用于智能电表的非隔离式ACDC降压转换器

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DC-DC Converter解析

DC-DC转换器之电气规格(1)
1. Input Specifications(输入规格)
a. Input voltage (输入电压) : 指单一机种能接受的最大电压及最小电压之比率，大致分成二大类：窄范围输入电压（±10%）、宽范围输入电压（2:1、4:1<W>、…）。
EX: 宽范围输入电压2:1 12V nominal input 9~18Vdc 24V nominal input 18~36Vdc 48V nominal input 36~75Vdc
h. Short circuit protection(短路保护) : 当发生短路时，转换器停止正常动作。 EX: Hiccup(打嗝 ), continuous (Auto Recovery) ◎ Hiccup Mode 断续模式: 输出故障(短路)时，这时转换器把每一周的占空比由开通到截止以及由截止到开通维持在使内部的功耗在一个安全的范围内，直到故障排除。 ◎ Auto Recovery: 当故障排除后，转换器自动恢复正常动作。
DC/DC Converter浅析
DC-DC Converter 简介 DC-DC Converter 之典型应用领域 DC-DC Converter 如何选型 DC-DC Converter 之电气规格
电子系统的常用电源
电压 (Voltage)
±12, ± 15
典型负载(Typical Loads) Linear Circuits (OP.AMP…etc)(线性电路，如运算放大器等)
a. Switching frequency (操作频率)：产品内部开关组件的切换频率。 EX: 300kHz
b. Reliability, calculated MTBF (平均无故障时间) : Mean Time Between Failure 。

——输出持续电流500mA(12W)

一款不带变压器的宽电压、低成本、非隔离式AC/DC降压转换器——输出持续电流500mA（12W)【关键词摘要】非隔离无变压器AC/DC电源芯片XD308H BUCK电路220V转5V220V转12V220V转24V380V转5V380V转12V380V转24V【概述】非隔离AC-DC电源芯片降压电路，一般采用BUCK电路拓扑结构，常见于小家电控制板电源以及工业控制电源供电。

其典型电路规格包含5V/500mA、12V/500mA和24V/500mA等，满足六级能效要求。

可通过EFT、雷击、浪涌等可靠性测试，可通过3C、UL、CE等认证。

其特点是：电路简单、BOM成本低（外围元件数目极少：无需变压器、光耦）,电源体积小、无音频噪声、损耗小发热低。

1）220V转5V降压电路：输入12~380Vac，输出5V/500mA如图1所示的电路为一个典型的输出为5V/500mA的非隔离电源。

它通常应用于家用电器的(电饭煲、洗衣机及其它白色家电)。

此电路还适合于其它非隔离供电的应用，比如LED驱动、智能电表、加热器以及辅助电源和工业控制等。

电源系统带有各种保护，包括过热保护（OTP）、VCC欠压闭锁（UVLO）、过载保护（OLP）、短路保护（SCP）等。

电路特点：无噪音,发热低。

220V转5V降压电路输入级由保险电阻RF1、防雷压敏电阻RV1、整流桥堆D1、EMI滤波电容C4和C5以及滤波电感L2组成。

保险电阻RF1为阻燃可熔的绕线电阻，它同时具备多个功能：a)将桥堆D1的浪涌电流限制在安全的范围；b)差模噪声的衰减；c)在其它任何元件出现短路故障时，充当输入保险丝的功能(元件故障时必须安全开路，不应产生任何冒烟、冒火及过热发光现象)。

压敏电阻RV1用于防雷保护，提高系统可靠性。

功率处理级由宽电压高效率电源芯片XD308H、续流二极管D2、输出电感L1及输出电容C3构成。

2）220V转12V降压电路：输入32~380Vac，输出12V/500mA如图2所示的电路为一个典型的输出为12V/500mA的非隔离电源。

XD308H非隔离降压芯片

1.2产品特性：•典型待机功耗小于40mW；•输出最大持续电流500mA （峰值800mA),无音频噪音、发热低；•18-600VDC 超宽输入电压,可适应12-380VAC超宽电压输入；•全面的保护功能：•过流保护（OCP）•过温保护（OTP）•过压保护（OVP）•SOP8贴片封装；1.3典型应用（非隔离）：•替代低效率的阻容降压供电电路(如低压电器，智能电表，自动化仪表电源等)；•LED驱动•小家电电源•工业控制电源•其他非隔离辅助电源1.4输入电压/输出电流表：序号输入电压范围（DC 单位：V）输出电压（DC 单位：V）持续工作输出电流（Max 单位：mA)瞬时峰值电流（单位：mA)参考电路图号118-600 3.3500800图B1218-600 5.0500800图B2345-60012500800图B3445-60024500800图B4XD308H 是一款18-600V 超宽范围输入的非隔离高压降型AC-DC 转换器电源芯片，可适应12-380VAC 超宽电压输入(外部加整流滤波)，最大输出持续电流可以达到500mA（峰值800mA)，无音频噪音、发热低，内部集成全面完善的保护功能（短路保护，过载保护，输出过压保护、输出欠压保护，过热保护等）。

该电源芯片以较低的BOM 成本（外围元件数目极少）方便的实现宽电压高压降压小功率电源解决方案,广泛应用于非隔离型家电产品和工业产品等。

1.5封装参考：1.6引脚功能：编号名称描述备注1VCC/BP所有控制电路的电源。

外部旁路电容连接点2GND/S芯片参考地。

内部功率MOSFET的源极。

3FB反馈输入4CS电流检测5,6,7,8DRAIN内部功率MOSFET的漏极1.7功能框图：图11.8典型应用电路：1.9绝对最大额定值(备注1)：1.10推荐的工作条件(备注2)：参数数值单位工作环境温度-40to85°C1.11电气特性：=+25℃。

NB680 28V、低Iq、高电流、固定3.3V-8A同步降压转换器说明书

NB68028V, Low Iq, High Current, Fixed 3.3V-8ASynchronous Buck ConverterDESCRIPTIONThe NB680 is a fully integrated, high-frequency, synchronous, rectified, step-down, switch-mode converter with a fixed 3.3 V Vout. It offers a very compact solution to achieve an 8 A continuous output current and a 10 A peak output current over a wide input supply range with excellent load and line regulation.The NB680 operates at high efficiency over a wide output current load range based on MPS proprietary switching loss reduction technology and internal low Ron power MOSFETs. Adaptive constant-on-time (COT) control mode provides fast transient response and eases loop stabilization. The DC auto-tune loop provides good load and line regulation.NB680 provides a fixed 3.3 V LDO, which can power the external peripheries, such as the keyboard controller in the laptop.Also, a 250 kHz CLK is available; its output can drive an external charge pump, generating gate drive voltage for the load switches without reducing the main converter’s eff iciency.Full protection features include OC limit, OVP,UVP, and thermal shutdown.NB680 requires a minimum number of externalcomponents and is available in a QFN2mm x 3mm package.FEATURES∙ Wide 4.8 V to 28 V Operating Input Range ∙ Fixed 3.3 V Vout∙ Ultrasonic Mode with Fs over 25 kHz ∙ 100 μA Low Quiescent Current ∙ 8 A Continous Output Current ∙ 10 A Peak Output Current∙ Adaptive COT for Fast Transient ∙ DC Auto-Tune Loop∙ Stable with POSCAP and Ceramic Output Capacitors∙ 250 kHz CLK for External Charge Pump ∙ Built-In 3.3 V, 100 mA LDO with Switch Over∙ 1% Reference Voltage ∙ Internal Soft Start ∙ Output Discharge∙ 700 kHZ Switching Frequency∙ OCL, OVP, UVP, and Thermal Shutdown. ∙ Latch-Off Reset via EN or Power Cycle. ∙QFN 2mm x 3mm Package APPLICATIONS∙ Laptop Computers ∙ Tablet PCs∙ Networking Systems ∙Servers∙Personal Video Recorders∙Flat Panel Television and Monitors ∙Distributed Power SystemsAll MPS parts are lead-free, halogen-free, and adhere to the RoHS directive. For MPS green status, please visit the MPS website under Quality Assurance. “MPS” and “The Future of Analog IC Technology” are registered trademarks of Monolithic Power Systems, Inc.TYPICAL APPLICATIONORDERING INFORMATION* For Tape & Reel, add suffix –Z (e.g. NB680GD –Z)TOP MARKINGALV: Product code of NB680GD Y: Year code LLL: Lot numberPACKAGE REFERENCEABSOLUTE MAXIMUM RATINGS (1) Supply voltage (V IN) .................................... 28 V V SW (DC) ......................................... -1 V to 26 V V SW (25 ns) .................................. -3.6 V to 28 V V BST ................................................. V SW + 4.5 V All other pins ............................. -0.3 V to +4.5 V Continuous power dissipation (T A=+25°C) (2) QFN-12 (2mm x 3mm) .............................. 1.8 W Junction temperature ............................... 150︒C Lead temperature .................................... 260︒C Storage temperature ................ -65︒C to +150︒C Recommended Operating Conditions (3) Supply voltage .............................. 4.8 V to 24 V Operating junction temp. (T J). .. -40°C to +125°C Thermal Resistance (4)θJA θJCQFN-12 (2mm x 3mm) ........... 70 ...... 15 ... ︒C/W NOTES:1) Exceeding these ratings may damage the device.2) The maximum allowable power dissipation is a function of themaximum junction temperature T J(MAX), the junction-to-ambient thermal resistance θJA, and the ambient temperature T A. The maximum allowable continuous power dissipation at any ambient temperature is calculated by P D(MAX)=(T J(MAX)-T A)/θJA. Exceeding the maximum allowable power dissipation produces an excessive die temperature, causing the regulator to go into thermal shutdown. Internal thermal shutdown circuitry protects the device from permanent damage.3) The device is not guaranteed to function outside of itsoperating conditions.4) Measured on JESD51-7, 4-layer PCB.ELECTRICAL CHARACTERISTICS V = 12 V, T = 25 C, unless otherwise noted.ELECTRICAL CHARACTERISTICS (continued) V = 12 V, T = 25︒C, unless otherwise noted.NOTE:5) Guaranteed by design.PIN FUNCTIONS NB680V IN = 12 V, V OUT = 3.3 V, L = 1.5 µH/10 mΩ, F S = 700 kHz, T J=+25°C, unless otherwise noted.V IN = 12 V, V OUT = 3.3 V, L = 1.5 µH/10 mΩ, F S = 700 kHz, T J=+25°C, unless otherwise noted.V IN=12 V, V OUT =3.3 V, L=1.5 µH/10 mΩ, F S=700 kHz, T J=+25°C, unless otherwise noted.FUNCTIONAL BLOCK DIAGRAMNB680Figure 1—Functional block diagramOPERATIONPWM OperationThe NB680 is a fully integrated, synchronous, rectified, step-down, switch-mode converter with a fixed 3.3 V output. Constant-on-time (COT) control provides fast transient response and eases loop stabilization. At the beginning of each cycle, the high-side MOSFET (HS-FET) is turned on when the feedback voltage (V FB) is below the reference voltage (V REF), which indicates insufficient output voltage. The on period is determined by the output voltage and the input voltage to make the switching frequency fairly constant over the input voltage range.After the on period elapses, the HS-FET is turned off or enters an off state. It is turned on again when V FB drops below V REF. By repeating operation this way, the converter regulates the output voltage. The integrated low-side MOSFET (LS-FET) is turned on when the HS-FET is in its off state to minimize the conduction loss. There is a dead short between the input and GND if both the HS-FET and the LS-FET are turned on at the same time (shoot-through). In order to avoid shoot-through, a dead time (DT) is generated internally between the HS-FET off and the LS-FET on period or the LS-FET off and the HS-FET on period.Internal compensation is applied for COT control for stable operation even when ceramic capacitors are used as output capacitors. This internal compensation improves the jitter performance without affecting the line or load regulation.CCM OperationFigure 2—CCM operationContinuous conduction mode (CCM) occurswhen the output current is high, and the inductorcurrent is always above zero amps (see Figure 2).When V FB is below V REF, the HS-FET is turned onfor a fixed interval. When the HS-FET is turnedoff, the LS-FET is turned on until the next period.In CCM operation, the switching frequency isfairly constant (PWM mode).DCM OperationWith the load decreases, the inductor current willdecrease as well. Once the inductor currentreaches zero, the device transitions from CCM todiscontinuous conduction mode (DCM).DCM operation is shown in Figure 3. When V FB isbelow V REF, the HS-FET is turned on for a fixedinterval, which is determined by the one-shot ontimer. See Equation (1). When the HS-FET isturned off, the LS-FET is turned on until theinductor current reaches zero. In DCM operation,the V FB does not reach V REF when the inductorcurrent is approaching zero. The LS-FET driverturns into tri-state (high Z) whenever the inductorcurrent reaches zero. A current modulator takesover the control of the LS-FET and limits theinductor current to less than -1 mA. Hence, theoutput capacitors discharge slowly to GNDthrough the LS-FET. As a result, the efficiencyduring a light-load condition is improved greatly.The HS-FET is not turned on as frequently duringa light-load condition as it is during a heavy-loadcondition (skip mode).At a light-load or no-load condition, the outputdrops very slowly, and the NB680 reduces theswitching frequency naturally, achieving highefficiency at light load.Figure 3—DCM OperationAs the output current increases from the light- load condition, the time period within which the current modulator regulates becomes shorter. The HS-FET is turned on more frequently. Hence, the switching frequency increases accordingly. The output current reaches the critical level when the current modulator time is zero. The critical level of the output current is determined with Equation (1):IN OUT OUTOUTSW IN(V V )V I 2L F V -⨯=⨯⨯⨯ (1) The part enters PWM mode once the output current exceeds the critical level. After that, the switching frequency stays fairly constant over the output current range. DC Auto-Tune LoopThe NB680 applies a DC auto-tune loop to balance the DC error between V FB and V REF by adjusting the comparator input REF to make V FB always follow V REF . This loop is quite slow, so it improves the load and line regulation without affecting the transient performance. The relationship between V FB , V REF , and REF is shown in Figure 4.Figure 4—DC auto-tune loop operation Ultrasonic Mode (USM)Ultrasonic mode (USM) keeps the switching frequency above an audible frequency area during light-load or no-load conditions. Once the part detects that both the HS-FET and the LS-FET are off (for about 32 µs), it shrinks the Ton to keep Vout under regulation with optimal efficiency. If the load continues to decrease, the part discharges Vout to make sure FB is less than 102 percent of the internal reference. The HS-FET turns on again once the internal FB reaches VREF and then stops switching.USM is selected by the EN voltage level. When EN is in the range of 1.38 V to 1.8 V, it enters USM. If EN is in the range of 2.6 V to 3.6 V, it enters normal mode.Configuring the EN ControlThe NB680 has two enable pins to control the on/off of the internal regulators and CLK. For NB680, the 3V3 LDO is always on when Vin passes UVLO. EN controls both the buck and the CLK. Once EN is on, the ENCLK is able to control the CLK on/off. See Table1 for the NB680 EN logic control.Table 1—ENCLK/EN controlFor automatic start-up, EN can be pulled up to the input voltage through a resistive voltage divider. Refer to the “UVLO Protection ” section for more details. Soft Start (SS)The NB680 employs a soft-start (SS) mechanism to ensure smooth output during power-up. When EN goes high, the internal reference voltage ramps up gradually; hence, the output voltage ramps up smoothly as well. Once the reference voltage reaches the target value, the soft start finishes, and the part enters steady-state operation.If the output is pre-biased to a certain voltage during start-up, the IC disables the switching of both the high-side and the low-side switches until the voltage on the internal reference exceeds the sensed output voltage at the internal FB node. 3.3 V Linear RegulatorThere is a built-in 100 mA standby linear regulator with a fixed output at 3.3 V, controlled by VIN UVLO. Once Vin passes its UVLO, it is on. The 3.3 V LDO is not controlled by EN or ENCLK. This LDO is intended mainly for an auxiliary 3.3 V supply for the notebook system in standby mode. Add a ceramic capacitor with a value between 4.7 μF and 22 uF placed close to the LDO pins to stabilize the LDOs.LDO Switch OverWhen the output voltage becomes higher than 3.15 V and the power good (PG) is ok, the internal LDO regulator is shut off, and the LDO output is connected to VOUT by the internal switch-over MOSFET, reducing power loss from the LDO.CLK for Charge PumpThe 250 kHz CLK signal drives an external charge pump circuitto generate approximately 10 V-12 V DC voltage. The CLK voltage becomes available once Vin is higher than the UVLO threshold, and ENCLK is pulled high (see Figure 5).Figure 5—Charge pump circuitPower Good (PG)The NB680 has power-good (PG) output used to indicate whether the output voltage of the buck regulator is ready. PG is the open drain of a MOSFET. It should be connected to V CC or another voltage source through a resistor (e.g. 100k). After the input voltage is applied, the MOSFET is turned on so that PG is pulled to GND before SS is ready. Once FB voltage rises to 95 percent of the REF voltage, PG is pulled high after 750 µs.When the FB voltage drops to 85 percent of the REF voltage, PG is pulled low.Over-Current Protection (OCP)NB680 has cycle-by-cycle over-current limiting control. The current-limit circuit employs a "valley" current-sensing algorithm. The part uses the Rds(on) of the LS-FET as a current-sensing element. If the magnitude of the current-sense signal is above the current-limit threshold, the PWM is not allowed to initiate a new cycle. The trip level is fixed internally. The inductor current is monitored by the voltage between GND and SW. GND is used as the positive currentsensing node, so GND should be connected to the source terminal of the bottom MOSFET. Since the comparison is done during the HS-FET off state and the LS-FET on state, the OC trip level sets the valley level of the inductor current. Thus, the load current at the over-current threshold (I OC ) is calculated with Equation (2):∆=+inductorOC I I I_limit 2(2) In an over-current condition, the current to the load exceeds the current to the output capacitor; thus, the output voltage tends to fall off. Eventually, it ends up crossing the under-voltage protection threshold and shuts down. Fault latching can be reset by EN going low or the power cycling of VIN.Over/Under-Voltage Protection (OVP/UVP) NB680 monitors the output voltage to detect over and under voltage. Once the feedback voltage becomes higher than 122 percent of the target voltage, the OVP comparator output goes high, and the circuit latches as the HS-FET driver turns off, and the LS-FET driver turns on, acting as an -1.8 A current source.To protect the part from damage, there is an absolute OVP on VOUT (usually set at 6.2 V). Once Vout > 6.2 V, the controller turns off both the HS-FET and the LS-FET. This protection is not latched off and will keep switching once the Vout returns to its normal value.When the feedback voltage drops below 75 percent of the Vref but remains higher than 50 percent of the Vref, the UVP-1 comparator output goes high, and the part latches if the FB voltage remains in this range for about 32 µs (latching the HS-FET off and the LS-FET on). The LS-FET remains on until the inductor current hits zero. During this period, the valley current limit helps control the inductor current.When the feedback voltage drops below 50 percent of the Vref, the UVP-2 comparator output goes high, and the part latches off directly after the comparator and logic delay (latching the HS-FET off and the LS-FET on). The LS-FET remains on until the inductor current hits zero. Fault latching can be re-set by EN going low or the power cycling of VIN.UVLO ProtectionThe part starts up only when the Vin voltage is higher than the UVLO rising threshold voltage. The part shuts down when the VIN is lower than the Vin falling threshold. The UVLO protection is non-latch off. Fault latching can be re-set by EN going low or the power cycling of VIN.If an application requires a higher under-voltage lockout (UVLO), use EN to adjust the input voltage UVLO by using two external resistors (see Figure 6).Figure 6—Adjustable UVLOTo avoid too much sink current on EN, the EN resistor (Rup) is usually in the range of 1 M-2 MΩ.A typical pull-up resistor is 2 MΩ.Thermal ShutdownThermal shutdown is employed in the NB680. The junction temperature of the IC is monitored internally. If the junction temperature exceeds the threshold value (140ºC, typically), the converter shuts off. This is a non-latch protection. There is about 25ºC hysteresis. Once the junction temperature drops to about 115ºC, it initiates a SS.Output DischargeNB680 discharges the output when EN is low, or the controller is turned off by the protection functions UVP, OCP, OCP, OVP, UVLO, and thermal shutdown. The part discharges outputs using an internal MOSFET.APPLICATION INFORMATIONInput CapacitorThe input current to the step-down converter is discontinuous, and therefore requires a capacitor to supply the AC current to the step-down converter while maintaining the DC input voltage. Ceramic capacitors are recommended for best performance and should be placed as close to the V IN pin as possible. Capacitors with X5R and X7R ceramic dielectrics are recommended because they are fairly stable with temperature fluctuations.The capacitors must have a ripple-current rating greater than the maximum input ripple current of the converter. The input ripple current can be estimated with Equation (3) and Equation (4):CIN OUT I I =The worst-case condition occurs at V IN = 2V OUT , where:OUTCIN I I 2=(4) For simplification, choose an input capacitor with an RMS current rating greater than half of the maximum load current.The input capacitance value determines the input voltage ripple of the converter. If there is an input voltage ripple requirement in the system, choose an input capacitor that meets the specification. The input voltage ripple can be estimated with Equation (5) and Equation (6):OUT OUT OUT IN SW IN IN INI V VV (1)F C V V ∆=⨯⨯-⨯ (5)The worst-case condition occurs at V IN = 2V OUT,where:OUT IN SW INI 1V 4F C ∆=⨯⨯ (6)Output CapacitorThe output capacitor is required to maintain the DC output voltage. Ceramic or POSCAP capacitors are recommended. The output voltage ripple can be estimated with Equation (7):OUT OUT OUT ESR SW INSW OUTV V 1V (1)(R )F LV 8F C ∆=⨯-⨯+⨯⨯⨯ (7)When using ceramic capacitors, the impedance at the switching frequency is dominated by the capacitance. The output voltage ripple is caused mainly by the capacitance. For simplification, the output voltage ripple can be estimated using Equation (8):OUT OUT OUT 2SW OUT INV VV (1)8F L C V ∆=⨯-⨯⨯⨯ (8) When using POSCAP capacitors, the ESRdominates the impedance at the switching frequency. The output ripple can be approximated using Equation (9):OUT OUT OUTESRSW INV V V (1)R F L V ∆=⨯-⨯⨯ (9)The maximum output capacitor limitation should be considered in design application. For a small soft-start time period (if the output capacitor value is too high), the output voltage cannot reach the design value during the soft-start time, causing it to fail to regulate. The maximum output capacitor value (C o_max ) can be limited approximately with Equation (10):O _MAX LIM_AVG OUT ss OUT C (I I )T /V =-⨯ (10)Where I LIM_AVG is the average start-up currentduring the soft-start period, and T ss is the soft-start time. InductorThe inductor is necessary to supply constant current to the output load while being driven by the switched input voltage. A larger value inductor results in less ripple current, resulting in a lower output ripple voltage. However, a larger value inductor has a larger physical footprint, a higher series resistance, and/or a lower saturation current. A good rule for determining the inductance value is to design the peak-to-peak ripple current in the inductor to be in the range of 30 percent to 50 percent of the maximum output current, with the peak inductor current below the maximum switch current limit. The inductance value can be calculated with Equation (11): OUT OUT SW L INV VL (1)F I V =⨯-⨯∆ (11)Where ΔI L is the peak-to-peak inductor ripple current.The inductor should not saturate under the maximum inductor peak current (including short current), so it is suggested to choose Isat > 10 A. PCB Layout GuidelinesEfficient PCB layout is critical for optimum IC performance. For best results, refer to Figure 7 and follow the guidelines below:1. Place the high-current paths (GND, IN, andSW) very close to the device with short, direct, and wide traces. The PGND trace should be as wide as possible (This should be the number one priority).2. Place the input capacitors as close to IN andGND as possible on the same layer as the IC. 3. Place the decoupling capacitor as close toVCC and GND as possible. Keep the switching node (SW) short and away from the feedback network.4. Keep the BST voltage path as short aspossible with a >50 mil trace.5. Keep the IN and GND pads connected with alarge copper plane to achieve better thermal performance. Add several vias with 8 mil drill/16 mil copper width close to the IN and GND pads to help thermal dissipation.6. A 4-layer layout is strongly recommended toachieve better thermal performance.Figure 7— Recommend PBC layoutTYPICAL APPLICATIONNOTE: If the charge pump function is not used, leave CLK open.Figure 8—Typical application schematic with ceramic output capacitorsNOTICE: The information in this document is subject to change without notice. Users should warrant and guarantee that third party Intellectual Property rights are not infringed upon when integrating MPS products into any application. MPS will not assume any legal responsibility for any said applications.PACKAGE INFORMATIONQFN-12 (2mm x 3mm)SIDE VIEWBOTTOM VIEWNOTE:1) ALL DIMENSIONS ARE IN MILLIMETERS.2) EXPOSED PADDLE SIZE DOES NOT INCLUDE MOLD FLASH.3) LEAD COPLANARITY SHALL BE 0.10 MILLIMETERS MAX.4) JEDEC REFERENCE IS MO-220.5) DRAWING IS NOT TO SCALE.TOP VIEW PIN 1 IDINDEX AREARECOMMENDED LAND PATTERN。

非隔离降压型电源设计方案

非隔离降压型电源设计方案一款不带变压器的宽电压、低成本、非隔离式AC/DC降压转换器——输出持续电流500mA（2.5~12W)【关键词摘要】非隔离恒流恒压AC/DC电源芯片XD308H BUCK电路220V转5V220V转12V220V转24V380V转5V380V转12V380V转24V【概述】非隔离AC-DC电源芯片XD308H设计组成的降压恒流恒压电路，采用了BUCK电路拓扑结构，常用于小家电控制板电源以及工业控制电源供电。

其典型电路规格包含24V/500mA、12V/500mA和5V/500mA等，满足六级能效要求。

可通过雷击、EFT、浪涌等可靠性测试，可通过UL、CE、3C等认证。

其特点是：电路简单、BOM成本低（外围元件数目极少：无需变压器、光耦）,电源体积小、无异常噪音、损耗小发热低。

1）220V转24V降压电路：输入32~380Vac，输出24V/500mA电源方案如图所示的电路为一个典型的输出为24V/500mA的非隔离电源。

它通常应用于家用电器的(电饭煲、洗衣机及其它白色家电)。

此电路还适合于其它非隔离供电的应用，比如LED驱动、智能电表、加热器以及辅助电源和工业控制等。

220V转24V降压电路输入级由保险电阻RF1、防雷压敏电阻RV1、整流桥堆D1、EMI滤波电容C4和C5以及滤波电感L2组成。

压敏电阻RV1用于防雷保护，提高系统可靠性。

功率处理级由宽电压高效率电源芯片XD308H、续流二极管D2、输出电感L1及输出电容C3构成。

2）220V转12V降压电路：输入32~380Vac，输出12V/500mA电源方案如图所示的电路为一个典型的输出为12V/500mA的非隔离电源。

用于智能电表的非隔离式AC／DC降压转换器

中的其他一些转换器可主动避免在声频范围内进行开关操作，从而有效地获得最大导通和断开时
Ｐ６２ｘ图１示了完整的转换器。整流器电路使用间。ＴＳ４０系列起初是为电池供电型应用而设显
一
．８．Ｖ的输入电压范围，以及非常个标准、快速开关整流器二极管桥接（）Ｄ１和计，拥有１Ｖ～６５最５个Ｌ滤波器（和Ｃ），我们将对其余组件低的静态电流（大为３Ａ）。在启动期间，ＣＬ１２ＴＳ４０被齐纳二极管Ｄ以及高压电阻１和ＲＰ６２３２ｔ２３偏置。５Ｖ电压上升以后，肖特基二极管Ｄ４允许５输出驱动控制器。Ｖ
一
进行更加详细的介绍。
图１ＡＣＤ／Ｃ降压转换器电路
功率ＦＴＱ必须具有足够高的Ｖ。电压额定Ｅ４
值，以使其不会被输入电压损坏，同时还要有足
够高的电流额定值以处理Ｉ０（ｓＩＵｆ１／Ｐｓ１ｏＴＭＲ＝ … ｘ￣ＭＤ。它的封装还必须能够驱散Ｐ。。＝（ …）１ｏＸ
问题。
降压功率级的Ｌ滤波器￣Ｔ￥４０系列产Ｃ／Ｐ６２ｘＩＩ
品说明书中介绍那样设计。利用高于输出电压的输入电压，所有ＴＳ４０控制器将运行在最小导Ｐ６２ｘ

XL7035 XL7035E1降压型直流电源变换器芯片(高电压型)

物理尺寸 TO263-5L
Datasheet XL7035
Symbol
A B C C2 D E e F L L2
Dimensions In Millimeters
Min
Max
4.440
4.650
0.710
0.970
0.360
0.640
1.255
1.285
8.390
8.890
9.960
10.360
1.550
0.0 -0.5 -1.0
-1.5
-2.0
-2.5
-3.0
-50
-25
0
25
50
75
Temperature(℃)
100
125
图 6. 反馈电压变化曲线
Datasheet XL7035
Rev 1.0
0755-82543821 6
XLSEMI
1A 150KHz 80V降压型DC-DC转换器系统典型应用 (VOUT=15V/0.6A)
Rev 1.0
0755-82543821 7
XLSEMI
1A 150KHz 80V降压型DC-DC转换器系统典型应用(VOUT=5V/1A)
Datasheet XL7035
图 9. XL7035 系统参数测量电路(VIN=10V~80V, VOUT=5V/1A)
Efficiency VS Output current
Datasheet XL7035
图 7. XL7035 系统参数测量电路 (VIN=20V~80V, VOUT=15V/0.6A)
Efficiency VS Output current
95
90

隔离型DCDC变换器

公司背景：某知名电子设备制造商
产品特点：高效、低噪声、高可靠性
设计原理：采用高频变压器进行隔离，提高效率
应用领域：广泛应用于通信、医疗、工业等领域
案例二：某航空航天器的电源系统设计
航空航天器的电源系统需求：高可靠性、高稳定性、低噪声
隔离型DCDC变换器的应用：为航空航天器的电子设备提供稳定、可靠的电源
正确选择变压器匝数比，保证输出功率
合理设计滤波器，提高输出质量
采用合适的控制策略，提高系统稳定性
注意散热设计，保证设备长期稳定运行
常见故障分析和排除方法
排除方法：调整输入电压、稳定负载、重新设置电路参数
故障现象：输出电流过大
原因分析：元器件老化、散热不良
原因分析：输入电压波动、负载变化、电路参数设置不当
航空航天和军事领域
航空航天领域：用于卫星、航天器等设备的电源系统
隔离型DCDC变换器在航空航天和军事领域中，需要满足高可靠性、高稳定性、高功率密度等要求
隔离型DCDC变换器在这些领域中的应用，有助于提高设备的性能和可靠性，保障设备的正常运行。
军事领域：用于军事装备、通信设备等的电源系统
电动汽车和智能交通系统
04
磁性元件的设计和优化
磁性元件的作用：在隔离型DCDC变换器中，磁性元件起着关键作用，如变压器、电感等。
磁性元件的设计原则：根据隔离型DCDC变换器的工作原理和性能要求，设计出合适的磁性元件。
磁性元件的优化方法：通过优化磁性元件的尺寸、材料、结构等参数，提高隔离型DCDC变换器的性能和可靠性。
磁性元件的设计和优化实例：列举一些成功的磁性元件设计和优化案例，说明其对隔离型DCDC变换器性能的影响。
隔离型DCDC变换器通常用于电子设备中，如笔记本电脑、手机等，以提供稳定的电源电压。

XL7015 0.8A 150KHz 100V降压型DC-DC转换器说明书

0.8A 150KHz 100V 降压型DC-DC转换器XL7015特点⏹最高输入电压100V⏹输出电压从1.25V到20V可调⏹最大占空比90%⏹最小压降2V⏹固定150KHz开关频率⏹最大0.8A输出电流⏹48V输入、5V输出推荐最大输出电流0.6A⏹48V输入、15V输出推荐最大输出电流0.4A⏹内置高压功率三极管⏹效率高达85%⏹出色的线性与负载调整率⏹EN脚TTL关机功能⏹内置过热关断保护功能⏹内置限流功能⏹内置输出短路保护功能⏹TO252-5L封装应用⏹电动车控制器供电⏹通信描述XL7015是一款高效、高压降压型DC-DC 转换器，固定150KHz开关频率，可提供最高0.8A输出电流能力，低纹波，出色的线性调整率与负载调整率。

XL7015内置固定频率振荡器与频率补偿电路，简化了电路设计。

PWM控制环路可以调节占空比从0~90%之间线性变化。

内置输出过电流保护功能，当输出短路时，开关频率从150KHz降至45KHz。

内部补偿模块可以减少外围元器件数量。

图1. XL7015封装0.8A 150KHz 100V 降压型DC-DC 转换器 XL7015引脚配置EN GND SW VINFB 12345TO252-5L图2. XL7015引脚配置表1.引脚说明引脚号引脚名描述1 VIN 电源输入引脚，需要在VIN 与GND 之间并联电解电容以消除噪声。

2 SW 功率开关输出引脚，SW 是输出功率的开关节点。

3 GND 接地引脚。

4 FB 反馈引脚，通过外部电阻分压网络，检测输出电压进行调整。

参考电压为1.25V 。

5EN使能引脚，低电平工作，高电平关机，悬空时为低电平。

0.8A 150KHz 100V 降压型DC-DC 转换器 XL7015方框图3.3V Regulator 1.25V ReferenceVINGND3.3V 1.25VEACOMPDriverOscillator 150KHz/45KHzENSWThermal ShutdownLatchCOMP150m ΩCurrent LimitFB Start Up150mVSwitch图3. XL7015方框图典型应用XL7015L1 100uH/1ACIN33uF/100VCOUT100uF/35VR230K 1%R12.7K 1%D1S310VOUT=1.25*(1+R2/R1)SWFBGNDENVINVIN12453CFF 33nFOUTPUT 15V/0~0.4A VOUT=1.25*(1+R2/R1)图4. XL7015系统参数测量电路0.8A 150KHz 100V降压型DC-DC转换器XL7015订购信息产品型号打印名称封装方式包装类型XL7015E1 XL7015E1 TO252-5L 2500只每卷XLSEMI无铅产品，产品型号带有“E1”后缀的符合RoHS标准。

用于智能电表的非隔离式ACDC降压转换器

用于智能电表的非隔离式AC-DC降压转换器用于智能电表的非隔离式AC/DC降压转换器中心议题：基本降压转换器驱动电路工作原理电流限制与软开关诸如智能电表或者功率监控器的离线设备都有一些要求10W以下非隔离DC电源的电子元件。

到目前为止，通过一个AC电源提供低功耗DC电源的唯一实用方法仍然是在整流器后面使用一个效率极低、未经调节的电阻/电容分压器，或者一个难以设计的反向DC/DC转换器。

MOSFET技术的一些进展以及创新的磁滞降压控制器栅极驱动电路带来了一种超低成本DC电源。

图1显示了完整的转换器。

整流器电路使用一个标准、快速开关整流器二极管桥接（D1）和一个LC滤波器（L1和C2），我们将对其余组件进行更加详细的介绍。

图1AC/DC降压转换器电路基本降压转换器TPS64203是一款磁滞降压转换器，专为驱动高端pFET而设计，拥有最小导通和断开开关时间要求。

传统的磁滞转换器有随负载电流变化的开关频率，与其不同的是，最小导通和断开时间在转换器以高输出功耗电平在连续导通模式下运行时，从根本上控制开关频率。

TPS6420x系列中的其他一些转换器可主动避免在声频范围内进行开关操作，从而有效地获得最大导通和断开时间。

TPS6420x系列起初是为电池供电型应用而设计，拥有1.8V～6.5V 的输入电压范围，以及非常低的静态电流（最大为35μA）。

在启动期间，TPS64203被齐纳二极管D2以及高压电阻R2和R3偏置。

5V电压上升以后，肖特基二极管D4允许5V输出驱动控制器。

功率FET Q4必须具有足够高的VDS电压额定值，以使其不会被输入电压损坏，同时还要有足够高的电流额定值以处理IPMOS（RMS）=IOUT（max）×√Dmax。

它的封装还必须能够驱散PCond=（I OUT（max）×√Dmax）2×RDS （on）。

一种非隔离DC／DCBUCK转换电路的应用

最大利用。较同时还具有外同元器件简单、功率密度大的
优点。大势所趋。３１Ｌ１６．Ｔ７７调整器的工作原理
图４直流３ＶＢＣ． — ＵＫ开关电源的等效３分析直流３３＿ＵＫ开关电源的工作．ＢＣＶ
８ＳＮＹＣ
同步引脚
的波形为矩形波，方波的电压平均该值为：。
３一种变频器通讯转接板３Ｖ电源的设计．３
电感Ｌ和，电容ｃ１５组成滤波器，接
于Ｖ和之间，使输出，电压成为幅１它处
变频器应用在工业现场时，需要同其他的自动化设备一起接入现场的多种现场总线和工业以太网。ＡＹＵ通讯转接板的作用ＮＢＳ
摘要：本文介绍了一种变频器通讯转接板的低压直流３ｖ开关电源的实现方案。此电源由恒频率，．３占空比可调的ＢＣＵＫ转换器实现。文中量化分析了电路工作原理和工作过程，确定主要外围元器件参数选择，并得出ＰＢＢａＣｏｒ电源工作的实际波形。ｄ和关键词：关电源；隔离ＤＣＤＣ；ＵＣ开非／ＢＫ转换器中图分类号：Ｔ７２１１Ｍ６．＋文献标识码：Ａ
，输入
并将采样值与误差放大器的同相输入端的
ＡＹＵ通讯转接板需要２电源：５ＮＢＳ路＋Ｖ和＋．。其中＋Ｖ电压取自驱动板上的Ａ／３３Ｖ５Ｃ

XD307S超小体积非隔离ACDC电源

XD307S 超小体积非隔离AC/DC电源1.1产品尺寸：裸板封装，超小体积：宽16mm*高13mm*厚11mmXD307S 是一款50-500V 超宽范围输入的高压降型DC-DC 转换器电源模块，可适应35-320VAC 超宽电压输入(外部加整流滤波)，输出持续电流高达350mA （最大400mA)，无音频噪音、发热低，具备全面完善的保护功能（短路保护，过载保护，输出过压保护、输出欠压保护，过热保护等）。

该超小体积电源模块以较低的BOM 成本（外围元件数目极少）方便的实现宽电压高压降压小功率电源解决方案,广泛应用于非隔离型家电产品和工业产品等。

*高压转换模块*超小体积*12V 400mA 输出*非隔离电源1.2产品特性：*典型待机功耗小于50mW；*输出最大持续电流350mA（峰值400mA),无音频噪音、发热低；*50-500VDC超宽输入电压,可适应35-320VAC超宽电压输入；*全面的保护功能：*过流保护（OCP）*过温保护（OTP）*过压保护（OVP）*裸板封装；1.3典型应用（非隔离）：*智能家居电源（电子开关，智能插座，智能排插等的供电电源）*替代低效率的阻容降压供电电路(如低压电器，智能电表，自动化仪表电源等)；*LED驱动电源*小家电电源*工业控制电源*电子断路器*无刷直流电机电源*其他非隔离辅助电源1.4基本应用电路：1）高压直流降压转换器（DC/DC转换器）2）高压交流降压转换器（AC/DC转换器）1.5典型应用电路（当应用于电磁兼容比较恶劣的环境时建议使用）：1.6产品外观图：标签：超小体积电源模块非隔离AC-DC DC-DC。

SC2987降压型PWM转换器说明书

一、概述SC2987是一款降压型PWM转换器，典型输出驱动电流为3.8A无需外加晶体管。

设计允许它可在8V～48V的宽输入电压下工作。

通过将COMP/EN脚逻辑电平拉低来控制外部关断功能，使其进入待机模式。

外部补偿使反馈控制具有良好的线性调整率和负载调整率，具有灵活的外围设计。

SC2987的特点之一是具有可编程的CV/CC模式控制功能。

CV（恒压）模式提供了一个稳定的输出电压，CC（恒流）模式提供了一个限流功能。

在电流检测放大器输入期间，CC电流值通过外部电阻设定。

SC2987适用于需要用到电流限制功能的DC/DC开关电源上。

该器件采用ESOP-8L封装，且工作时只需要很少的外围器件。

二、特性●电压输入范围：8V～48V●线电压Vout（Vref=1.2V）精度为±1%●CC/CV模式控制（恒流和恒压）●限流精度为±5%●输出短路保护●过压保护（超出输出电压的118%）●过温保护●内置软启动，启动时间12ms●固定频率120kHz●UVLO保护●占空比范围（0～90%）●单独的引脚进行外部补偿和关断控制●集成N-MOSFET●ESOP-8L封装三、应用●车充●便携式充电设备●高亮度照明设备●具有限流功能的多功能DC/DC变换器四、极限参数描述范围单位输入电压V VCC-0.3~50 VBST相对LX 0.3~7 VLX相对GND的直流电压-1~V VCC+1 VBST相对GND的直流电压-0.3~7 VFB,COMP相对GND的直流电压0.3~7 V ISEN-,ISEN+相对GND的直流电压0.3~9 V储存温度范围-65~150 ℃结点温度-20~150 ℃导热温度(焊接10s) 260 ℃人体模式ESD 2 KV机器模式ESD 200 V封装热阻ESOP-8L 60 ℃注意：如果器件工作条件超出上述各项极限值，可能对器件造成永久性损坏。

上述参数仅仅是工作条件的极限值，不建议器件工作在推荐条件以外的情况。

第三章节TOPSwitch系列芯片简介doc-浙江大学城市

第三章TOPSwitch系列芯片简介美国功率集成公司（PI公司）在1994年推出第一代TOP Switch芯片，1997年，美国功率集成公司又推出了TOP SwitchⅡ系列器件。

TOP SwitchⅡ系列器件和TOP Switch系列器件相比，内电路作了许多改进，器件对于电路板布局以及输入总线瞬变的敏感性大大减少，故设计更为方便，性能又有了增强，性能价格比更高。

与TOP Switch系列器件相比，TOP SwitchⅡ系列器件在输入电压为100V、115V或230V AC时，系统功率从（0～100）W提高到（0～150）W，在三种电压下均可工作时，系统的功率从（0～50）W提高到（0～90）W，从而使得TOP SwitchⅡ器件可在如电视、监视器以及音频放大器等许多新的应用范围内使用。

1998年推出绿色、低价的Tiny Switch和TOP Switch-FX开关电源IC 系列，它为设计高度集成的电源提供了更大的灵活性，采用的Eco Smart节能技术可以帮助工程师生产出符合环保要求的更加“绿色”的电子产品。

器件输出功率最高达75W，可广泛应用于手机充电器、PC待机电源、机顶盒、DVD和LCD 显示器等不同领域。

2000年11月最新推出TOP Switch-GX系列高压AC/DC转换芯片，把最大输出功率提高到250W，具有更高的开关频率，在轻负载时能线性缩减频率以降低待机功耗；更宽的占空比；并且，通过增加3个引脚，使用户具有更多可配置的功能（如限流调整、欠压检测、过压关断、电压前馈、两种可选频率及远程On/Off等）。

TOP Switch主要用于AC/DC转换器，具有体积小，重量轻，宽输入范围（85V-265V），提供了PI Expert专家系统设计软件，便于用户更快地设计出自已的产品。

采用TOP Switch器件的开关电源与采用分立的MOSFET功率开关及PWM 集成控制器的开关电源相比，具有以下特点：1、成本低廉。