Light Load High Efficiency Synchronous Buck Regulator IC NR263S DATA SHEET General Descriptions The NR263S is Synchronous Rectification buck regulator ICs integrates PowerMOSFETs. With the current mode control, ultra low ESR capacitors such as ceramic capacitors can be used. The ICs can realize super-high efficiency by performing pulse skip operation at light load condition. The ICs have protection functions such as Over-Current Protection (OCP), Under-Voltage Lockout (UVLO) and Thermal Shutdown (TSD). Soft starting time can be set up by selecting an external capacitor value. The ON/OFF pin (EN Pin) turns the regulator ON/OFF. The NR263S is available in an 8-pin SOP package. Features & Benefits ● Synchronous Rectification with internal PowerMOSFETs ● Current mode PWM control (Normal load) ● Pulse Skip Operation(at Light Load Condition) ● Up to 94% efficiency at normal load condition ● Up to 86% efficiency at light load condition (@Vin=12V,Vout=5V,Iout=10mA) ● Stable with low ESR ceramic output capacitors ● Built-in protection function Drooping type Over Current Protection (OCP) with Auto-restart Thermal Shutdown (TSD) with Auto-restart Under Voltage Lockout(UVLO) Vo Short Circuit Protection (HICCUP) ● By Vo = 5V fixed and external component count reduction (NR263S) ● Soft-start Function by External Timing Capacitor ● Turn ON/OF the regulator function Package SOP8 Package *Image: Not to scale Electrical Characteristics ● ● ● ● Input Voltage Range VIN = 8.0V～31V Output Voltage VO=5V Fixed Output Current IO=1A Operationg Frequency Fsw=500kHz Fixed Applications ● ● ● ● ● Refrigerator Air conditioner LCD-TV Blu-ray Power supply for digital consumer Basic Circuit Connection NR263S (Vo=5V Fixed) NR263S series-DSE Rev.1.0 SANKEN ELECTRIC CO.,LTD 2016.03.09 http://www.sanken-ele.co.jp/en/ © SANKEN ELECTRIC CO.,LTD. 2016 1 NR263S NNNNN CONTENTS General Descriptions ------------------------------------------------------------------------------------------ 1 1. Electrical Characteristics -------------------------------------------------------------------------------- 3 1.1 Absolute Maximum Ratings ----------------------------------------------------------------------- 3 1.2 Recommended Operating Conditions ----------------------------------------------------------- 3 1.3 Electrical Characteristics -------------------------------------------------------------------------- 4 2. Block Diagram & Pin Functions ----------------------------------------------------------------------- 5 2.1 Block Diagram --------------------------------------------------------------------------------------- 5 2.2 Pin Assignments & Functions --------------------------------------------------------------------- 6 3. Typical Application Circuit ----------------------------------------------------------------------------- 7 4. Allowable package power dissipation ----------------------------------------------------------------- 7 5. Package Outline ------------------------------------------------------------------------------------------- 9 5.1 Outline, Size ------------------------------------------------------------------------------------------ 9 6. Marking --------------------------------------------------------------------------------------------------- 10 7. Operational Descriptions ------------------------------------------------------------------------------ 11 7.1 PWM(Pulse Width Modulation) Output Control ------------------------------------------- 11 7.2 UVLO and Enable Function -------------------------------------------------------------------- 12 7.3 Soft-start Function -------------------------------------------------------------------------------- 13 7.4 Over current and Short circuit protection Function (OCP & HICCUP) -------------- 15 7.5 Thermal Shutdown (TSD) ----------------------------------------------------------------------- 16 7.6 About the "Pulse-Skip-Mode" in the Light-load condition ------------------------------- 16 8. Design Notes ---------------------------------------------------------------------------------------------- 18 8.1 External Components ---------------------------------------------------------------------------- 18 8.1.1 Inductor L1 ----------------------------------------------------------------------------------- 18 8.1.2 Input Capacitor CIN ------------------------------------------------------------------------- 20 8.1.3 Output Capacitor CO ----------------------------------------------------------------------- 20 8.2 Pattern Design ------------------------------------------------------------------------------------- 21 8.2.1 Input / Output Capacitors(CIN,CO) ------------------------------------------------------ 21 8.2.2 PCB Layout & Recommended Land Pattern ------------------------------------------ 22 8.3 Applied Design ------------------------------------------------------------------------------------- 23 8.3.1 Spike Noise Reduction(1) ------------------------------------------------------------------ 23 8.3.2 Spike Noise Reduction(2) ------------------------------------------------------------------ 23 8.3.3 Attention about the insertion of the bead-core ---------------------------------------- 24 8.3.4 Reverse Bias Protection -------------------------------------------------------------------- 24 8.3.5 Overvoltage protection of VO terminal ------------------------------------------------- 24 9. Typical characteristics (Ta=25°C) ------------------------------------------------------------------- 26 10. Packing specifications ---------------------------------------------------------------------------------- 28 10.1 Taping & Reel outline ---------------------------------------------------------------------------- 28 IMPORTANT NOTICE ------------------------------------------------------------------------------------ 29 NR263S series-DSE Rev.1.0 SANKEN ELECTRIC CO.,LTD 2016.03.09 http://www.sanken-ele.co.jp/en/ © SANKEN ELECTRIC CO.,LTD. 2016 2 NR263S NNNNN 1. Electrical Characteristics 1.1 Absolute Maximum Ratings ● The polarity value for current specifies a sink as “+” and a source as “−”, referencing the IC. ● Ta=25°C,unless otherwise noted. Parameter Symbol Ratings Units DC input voltage VIN 0.3 to 35 V BS terminal voltage VBS SW terminal voltage VSW VO terminal voltage EN terminal voltage SS terminal voltage VO VEN VSS 0.3 to 40.5 -0.3 to 5.5 8 1 to 35 2 to 35 6 to 35 0.3 to 6 0.3 to 35 0.3 to 7.0 SS terminal sink current Issb 5.0 mA BS to SW voltage VBS-SW V V V V (1) PD 1.56 W Junction temperature (2) TJ 40 to 150 °C Tstg 40 to 150 °C Thermal resistance (Junction to θJP 60 PGND Lead) Thermal resistance (Junction θJA 80 toAmbient air) (1) Limited by thermal shutdown (2) The temperature detection of thermal shutdown is about 165°C 1.2 DC * Pulse Width Limitation ≦10[ns] DC * Pulse Width Limitation ≦100[ns] * Pulse Width Limitation ≦10[ns] V V V Power dissipation Storage temperature Conditions Glass-epoxy board mounting in a 40×40mm. * The implementation in our Demo- Board, Tj=150°C °C /W °C /W Glass-epoxy board mounting in a 40×40mm. * The implementation in our Demo- Board Recommended Operating Conditions Operating IC in recommended operating conditions is required for normal operating of circuit functions shown in Table 3 Electrical characteristics of NR263S. Parameter Symbol DC input voltage range Ratings Units MIN MAX VIN 8 31 V IO 0 1 A Ta 40 85 °C Conditions (3) DCoutput current range Operating ambient temperature (4) (4) Operating junction temperature Tj 125 40 Refer to “Fig3-1 Typical Application Circuit” (4) To be used within the allowable package power dissipation characteristics (Fig 4) (4) °C (3) NR263S series-DSE Rev.1.0 SANKEN ELECTRIC CO.,LTD 2016.03.09 http://www.sanken-ele.co.jp/en/ © SANKEN ELECTRIC CO.,LTD. 2016 3 NR263S NNNNN 1.3 Electrical Characteristics ● The polarity value for current specifies a sink as “+” and a source as “−”, referencing the IC. ● Ta=25°C,unless otherwise noted. Table.3 Electrical Characteristics Ratings Parameter Symbol Units MIN TYP MAX VO Output voltage 4.85 ⊿VO /⊿T Output voltage temperature coefficient fsw Operating frequency 5.00 5.15 ±0.3 -30% 500 V mV/°C +30% kHz Line regulation (5) VLine 50 mV Load regulation (5) VLoad 50 mV Over current protection threshold IS Supply Current IIN 250 Shutdown Supply Current IIN(off) 1.2 Input UVLO Threshold Vuvlo 6 5 Vuvlo_hys Uvlo hysteresis SS terminal source current EN terminal 1.1 ISS Sink current IEN Turn-ON thereshold VEN Hysteresis voltage 1.5 2.6 0.8 VIN = 12V，Io = 0.5A IN = 12V, Io = 0.5A -40°C ～+85°C VIN=12V, Vo=5.0V, IO=1A VIN= 8V～17V, Vo=5.0V, IO=0.5A VIN=12V, Vo=5.0V, IO=0.1A～1.0A A VIN=12V, Vo=5.0V, uA VIN= 12V, VEN=12V IO=0mA 10 uA VIN=12V, VEN=0V 7 V VIN Rising 0.55 2.5 Conditions UVLO ON～UVLO OFF 5.0 8.5 μA VSS=0V, VIN=12V 14 30 μA VEN= 12V 1.1 2.1 V VIN=12V VEN_hys 0.15 V Maximum ON Duty (5) DMAX 85 % VIN=12V Minimum ON Period (5) TON(MIN) 200 nsec VIN=12V (5) TSD 165 °C VIN=12V (5) TSD_hys 15 °C VIN=12V (5) RonH 250 mΩ VIN=12V (5) RonL 200 mΩ VIN=12V Thermal shutdown threshold temperature Thermal shutdown restart hysteresis of temperature ON Resistance of Hi-side SW MOSFET ON Resistance of Lo-side SW MOSFET (5) Guaranteed by design,not tested 151 NR263S series-DSE Rev.1.0 SANKEN ELECTRIC CO.,LTD 2016.03.09 http://www.sanken-ele.co.jp/en/ © SANKEN ELECTRIC CO.,LTD. 2016 4 NR263S NNNNN 2. 2.1 Block Diagram & Pin Functions Block Diagram Fig. 2-1 NR263S Block Diagram NR263S series-DSE Rev.1.0 SANKEN ELECTRIC CO.,LTD 2016.03.09 http://www.sanken-ele.co.jp/en/ © SANKEN ELECTRIC CO.,LTD. 2016 5 NR263S NNNNN 2.2 Pin Assignments & Functions SS 1 BS 2 8 NC 7 VO NR263S SW 3 GND 4 Fig. 2-2 6 EN 5 IN Pin Assignments Table.4 Terminal Functions Pin No. Symbol Functions 1 SS 2 BS 3 SW 4 GND 5 IN 6 EN Enable signal input Drive EN Pin high to turn ON the regulator, low to turn it OFF 7 VO Feedback signal input terminal to compare Output voltage The feedback threshold (VREF) is 5.0V Connect the VO terminal directly to the output voltage VO. 8 NC No connection Soft-start control input To set the soft-start period, connect to a capacitor CSS between SS and AGND terminal Boost Input A BS terminal supplies the drive power of the internal PowerMOSFET Connect a capacitor between the SW terminal and the BS terminal Power switching output SW supplies power to the output Connect the LC filter between SW and the output Note that a capacitor CBS is required between SW and BS to supply the power the High-side driver Ground terminal By the synchronous rectification, the switching current flows Power Input Supply power to the IC NR263S series-DSE Rev.1.0 SANKEN ELECTRIC CO.,LTD 2016.03.09 http://www.sanken-ele.co.jp/en/ © SANKEN ELECTRIC CO.,LTD. 2016 6 NR263S NNNNN 3. Typical Application Circuit Standard connection is shown in Fig3-1. VIN RBS REN 5 IN 6 CIN CBS 2 BS EN SW VO L 3 NR263S 1 SS GND CSS VO NC 4 7 CO 8 GND GND Fig. 3-1 NR263S Standard connection CIN: 10μF / 25V REN:100kΩ CO: 22μF / 16V RBS:≦10Ω CBS: 0.1μF CSS: 0.1μF L: 6.8μH *As for the circuit diagram of the Demo-Board, please refer to the Demo-Board circuit diagram of the "8.2.2 mounting board pattern example" section. 4. Allowable package power dissipation Fig. 4-1 Allowable package powe disspation of NR263S NR263S series-DSE Rev.1.0 SANKEN ELECTRIC CO.,LTD 2016.03.09 http://www.sanken-ele.co.jp/en/ © SANKEN ELECTRIC CO.,LTD. 2016 7 NR263S NNNNN Notes: 1) Because the Fig5 is defined in "PD=1.56[W]" at "Tj=150 [°C]", please keep enough margin when you use. (Our Demo-board implementation in the Fig21) 2) Losses can be calculated by the following equation. In addition, efficiency ηx will vary depending on the conditions of the input voltage, output current. By measuring the ηx in the actual operation, assigns a numerical value to the equation (1) , as a ηx remain of percent display. η (1) Main sources of heat generation are an inductor which is flowing the load current , and the IC which has the PowerMOSFET and the control circuit. By subtracting the steady loss of the inductor from the overall efficiency, the loss of the IC is calculated by equation (1). VO: Output voltage If following situations are ...VO = 5[V], IO = 1[A] continuous, the inductor DCR = 80[mΩ], the Loss of IC when the overall efficiencyis 90 percent, it will be 0.476[W] from the equation (1). ηx: Efficiency(%) NR263S series-DSE Rev.1.0 SANKEN ELECTRIC CO.,LTD 2016.03.09 http://www.sanken-ele.co.jp/en/ © SANKEN ELECTRIC CO.,LTD. 2016 VIN: Input voltage IO: Output current L(DCR)：DC serial resistance of inductor (Ω) 8 NR263S NNNNN 5. Package Outline 5.1 Outline, Size Top view 8 1 7 2 6 3 5 4 Side view1 Side view2 Notes: 1) Dimension is in millimeters (mm) 2) Drawing is not to scale. Fig. 5-1 SOP8 Package outline NR263S series-DSE Rev.1.0 SANKEN ELECTRIC CO.,LTD 2016.03.09 http://www.sanken-ele.co.jp/en/ © SANKEN ELECTRIC CO.,LTD. 2016 9 NR263S NNNNN 6. Marking As for the Marking, the product name and lot number, those are laser marking to mold package surface. *1. Product name *2. Lot number (3 digits) The 1st letter : Last one digit of the year (Y) The 2nd letter : manufacturing Month (M) Jan - Sep：1 – 9 Oct：O Nov：N Dec：D The 3rd letter : manufacturing Week (W) First week - Fifth week：1 - 5 *1 NR263S SK *2 *3 *3. Our control number (4 digits) Fig. 6-1 NR263S series-DSE Rev.1.0 SANKEN ELECTRIC CO.,LTD 2016.03.09 http://www.sanken-ele.co.jp/en/ © SANKEN ELECTRIC CO.,LTD. 2016 Marking Specification 10 NR263S NNNNN 7. Operational Descriptions The Characteristic value of, unless otherwise noted, it writes the TYP value in accordance with the NR263S specifications. 7.1 PWM(Pulse Width Modulation) Output Control The PWM control circuit of the NR263S consists of the current sense amplifier, the error amplifier, the PWM comparator, the slope superimposing circuit. The Vtrip is the drain current feedback signal detected by current sense amplifier. And the VCOMP is the error amplification signal generated by the error amplifier with the output voltage and the reference voltage. By comparing with the Vtrip and the VCOMP in the PWM comparator, it performs control of the ON-Duty. In the slope superimposition circuit, by superimposing the slope signal with respect to the current feedback signal Vtrip, it can avoid the sub-harmonic oscillation that occur at ON-Duty 50% or more. Fig. 7-1 Basic Structure of Buck Regulator with PWM Control by Current mode Control When the UVLO was released or, the EN terminal voltage exceeded threshold, the SS terminal voltage starts to rise. In the period until the SS terminal voltage reaches to 0.6V (typ), to drive the High-side driver and the High-side switch (the following M1), by turning on the Low-side switch (the following M2), the boost capacitor CBS is charged. After that, the switching operation is started when the SS terminal voltage exceeds 0.6V (typ). M1 and M2 are the switching-MOSFET for suppling the power to the Output. By M1&M2 repeating ON and OFF alternately, and energy is supplied to the Output stage. In the period when M1 turns on, the current of Inductor L increase, and the output of the current sense amplifier is raised, too. In the PWM comparator, the error amplifier output VCOMP signal is compared with the Vtrip signal which is the addition of the current sense amplifier signal and the slope compensation signal. When the Vtrip exceeds the VCOMP, M1 turns OFF, and M2 turns ON, the regenerative current of the inductor L flows via M2 from the GND. Then, upon receiving a set signal from the oscillator OSC, M1 is turned ON again. NR263S series-DSE Rev.1.0 SANKEN ELECTRIC CO.,LTD 2016.03.09 http://www.sanken-ele.co.jp/en/ © SANKEN ELECTRIC CO.,LTD. 2016 11 NR263S NNNNN 7.2 UVLO and Enable Function In the condition that the EN terminal is connected to the IN terminal, when the input voltage V IN is increased beyond 6V(typ.), the UVLO is released and started the switching operation. And, in the condition that the input voltage V IN is applied beyond 6V(typ.), when the EN terminal voltage exceeds 1.1V (typ.), it is started the switching operation. VIN VIN REN1 REN1 IN EN IN EN GND GND (A) Fig. 7-2 (B) Remote ON/OFF by EN terminal The Fig7-2 (B) is the option of the "Remote ON/OFF control" by using the EN terminal. By using switch such as Open-collector and, by removing the EN terminal voltage VEN to GND level (Low), it is possible to turn OFF. In case of without ON / OFF operation by external signal, please use the Fig7-2 (A) connection. It is started by the applying of the VIN, and it is stopped by shut-off of the VIN. REN1 is recommended 100[kΩ]. NR263S series-DSE Rev.1.0 SANKEN ELECTRIC CO.,LTD 2016.03.09 http://www.sanken-ele.co.jp/en/ © SANKEN ELECTRIC CO.,LTD. 2016 12 NR263S NNNNN 7.3 Soft-start Function By connecting a capacitor between the SS terminal and the GND terminal, when the input voltage is supplied to the IC, the soft-start function will be effective.The output voltage (Vo) is ramped up by the charging voltage level of Css. Because the internal constant current source I SS supplied from the SS terminal is 5 μA, the soft-start period depends on the charging time constant of the CSS. When the charging of CSS is started by the constant current I SS, the SS terminal voltage VSS is linearly increased. The soft-start period is the time that the VSS passes between the "Soft-start start threshold voltage VSS1(=0.6V)" and "Soft-start completion threshold voltage VSS2(=1.4V)". During the Soft-start, the rise-time is controlled by controlling the OFF period of PWM control. The rise time t_SS and the delay time t_delay are calculated in the following equations… (2) Note: VSS1(=0.6V) ≦VSS≦ VSS2 (=1.4V), ISS=5μA (3) Note: 0V ≦VSS＜VSS1 (0.5V), ISS=5μA The rise time of the output voltage Vo is " t_delay + tSS ". Fig. 7-3 The timing chart of the Soft-start in the normal startup Vss Vss Vss2=1.4V Vss2=1.4V Vss1=0.6V Vss1=0.6V Vo Fig. 7-4 T Vo T T T The occurrence of the overshoot on Vo rising waveform NR263S series-DSE Rev.1.0 SANKEN ELECTRIC CO.,LTD 2016.03.09 http://www.sanken-ele.co.jp/en/ © SANKEN ELECTRIC CO.,LTD. 2016 13 NR263S NNNNN Adjust the capacitance of CSS so that the excessive overshoot may not occur on the Rising-Waveform of the output voltage Vo at the start-up. The overshoot occurs when tss is short.If the soft-start is finished before the constant voltage control follows Vo rising speed,it may become such waveform of Fig7-4. When a capacitance of the CSS is increased, though the overshoot will not occur , please understand that the start-up time is longer. In actual operation, please confirm the Rising-waveform, and adjust the capacitance of the C SS. Note: About CSS discharge to restart It is explained about discharging of the CSS capacitor when this IC is restarted such as ON/OFF operation in the EN terminal. When it was restarted, there is a case where the voltage is remaining in the soft-start capacitor CSS. In this IC, it has adopted the forced discharge sequence as shown in the Fig7-5. By the internal impedance, after once discharging the SS terminal voltage to 0.6V or less, and then resume the soft-start. Discharge of the capacitor Css, it is discharged by the internal impedance 600 Ω (typ) in the IC. VEN(th)=1.1[V](typ) Discharge impedance 600Ω(typ.) VSS2=1.4[V](typ.) VSS1=0.6[V](typ.) Fig. 7-5 Discharge of the capacitor Css at restart Under the condition that the voltage is remaining in the Css, after the ON-signal is inputted, it takes the time of “t_discharge+tss” until Vo-waveform rise and stabilize. The soft-start capacitor Css has been charged to the internal regulator voltage 1.8V. It considers the discharge from the condition that the soft-start capacitor CSS has been charged up to 1.8V in the steady condition. The SS terminal voltage VSS at optional time t after the start of discharge will be calculated by the equation (4). For the time t_discharge that the V SS is discharged to 0.6 V from 1.8 V, it can be calculated by equation (5). Ω Ω (4) (5) When there is a mode for continuous “ON/OFF” operation, consider delay by discharging of the C SS. NR263S series-DSE Rev.1.0 SANKEN ELECTRIC CO.,LTD 2016.03.09 http://www.sanken-ele.co.jp/en/ © SANKEN ELECTRIC CO.,LTD. 2016 14 NR263S NNNNN 7.4 Over current and Short circuit protection Function (OCP & HICCUP) An OCP characteristic is shown in the Fig7-6. The "drooping type" over-current-protection is equipped in the NR263S. As for the over-current-protection circuit,this IC detects a peak current to flow to the switching-transistor. When peak current exceeds setup value, a Ton-period of the transistor is made to shorten forcibly, and an output voltage VO is made to decrease, and an output current is restricted. In this case, by the decline of the output voltage VO, when a VO-terminal- voltage VO decreases to 3.5V 70% of the internal-reference -voltage (5V) , by the reducing of the switching-frequency (the FDOWN mode),the "drooping characteristic" is improved in the low output voltage.As shown in the Fig12, Moreover, when a VO-terminal-voltage VO decreases more and it becomes under 30% of the internal reference voltage (*5V→1.5V), the Soft-start capacitor CSS is charged by internal current source ISS=5μA.When a SS-terminal-voltage VSS rises to 2.2V, the interval-operation mode (HICCUP) becomes effective, and the continuous-switching-operation is canceled. After that, the soft-start capacitor CSS is discharged by the constant current (=-2.5[μA]) , and the suspension-period of interval-operation is set up. The soft-start is restarted when a SS-terminal-voltage VSS decreases to 0.23[V]. The interval-operation mode (HICCUP) is maintained due to this repetition. By becoming the interval-operation mode, part stress such as heat-generation can be eased. An output voltage is resumed to normal condition automatically when over-current condition is canceled. * When a HICCUP function is invalidated, the short-current becomes continuously such as a characteristic of the red line in the Fig7-7. Fig. 7-6 OCP (HICCUP Mode) Timing Chart HICCUP Fig. 7-7 OCP characteristic curve (Condition example ：VIN=12V, VO=5V) NR263S series-DSE Rev.1.0 SANKEN ELECTRIC CO.,LTD 2016.03.09 http://www.sanken-ele.co.jp/en/ © SANKEN ELECTRIC CO.,LTD. 2016 15 NR263S NNNNN 7.5 Thermal Shutdown (TSD) Output Voltage 出力電圧 The thermal shutdown circuit detects the IC junction temperature. When the junction temperature exceeds the rated value (around 165°C), it shuts-down the output transistor and turns the output OFF. If the junction temperature falls below the thermal shutdown rated value by around 15°C, the operation returns automatically. * (Thermal Shutdown Characteristics) Notes The circuit protects the IC against temporary heat generation. It does not guarantee the operation including reliabilities under the continuous heat generation conditions, such as short circuit for a long time. 7.6 Restart setup temperature 復帰設定温度 Shutdown setup 保護設定温度 temperature Junction temperature 接合温度 Fig. 7-8 TSD Operation About the "Pulse-Skip-Mode" in the Light-load condition A NR263S is equipped with the "Pulse-Skip-Mode (naming of our company) " to realize high efficiency in Light-load. The more load current decrease,it is controlled so that a COMP voltage V COMP may decrease. In the condition that the load-current decreases and the VCOMP is under the Vskip (Vskip=Light-load detection threshold), the operation changes to the Pulse-Skip-Mode when the discontinuous-condition of inductor-current is longer than the internal timer setup. In the Pulse-Skip-Mode, the peak value of the "Hi-side MOSFET Drain-current (=ILP)" is limited to about 600mA. And, the variable-frequency-operation is done that changes the switching-frequency corresponding to the load. The more switching-frequency decreases, the efficiency in the light-load condition is possible to improve because the switching-loss decreases in the Hi-side MOSFET and the Lo-side MOSFET. And, when the load condition changes from light-load to heavy-load,the operation changes from the Pulse-Skip-Mode to the normal PWM switching mode in a moment. Notes: *The VCOMP, the Skip signal, and, the light-load detection threshold Vsk will not be able to confirm directly from the outside of the package. *The pulse-skip mode can't be intentional cancellation by the external signal. Fig. 7-9 Timing chart of the Pulse-Skip-Mode In addition, pulse-skipping mode frequency as described above will be decreased. There is also a case to be audible frequency band (20kHz or less). Pulse skip frequency Fskip can be roughly calculated by the following equation. NR263S series-DSE Rev.1.0 SANKEN ELECTRIC CO.,LTD 2016.03.09 http://www.sanken-ele.co.jp/en/ © SANKEN ELECTRIC CO.,LTD. 2016 16 NR263S NNNNN (6) In actual operation confirmation of the standby-light load, if the audible-noise by the operation of an audible-frequency-range occurs, please adjust the inductance(L) of the inductor in reference to the equation (6). However, if the Fskip becomes higher, power consumption will increase. Please be careful. In pulse skipping operation, the ILP of equation (6) is limited to a constant value determined by the input voltage V IN and use inductor inductance L. But, it has the input voltage dependence such as Fig7-10. If you wish to calculate the Fskip, please pick up the value of the ILP from Fig7-10 and substitute the ILP to equation (6). 1.2 1 L=6.8μH ILP(A) 0.8 L=10μH 0.6 L=22μH 0.4 L=33μH L=47μH 0.2 L=68μH 0 0 5 10 15 20 25 30 35 VIN(V) Fig. 7-10 VIN vs. IL characteristics (with inductance L variation) NR263S series-DSE Rev.1.0 SANKEN ELECTRIC CO.,LTD 2016.03.09 http://www.sanken-ele.co.jp/en/ © SANKEN ELECTRIC CO.,LTD. 2016 17 NR263S NNNNN 8. Design Notes 8.1 External Components All components are required for matching to the condition of use. 8.1.1 Inductor L1 The Inductor is one of the most important components in the Buck regulators. In order to maintain the stabilized regulator operation, the Inductor should be carefully selected so it must not saturate or overheat excessively at any conditions. Please select an inductor with care to six items listed below. It is for switching regulator use only Because the coil for the noise filter (For EMI Countermeasure) has large loss and large heat generation, please do not use. Avoidance of sub-harmonic oscillation Under the peak detection current control, when the control Duty is more than 0.5 in use conditions, the inductor current may fluctuate at a frequency that is an integer multiple of switching operation frequency. This phenomenon is the known as sub-harmonic oscillation and this phenomenon theoretically occurs in the peak detection current control mode. In order to stabilize the operation, although the inductor current compensation is made internally, the inductance corresponding to the output voltage should be selected as an application. Specifically, for slope compensation amount is fixed in the IC, it is necessary to moderate the slope of the inductor current. The ripple portion of Inductor current ΔIL and the peak current ILP are calculated from the following equations: Large Inductance Δ small Inductance (6) Δ (7) Fig. 8-1 Relationship between the inductance and ripple current ΔIL According to the equations, if the inductance of the inductor L is small, both ΔIL and ILp is increased. Consequently, the inductor current becomes very steep if inductance is too small, so that the operation of the converter might become unstable. It is necessary to take care of an inductance decrease due to magnetic saturation such as in overload and load shortage. (Inductance L calculation in case of "D≧0.5") The duty control is represented by the ratio of the output voltage V O and the input voltage VIN. The control duty will be 0.5 or more in case that the input voltage V IN is 10V or less. If the inductor current is used as the continuous current mode (CCM) in this input / output condition, the ΔI L in equation (9) is recommended the setting of less than 0.2A in order to avoid the sub-harmonic oscillation (Slope relaxation of the inductor current). (9) (Inductance L calculation in case of "D＜0.5") In the case of "D<0.5", the settable range of the ΔIL becomes "0.2≦ΔIL≦1A". 6.8μH that is a reference constant in the Typical Application Circuit is roughly the upper limit of the settable range of the ΔIL. It is a setting that is able to give the smallest inductance L. If the ΔI L becomes smaller, the necessary inductance L will be larger. Please calculate the inductance L using the equation (9) in the range of "ΔI L=0.2A-1A". NR263S series-DSE Rev.1.0 SANKEN ELECTRIC CO.,LTD 2016.03.09 http://www.sanken-ele.co.jp/en/ © SANKEN ELECTRIC CO.,LTD. 2016 18 NR263S NNNNN ΔIL / Io ratio When the ΔIL/Io ratio is increased, the Inductance decreases.However, there is a matter of trade-off, for example, the output ripple voltage increases.When the ΔI L/Io ratio is decreased, required inductance increases, and the outer shape of the Inductor becomes larger. Setting of the ΔI L/Io ratio to 0.2 or 0.3 is conventionally regarded as a setting for good cost performance. Diameter of the wire winding When the Inductance is increased, if the core-size of the Inductor is identical, the number of turns of windings will increase, and the diameter of wire windings will be thinner. Because the DC resistance DCR also increases, the large current can't to flow. If the DCR is in priority, the core size of the Inductor enlarges. DC superposition characteristics Depending on the material or shape of the core, the inductance of inductor has DC superposition characteristics that decreases gradually by the flowing DC current. Be sure to confirm if the inductance value is significantly lower than the design value when making the maximum load current for practical use flow. Obtain the data of the DC superposition characteristics including graphs from the manufacturer of the coil to understand the characteristics of the Inductor used in advance. In doing so, important parameters are: 1) Saturation point...At what ampere does magnetic saturation occur? 2) Inductance fluctuation with the practical load current For example, for using it up to 1 A in the actual load Io, it can not use the Inductor which the saturation point is such as 0.5 A. In addition, in spite of having an inductance of 10 μH at the no-load, please pay caution for the thing which has the characteristic that it decreases to such as 5μH by the superposition current of 1A. Less noise If the core is the open magnetic circuit type shaped like a drum, the magnetic flux passes outside the Inductor, so that the peripheral circuit might be damaged due to noise. Use the Inductor which has a core/structure of the low-leakage magnetic flux type. For details, consult the manufacturer of the Inductor. Heat generation In actuality, when using the coil for mounting the PCB, heat generation of the coil main body might be influenced by peripheral parts. In most cases, temperature rise of the coil includes the Inductor’s own heat generation, and there are temperature limitations such as below: 1) onboard(Cars) grade product: 150°C 2) highly-reliable product: 125°C 3) general product: 85-100°C Be sure to evaluate heat generation because temperature rise differs when the PCB on which the Inductor is mounted is designed differently.In general, Inductors with a smaller DCR value on the specification sheet have smaller loss. * Select the most appropriate one in consideration of the conditions of use, mounting, heat dissipation, etc. NR263S series-DSE Rev.1.0 SANKEN ELECTRIC CO.,LTD 2016.03.09 http://www.sanken-ele.co.jp/en/ © SANKEN ELECTRIC CO.,LTD. 2016 19 NR263S NNNNN 8.1.2 Input Capacitor CIN Please use the ceramic capacitor to the input capacitor. It will lower the input impedance and it will contribute to the stable operation of the IC. The input capacitor CIN must be arranged in as much as possible the shortest distance to between IN - GND of the IC. Even if there is a smoothing capacitor CF in the transformer secondary side rectifying and smoothing circuit, please place the CIN in the immediate vicinity of the IC. As a point of CIN selection, it will include the following: Satisfaction of the withstand voltage and, that capacitance change with respect to the applied voltage is low The rate of capacity change in the ambient temperature range to be used is small Parts temperature which contains the heat-generation is must satisfy the specifications of the maximum operating temperature Its impedance Z is sufficiently low in the temperature conditions and using frequency * Please query the product information of the capacitor manufacturer. * Even in the ceramic capacitor, in case of the insertion parts having a lead, its impedance will be higher than surface-mounted type, therefore please be careful. * In generally, in case of ceramic capacitors, the allowable ripple current is not included in the specification. But,because it has the equivalent series resistance ESR inside, the ceramic capacitor occurs slightly heat-generation by flowing ripple current. Therefore there is a need to comply with the maximum operating temperature containing the heat generation. In this case, also please consider the heat conduction from the heat generating parts of the surrounding. Select the most suitable parts which has a margin in consideration of the use condition, the mounting condition, the radiation condition, and so on. 8.1.3 Output Capacitor CO In the current control mode, the feedback loop which detects the inductor current is added to the voltage control mode. The stable operation is achieved by adding inductor current to the feedback loop without considering the effect of secondary delay factor of LC filter. It is possible to reduce the capacitance of LC filter that is needed to make compensations for the secondary delay, and the stable operation is achieved even by using the low ESR capacitor (ceramic capacitor). The output capacitor CO comprises the LC low-pass filter with the Inductor L1 and works as the rectifying capacitor of switching output. The current equal to ripple portion ΔIL of the Inductor current charges and discharges the output capacitor. The equivalent serial resistance ESR exists in the ceramics capacitor, and the voltage multiplied by ESR and ΔIL becomes the output ripple voltage and it appears as VOripple. Ω Δ (10) To suppress output ripple voltage VO ripple to any value, the required ESR conditions in the ceramic capacitor can be calculated by the following equation (10). Ω Δ (11) Therefore, if the ripple portion of the inductor current ΔIL is small, the output ripple voltage VO ripple will be relatively small. If the ΔIL is large, as parallel connection of the ceramic capacitor, it may be necessary to reduce the ESR. As a point of CO selection, it will include the following: In the same way as the input capacitor CIN, as the point of CO selection, it will include the following: Satisfaction of the withstand voltage and, that capacitance change with respect to the applied voltage is low The rate of capacity change in the ambient temperature range to be used is small Parts temperature which contains the heat-generation is must satisfy the specifications of the maximum operating temperature Its impedance Z is sufficiently low in the temperature conditions and using frequency NR263S series-DSE Rev.1.0 SANKEN ELECTRIC CO.,LTD 2016.03.09 http://www.sanken-ele.co.jp/en/ © SANKEN ELECTRIC CO.,LTD. 2016 20 NR263S NNNNN *Please query the product information of the capacitor manufacturer *Even in the ceramic capacitor, in case of the insertion parts having a lead, its impedance will be higher than surface-mounted type, therefore please be careful. *In generally, in case of ceramic capacitors, the allowable ripple current is not included in the specification. But,because it has the equivalent series resistance ESR inside, the ceramic capacitor occurs slightly heat-generation by flowing ripple current. Therefore there is a need to comply with the maximum operating temperature containing the heat generation. In this case, also please consider the heat conduction from the heat generating parts of the surrounding. Select the most suitable parts which has a margin in consideration of the use condition, the mounting condition, the radiation condition, and so on. 8.2 Pattern Design High current paths in the circuit are marked as bold lines in the circuit diagram below. These paths are required for wide and short trace as possible. In addition, the pattern trace which is the signal system GND, and the pattern trace which the main circuit current flows, please to so that it does not become common impedance. Fig. 8-2 8.2.1 Note points in the wiring pattern Input / Output Capacitors(CIN,CO) The input capacitor CIN and the output capacitor CO are required to connect to the IC as short as possible. Think about the image to connect it between the pins of the IC ideally and directly. In such cases as the secondary side of the switching power supply, when there is a filter capacitor on the input side in advance, though it is possible that it is included with a input capacitor for NR263S, in case of long distance between filter capacitor and NR263S , it is necessary to connect as “line-bypass-capacitor”,aside from the one for the filter. The ripple current flows to the capacitor of input and output, you must make Low impedance and ESR. When you design a circuit board, set to shorter length the pattern of input and output capacitor. In the same way,consideration is necessary for route of the capacitor pattern. NR263S series-DSE Rev.1.0 SANKEN ELECTRIC CO.,LTD 2016.03.09 http://www.sanken-ele.co.jp/en/ © SANKEN ELECTRIC CO.,LTD. 2016 (A) (B) (A)･･･Recommended Pattern (B)･･･No good pattern example Fig. 8-3 CIN,CO pattern example 21 NR263S NNNNN 8.2.2 PCB Layout & Recommended Land Pattern The pattern example of the printed circuit board for our Demo Board is shown in the Fig8-6. (Double sided PCB) PCB Size：40mm×40mm Thickness：1.6mm Copper foil thickness：35μm Fig. 8-4 Component mounting side (surface) Fig. 8-5Back side (see from surface) Fig. 8-6 Our demo board circuit diagram for NR260S series (In reference for NR263S) C1,C2:10μF/25V C3:0.1μF C4,C5:22μF/16V C7:0.047μF R3:≦10Ω R1:100kΩ R4 & R5:Short R6:Open L1:6.8μH *Part number will match the silk-prints of the demo board. *Optional Parts C11：Phase advance capacitor･･･For experiment C12：Bypass capacitor (IN to AGND&PGND)･･･For experiment C13：Snubber circuit capacitor･･･For experiment, R10：Snubber circuit resistor･･･For experiment R2：Open (R2 is not used in the NR260S series) R3：Resistor for spike noise reduction･･･For experiment D1：The Schottky barrier diode for Efficiency improvement･･･For experiment It is recommended a Schottky barrier diode having a smaller V F than the parasitic diode VF of the Lo-side MOSFET. NR263S series-DSE Rev.1.0 SANKEN ELECTRIC CO.,LTD 2016.03.09 http://www.sanken-ele.co.jp/en/ © SANKEN ELECTRIC CO.,LTD. 2016 22 NR263S NNNNN Notes: 1) Dimension is in millimeters, *Dimensions in brackets are in inches 2) Drawing is not to scale Fig. 8-7 Foot printing for SOP8(recommended land Pad) 8.3 Applied Design 8.3.1 Spike Noise Reduction(1) The addition of the BS serial resistor The “turn-on switching speed” of the internal Power-MOSFET can be slowed down by inserting RBS (option) of the Fig8-10.It is tendency that Spike noise becomes small by reducing the switching-speed. Set up 10-ohm as an upper limit when you use RBS. *Attention 1) When the resistance value of RBS is enlarged by mistake too much, the internal power-MOSFET becomes an under-drive,it may be damaged worst. 2) The “defective starting-up” is caused when the resistance value of RBS is too big. *The BS serial resistor RBS is R3 in the Demonstration Board. 8.3.2 RBS BS NR263S Fig. 8-8 SW CBS The addition of the BS serial resistor Spike Noise Reduction(2) The addition of the Snubber circuit In order to reduce the spike noise, it is possible to compensate the output waveform and the recovery time of internal parasitic diode by connecting a capacitor and resistor parallel to the internal parasitic diode (snubber method). This method however may slightly reduce the efficiency. * For observing the spike noise with an oscilloscope, the probe lead (GND) should be as short as possible and connected to the root of output capacitor. If the probe GND lead is too long, the lead may act like an antenna and the observed spike noise may be much higher and may not show the real values. *The snubber circuit parts are C13 and R10. IN SW NR263S PGND ≒10Ω *Option ≒1000pF Fig. 8-9 NR263S series-DSE Rev.1.0 SANKEN ELECTRIC CO.,LTD 2016.03.09 http://www.sanken-ele.co.jp/en/ © SANKEN ELECTRIC CO.,LTD. 2016 The addition of the Snubber circuit 23 NR263S NNNNN 8.3.3 Attention about the insertion of the bead-core Fig. 8-10 Bead core insertion prohibited area In the area surrounded by the red dotted line within the Fig8-12, don’t insert the bead-core such as Ferrite-bead. As for the pattern-design of printed-circuit-board, it is recommended that the parasitic-inductance of wiring-pattern is made small for the safety and the stability. When bead-core was inserted, the inductance of the bead-core is added to parasitic-inductance of the wiring-pattern. By this influence, the surge-voltage occurs often, or , AGND & PGND of IC becomes unstable, and also, negative voltage occurs often. Because of this, faulty operation occurs in the IC. The IC has the possibility of damage in the worst case. About the Noise-reduction, fundamentally, Cope by “The addition of BS serial resistor” and “The addition of CR snubber circuit”. 8.3.4 Reverse Bias Protection A diode for reverse bias protection may be required between input and output in case the output voltage is expected to be higher than the input Pin voltage (a common case in battery charger applications). IN 2. IN NR263S NR885E Fig. 8-11 8.3.5 SW 3.SW Reverse bias protection diode Overvoltage protection of VO terminal If the hot-swap is done by such as load-line connector when the DC / DC converter circuit is in operation, the surge voltage due to hot-swap will occur on the Vo output circuit. In your use condition, please be careful so that the voltage applied to the VO terminal does not exceed the absolute maximum rating (6V). For problems such as the reverse-flow from the external circuit, please take measures. Nevertheless, if you can not suppress an overvoltage factors by the surge voltage such as when the hot-swap was done, please protect the VO terminal by inserting the RVO as shown in Fig8-14. The resistance of RVO as a guide is defined as 100Ω. And, by inserting of the R VO (= 100Ω) to the sensing line, the output voltage VO(=5V(typ)) will rise further +5mV equivalent. NR263S series-DSE Rev.1.0 SANKEN ELECTRIC CO.,LTD 2016.03.09 http://www.sanken-ele.co.jp/en/ © SANKEN ELECTRIC CO.,LTD. 2016 24 NR263S NNNNN 100Ω Fig. 8-12 The resistor RVO for overvoltage protection of theVO terminal NR263S series-DSE Rev.1.0 SANKEN ELECTRIC CO.,LTD 2016.03.09 http://www.sanken-ele.co.jp/en/ © SANKEN ELECTRIC CO.,LTD. 2016 25 NR263S NNNNN 9. Typical characteristics (Ta=25°C) (1)Efficiency 100 90 80 Efficiency[%] 70 VIN=8V VIN=12V VIN=18V VIN=24V VIN=31V 60 50 40 30 20 10 0 0.001 0.010 0.100 1.000 Output Current IO [A] Fig. 9-1 Io=1A (4) Supply Current : IIN 2.5 6.0 Input current Iin [mA] Output voltage VO [V] (2) Output startup 5.0 4.0 3.0 2.0 1.0 0.0 4.0 5.0 6.0 7.0 2 1.5 1 0.5 0 8.0 0 5 Input voltage VIN [V] Fig. 9-3 15 20 25 30 Input voltage VIN [V] Fig. 9-2 (5) Shutdown Supply Current : Iin(off) (3) Load Regulation : VLoad 10 Input current Iin [uA] 5.20 Output voltage VO [V] 10 5.15 5.10 5.05 5.00 4.95 4.90 4.85 4.80 9 8 7 6 5 4 3 2 1 0 0.0 0.2 0.4 0.6 0.8 1.0 0 Output current IO [A] Fig. 9-4 NR263S series-DSE Rev.1.0 SANKEN ELECTRIC CO.,LTD 2016.03.09 http://www.sanken-ele.co.jp/en/ © SANKEN ELECTRIC CO.,LTD. 2016 5 10 15 20 25 30 Input voltage VIN [V] Fig. 9-5 26 NR263S NNNNN (6)Switching frequency : Fosc (7)Over current protection 6.0 Output voltage VO [V] Frequency Fosc [Khｚ] 1000 100 10 1 0 0.2 0.4 0.6 0.8 1 5.0 VIN=8V VIN=12V VIN=18V VIN=24V VIN=31V 4.0 3.0 2.0 1.0 0.0 0.0 Output current IO [A] Fig. 9-7 NR263S series-DSE Rev.1.0 SANKEN ELECTRIC CO.,LTD 2016.03.09 http://www.sanken-ele.co.jp/en/ © SANKEN ELECTRIC CO.,LTD. 2016 0.5 1.0 1.5 2.0 2.5 Output current IO [A] Fig. 9-6 27 NR263S NNNNN 10. Packing specifications Taping & Reel outline Pocket 5.55 12.0 Round Sprocket φ1.55 Holes 5.5 0.3 1.75 10.1 φ2.05 6.7 2.47 8.0 4.0 EIAJ No.TE1208 2.0 Notes: 1) All dimensions in millimeters (mm) 2) Surface resistance：under 109Ω 3 )Drawing is not to scale Fig. 10-1 Taping outline Notes: 1) All dimensions in millimeters (mm) 2) Drawing is not to scale EIAJ No.RRM-12DC φ13 Fig. 10-2 ±0.2 Reel outline NR263S series-DSE Rev.1.0 SANKEN ELECTRIC CO.,LTD 2016.03.09 http://www.sanken-ele.co.jp/en/ © SANKEN ELECTRIC CO.,LTD. 2016 Quantity (TBD) 4000pcs／reel φ330±2 ±0.8 φ80±1 φ21 13.5 17.5 ±0.5 ±1.0 28 NR263S NNNNN IMPORTANT NOTICE ●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. 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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. NR263S series-DSE Rev.1.0 SANKEN ELECTRIC CO.,LTD 2016.03.09 http://www.sanken-ele.co.jp/en/ © SANKEN ELECTRIC CO.,LTD. 2016 29