Off-Line PWM Controllers with Integrated Power MOSFET STR-A6000 Series General Descriptions Package The STR-A6000 series are power ICs for switching power supplies, incorporating a MOSFET and a current mode PWM controller IC. 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 Not to Scale Lineup Features Electrical Characteristics Current Mode Type PWM Control Brown-In and Brown-Out function Auto Standby Function Products No Load Power Consumption < 25mW Operation Mode Normal Operation ----------------------------- PWM Mode Standby ---------------------------- Burst Oscillation Mode Random Switching Function Slope Compensation Function Leading Edge Blanking Function Bias Assist Function Audible Noise Suppression function during Standby mode Protections ・Overcurrent Protection (OCP)*; Pulse-by-Pulse, built-in compensation circuit to minimize OCP point variation on AC input voltage ・Overload Protection (OLP); auto-restart ・Overvoltage Protection (OVP); latched shutdown ・Thermal Shutdown Protection (TSD); latched shutdown STR-A605×M 650 V STR-A607×M 800 V STR-A605×H 650 V STR-A606×H 700 V STR-A606×HD 700 V Typical Application Circuit VOUT (+) Products PC1 D1 S D2 D/ST D/ST RA C5 R52 U51 VCC C2 STR-A6051M D R56 (-) RB S/OCP BR GND FB/OLP RC 3 4 C4 C3 14 W 31 W 21 W 22 W 17.5W 35 W 24.5 W STR-A6053M 1.9 Ω 26 W 21W 40 W 28 W STR-A6079M 19.2 Ω 8W 6W 13 W 9W 6Ω 17 W 11 W 30 W 19.5 W 3.95Ω 20 W 15 W 35 W 23.5 W 2.8 Ω 23 W 18 W 38 W 26.5 W STR-A6063HD 2.3 Ω 25 W 20 W 40 W STR-A6061HD 28 W * The output power is actual continues power that is measured at 50 °C ambient. The peak output power can be 120 to 140 % of the value stated here. Core size, ON Duty, and thermal design affect the output power. It may be less than the value stated here. STR-A6000 2 3.95 Ω 18.5 W 2.8 Ω STR-A6052M STR-A6062HD U1 1 POUT POUT (Adapter) (Open frame) AC85 AC85 AC230V AC230V ~265V ~265V fOSC(AVG) = 67 kHz STR-A6062H C53 C52 R53 R2 5 NC R51 R55 C51 7 RDS(ON) (max.) R54 P 8 100 kHz MOSFET ON Resistance and Output Power, POUT* STR-A6061H L51 D51 R1 C1 100 kHz STR-A6069HD T1 C6 67 kHz *STR-A60××HD has two types OCP STR-A6069H BR1 fOSC(AVG) fOSC(AVG) = 100 kHz STR-A6059H *STR-A60××HD has two types OCP VAC VDSS (min.) PC1 ROCP Applications CY TC_STR-A6000_1_R1 STR-A6000 - DS Rev.4.3 Mar. 13, 2015 Low power AC/DC adapter White goods Auxiliary power supply OA, AV and industrial equipment SANKEN ELECTRIC CO.,LTD. http://www.sanken-ele.co.jp/en/ 1 STR-A6000 Series CONTENTS General Descriptions ----------------------------------------------------------------------- 1 1. Absolute Maximum Ratings --------------------------------------------------------- 3 2. Electrical Characteristics ------------------------------------------------------------ 4 3. Performance Curves ------------------------------------------------------------------ 6 3.1 Derating Curves --------------------------------------------------------------- 6 3.2 Ambient Temperature versus Power Dissipation Curve ------------- 6 3.3 MOSFET Safe Operating Area Curves ---------------------------------- 7 3.4 Transient Thermal Resistance Curves ----------------------------------- 9 4. Functional Block Diagram ---------------------------------------------------------- 11 5. Pin Configuration Definitions ------------------------------------------------------ 11 6. Typical Application Circuit -------------------------------------------------------- 12 7. Package Outline ----------------------------------------------------------------------- 13 8. Marking Diagram -------------------------------------------------------------------- 13 9. Operational Description ------------------------------------------------------------- 14 9.1 Startup Operation ----------------------------------------------------------- 14 9.2 Undervoltage Lockout (UVLO) ------------------------------------------- 15 9.3 Bias Assist Function --------------------------------------------------------- 15 9.4 Constant Output Voltage Control ---------------------------------------- 15 9.5 Leading Edge Blanking Function ---------------------------------------- 16 9.6 Random Switching Function ---------------------------------------------- 16 9.7 Automatic Standby Mode Function-------------------------------------- 16 9.8 Brown-In and Brown-Out Function ------------------------------------- 17 9.9 Overcurrent Protection Function (OCP) ------------------------------- 19 9.10 Overload Protection Function (OLP) ----------------------------------- 20 9.11 Overvoltage Protection (OVP) -------------------------------------------- 20 9.12 Thermal Shutdown Function (TSD) ------------------------------------- 20 10. Design Notes --------------------------------------------------------------------------- 21 10.1 External Components ------------------------------------------------------- 21 10.2 PCB Trace Layout and Component Placement ----------------------- 22 11. Pattern Layout Example ------------------------------------------------------------ 24 12. Reference Design of Power Supply ----------------------------------------------- 25 OPERATING PRECAUTIONS -------------------------------------------------------- 27 IMPORTANT NOTES ------------------------------------------------------------------- 28 STR-A6000 - DS Rev.4.3 Mar. 13, 2015 SANKEN ELECTRIC CO.,LTD. 2 STR-A6000 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, 7 pin = 8 pin Parameter Symbol Test Conditions Pins Rating Units 1.2 A6079M 1.8 Drain Peak Current(1) IDPEAK Single pulse 8–1 2.5 A 3.0 4.0 Avalanche Energy(2)(3) EAS ILPEAK=1.2A 7 A6079M ILPEAK=1.8A 24 A6059H / 69H / 69HD ILPEAK=2A 46 A6061H / 61HD ILPEAK=2A 47 8–1 mJ A6051M ILPEAK=2.2A 56 A6062H / 62HD ILPEAK=2.3A 62 A6052M ILPEAK=2.5A 72 A6063HD ILPEAK=2.7A 86 A6053M 1−3 − 2 to 6 V BR Pin Voltage VBR 2−3 − 0.3 to 7 V BR Pin Sink Current IBR 2−3 1.0 mA FB/OLP Pin Voltage VFB 4−3 − 0.3 to 14 V FB/OLP Pin Sink Current IFB 4−3 1.0 mA VCC Pin Voltage MOSFET Power Dissipation(4) Control Part Power Dissipation Operating Ambient Temperature(6) Storage Temperature VCC 5−3 32 V 8–1 1.35 W PD2 5–3 1.2 W TOP − − 20 to 125 °C Tstg − − 40 to 125 °C Channel Temperature Tch − 150 °C PD1 A6059H / 69H / 69HD A6051M / 61H / 61HD A6052M / 62H / 62HD A6053M / 63HD VS/OCP S/OCP Pin Voltage Notes (5) (1) Refer to 3.3 MOSFET Safe Operating Area Curves Refer to Figure 3-2 Avalanche Energy Derating Coefficient Curve (3) Single pulse, VDD = 99 V, L = 20 mH (4) Refer to Figure 3-3 Ambient temperature versus power dissipation curve (5) When embedding this hybrid IC onto the printed circuit board (cupper area in a 15 mm × 15 mm) (6) The recommended internal frame temperature, T F, is 115°C (max.) (2) STR-A6000 - DS Rev.4.3 Mar. 13, 2015 SANKEN ELECTRIC CO.,LTD. 3 STR-A6000 Series 2. Electrical Characteristics The polarity value for current specifies a sink as "+," and a source as "−," referencing the IC. Unless otherwise specified, TA = 25 °C, VCC = 18 V, 7 pin = 8 pin Parameter Symbol Test Conditions Pins Min. Typ. Max. Units VCC(ON) 5−3 13.8 15.3 16.8 V VCC(OFF) 5−3 7.3 8.1 8.9 V 5−3 − − 2.5 mA − 38 − V − 3.7 − 2.5 − 1.5 mA 8.5 9.5 10.5 V 60 67 74 90 100 110 − 5 − − 8 − 77 83 89 % − 540 − ns − 470 − − 340 − − 280 − − 20 − − 33 − Notes Power Supply Startup Operation Operation Start Voltage Operation Stop Voltage (1) Circuit Current in Operation ICC(ON) Startup Circuit Operation Voltage VST(ON) 8−3 Startup Current ISTARTUP VCC = 13.5 V 5 − 3 Startup Current Biasing Threshold Voltage VCC(BIAS) ICC = − 100 µA VCC = 12 V 5−3 Normal Operation Average Switching Frequency Switching Frequency Modulation Deviation fOSC(AVG) 8−3 Δf 8−3 A60××M kHz A60××H / HD A60××M kHz A60××H / HD Maximum ON Duty DMAX 8−3 Minimum ON Time tON(MIN) 8−3 tBW − OCP Compensation Coefficient DPC − OCP Compensation ON Duty DDPC − − 36 − % VOCP(L) 1−3 0.70 0.78 0.86 V 1−3 0.81 0.9 0.99 V 1−3 1.32 1.55 1.78 V 4−3 − 340 − 230 − 150 µA A60××M A60××H / HD Protection Function Leading Edge Blanking Time A60××M ns A60××H / HD mV/μs A60××H / HD OCP Threshold Voltage at Zero ON Duty OCP Threshold Voltage at 36% ON Duty OCP Threshold Voltage in Leading Edge Blanking Time VOCP(LEB) Maximum Feedback Current IFB(MAX) Minimum Feedback Current IFB(MIN) 4−3 − 30 − 15 −7 µA FB/OLP pin Oscillation Stop Threshold Voltage VFB(STB) 4−3 0.85 0.95 1.05 V OLP Threshold Voltage VFB(OLP) 4−3 7.3 8.1 8.9 V OLP Operation Current ICC(OLP) 5−3 − 300 600 µA tOLP − 54 68 82 ms VFB(CLAMP) 4−3 11 12.8 14 V OLP Delay Time FB/OLP Pin Clamp Voltage (1) VOCP(H) VCC = 32 V VCC = 12 V VCC = 12 V A60××M A60××HD VCC(BIAS) > VCC(OFF) always. STR-A6000 - DS Rev.4.3 Mar. 13, 2015 SANKEN ELECTRIC CO.,LTD. 4 STR-A6000 Series Parameter Symbol Test Conditions Pins Min. Typ. Max. Units Brown-In Threshold Voltage VBR(IN) VCC = 32 V 2−3 5.2 5.6 6 V VBR(OUT) VCC = 32 V 2−3 4.45 4.8 5.15 V VBR(CLAMP) VCC = 32 V 2−3 6 6.4 7 V 2−3 0.3 0.48 0.7 V 5−3 26 29 32 V 5−3 − 700 − μA − 135 − − °C 650 − − 700 − − 800 − − − − 300 − − 19.2 − − 6 − − 3.95 − − 2.8 − − 2.3 A6063HD − − 1.9 A6053M − − 250 ns − − 400 ns − − 22 °C/W Brown-Out Threshold Voltage BR Pin Clamp Voltage BR Function Disabling Threshold VBR(DIS) OVP Threshold Voltage VCC(OVP) Latch Circuits Holding Current(2) Thermal Shutdown Operating Temperature ICC(LATCH) VCC = 32 V VCC = 9.5 V Tj(TSD) Notes MOSFET Drain-to-Source Breakdown Voltage Drain Leakage Current On Resistance Switching Time Thermal Resistance Channel to Case Thermal Resistance(3) 8–1 VDSS 8–1 IDSS RDS(ON) IDS = 0.4A 8−1 tf 8–1 θch-C − A605× V A606× A607× μA A6079M Ω A6059H / 69H / 69HD A6051M / 61H / 61HD A6052M / 62H / 62HD A6053M (2) A latch circuit is a circuit operated with Overvoltage Protection function (OVP) and/or Thermal Shutdown function (TSD) in operation. (3) θch-C is thermal resistance between channel and case. Case temperature (T C) is measured at the center of the case top surface. STR-A6000 - DS Rev.4.3 Mar. 13, 2015 SANKEN ELECTRIC CO.,LTD. 5 STR-A6000 Series 3. 3.1 Performance Curves Derating Curves EAS Temperature Derating Coefficient (%) Safe Operating Area Temperature Derating Coefficient (%) 100 80 60 40 20 0 0 25 50 75 100 125 150 100 80 60 40 20 0 25 3.2 75 100 125 150 Channel Temperature, Tch (°C) Channel Temperature, Tch (°C) Figure 3-1 SOA Temperature Derating Coefficient Curve 50 Figure 3-2 Avalanche Energy Derating Coefficient Curve Ambient Temperature versus Power Dissipation Curve 1.6 Power Dissipation, PD1 (W) 1.4 1.35W 1.2 1 0.8 0.6 0.4 0.2 0 0 20 40 60 80 100 120 140 160 Ambient Temperature, TA (°C ) Figure 3-3 Ambient temperature versus power dissipation curve STR-A6000 - DS Rev.4.3 Mar. 13, 2015 SANKEN ELECTRIC CO.,LTD. 6 STR-A6000 Series 3.3 MOSFET Safe Operating Area Curves When the IC is used, the safe operating area curve should be multiplied by the temperature derating coefficient derived from Figure 3-1. The broken line in the safe operating area curve is the drain current curve limited by on-resistance. Unless otherwise specified, TA = 25 °C, Single pulse STR-A6051M STR-A6052M 10 10 0.1ms Drain Current, ID (A) Drain Current, ID (A) 0.1ms 1 1ms 0.1 1 1ms 0.1 0.01 0.01 1 10 100 Drain-to-Source Voltage (V) 1 1000 STR-A6053M 10 100 Drain-to-Source Voltage (V) 1000 STR-A6079M 10 10 0.1ms 1 Drain Current, ID (A) Drain Current, ID (A) 0.1ms 1ms 0.1 0.01 1 1ms 0.1 0.01 1 10 100 Drain-to-Source Voltage (V) STR-A6000 - DS Rev.4.3 Mar. 13, 2015 1000 1 10 100 Drain-to-Source Voltage (V) SANKEN ELECTRIC CO.,LTD. 1000 7 STR-A6000 Series STR-A6059H STR-A6061H / 61HD 10 10 Drain Current, ID (A) Drain Current, ID (A) 0.1ms 1 0.1 0.01 1 1ms 0.1 0.01 1 10 100 1000 1 Drain-to-Source Voltage (V) 10 100 1000 Drain-to-Source Voltage (V) STR-A6062H / 62HD STR-A6063HD 10 0.1ms 1 Drain Current, ID (A) Drain Current, ID (A) 0.1ms 1ms 0.1 1ms 0.01 1 10 100 Drain-to-Source Voltage (V) 1000 Drain-to-Source Voltage (V) STR-A6069H / 69HD 10 Drain Current, ID (A) 0.1ms 1 1ms 0.1 0.01 1 10 100 1000 Drain-to-Source Voltage (V) STR-A6000 - DS Rev.4.3 Mar. 13, 2015 SANKEN ELECTRIC CO.,LTD. 8 STR-A6000 Series 3.4 Transient Thermal Resistance Curves STR-A6051M / 61H / 61HD Transient Thermal Resistance θch-c (°C/W) 10 1 0.1 0.01 1µ 10µ STR-A6252 100µ 1m 過渡熱抵抗曲線 Time (s) curve Transient thermal resistance 10m 100m STR-A6052M / 62H / 62HD 過渡熱抵抗 θch-c[℃/W] Thermal Transient resistance thermalResistance Transient θch-c (°C/W) 10 10 11 0.1 0.1 0.01 0.01 1µ 1.0E-06 10µ 1.0E-05 100µ 1.0E-04 STR-A6053M 1.0E-03 10m 1.0E-02 100m 1.0E-01 時間 t [sec] time 10 Transient Thermal Resistance θch-c (°C/W) 1m Time (s) 1 0.1 0.01 1µ 10µ 100µ 1m 10m 100m Time (s) STR-A6059M / 69H / 69HD Transient Thermal Resistance θch-c (°C/W) 10 1 0.1 0.01 1µ 10µ 100µ 1m 10m 100m Time (s) STR-A6000 - DS Rev.4.3 Mar. 13, 2015 SANKEN ELECTRIC CO.,LTD. 9 STR-A6000 Series STR-A6079M Transient Thermal Resistance θch-c (°C/W) 10 1 0.1 0.01 100n 1µ 10µ 100µ 1m 10m 100m STR-A6063HD Time (s) 過 渡 熱 抵 抗 曲 線 Transient thermal resistance curve STR-A6063HD 過渡熱抵抗 θch-c[℃/W] Transient thermal resistance Transient Thermal Resistance θch-c (°C/W) 10 10 11 0.1 0.1 0.01 0.01 0.001 0.001 1µ 1.0E-06 10µ 1.0E-05 100µ 1.0E-04 1m 1.0E-03 10m 1.0E-02 100m 1.0E-01 Time (s) 時間 t [sec] time STR-A6000 - DS Rev.4.3 Mar. 13, 2015 SANKEN ELECTRIC CO.,LTD. 10 STR-A6000 Series 4. Functional Block Diagram VCC 5 Startup UVLO BR 2 REG VREG OVP D/ST 7,8 TSD Brown-in Brown-out 6.4V DRV PWM OSC S Q R OCP 7V VCC Drain peak current compensation OLP Feedback control FB/OLP 4 12.8V LEB S/OCP 1 GND 3 Slope compensation BD_STR-A6000_R1 5. Pin Configuration Definitions Pin Name S/GND 1 8 D/ST 1 S/OCP BR 2 7 D/ST 2 BR 3 GND GND 3 6 4 FB /OLP FB/OLP 4 5 5 VCC 6 − VCC 7 8 STR-A6000 - DS Rev.4.3 Mar. 13, 2015 D/ST Descriptions MOSFET source and overcurrent protection (OCP) signal input Brown-In and Brown-Out detection voltage input Ground Constant voltage control signal input and over load protection (OLP) signal input Power supply voltage input for control part and overvoltage protection (OVP) signal input (Pin removed) MOSFET drain and startup current input SANKEN ELECTRIC CO.,LTD. 11 STR-A6000 Series 6. Typical Application Circuit The following drawings show circuits enabled and disabled the Brown-In/Brown-Out function. The PCB traces D/ST pins should be as wide as possible, in order to enhance thermal dissipation. In applications having a power supply specified such that D/ST pin has large transient surge voltages, a clamp snubber circuit of a capacitor-resistor-diode (CRD) combination should be added on the primary winding P, or a damper snubber circuit of a capacitor (C) or a resistor-capacitor (RC) combination should be added between the D/ST pin and the S/OCP pin. CRD clamp snubber BR1 VOUT (+) R54 R1 C6 RA L51 D51 T1 VAC R51 PC1 C1 P R55 C51 D1 RB D2 8 U51 VCC NC C53 C52 R53 R2 5 7 D/ST D/ST C5 R52 S R56 D C2 (-) U1 STR-A6000 S/OCP BR GND FB/OLP C（RC） damper snubber 1 RC 2 3 4 C4 C3 PC1 ROCP CY TC_STR-A6000_2_R1 Figure 6-1 Typical application circuit (enabled Brown-In/Brown-Out function, DC line detection) CRD clamp snubber BR1 VAC L51 D51 T1 VOUT (+) R54 R1 C6 PC1 C1 P R55 C51 D1 S D2 8 D/ST D/ST C5 NC R52 U51 VCC C2 C53 C52 R53 R2 5 7 R51 R56 D (-) U1 STR-A6000 S/OCP BR GND FB/OLP C（RC） damper snubber 1 2 3 4 C3 ROCP PC1 CY TC_STR-A6000_3_R1 Figure 6-2 Typical application circuit (disabled Brown-In/Brown-Out function) STR-A6000 - DS Rev.4.3 Mar. 13, 2015 SANKEN ELECTRIC CO.,LTD. 12 STR-A6000 Series 7. Package Outline DIP8 The following show a representative type of DIP8. NOTES: 1) Dimension is in millimeters 2) Pb-free. Device composition compliant with the RoHS directive 8. Marking Diagram STR-A60××M STR-A60××H 8 STR-A60××HD 8 A60××H A60××× Part Number SKYMDD SKYMD Lot Number 1 Lot Number Y is the Last digit of the year (0 to 9) M is the Month (1 to 9, O, N or D) 1 D is a period of days: 1 : 1st to 10th 2 : 11th to 20th st 3 : 21 to 31 Y is the Last digit of the year (0 to 9) M is the Month (1 to 9, O, N or D) D is a period of days: 1 : 1st to 10th 2 : 11th to 20th st 3 : 21st to 31st Sanken Control Number STR-A6000 - DS Rev.4.3 Mar. 13, 2015 Part Number SANKEN ELECTRIC CO.,LTD. Sanken Control Number 13 STR-A6000 Series 9. 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). 9.1 With Brown-In / Brown-Out function When BR pin voltage is more than VBR(DIS) = 0.48 V and less than VBR(IN) = 5.6 V, the Bias Assist Function (refer to Section 9.3) is disabled. Thus, VCC pin voltage repeats increasing to VCC(ON) and decreasing to VCC(OFF) (shown in Figure 9-3). When BR pin voltage becomes VBR(IN) or more, the IC starts switching operation. Startup Operation BR1 Figure 9-1 shows the circuit around IC. Figure 9-2 shows the start up operation. 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 VST(ON) = 38 V, the startup circuit starts operation. During the startup process, the constant current, ISTARTUP = − 2.5 mA, charges C2 at VCC pin. When VCC pin voltage increases to VCC(ON) = 15.3 V, the control circuit starts operation. During the IC operation, the voltage rectified the auxiliary winding voltage, VD, of Figure 9-1 becomes a power source to the VCC pin. After switching operation begins, the startup circuit turns off automatically so that its current consumption becomes zero. The approximate value of auxiliary winding voltage is about 15 V to 20 V, taking account of the winding turns of D winding so that VCC pin voltage becomes Equation (1) within the specification of input and output voltage variation of power supply. C1 7, 8 D/ST U1 VCC 5 D2 C2 BR 2 GND P R2 D VD 3 Figure 9-1 VCC pin peripheral circuit (Without Brown-In / Brown-Out) VCC pin voltage VCC(ON) tSTART VCC( BIAS) (max .) VCC VCC(OVP ) (min .) Drain current, ID ⇒10.5 (V) VCC 26 (V) (1) The oscillation start timing of IC depends on Brown-In / Brown-Out function (refer to Section 9.8). Without Brown-In / Brown-Out function (BR pin voltage is VBR(DIS) = 0.48 V or less) When VCC pin voltage increases to VCC(ON), the IC starts switching operation, As shown in Figure 9-2. The startup time of IC is determined by C2 capacitor value. The approximate startup time tSTART (shown in Figure 9-2) is calculated as follows: t START C2 × T1 VAC VCC( ON )－VCC( INT ) Figure 9-2 Startup operation (Without Brown-In / Brown-Out) VCC pin voltage tSTART VCC(ON) VCC(OFF) BR pin voltage VBR(IN) (2) I STRATUP where, tSTART : Startup time of IC (s) VCC(INT) : Initial voltage on VCC pin (V) Drain current, ID Figure 9-3 Startup operation (With Brown-In / Brown-Out) STR-A6000 - DS Rev.4.3 Mar. 13, 2015 SANKEN ELECTRIC CO.,LTD. 14 STR-A6000 Series 9.2 Undervoltage Lockout (UVLO) Figure 9-4 shows the relationship of VCC pin voltage and circuit current ICC. When VCC pin voltage decreases to VCC(OFF) = 8.1 V, the control circuit stops operation by UVLO (Undervoltage Lockout) circuit, and reverts to the state before startup. Circuit current, ICC ICC（ON） Stop Start pin voltage decreases to the startup current threshold biasing voltage, VCC(BIAS) = 9.5 V. While the Bias Assist function is activated, any decrease of the VCC pin voltage is counteracted by providing the startup current, ISTARTUP, from the startup circuit. Thus, the VCC pin voltage is kept almost constant. By the Bias Assist function, the value of C2 is allowed to be small and the startup time becomes shorter. Also, because the increase of VCC pin voltage becomes faster when the output runs with excess voltage, the response time of the OVP function becomes shorter. It is necessary to check and adjust the startup process based on actual operation in the application, so that poor starting conditions may be avoided. 9.4 VCC（ON） VCC pin voltage VCC（OFF） Figure 9-4 Relationship between VCC pin voltage and ICC 9.3 Bias Assist Function Figure 9-5 shows VCC pin voltage behavior during the startup period. After VCC pin voltage increases to VCC(ON) = 15.3 V at startup, the IC starts the operation. Then circuit current increases and VCC pin voltage decreases. At the same time, the auxiliary winding voltage VD increases in proportion to output voltage. These are all balanced to produce VCC pin voltage. Constant Output Voltage Control The IC achieves the constant voltage control of the power supply output by using the current-mode control method, which enhances the response speed and provides the stable operation. The FB/OLP pin voltage is internally added the slope compensation at the feedback control (refer to Section 4 Functional Block Diagram), and the target voltage, V SC, is generated. The IC compares the voltage, VROCP, of a current detection resistor with the target voltage, VSC, by the internal FB comparator, and controls the peak value of VROCP so that it gets close to VSC, as shown in Figure 9-6 and Figure 9-7. U1 S/OCP 1 VCC pin voltage GND FB/OLP 3 4 Startup success IC starts operation VCC(ON) VCC(BIAS) VCC(OFF) Target operating voltage Increase with rising of output voltage PC1 VROCP ROCP IFB Figure 9-6 FB/OLP pin peripheral circuit Bias assist period Target voltage including Slope Compensation Startup failure Time Figure 9-5 VCC pin voltage during startup period The surge voltage is induced at output winding at turning off a power MOSFET. When the output load is light at startup, the surge voltage causes the unexpected feedback control. This results the lowering of the output power and VCC pin voltage. When the VCC pin voltage decreases to VCC(OFF) = 8.1 V, the IC stops switching operation and a startup failure occurs. In order to prevent this, the Bias Assist function is activated when the VCC STR-A6000 - DS Rev.4.3 Mar. 13, 2015 C3 - VSC + VROCP FB Comparator Voltage on both sides of ROCP Drain current, ID Figure 9-7 Drain current, ID, and FB comparator operation in steady operation SANKEN ELECTRIC CO.,LTD. 15 STR-A6000 Series Light load conditions When load conditions become lighter, the output voltage, VOUT, increases. Thus, the feedback current from the error amplifier on the secondary-side also increases. The feedback current is sunk at the FB/OLP pin, transferred through a photo-coupler, PC1, and the FB/OLP pin voltage decreases. Thus, VSC decreases, and the peak value of VROCP is controlled to be low, and the peak drain current of I D decreases. This control prevents the output voltage from increasing. Heavy load conditions When load conditions become greater, the IC performs the inverse operation to that described above. Thus, VSC increases and the peak drain current of ID increases. This control prevents the output voltage from decreasing. In the current mode control method, when the drain current waveform becomes trapezoidal in continuous operating mode, even if the peak current level set by the target voltage is constant, the on-time fluctuates based on the initial value of the drain current. This results in the on-time fluctuating in multiples of the fundamental operating frequency as shown in Figure 9-8. This is called the subharmonics phenomenon. In order to avoid this, the IC incorporates the Slope Compensation function. Because the target voltage is added a down-slope compensation signal, which reduces the peak drain current as the on-duty gets wider relative to the FB/OLP pin signal to compensate V SC, the subharmonics phenomenon is suppressed. Even if subharmonic oscillations occur when the IC has some excess supply being out of feedback control, such as during startup and load shorted, this does not affect performance of normal operation. 9.5 Leading Edge Blanking Function The IC uses the peak-current-mode control method for the constant voltage control of output. In peak-current-mode control method, 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 (STR-A60××H for 340 ns, STR-A60××H and STR-A60××HD for 280 ns) is built-in. During tBW, the OCP threshold voltage becomes about 1.7 V which is higher than the normal OCP threshold voltage (refer to Section 9.9). 9.6 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. 9.7 Automatic Standby Mode Function Automatic standby mode is activated automatically when the drain current, ID, reduces under light load conditions, at which ID is less than 15 % to 20 % of the maximum drain current (it is in the OCP state). The operation mode becomes burst oscillation, as shown in Figure 9-9. Burst oscillation mode reduces switching losses and improves power supply efficiency because of periodic non-switching intervals. Output current, IOUT Burst oscillation Target voltage without Slope Compensation Below several kHz Drain current, ID tON1 T Normal operation tON2 T T Normal operation Figure 9-9 Auto Standby mode timing Figure 9-8 Drain current, ID, waveform in subharmonic oscillation STR-A6000 - DS Rev.4.3 Mar. 13, 2015 Standby operation Generally, to improve efficiency under light load conditions, the frequency of the burst oscillation mode becomes just a few kilohertz. Because the IC suppresses the peak drain current well during burst oscillation mode, audible noises can be reduced. If the VCC pin voltage decreases to VCC(BIAS) = 9.5 V SANKEN ELECTRIC CO.,LTD. 16 STR-A6000 Series during the transition to the burst oscillation mode, the Bias Assist function is activated and stabilizes the Standby mode operation, because ISTARTUP is provided to the VCC pin so that the VCC pin voltage does not decrease to VCC(OFF). However, if the Bias Assist function is always activated during steady-state operation including standby mode, the power loss increases. Therefore, the VCC pin voltage should be more than VCC(BIAS), for example, by adjusting the turns ratio of the auxiliary winding and secondary winding and/or reducing the value of R2 in Figure 10-2 (refer to Section 10.1 Peripheral Components for a detail of R2). 9.8 Brown-In and Brown-Out Function This function stops switching operation when it detects low input line voltage, and thus prevents excessive input current and overheating. This function turns on and off switching operation according to the BR pin voltage detecting the AC input voltage. When BR pin voltage becomes more than VBR(DIS) = 0.48 V, this function is activated. Figure 9-10 shows waveforms of the BR pin voltage and the drain currnet. Even if the IC is in the operating state that the VCC pin voltage is VCC(OFF) or more, when the AC input voltage decreases from steady-state and the BR pin voltage falls to VBR(OUT) = 4.8 V or less for the OLP Delay Time, tOLP = 68 ms, the IC stops switching operation. When the AC input voltage increases and the BR pin voltage reaches VBR(IN) = 5.6 V or more in the operating state that the VCC pin voltage is VCC(OFF) or more, the IC starts switching operation. In case the Brown-In and Brown-Out function is unnecessary, connect the BR pin trace to the GND pin trace so that the BR pin voltage is VBR(DIS) or less. operation period becomes tOLP = 68 ms or more, the IC stops switching operation. STR-A60××HD: When the BR pin voltage falls to VBR(OUT) = 4.8 V or less for tOLP = 68 ms, the IC stops switching operation. There are two types of detection method as follows: 9.8.1 DC Line Detection Figure 9-11 shows BR pin peripheral circuit of DC line detection. There is a ripple voltage on C1 occurring at a half period of AC cycle. In order to detect each peak of the ripple voltage, the time constant of RC and C4 should be shorter than a half period of AC cycle. Since the cycle of the ripple voltage is shorter than tOLP, the switching operation does not stop when only the bottom part of the ripple voltage becomes lower than VBR(OUT). Thus it minimizes the influence of load conditions on the voltage detection. BR1 VAC RA VDC U1 C1 RB 2 RC BR C4 GND 3 Figure 9-11 DC line detection BR pin voltage VBR(IN) VBR(OUT) Drain current, ID ・ RA and RB are a few megohms. Because of high voltage applied and high resistance, it is recommended to select a resistor designed against electromigration or use a combination of resistors in series for that to reduce each applied voltage, according to the requirement of the application. tOLP Figure 9-10 BR pin voltage and drain current waveforms During burst oscillation mode, this function operates as follows: STR-A60××M and STR-A60××H: This function is disabled during switching operation stop period in burst oscillation mode. When the BR pin voltage falls to VBR(OUT) or less in burst oscillation mode and the sum of switching STR-A6000 - DS Rev.4.3 Mar. 13, 2015 The components around BR pin: ・ RC is a few hundred kilohms ・ C4 is 470 pF to 2200 pF for high frequency noise reduction Neglecting the effect of both input resistance and forward voltage of rectifier diode, the reference value of C1 voltage when Brown-In and Brown-Out function is activated is calculated as follows: SANKEN ELECTRIC CO.,LTD. 17 STR-A6000 Series R RB VDC ( OP ) VBR ( TH) 1 A R C where, VDC(OP) (3) : C1 voltage when Brown-In and Brown-Out function is activated : Any one of threshold voltage of BR pin (see Table 9-1) VBR(TH) Table 9-1 BR pin threshold voltage Parameter VBR(IN) Value (Typ.) 5.6 V VBR(OUT) 4.8 V Symbol Brown-In Threshold Voltage Brown-Out Threshold Voltage VDC(OP) can be expressed as the effective value of AC input voltage using Equation (4). VAC ( OP ) RMS 1 2 VDC ( OP ) (4) RA, RB, RC and C4 should be selected based on actual operation in the application. 9.8.2 AC Line Detection Figure 9-12 shows BR pin peripheral circuit of AC line detection. In order to detect the AC input voltage, the time constant of RC and C4 should be longer than the period of AC cycle. Thus the response of BR pin detection becomes slow compared with the DC line detection. This method detects the AC input voltage, and thus it minimizes the influence from load conditions. Also, this method is free of influence from C1 charging and discharging time, the latch mode can be released quickly* VAC BR1 RA 3 VCC RS VDC RB C1 2 RC BR C4 * High-Speed Latch Release When Overvoltage Protection function (OVP) or Thermal Shutdown function (TSD) are activated, the IC stops switching operation in latch mode. Releasing the latch mode is done by decreasing the VCC pin voltage below VCC(OFF) or by decreasing the BR pin voltage below VBR(OUT). In case of the DC line detection or without Brown-in / Brown-Out function, the release time depends on discharge time of C1 and takes longer time until VCC pin voltage decreases to release voltage. In case of the AC line detection, BR pin voltage is decreased quickly when AC input voltage, VAC, is turned off, and thus the latch mode is quickly released. The components around BR pin: ・ RA and RB are a few megohms. Because of high voltage applied and high resistance, it is recommended to select a resistor designed against electromigration or use a combination of resistors in series for that to reduce each applied voltage, according to the requirement of the application. ・ RC is a few hundred kilohms ・ RS must be adjusted so that the BR pin voltage is more than VBR(DIS) = 0.48 V when the VCC pin voltage is VCC(OFF) = 8.1 V ・ C4 is 0.22 μF to 1 μF for averaging AC input voltage and high frequency noise reduction. Neglecting the effect of input resistance is zero, the reference effective value of AC input voltage when Brown-In and Brown-Out function is activated is calculated as follows: VAC ( OP ) RMS R RB VBR ( TH) 1 A R C 2 (5) where, VAC(OP)RMS :The effective value of AC input voltage when Brown-In and Brown-Out function is activated VBR(TH) :Any one of threshold voltage of BR pin (see Table 9-1) RA, RB, RC and C4 should be selected based on actual operation in the application. U1 GND 3 Figure 9-12 AC line detection STR-A6000 - DS Rev.4.3 Mar. 13, 2015 SANKEN ELECTRIC CO.,LTD. 18 STR-A6000 Series Overcurrent Protection Function (OCP) Overcurrent Protection Function (OCP) detects each drain peak current level of a power MOSFET on pulse-by-pulse basis, and limits the output power when the current level reaches to OCP threshold voltage. During Leading Edge Blanking Time, the operation of OCP is different depending on the products as follows. STR-A60××HD: During Leading Edge Blanking Time, the OCP threshold voltage becomes VOCP(LEB) = 1.55 V which is higher than the normal OCP threshold voltage as shown in Figure 9-13. Changing to this threshold voltage prevents the IC from responding to the surge voltage in turning-on the power MOSFET. This function operates as protection at the condition such as output windings shorted or unusual withstand voltage of secondary-side rectifier diodes. STR-A60××M and STR-A60××H: OCP is disabled during Leading Edge Blanking Time. When power MOSFET turns on, the surge voltage width of S/OCP pin should be less than tBW, as shown in Figure 9-13. In order to prevent surge voltage, pay extra attention to ROCP trace layout (refer to Section ). In addition, if a C (RC) damper snubber of Figure 9-14 is used, reduce the capacitor value of damper snubber. tBW VOCP(LEB)(STR-A60××HD) VOCP’ < Input Compensation Function > ICs with PWM control usually have some propagation delay time. The steeper the slope of the actual drain current at a high AC input voltage is, the larger the detection voltage of actual drain peak current is, compared to VOCP. Thus, the peak current has some variation depending on the AC input voltage in OCP state. In order to reduce the variation of peak current in OCP state, the IC incorporates a built-in Input Compensation function. The Input Compensation Function is the function of correction of OCP threshold voltage depending with AC input voltage, as shown in Figure 9-15. When AC input voltage is low (ON Duty is broad), the OCP threshold voltage is controlled to become high. The difference of peak drain current become small compared with the case where the AC input voltage is high (ON Duty is narrow). The compensation signal depends on ON Duty. The relation between the ON Duty and the OCP threshold voltage after compensation VOCP' is expressed as Equation (6). When ON Duty is broader than 36 %, the VOCP' becomes a constant value VOCP(H) = 0.9 V 1.0 OCP Threshold Voltage after compensation, VOCP' 9.9 VOCP(H) VOCP(L) 0.5 0 Surge pulse voltage width at turning on Figure 9-13 S/OCP pin voltage DDPC DMAX 50 100 ON Duty (%) Figure 9-15 Relationship between ON Duty and Drain Current Limit after compensation C（RC） Damper snubber T1 VOCP ' VOCP ( L) DPC ONTime D51 C1 C51 VOCP ( L ) DPC 7,8 D/ST U1 S/OCP 1 ONDuty f OSC ( AVG ) (6) where, VOCP(L): OCP Threshold Voltage at Zero ON Duty DPC: OCP Compensation Coefficient ONTime: On-time of power MOSFET ONDuty: On duty of power MOSFET fOSC(AVG): Average PWM Switching Frequency C（RC） Damper snubber ROCP Figure 9-14 Damper snubber STR-A6000 - DS Rev.4.3 Mar. 13, 2015 SANKEN ELECTRIC CO.,LTD. 19 STR-A6000 Series 9.10 Overload Protection Function (OLP) 9.11 Overvoltage Protection (OVP) Figure 9-16 shows the FB/OLP pin peripheral circuit, and Figure 9-17 shows each waveform for OLP operation. When the peak drain current of ID is limited by OCP operation, the output voltage, VOUT, decreases and the feedback current from the secondary photo-coupler becomes zero. Thus, the feedback current, IFB, charges C3 connected to the FB/OLP pin and the FB/OLP pin voltage increases. When the FB/OLP pin voltage increases to VFB(OLP) = 8.1 V or more for the OLP delay time, tOLP = 68 ms or more, the OLP function is activated, the IC stops switching operation. During OLP operation, Bias Assist Function is disabled. Thus, VCC pin voltage decreases to VCC(OFF), the control circuit stops operation. After that, the IC reverts to the initial state by UVLO circuit, and 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. This intermittent operation reduces the stress of parts such as power MOSFET and secondary side rectifier 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. When a voltage between VCC pin and GND pin increases to VCC(OVP) = 29 V or more, OVP function is activated, the IC stops switching operation at the latched state. In order to keep the latched state, when VCC pin voltage decreases to VCC(BIAS), the bias assist function is activated and VCC pin voltage is kept to over the VCC(OFF). Releasing the latched state is done by turning off the input voltage and by dropping the VCC pin voltage below VCC(OFF), or by dropping the BR pin voltage below VBR(OUT). In case the VCC pin voltage is provided by using auxiliary winding of transformer, the overvoltage conditions such as output voltage detection circuit open can be detected because the VCC pin voltage is proportional to output voltage. The approximate value of output voltage VOUT(OVP) in OVP condition is calculated by using Equation (7). U1 GND FB/OLP 4 3 5 D2 R2 C3 VOUT ( NORMAL ) VCC( NORMAL ) 29 (V) (7) where, VOUT(NORMAL): Output voltage in normal operation VCC(NORMAL): VCC pin voltage in normal operation 9.12 Thermal Shutdown Function (TSD) VCC PC1 VOUT(OVP) C2 D Figure 9-16 FB/OLP pin peripheral circuit When the temperature of control circuit increases to Tj(TSD) = 135 °C (min.) or more, Thermal Shutdown function (TSD) is activated, the IC stops switching operation at the latched state. In order to keep the latched state, when VCC pin voltage decreases to VCC(BIAS), the bias assist function is activated and VCC pin voltage is kept to over the VCC(OFF). Releasing the latched state is done by turning off the input voltage and by dropping the VCC pin voltage below VCC(OFF), or by dropping the BR pin voltage below VBR(OUT). Non-switching interval VCC pin voltage VCC(ON) VCC(OFF) FB/OLP pin voltage tOLP tOLP VFB(OLP) Drain current, ID Figure 9-17 OLP operational waveforms STR-A6000 - DS Rev.4.3 Mar. 13, 2015 SANKEN ELECTRIC CO.,LTD. 20 STR-A6000 Series 10. Design Notes 10.1 External Components Take care to use properly rated, including derating as necessary and proper type of components. CRD clamp snubber BR1 T1 VAC R1 C6 RA C1 P D1 RB D2 8 D/ST D/ST C5 R2 5 7 NC VCC C2 D U1 S/OCP BR GND FB/OLP C(RC) damper snubber 1 RC 2 3 4 C4 C3 PC1 ROCP Figure 10-1 The IC peripheral circuit Input and Output Electrolytic Capacitor Apply proper derating to ripple current, voltage, and temperature rise. Use of high ripple current and low impedance types, designed for switch mode power supplies, is recommended. FB/OLP Pin Peripheral Circuit C3 is for high frequency noise reduction and phase compensation, and should be connected close to these pins. The value of C3 is recommended to be about 2200 pF to 0.01µF, and should be selected based on actual operation in the application. VCC Pin Peripheral Circuit The value of C2 in Figure 10-1 is generally recommended to be 10µ to 47μF (refer to Section 9.1 Startup Operation, because the startup time is determined by the value of C2). In actual power supply circuits, there are cases in which the VCC pin voltage fluctuates in proportion to the output current, IOUT (see Figure 10-2), and the Overvoltage Protection function (OVP) on the VCC pin may be activated. This happens because C2 is charged to a peak voltage on the auxiliary winding D, which is caused by the transient surge voltage coupled from the primary winding when the power MOSFET turns off. For alleviating C2 peak charging, it is effective to add some value R2, of several tenths of ohms to several ohms, in series with D2 (see Figure 10-1). The optimal value of R2 should be determined using a transformer matching what will be used in the actual application, because the variation of the auxiliary winding voltage is affected by the transformer structural design. VCC pin voltage S/OCP Pin Peripheral Circuit In Figure 10-1, ROCP is the resistor for the current detection. A high frequency switching current flows to ROCP, and may cause poor operation if a high inductance resistor is used. Choose a low inductance and high surge-tolerant type. BR pin peripheral circuit Because RA and RB (see Figure 10-1) are applied high voltage and are high resistance, the following should be considered according to the requirement of the application: ▫ Select a resistor designed against electromigration, or ▫ Use a combination of resistors in series for that to reduce each applied voltage See the section 9.8 about the AC input voltage detection function and the components around BR pin. When the detection resistor (RA, RB, RC) value is decreased and the C4 value is increased to prevent unstable operation resulting from noise at the BR pin, pay attention to the low efficiency and the slow response of BR pin. STR-A6000 - DS Rev.4.3 Mar. 13, 2015 Without R2 With R2 Output current, IOUT Figure 10-2 Variation of VCC pin voltage and power Snubber Circuit In case the surge voltage of VDS is large, the circuit should be added as follows (see Figure 10-1); ・ A clamp snubber circuit of a capacitor-resistordiode (CRD) combination should be added on the primary winding P. ・ A damper snubber circuit of a capacitor (C) or a resistor-capacitor (RC) combination should be added between the D/ST pin and the S/OCP pin. In case the damper snubber circuit is added, this components should be connected near D/ST pin and S/OCP pin. SANKEN ELECTRIC CO.,LTD. 21 STR-A6000 Series VOUT (+) D51 PC1 R55 C51 S R54 R51 R52 C53 C52 R53 U51 R56 (-) Figure 10-3 Peripheral circuit of secondary side shunt regulator (U51) Transformer Apply proper design margin to core temperature rise by core loss and copper loss. Because the switching currents contain high frequency currents, the skin effect may become a consideration. Choose a suitable wire gauge in consideration of the RMS current and a current density of 4 to 6 A/mm2. If measures to further reduce temperature are still necessary, the following should be considered to increase the total surface area of the wiring: ▫ Increase the number of wires in parallel. ▫ Use litz wires. ▫ Thicken the wire gauge. In the case of multi-output power supply, the coupling of the secondary-side stabilized output winding, S1, and the others (S2, S3…) should be maximized to improve the line-regulation of those outputs. Figure 10-4 shows the winding structural examples of two outputs. Winding structural example (a): S1 is sandwiched between P1 and P2 to maximize the coupling of them for surge reduction of P1 and P2. D is placed far from P1 and P2 to minimize the coupling to the primary for the surge reduction of D. Winding structural example (b) P1 and P2 are placed close to S1 to maximize the coupling of S1 for surge reduction of P1 and P2. D and S2 are sandwiched by S1 to maximize the coupling of D and S1, and that of S1 and S2. This structure reduces the surge of D, and improves the line-regulation of outputs. Margin tape Bobbin L51 T1 output winding S should be maximized to reduce the leakage inductance. ▫ The coupling of the winding D and the winding S should be maximized. ▫ The coupling of the winding D and the winding P should be minimized. P1 S1 P2 S2 D Margin tape Winding structural example (a) Margin tape Bobbin Peripheral circuit of secondary side shunt regulator Figure 10-3 shows the secondary side detection circuit with the standard shunt regulator IC (U51). C52 and R53 are for phase compensation. The value of C52 and R53 are recommended to be around 0.047μF to 0.47μF and 4.7 kΩ to 470 kΩ, respectively. They should be selected based on actual operation in the application. P1 S1 D S2 S1 P2 Margin tape Winding structural example (b) In the following cases, the surge of VCC pin voltage becomes high. ▫ The surge voltage of primary main winding, P, is high (low output voltage and high output current power supply designs) ▫ The winding structure of auxiliary winding, D, is susceptible to the noise of winding P. 10.2 PCB Trace Layout and Component Placement When the surge voltage of winding D is high, the VCC pin voltage increases and the Overvoltage Protection function (OVP) may be activated. In transformer design, the following should be considered; ▫ The coupling of the winding P and the secondary 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. STR-A6000 - DS Rev.4.3 Mar. 13, 2015 Figure 10-4 Winding structural examples SANKEN ELECTRIC CO.,LTD. 22 STR-A6000 Series Figure 10-5 shows the circuit design example. (4) ROCP Trace Layout ROCP should be placed as close as possible to the S/OCP pin. The connection between the power ground of the main trace and the IC ground should be at a single point ground (point A in Figure 10-5) which is close to the base of ROCP. (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. If C1 and the IC are distant from each other, placing a capacitor such as film capacitor (about 0.1 μF and with proper voltage rating) close to the transformer or the IC is recommended to reduce impedance of the high frequency current loop. (5) Peripheral components of the IC The components for control connected to the IC should be placed as close as possible to the IC, and should be connected as short as possible to the each pin. (2) 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 a single point grounding of point A in Figure 10-5 as close to the ROCP pin as possible. (6) Secondary Rectifier Smoothing Circuit Trace Layout: This is the trace of the rectifier smoothing loop, carrying the switching current, and thus it should be as wide trace and small loop as possible. If this trace is thin and long, inductance resulting from the loop may increase surge voltage at turning off the power MOSFET. Proper rectifier smoothing trace layout helps to increase margin against the power MOSFET breakdown voltage, and reduces stress on the clamp snubber circuit and losses in it. (3) VCC Trace Layout This is the trace for supplying power to the IC, and thus it should be as small loop as possible. If C2 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 GND pin is recommended. (7) 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 D/ST pin trace act as a heatsink, its traces should be as wide as possible. (1) Main trace should be wide trace and small loop (6) Main trace of secondary side should be wide trace and small loop D51 T1 R1 C6 RA C1 P DST (7)Trace of D/ST pin should be wide for heat release C51 D1 RB S D2 8 D/ST D/ST C5 R2 5 7 NC C2 VCC D U1 STR-A6000 (3) Loop of the power supply should be small S/OCP BR GND FB/OLP 1 2 3 4 ROCP C3 C4 RC PC1 (5)The components connected to the IC should be as close to the IC as possible, and should be connected as short as possible CY A (4)ROCP should be as close to S/OCP pin as possible. (2) Control GND trace should be connected at a single point as close to the ROCP as possible Figure 10-5 Peripheral circuit example around the IC STR-A6000 - DS Rev.4.3 Mar. 13, 2015 SANKEN ELECTRIC CO.,LTD. 23 STR-A6000 Series 11. Pattern Layout Example The following show the PCB pattern layout example and the schematic of circuit using STR-A6000 series. The above circuit symbols correspond to these of Figure 11-1.Only the parts in the schematic are used. Other parts in PCB are leaved open. Figure 11-1 PCB circuit trace layout example T1 L52 D52 CN51 1 OUT2(+) 2 OUT2(-) 3 OUT1(+) 4 OUT1(-) R59 C57 R58 C55 R61 C56 R60 CN1 1 F1 L1 JW51 JW52 JW54 JW6 C1 C12 C2 C13 D1 D2 TH1 D4 D3 L51 L2 C3 D51 C4 P1 C5 R51 C54 R1 3 R55 R52 PC1 R2 S1 R54 C51 C53 D7 C52 U51 JW2 R57 R53 R56 R7 D2 JW10 R6 U1 8 7 D/ST D/ST 5 NC JW4 D8 R3 JW31 D1 C9 C8 STR-A6000 C31 C32 BR 1 2 GND FB/OLP C11 3 JW3 JW8 JW7 C6 C7 2 OUT4(-) JW21 U21 D21 1 IN R4 OUT4(+) JW53 4 JW11 R5 1 R31 C10 S/OCP CN31 D31 VCC CP1 JW9 C21 CN21 3 OUT GND 2 C22 1 OUT3(+) 2 OUT3(-) R21 Figure 11-2 Circuit schematic for PCB circuit trace layout STR-A6000 - DS Rev.4.3 Mar. 13, 2015 SANKEN ELECTRIC CO.,LTD. 24 STR-A6000 Series 12. Reference Design of Power Supply 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 cirrent STR-A6059H AC85V to AC265V 7.5W 5V 1.5A (max.) Circuit schematic 1 F1 L1 D1 D2 D4 D3 L2 TH1 L51 T1 D51 C1 3 C4 R1 C3 R51 C55 R4 VOUT(+) 5V/1.5A 4 VOUT(-) S1 C2 R55 R52 PC1 D5 3 R54 R57 C51 P1 C53 R53 C52 S2 U51 8 D/ST R8 D/ST VCC BR 1 2 R2 R56 C5 D STR-A6000 S/OCP GND FB/OLP 3 C7 R7 NC D6 U1 C8 R9 5 7 4 C6 PC1 R3 C9 TC_STR-A6000_4_R1 Bill of materials Symbol F1 L1 L2 TH1 D1 D2 Part type Ratings(1) Recommended Sanken Parts Symbol (3) Part type Fuse CM inductor Inductor NTC thermistor General General AC250V, 3A 3.3mH 470μH Short 600V, 1A 600V, 1A EM01A EM01A R4 R7 R8 R9 PC1 U1 D3 General 600V, 1A EM01A T1 Transformer D4 D5 D6 C1 C2 C3 C4 C5 C6 C7 C8 C9 R1 General Fast recovery Fast recovery Film, X2 Electrolytic Electrolytic Ceramic Electrolytic Ceramic Ceramic Ceramic Ceramic, Y1 General 600V, 1A 1000V, 0.5A 200V, 1A 0.047μF, 275V 10μF, 400V 10μF, 400V 1000pF, 630V 22μF, 50V 0.01μF 1000pF Open 2200pF, 250V Open EM01A EG01C AL01Z L51 D51 C51 C52 C53 C55 R51 R52 R53 R54 R55 R56 R57 Inductor Schottky Electrolytic Ceramic Electrolytic Ceramic General General General General, 1% General, 1% General, 1% General General 4.7Ω R2 (2) (2) (2) (2) (2) (2) (2) (2) (2) U51 (3) (3) (2) (2) (2) Metal oxide General General General Photo-coupler IC Shunt regulator Ratings(1) Recommended Sanken Parts 330kΩ, 1W 330kΩ 2.2MΩ 2.2MΩ PC123 or equiv － See the specification 5μH 90V, 4A 680μF, 10V 0.1μF, 50V 330µF, 10V 1000pF, 1kV 220Ω 1.5kΩ 22kΩ Short 10kΩ 10kΩ Open VREF=2.5V TL431 or equiv STR-A6059H FMB-G19L R3 General 1.5Ω, 1/2W 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. (3) Resistors applied high DC voltage and of high resistance are recommended to select resistors designed against electromigration or use combinations of resistors in series for that to reduce each applied voltage, according to the requirement of the application. (1) STR-A6000 - DS Rev.4.3 Mar. 13, 2015 SANKEN ELECTRIC CO.,LTD. 25 STR-A6000 Series Transformer specification ▫ Primary inductance, LP ▫ Core size ▫ Al-value ▫ Winding specification Winding ：704 μH ：EI-16 ：132 nH/N2 (Center gap of about 0.26 mm) Wire diameter (mm) Symbol Number of turns (T) Primary winding P1 73 2UEW-φ0.18 Auxiliary winding D 17 2UEW-φ0.18×2 Output winding 1 S1 6 TEX-φ0.3×2 Output winding 2 S2 6 TEX-φ0.3×2 VDC VOUT(+) 5V P1 D S2 S1 S1 P1 D/ST VCC Bobbin GND VOUT(-) D S2 Cross-section view STR-A6000 - DS Rev.4.3 Mar. 13, 2015 Construction Two-layer, solenoid winding Single-layer, solenoid winding Single-layer, solenoid winding Single-layer, solenoid winding SANKEN ELECTRIC CO.,LTD. : Start at this pin 26 STR-A6000 Series OPERATING PRECAUTIONS In the case that you use Sanken products or design your products by using Sanken products, the reliability largely depends on the degree of derating to be made to the rated values. Derating may be interpreted as a case that an operation range is set by derating the load from each rated value or surge voltage or noise is considered for derating in order to assure or improve the reliability. In general, derating factors include electric stresses such as electric voltage, electric current, electric power etc., environmental stresses such as ambient temperature, humidity etc. and thermal stress caused due to self-heating of semiconductor products. For these stresses, instantaneous values, maximum values and minimum values must be taken into consideration. In addition, it should be noted that since power devices or IC’s including power devices have large self-heating value, the degree of derating of junction temperature affects the reliability significantly. Because reliability can be affected adversely by improper storage environments and handling methods, please observe the following cautions. Cautions for Storage Ensure that storage conditions comply with the standard temperature (5 to 35°C) and the standard relative humidity (around 40 to 75%); avoid storage locations that experience extreme changes in temperature or humidity. Avoid locations where dust or harmful gases are present and avoid direct sunlight. Reinspect for rust on leads and solderability of the products that have been stored for a long time. Cautions for Testing and Handling When tests are carried out during inspection testing and other standard test periods, protect the products from power surges from the testing device, shorts between the product pins, and wrong connections. Ensure all test parameters are within the ratings specified by Sanken for the products. Remarks About Using Thermal Silicone Grease When thermal silicone grease is used, it shall be applied evenly and thinly. If more silicone grease than required is applied, it may produce excess stress. The thermal silicone grease that has been stored for a long period of time may cause cracks of the greases, and it cause low radiation performance. In addition, the old grease may cause cracks in the resin mold when screwing the products to a heatsink. Fully consider preventing foreign materials from entering into the thermal silicone grease. When foreign material is immixed, radiation performance may be degraded or an insulation failure may occur due to a damaged insulating plate. The thermal silicone greases that are recommended for the resin molded semiconductor should be used. Our recommended thermal silicone grease is the following, and equivalent of these. Type Suppliers G746 Shin-Etsu Chemical Co., Ltd. YG6260 Momentive Performance Materials Japan LLC SC102 Dow Corning Toray Co., Ltd. Soldering When soldering the products, please be sure to minimize the working time, within the following limits: • 260 ± 5 °C 10 ± 1 s (Flow, 2 times) • 380 ± 10 °C 3.5 ± 0.5 s (Soldering iron, 1 time) Soldering should be at a distance of at least 1.5 mm from the body of the products. Electrostatic Discharge When handling the products, the operator must be grounded. Grounded wrist straps worn should have at least 1MΩ of resistance from the operator to ground to prevent shock hazard, and it should be placed near the operator. Workbenches where the products are handled should be grounded and be provided with conductive table and floor mats. When using measuring equipment such as a curve tracer, the equipment should be grounded. When soldering the products, the head of soldering irons or the solder bath must be grounded in order to prevent leak voltages generated by them from being applied to the products. The products should always be stored and transported in Sanken shipping containers or conductive containers, or be wrapped in aluminum foil. STR-A6000 - DS Rev.4.3 Mar. 13, 2015 SANKEN ELECTRIC CO.,LTD. 27 STR-A6000 Series IMPORTANT NOTES The contents in this document are subject to changes, for improvement and other purposes, without notice. Make sure that this is the latest revision of the document before use. Application examples, operation examples and recommended examples described in this document are quoted for the sole purpose of reference for the use of the products herein and Sanken can assume no responsibility for any infringement of industrial property rights, intellectual property rights, life, body, property or any other rights of Sanken or any third party which may result from its use. Unless otherwise agreed in writing by Sanken, Sanken makes no warranties of any kind, whether express or implied, as to the products, including product merchantability, and fitness for a particular purpose and special environment, and the information, including its accuracy, usefulness, and reliability, included in this document. Although Sanken undertakes to enhance the quality and reliability of its products, the occurrence of failure and defect of semiconductor products at a certain rate is inevitable. Users of Sanken products are requested to take, at their own risk, preventative measures including safety design of the equipment or systems against any possible injury, death, fires or damages to the society due to device failure or malfunction. Sanken products listed in this document are designed and intended for the use as components in general purpose electronic equipment or apparatus (home appliances, office equipment, telecommunication equipment, measuring equipment, etc.). When considering the use of Sanken products in the applications where higher reliability is required (transportation equipment and its control systems, traffic signal control systems or equipment, fire/crime alarm systems, various safety devices, etc.), and whenever long life expectancy is required even in general purpose electronic equipment or apparatus, please contact your nearest Sanken sales representative to discuss, prior to the use of the products herein. The use of Sanken products without the written consent of Sanken in the applications where extremely high reliability is required (aerospace equipment, nuclear power control systems, life support systems, etc.) is strictly prohibited. When using the products specified herein by either (i) combining other products or materials therewith or (ii) physically, chemically or otherwise processing or treating the products, please duly consider all possible risks that may result from all such uses in advance and proceed therewith at your own responsibility. Anti radioactive ray design is not considered for the products listed herein. Sanken assumes no responsibility for any troubles, such as dropping products caused during transportation out of Sanken’s distribution network. The contents in this document must not be transcribed or copied without Sanken’s written consent. STR-A6000 - DS Rev.4.3 Mar. 13, 2015 SANKEN ELECTRIC CO.,LTD. 28