Figure 8-7. When ION flows through the internal current detection resistor, ROCP, IC detects VROCP that is the voltage between both ends of ROCP. The divided voltage of C3 is input to FB pin. The target voltage, VSC is made from FB pin voltage. When the current detection voltage, VROCP, reaches to VSC, the power MOSFET turns off. MOSFET ON OFF 1/fOSC(AVG) Figure 8-8 Operational waveforms in the buck converter 2) PWM Off-Time Period When the internal power MOSFET turns off, the freewheeling diode, D3, is forward biased by the STR5A460-DSE Rev.2.2 SANKEN ELECTRIC CO.,LTD. Nov. 11, 2015 http://www.sanken-ele.co.jp/en © SANKEN ELECTRIC CO.,LTD. 2013 12 STR5A460 Series 8.4.2 Inverting Converter Operation Figure 8-9 shows the output current path in the inverting converter. Figure 8-10 shows the operational waveforms. In this case, the operation range satisfies the Equation (9), (10), (11), and (12). shown inFigure 8-9. After the Average PWM Switching Cycle, 1 / fOSC(AVG), the internal power MOSFET turns-on again, and the PWM on-time period repeats as shown in Figure 8-10. In the inverting converter, the output current is supplied only in the off period. Thus, output ripple becomes larger compared with the buck converter. (9) VCC 2(1) FB 1(2) Contro1 U1 (10) D2 D1 C3 C4 VROCP ROCP 4 (11) S/GND IL C2 VIN ION (MOSFET ON) VL IOFF (MOSFET OFF) C5 R4 L2 (12) where, VIN is C2 voltage, VOUT is output voltage, DMAX is maximum ON Duty, VRON is on voltage of internal MOSFET, VSTARTUP (max.) is maximum value of Startup Circuit Operation Voltage, VCC(OFF) (max.) is maximum value of Operation Stop Voltage, VCC(OVP) (min.) is minimum value of OVP Threshold Voltage, VFD1 is forward voltage of D1, VFD2 is forward voltage of D2, and VFD3 is forward voltage of D3. VOUT (－) D3 5~8 D/ST (＋) Figure 8-9 Output current flow in inverting converter VL MOSFET ON OFF ON VIN‐VRON t 0 -(VOUT-VFD3) IL t ION In the inverting converter, the current control of internal PWM is described in the following. 1) PWM On-Time Period At startup or during normal operation before the current reaches the target level, internal power MOSFET turns on and the current flows through the ION path shown in Figure 8-9. When ION flows through the internal current detection resistor, ROCP, the IC detects VROCP that is the voltage of both end of ROCP. The divided voltage of C3 is input to FB pin. The target voltage, VSC is made from FB pin voltage. When the current detection voltage, VROCP, reaches to VSC, the power MOSFET turns off. 2) t IOFF t 1/fOSC(AVG) Figure 8-10 Operational waveforms in inverting converter PWM Off-Time Period When the internal power MOSFET turns off, the freewheeling diode, D3, is forward biased by the back electromotive force in the inductor, L2 and D3 turns on. Then the energy stored in L2 during the PWM on-time flows through the IOFF path STR5A460-DSE Rev.2.2 SANKEN ELECTRIC CO.,LTD. Nov. 11, 2015 http://www.sanken-ele.co.jp/en © SANKEN ELECTRIC CO.,LTD. 2013 13 STR5A460 Series 8.5 Leading Edge Blanking Function Since the IC uses the peak-current-mode control method for the constant voltage control of output, there is a case that the power MOSFET turns off due to unexpected response of FB comparator or overcurrent protection circuit (OCP) to the steep surge current in turning on a power MOSFET. In order to prevent this response to the surge voltage in turning-on the power MOSFET, the Leading Edge Blanking (tBW = 230 ns) is built-in. Switching Frequency, fOSC Normal operation 60kHz B About 23kHz A Burst oscillation mode Green mode TSTBOP = 740 µs Light load Output power PO(MAX) Figure 8-12 Relationship between PO and fOSC tBW Point A ID TSTBOP Time Surge pulse voltage width at turning on Point B ID TSTBOP Figure 8-11 Leading Edge Blanking Time 8.6 Random Switching Function The IC modulates its switching frequency randomly by superposing the modulating frequency on fOSC(AVG) in normal operation. This function reduces the conduction noise compared to others without this function, and simplifies noise filtering of the input lines of power supply. 8.7 Auto Standby Function Auto Standby Function automatically changes the oscillation mode to green mode or burst oscillation mode, when the output load becomes lower, the drain current ID decreases and the oscillation frequency becomes lower gradually (Green Mode) as shown in Figure 8-12. In order to reduce the switching loss, the number of switching is reduced in green mode and the switching operation is stopped during a constant period in burst oscillation mode. Figure 8-13 shows the drain current waveforms of point A and B in Figure 8-12 The burst oscillation mode operates by the Standby Operation Cycle, TSTBOP = 740 ms. In light load, the number of minimum switching times is one in T STBOP as shown in Figure 8-13. Since the oscillator of burst oscillation cycle setting and the oscillator of switching oscillation frequency setting are not synchronized each other, the switching frequency may be high. Figure 8-13 Switching waveform at burst oscillation mode 8.8 Overload Protection (OLP) When output power reaches certain power, the drain current of a power MOSFET is limited by IDLIM and the output voltage decreases. Thus, the current characteristic is as shown in Figure 8-14. The switching frequency is decreased with decreasing output voltage in order to inhibit increasing output current at low output voltage. When output voltage decreases in the state such as output short mode, FB pin voltage decreases. When the FB pin voltage keeps less than 1.6 V, Overload Protection (OLP) is activated, and the IC stops switching operation. When VCC pin voltage decreases to VCC(OFF), the control circuit stops operation. After that, the IC starts operation when VCC pin voltage increases to VCC(ON) by startup current. Thus, the intermittent operation by UVLO is repeated in OLP state. The switching time in the intermittent operation is OLP Delay Time at Startup, tOLP = 72 ms (Refer to Figure 8-15). This intermittent operation reduces the stress of parts including a power MOSFET and a free wheel diode. In addition, this operation reduces power consumption because the switching period in this intermittent operation is short compared with oscillation stop period. When the abnormal condition is removed, the IC returns to normal operation automatically. STR5A460-DSE Rev.2.2 SANKEN ELECTRIC CO.,LTD. Nov. 11, 2015 http://www.sanken-ele.co.jp/en © SANKEN ELECTRIC CO.,LTD. 2013 14 STR5A460 Series 8.10 Thermal Shutdown (TSD) Output voltage, VOUT CV mode Output current, IOUT Figure 8-14 Overload characteristics Non-switching interval VCC pin voltage VCC(ON) VCC(OFF) Drain current, ID tOLP Figure 8-16 shows the Thermal Shutdown (TSD) operational waveforms. When the temperature of control circuit increases to Tj(TSD) = 135 °C (min.) or more, the TSD is activated, and the IC stops switching operation. After that, VCC pin voltage decreases. When the VCC pin voltage decreases to about 9.4 V, the Bias Assist Function is activated and the VCC pin voltage is kept to over the VCC(OFF). When the temperature reduces to less than Tj(TSD)−Tj(TSD)HYS, the Bias Assist Function is disabled and the VCC pin voltage decreases to VCC(OFF). At that time, the IC stops operation by the Undervoltage Lockout (UVLO) circuit and reverts to the state before startup. After that, the startup circuit is activated, the VCC pin voltage increases to VCC(ON), and the IC starts switching operation again. In this way, the intermittent operation by TSD and UVLO is repeated while there is an excess thermal condition. When the fault condition is removed, the IC returns to normal operation automatically. tOLP Junction Temperature, Tj Tj(TSD) Figure 8-15 OLP operational waveform 8.9 Tj(TSD)−Tj(TSD)HYS Bias assist function Overvoltage Protection (OVP) When a voltage between VCC pin and S/GND terminal increases to VCC(OVP) = 29.3 V or more, Overvoltage Protection (OVP) is activated and stops switching operation. The intermittent operation by UVLO is repeated in OVP state. When the abnormal condition is removed, the IC returns to normal operation automatically. The approximate value of output voltage VOUT(OVP) in OVP condition is calculated by using Equation (13). ON ON OFF OFF VCC pin voltage VCC(ON) VCC(BIAS) VCC(OFF) Drain current ID Figure 8-16 TSD operational waveforms (13) where, VOUT(OVP) is voltage of between VOUT(+) and VOUT(−), VFD1 is forward voltage of D1, VFD2 is forward voltage of D2, and VFD3 is forward voltage of D3. STR5A460-DSE Rev.2.2 SANKEN ELECTRIC CO.,LTD. Nov. 11, 2015 http://www.sanken-ele.co.jp/en © SANKEN ELECTRIC CO.,LTD. 2013 15 STR5A460 Series 9. 9.1.2 Design Notes 9.1 External Components Take care to use properly rated, including derating as necessary and proper type of components. Figure 9-1 shows the peripheral circuit of IC. The pin number of SOIC8 package products in the circuits is shown in bracket. D1 9.1.3 STR5A400 1(2) 2(1) FB VCC S/GND S/GND 8 C4 R1 C3 7 6 S/GND VOUT L1 DR1 Apply proper design margin to core temperature rise by core loss and copper loss. The value of inductor should be designed so that the inductor current does not saturate. The on time must be longer than Leading Edge Blanking Time in order to control the output voltage constantly. In the universal input voltage design, the on time becomes short in the condition of maximum AC input voltage and light road. Be careful not to reduce the value of inductor ( ≥ 820 μH recommended) too much. D2 R3 R2 Inductor VCC Pin Peripheral Circuit The reference value of C4 (see Figure 9-1) is generally from 10 μF to 47 μF. The startup time is determined by the value of C4 (refer to Section 8.1 Startup Operation). 5 4 D/ST S/GND (+) L2 VAC C1 C2 D3 C5 9.1.4 R4 DR2 (-) Figure 9-1 Peripheral circuit of IC 9.1.1 Input and Output Electrolytic Capacitor Apply proper derating to ripple current, voltage, and temperature rise. The value of output electrolytic capacitor, C5, should be set to fulfill as following conditions: - The specification of output ripple is fulfilled. - The output voltage rising time in startup is enough shorter than the OLP Delay Time at Startup, tOLP = 72 ms. Use of low impedance types, designed for switch mode power supplies, is recommended. The ESR of C5 should be set within the range of Equation (14). FB Pin Peripheral Circuit The divided voltage of output voltage, VOUT(+), is input to FB pin as shown in Figure 9-1. C3 is capacitor for smoothing of output. The value of C3 depends on the value of output electrical capacitor and is 0.022 μF to 0.22 μF. When C3 value is set larger, the line regulation characteristic becomes better. But the dynamic response of the output voltage becomes worse. R1, R2 and R3 is set by the reference voltage, VFB(REF) = 2.50 V, and the output voltage, VOUT. When S/GND pin is ground reference, there is the relationship as following Equation (15). The target value of R1 is about 10 kΩ to 22 kΩ. R2 and R3 should be adjusted in actual operation condition. (15) (14) where, ZCO is ESR of Electrolytic capacitor at fOSC(AVG)(min.) = 53 kHz (Since the ESR in most general catalog is the value of 100 kHz, check the frequency specification.), ΔVOR is output ripple voltage specification, and IRP is the peak current of inductor (see Section 9.3). where, VFD2 is forward voltage of D2, and VFD3 is forward voltage of D3. The VF of D2 and D3 affects the output voltage. Thus, diodes of the low VF should be selected. STR5A460-DSE Rev.2.2 SANKEN ELECTRIC CO.,LTD. Nov. 11, 2015 http://www.sanken-ele.co.jp/en © SANKEN ELECTRIC CO.,LTD. 2013 16 STR5A460 Series 9.1.5 Freewheeling diode D3 is freewheeling diode shown in Figure 9-1. When the internal power MOSFET turns on, recovery current flows through D3. Recovery current affects power loss and noise. The VF affects the output voltage. Thus, fast recovery and low VF characteristic diode should be selected. 9.1.6 Bleeder resistance For light load application, the breeder resistance, R4, should be connected to both ends of output capacitor, C5, as shown in Figure 9-1, in order to prevent the increase of output voltage. The value of R4 should satisfy Equation (16). R4 should be adjusted in actual operation condition. (16) 9.2 D/ST Pin The internal power MOSFET connected to D/ST pin is permanently damaged when the D/ST pin voltage and the current exceed the Absolute Maximum Ratings. The D/ST pin voltage is tuned to be less than about 90 % of the Absolute Maximum Ratings (630 V) in all condition of actual operation, and the value of transformer and components should be selected based on actual operation in the application. And the D/ST pin voltage in normal operation is tuned to be less than 560 V. STR5A460-DSE Rev.2.2 SANKEN ELECTRIC CO.,LTD. Nov. 11, 2015 http://www.sanken-ele.co.jp/en © SANKEN ELECTRIC CO.,LTD. 2013 17 STR5A460 Series 9.3 Output Inductor Value Setting In general, the inductance value is set so that the inductance current becomes Discontinues Condition Mode (DCM) or Continuous Conduction Mode (CCM) in normal operation. Table 9-1 shows the operating condition and the features of DCM and CCM. On duty, D, is set within the range of Equation (17); (17) where, tON(MIN) is minimum on time, ≥ 400 ns, fOSC(AVG) is average PWM Switching Frequency, 60 kHz, and DMAX(min.) is minimum value of Maximum ON Duty, 50 %. Table 9-1 Comparison of DCM and CCM operation Discontinues Condition Mode (DCM) Continuous Conduction Mode (CCM) IL IL IRP Inductor current, IL ΔIOFF ΔION ΔIOFF IR IL(AVG) IR IRL ΔION IL(AVG) IRL 0 t t tON tOFF IRP tIDL tON tOFF Operating condition Feature Smaller Inductor size. Lower switching losses. Lower output current ripple. Higher output power. in Table 9-1, IL(AVG) is average inductor current, IR is output ripple current (In DCM mode, IR = IL(AVG). In CCM mode, IR = 0.2 × IO(AVG) to 0.5 × IO(AVG) ), IRP is maximum ripple current, IRL is minimum ripple current, tON is the period in which the power MOSFET is on status and D3 is off status, tOFF is the period in which the power MOSFET is off status and D3 is on status, and tIDL is the period in which the power MOSFET and D3 are off status. STR5A460-DSE Rev.2.2 SANKEN ELECTRIC CO.,LTD. Nov. 11, 2015 http://www.sanken-ele.co.jp/en © SANKEN ELECTRIC CO.,LTD. 2013 18 STR5A460 Series 9.3.1 Buck Converter Figure 9-2 shows the output current flow in the buck converter. Figure 9-3 and Figure 9-4 show the DCM and the CCM operational waveforms. In the following equations, IRL is zero in the DCM operation and tIDL is zero in CCM operation. U1 VL D/ST L2 S/GND (+) IL VRON ION VIN VFD3 C2 VOUT IOFF D3 C5 R4 (-) Figure 9-2 The output current flow in the buck converter VL VL VIN-VRON-VOUT VIN-VRON-VOUT t 0 -(VOUT+VFD3) IL t 0 -(VOUT+VFD3) IL IRP ΔIOFF ΔION ΔIOFF IR IL(AVG) IR IRL ΔION IL(AVG) t t 0 tON tOFF tIDL Figure 9-3 DCM operational waveforms in the buck converter IRP tON tOFF Figure 9-4 CCM operational waveforms in the buck converter 1) The average Output Current, IO(AVG) The average output current, IO(AVG) is inductor current. IO(AVG) is expressed as follows: (18) STR5A460-DSE Rev.2.2 SANKEN ELECTRIC CO.,LTD. Nov. 11, 2015 http://www.sanken-ele.co.jp/en © SANKEN ELECTRIC CO.,LTD. 2013 19 STR5A460 Series 2) On Duty, D ΔION is inductor current during tON. ΔIOFF is inductor current during tOFF. ΔION and ΔIOFF are expressed as follows: (19) (20) where, VIN is input voltage (C2 voltage), VFD3 is forward voltage of D3, VOUT is output voltage, VRON is the voltage between the D/ST pin and the S/GND pin during on time, and L is inductance value of L2. Ripple current, IR, is expressed as follows: (21) The on duty, D is expressed as follows: (22) From Equation (19), (20), and (21), Equation (23) is converted into following equation. (23) 3) Inductance Value, L The average frequency, fOSC(AVG) is as follows: (24) From Equation (22), and (24), the on duty, D is converted into following equation. From Equation (19), (20), (21), and (23), the inductance value, L is expressed as follows: (25) STR5A460-DSE Rev.2.2 SANKEN ELECTRIC CO.,LTD. Nov. 11, 2015 http://www.sanken-ele.co.jp/en © SANKEN ELECTRIC CO.,LTD. 2013 20 STR5A460 Series 4) Peak Current of The Inductor, IRP Ripple current, IR is expressed as follows: From Equation (18), (19), (20), and (21), the peak current of the inductor, IRP is expressed as follows: (26) Table 9-2 shows the circuit characteristics of DCM operation and CCM operation for buck converter. These are the result of the calculation from the operating condition of Table 9-1 and Equation (18), (23), (25), and (26). Table 9-2 Circuit characteristics (Buck converter) Parameter Operation mode Circuit characteristics DCM IO(AVG) CCM DCM D CCM DCM L CCM DCM IRP CCM STR5A460-DSE Rev.2.2 SANKEN ELECTRIC CO.,LTD. Nov. 11, 2015 http://www.sanken-ele.co.jp/en © SANKEN ELECTRIC CO.,LTD. 2013 21 STR5A460 Series 9.3.2 Inverting Converter Figure 9-5 shows the output current flow in the inverting converter. Figure 9-6 and Figure 9-7 show the DCM and the CCM operational waveforms. In the following equations, IRL is zero in the DCM operation and tIDL is zero in CCM operation. Since output current is flowed when the power MOSFET is off status, the output ripple becomes larger than the buck converter. U1 VFD3 4 D/ST S/GND 5~8 (-) D3 VRON ION VIN C5 R4 IL VL C2 IOFF VOUT L2 (+) Figure 9-5 The output current flow in the inverting converter VL VL VIN-VRON VIN-VRON t 0 -(VOUT+VFD3) IL t 0 -(VOUT+VFD3) IL IRP ΔIOFF ΔION ΔIOFF IR IL(AVG) IR IRL ΔION IL(AVG)DCM t t 0 tON tOFF tIDL Figure 9-6 DCM operational waveforms in the inverting converter IRP tON tOFF Figure 9-7 CCM operational waveforms in the inverting converter 1) The average Output Current, IO(AVG) The average output current, IO(AVG) is average inductor current during off time of the power MOSFET. IO(AVG) is expressed as follows: (27) where, IL(AVG) is average inductor current. STR5A460-DSE Rev.2.2 SANKEN ELECTRIC CO.,LTD. Nov. 11, 2015 http://www.sanken-ele.co.jp/en © SANKEN ELECTRIC CO.,LTD. 2013 22 STR5A460 Series 2) On Duty, D ΔION is inductor current during tON. ΔIOFF is inductor current during tOFF. ΔION and ΔIOFF are expressed as follows: (28) (29) where, VIN is input voltage (C2 voltage), VFD3 is forward voltage of D3, VOUT is output voltage, VRON is the voltage between the D/ST pin and the S/GND pin during on time, and L is inductance value of L2. Ripple current, IR, is expressed as follows: (30) The on duty, D is expressed as follows: (31) From Equation (28), (29), and (30), Equation (32) is converted into following equation. (32) 3) Inductance Value, L The average frequency, fOSC(AVG) is as follows: (33) From Equation (31), and (33), the on duty, D is converted into following equation. From Equation (28), (29), (30), and (32), the inductance value, L is expressed as follows: (34) STR5A460-DSE Rev.2.2 SANKEN ELECTRIC CO.,LTD. Nov. 11, 2015 http://www.sanken-ele.co.jp/en © SANKEN ELECTRIC CO.,LTD. 2013 23 STR5A460 Series 4) Peak Current of The Inductor, IRP Ripple current, IR is expressed as follows: From Equation (27), (28), (29), and (30), the peak current of the inductor, IRP is expressed as follows: (35) Table 9-3 shows the circuit characteristics of DCM operation and CCM operation for the inverting converter. These are the result of the calculation from the operating condition of Table 9-1 and Equation (27), (32), (34), and (35). Table 9-3 Circuit characteristics (Inverting converter) Parameter Operation mode Circuit characteristics DCM IO(AVG) CCM DCM D CCM DCM L CCM DCM IRP CCM STR5A460-DSE Rev.2.2 SANKEN ELECTRIC CO.,LTD. Nov. 11, 2015 http://www.sanken-ele.co.jp/en © SANKEN ELECTRIC CO.,LTD. 2013 24 STR5A460 Series 9.4 point grounding. PCB Trace Layout Since the PCB circuit trace design and the component layout significantly affects operation, EMI noise, and power dissipation, the high frequency PCB trace should be low impedance with small loop and wide trace. In addition, the ground traces affect radiated EMI noise, and wide, short traces should be taken into account. Figure 9-8 and Figure 9-9 show the circuit design example. 1) Main Circuit Trace Layout This is the main trace containing switching currents, and thus it should be as wide trace and small loop as possible. 2) Freewheeling Loop Layout This is the trace for the current of freewheeling diode, D3, and thus it should be as wide trace and small loop as possible. 3) Control Ground Trace Layout Since the operation of IC may be affected from the large current of the main trace that flows in control ground trace, the control ground trace should be separated from main trace and connected at single 4) VCC Trace Layout This is the trace for supplying power to the IC, and thus it should be as small loop as possible. If C4 and the IC are distant from each other, placing a capacitor such as film capacitor Cf (about 0.1 μF to 1.0 μF) close to the VCC pin and the S/GND pin is recommended. 5) FB Trace Layout The divided voltage by R2, R3 and R1 of output voltage is input to the FB pin. In order to increase the detection accuracy, R3 and R1 should be connected to bottom of C3 and the S/GND pin, The trace between R1, R2 and the FB pin should be as short as possible. 6) Thermal Considerations Because the power MOSFET has a positive thermal coefficient of RDS(ON), consider it in thermal design. Since the copper area under the IC and the S/GND pin trace act as a heatsink, its traces should be as wide as possible. (6) Trace of S/GND pin should be wide for heat release D1 D2 (4) Loop of the power supply should be small R3 (5) The trace between R1, R2 and FB pin should be as short as possible. R2 1 FB S/GND 2 VCC S/GND 8 C3 C4 R1 7 6 S/GND VOUT 5 4 D/ST (＋) S/GND L2 U1 C2 C5 D3 R4 (－) (1)Main trace should be wide trace and small loop (2) Freewheeling Loop trace should be wide trace and small loop (3) Control GND trace should be connected at a single point Figure 9-8 Peripheral circuit example around the IC for the buck converter (DIP8) STR5A460-DSE Rev.2.2 SANKEN ELECTRIC CO.,LTD. Nov. 11, 2015 http://www.sanken-ele.co.jp/en © SANKEN ELECTRIC CO.,LTD. 2013 25 STR5A460 Series (6) Trace of S/GND pin should be wide for heat release D1 D2 (4) Loop of the power supply should be small R3 (5) The trace between R1, R2 and FB pin should be as short as possible. R2 1 FB S/GND VCC S/GND 2 8 C3 C4 R1 7 6 S/GND D/ST VOUT D3 5 4 (－) S/GND U1 C2 C5 R4 L2 (＋) (1)Main trace should be wide trace and small loop (2) Freewheeling Loop trace should be wide trace and small loop (3) Control GND trace should be connected at a single point Figure 9-9 Peripheral circuit example around the IC for the inverting converter (DIP8) STR5A460-DSE Rev.2.2 SANKEN ELECTRIC CO.,LTD. Nov. 11, 2015 http://www.sanken-ele.co.jp/en © SANKEN ELECTRIC CO.,LTD. 2013 26 STR5A460 Series 10. Pattern Layout Example (DIP8) 10.1 Buck Converter The following show the PCB pattern layout example and the schematic of circuit using STR5A460D series. The parts in Figure 10-2 are only used. The PCB pattern layout example of STR5A460S series is same except for some pin arrangements. Figure 10-1 PCB circuit trace layout example for the buck converter Z1 1 FB S/GND VCC S/GND 2 D5 JW10 R2 R3 D6 8 7 R1 C4 C5 6 S/GND L2 L1 D/ST VAC D4 S/GND D3 C1 VOUT 5 4 C2 (+) D7 C6 R6 F1 JW9 D2 D1 (-) TC_STR5A400D_5_R1 Figure 10-2 Circuit schematic for PCB circuit trace layout for the buck converter STR5A460-DSE Rev.2.2 SANKEN ELECTRIC CO.,LTD. Nov. 11, 2015 http://www.sanken-ele.co.jp/en © SANKEN ELECTRIC CO.,LTD. 2013 27 STR5A460 Series 10.2 Inverting Converter The following show the PCB pattern layout example and the schematic of circuit using STR5A460D. The PCB pattern layout example of STR5A460S series is same except for some pin arrangements. Figure 10-3 PCB circuit trace layout example for the inverting converter circuit D5 R2 Z1 1 FB S/GND VCC S/GND 2 D6 R3 8 7 R1 C4 C5 6 S/GND L1 JW1 D/ST VAC DR4 S/GND (-) DR3 C1 C2 F1 DR2 VOUT D7 5 4 L2 DR1 C6 C7 R6 L3 (+) TC_STR5A400D_6_R2 Figure 10-4 Circuit schematic for PCB circuit trace layout for the inverting converter circuit STR5A460-DSE Rev.2.2 SANKEN ELECTRIC CO.,LTD. Nov. 11, 2015 http://www.sanken-ele.co.jp/en © SANKEN ELECTRIC CO.,LTD. 2013 28 STR5A460 Series 11. Reference Design of Power Supply 11.1 Buck Converter As an example, the following show the power supply specification, the circuit schematic, the bill of materials, and the transformer specification. ● Power supply specification IC Input voltage Maximum output power Output voltage Output current STR5A464D 85 VAC to 265 VAC 3 W (max.) 15 V 0.2 A ● Circuit schematic D1 R2 U1 1 FB S/GND VCC S/GND 2 D2 R3 8 7 R1 C4 C3 6 S/GND F1 L2 L1 DR1 D/ST C1 VOUT 5 4 S/GND (+) C5 C2 VAC R4 D3 DR2 (-) TC_STR5A400D_7_R1 ● Bill of materials Symbol Part type Ratings(1) Recommended Sanken Parts DR1 General 600 V, 1 A AM01A DR2 General 600 V, 1 A AM01A F1 Fuse 250 V, 1 A (2) CM inductor L1 680μH Inductor L2 1 mH C1 Electrolytic 400 V, 4.7 μF C2 Electrolytic 400 V, 4.7μF C3 Ceramic 50 V, 0.22 µF C4 Electrolytic 50 V, 10 µF C5 Electrolytic, Low impedance 50 V, 220 µF R1 General 10 kΩ (2) R2 General 47 kΩ (2) R3 General 5.6 kΩ (2) R4 General 4.7 kΩ D1 Fast recovery 200V, 1 A SJPL-D2 D2 Fast recovery 500 V, 1 A SJPD-D5 D3 Fast recovery 500 V, 1 A SJPD-D5 U1 IC STR5A464D (1) Unless otherwise specified, the voltage rating of capacitor is 50 V or less and the power rating of resistor is 1/8 W or less. (2) It is necessary to be adjusted based on actual operation in the application. STR5A460-DSE Rev.2.2 SANKEN ELECTRIC CO.,LTD. Nov. 11, 2015 http://www.sanken-ele.co.jp/en © SANKEN ELECTRIC CO.,LTD. 2013 29 STR5A460 Series 11.2 Inverting Converter As an example, the following show the power supply specification, the circuit schematic, the bill of materials, and the transformer specification. ● Power supply specification IC Input voltage Maximum output power Output voltage Output current STR5A464D 85 VAC to 265 VAC 3 W (max.) − 15 V 0.2 A ● Circuit schematic D1 R2 U1 1 FB S/GND VCC S/GND 2 D2 R3 8 7 R1 C4 C3 6 S/GND L1 F1 DR1 D/ST C1 D3 5 4 VOUT S/GND (-) C5 C2 VAC R4 L2 DR2 (+) TC_STR5A400D_8_R1 ● Bill of materials Symbol Part type Ratings(1) Recommended Sanken Parts DR1 General 600 V, 1 A AM01A DR2 General 600 V, 1 A AM01A F1 Fuse 250 V, 1 A (2) CM inductor L1 680μH Inductor L2 1 mH C1 Electrolytic 400 V, 10 μF C2 Electrolytic 400 V, 10 μF C3 Ceramic 50 V, 0.22 µF C4 Electrolytic 50 V, 10 µF C5 Electrolytic, Low impedance 50 V, 220 µF R1 General 10 kΩ (2) R2 General 47 kΩ (2) R3 General 5.6 kΩ (2) R4 General 4.7 kΩ D1 Fast recovery 200 V, 1 A SJPL-D2 D2 Fast recovery 500 V, 1 A SJPD-D5 D3 Fast recovery 500 V, 1 A SJPD-D5 U1 IC STR5A464D (1) Unless otherwise specified, the voltage rating of capacitor is 50 V or less and the power rating of resistor is 1/8 W or less. (2) It is necessary to be adjusted based on actual operation in the application. STR5A460-DSE Rev.2.2 SANKEN ELECTRIC CO.,LTD. Nov. 11, 2015 http://www.sanken-ele.co.jp/en © SANKEN ELECTRIC CO.,LTD. 2013 30 STR5A460 Series IMPORTANT NOTES ● All data, illustrations, graphs, tables and any other information included in this document as to Sanken’s products listed herein (the “Sanken Products”) are current as of the date this document is issued. All contents in this document are subject to any change without notice due to improvement, etc. Please make sure that the contents set forth in this document reflect the latest revisions before use. ● The Sanken Products are intended for use as components of general purpose electronic equipment or apparatus (such as home appliances, office equipment, telecommunication equipment, measuring equipment, etc.). Prior to use of the Sanken Products, please put your signature, or affix your name and seal, on the specification documents of the Sanken Products and return them to Sanken. If considering use of the Sanken Products for any applications that require higher reliability (transportation equipment and its control systems, traffic signal control systems or equipment, disaster/crime alarm systems, various safety devices, etc.), you must contact a Sanken sales representative to discuss the suitability of such use and put your signature, or affix your name and seal, on the specification documents of the Sanken Products and return them to Sanken, prior to the use of the Sanken Products. Any use of the Sanken Products without the prior written consent of Sanken in any applications where extremely high reliability is required (aerospace equipment, nuclear power control systems, life support systems, etc.) is strictly prohibited. ● In the event of using the Sanken Products by either (i) combining other products or materials therewith or (ii) physically, chemically or otherwise processing or treating the same, you must duly consider all possible risks that may result from all such uses in advance and proceed therewith at your own responsibility. ● Although Sanken is making efforts to enhance the quality and reliability of its products, it is impossible to completely avoid the occurrence of any failure or defect in semiconductor products at a certain rate. You must take, at your own responsibility, preventative measures including using a sufficient safety design and confirming safety of any equipment or systems in/for which the Sanken Products are used, upon due consideration of a failure occurrence rate or derating, etc., in order not to cause any human injury or death, fire accident or social harm which may result from any failure or malfunction of the Sanken Products. Please refer to the relevant specification documents and Sanken’s official website in relation to derating. ● No anti-radioactive ray design has been adopted for the Sanken Products. ● No contents in this document can be transcribed or copied without Sanken’s prior written consent. ● The circuit constant, operation examples, circuit examples, pattern layout examples, design examples, recommended examples and evaluation results based thereon, etc., described in this document are presented for the sole purpose of reference of use of the Sanken Products and Sanken assumes no responsibility whatsoever for any and all damages and losses that may be suffered by you, users or any third party, or any possible infringement of any and all property rights including intellectual property rights and any other rights of you, users or any third party, resulting from the foregoing. ● All technical information described in this document (the “Technical Information”) is presented for the sole purpose of reference of use of the Sanken Products and no license, express, implied or otherwise, is granted hereby under any intellectual property rights or any other rights of Sanken. ● Unless otherwise agreed in writing between Sanken and you, Sanken makes no warranty of any kind, whether express or implied, as to the quality of the Sanken Products (including the merchantability, or fitness for a particular purpose or a special environment thereof), and any information contained in this document (including its accuracy, usefulness, or reliability). ● In the event of using the Sanken Products, you must use the same after carefully examining all applicable environmental laws and regulations that regulate the inclusion or use of any particular controlled substances, including, but not limited to, the EU RoHS Directive, so as to be in strict compliance with such applicable laws and regulations. ● You must not use the Sanken Products or the Technical Information for the purpose of any military applications or use, including but not limited to the development of weapons of mass destruction. In the event of exporting the Sanken Products or the Technical Information, or providing them for non-residents, you must comply with all applicable export control laws and regulations in each country including the U.S. Export Administration Regulations (EAR) and the Foreign Exchange and Foreign Trade Act of Japan, and follow the procedures required by such applicable laws and regulations. ● Sanken assumes no responsibility for any troubles, which may occur during the transportation of the Sanken Products including the falling thereof, out of Sanken’s distribution network. ● Although Sanken has prepared this document with its due care to pursue the accuracy thereof, Sanken does not warrant that it is error free and Sanken assumes no liability whatsoever for any and all damages and losses which may be suffered by you resulting from any possible errors or omissions in connection with the contents included herein. ● Please refer to the relevant specification documents in relation to particular precautions when using the Sanken Products, and refer to our official website in relation to general instructions and directions for using the Sanken Products. STR5A460-DSE Rev.2.2 SANKEN ELECTRIC CO.,LTD. Nov. 11, 2015 http://www.sanken-ele.co.jp/en © SANKEN ELECTRIC CO.,LTD. 2013 31