MP157 Smallest Energy Efficient Off-line Regulator with Extended Power Range The Future of Analog IC Technology DESCRIPTION FEATURES MP157 is a primary side regulator providing accurate constant voltage (CV) regulation without the Opto-coupler. It supports Buck, Buck-Boost, Boost and Flyback topologies. A 500V MOSFET is integrated in the regulator, so very simple structure and low cost can be achieved. These features make MP157 an ideal solution for off-line low power applications. Typical applications include home appliance, standby power and industrial control. • MP157 is a green mode operation regulator. When the load decreases, the peak current and the switching frequency decrease with the load. As a result, it still offers excellent efficiency performance at light load, thus better average efficiency is achieved. • • • • • • • • MP157 features various protections like Thermal Shutdown (TSD), VCC under Voltage Lockout (UVLO), Over Load Protection (OLP), Short Circuit Protection (SCP), Open Loop Protection. MP157 is available in the TSOT23-5 and SOIC8 packages. • • • • • • • Primary side constant voltage (CV) control, supporting Buck, Buck-Boost, Boost and Flyback topologies Integrated 500V/10Ω MOSFET < 100mW No-load power consumption Up to 6W output power Maximum discontinuous conduction mode (DCM) output current less than 225mA, maximum continuous conduction mode (CCM) output current less than 360mA Low Vcc Operating Current Frequency Foldback Limited maximum frequency Peak Current Compression Internal High Voltage Current Source Internal 400ns Leading Edge Blanking Thermal Shutdown (auto restart) VCC Under Voltage Lockout with Hysteresis (UVLO) Timer based Over Load Protection Short Circuit Protection Open Loop Protection APPLICATIONS • • • Home Appliances, White Goods and Consumer Electronics Industrial Controls Standby Power All MPS parts are lead-free and adhere to the RoHS directive. For MPS green status, please visit MPS website under Products, Quality Assurance page. “MPS” and “The Future of Analog IC Technology” are registered trademarks of Monolithic Power Systems, Inc. MP157 Rev. 1.03 11/17/2015 www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2015 MPS. All Rights Reserved. 1 MP157 –SMALLEST ENERGY EFFICIENT OFF-LINE REGULATOR WITH EXTENDED POWER RANGE TYPICAL APPLICATION MP157 Rev. 1.03 11/17/2015 www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2015 MPS. All Rights Reserved. 2 MP157 –SMALLEST ENERGY EFFICIENT OFF-LINE REGULATOR WITH EXTENDED POWER RANGE ORDERING INFORMATION Part Number* MP157GJ MP157GS Package TSOT23-5 SOIC8 Top Marking AFC MP157 * For Tape & Reel, add suffix –Z (e.g. MP157GJ–Z); * For Tape & Reel, add suffix –Z (e.g. MP157GS–Z); PACKAGE REFERENCE TOP VIEW VCC 1 FB 2 SOURCE 3 TOP VIEW 5 4 DRAIN SOURCE TSOT23-5 VCC 1 8 N/C FB 2 7 DRAIN SOURCE 3 6 N/C SOURCE 4 5 N/C SOIC8 ABSOLUTE MAXIMUM RATINGS (1) Thermal Resistance Drain to SOURCE .........................-0.3V to 500V All the other Pin .............................-0.3V to 6.5V (2) Continuous Power Dissipation (TA = +25°C) TSOT23-5 ..................................................... 1W SOIC8 ........................................................... 1W Junction Temperature ...............................150°C Lead Temperature ....................................260°C Storage Temperature............... -60°C to +150°C ESD Capability Human Body Mode .......... 2.0kV ESD Capability Machine Mode .................. 200V TSOT23-5.............................. 100 ..... 55... °C/W SOIC8..................................... 96 ...... 45... °C/W Recommended Operating Conditions (3) Operating Junction Temp. (TJ). -40°C to +125°C Operating VCC range ...................4.45V to 4.6V MP157 Rev. 1.03 11/17/2015 (4) θJA θJC Notes: 1) Exceeding these ratings may damage the device. 2) The maximum allowable power dissipation is a function of the maximum junction temperature TJ (MAX), the junction-toambient thermal resistance θJA, and the ambient temperature TA. The maximum allowable continuous power dissipation at any ambient temperature is calculated by PD (MAX) = (TJ (MAX)-TA)/θJA. Exceeding the maximum allowable power dissipation will cause excessive die temperature, and the regulator will go into thermal shutdown. Internal thermal shutdown circuitry protects the device from permanent damage. 3) The device is not guaranteed to function outside of its operating conditions. 4) Measured on JESD51-7, 4-layer PCB. www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2015 MPS. All Rights Reserved. 3 MP157 –SMALLEST ENERGY EFFICIENT OFF-LINE REGULATOR WITH EXTENDED POWER RANGE ELECTRICAL CHARACTERISTICS VCC = 5V, TA = 25°C, unless otherwise noted. Parameter Symbol Condition Min Typ Max Units VCC=4V;VDrain=100V VCC=5V;Vdarin=400V 2.5 -500 3.5 10 -- 4.5 25 -- mA μA V 4.5 4.6 4.9 V 4.3 4.45 4.7 V -- 230 -- mV 3.2 3.35 3.5 V 2.05 2.35 2.65 V -- -- 500 μA -- -- 165 uA -- 16 -- μA VBRDSS 500 -- -- V Ron -- 10 -- Ω Peak Current Limit ILimit 500 640 780 mA Leading edge blanking TLEB1 -- 400 -- ns SCP point Leading edge blanking for SCP (5) Feedback input (FB Pin) Minimum off time Feedback Threshold to turn on the primary MOSFET Feedback Threshold to trigger the OLP Over Load Protection Delay time Open loop detection Thermal Shutdown ISCP TLEB2 --- 900 180 1200 -- mA ns Tminoff 10.6 13.1 15.6 us VFB 2.45 2.55 2.65 V VFB_OLP 1.6 1.7 1.8 V --- 150 60 --- ms mV -- 150 -- ºC Start-up Current Source (Drain Pin) Internal regulator supply current Iregulator Leakage Current from Pin Drain ILeak Break Down Voltage V(BR)DSS Supply Voltage Management (VCC Pin) VCC Increasing Level at which the VCCOFF internal regulator stops VCC Decreasing Level at which the VCCON internal regulator Turns-On VCC Regulator on and off Hysteresis VCC Decreasing level at which the IC VCCstop stops working VCC Decreasing Level at which the VCCpro protection Phase Ends Internal IC Consumption ICC Internal IC Consumption (No Switch) Internal IC Consumption, Latch off Phase Internal MOSFET (Drain Pin) Break Down Voltage ICC On-State resistance ICCLATCH VCC=4.6V, Fs=45kHz Duty= 40% VCC=4.6V VCC=5V Internal Current Sense Thermal shutdown threshold (5) TOLP VOLD Fs=37kHz Notes: 5) Guarantee by Characterization MP157 Rev. 1.03 11/17/2015 www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2015 MPS. All Rights Reserved. 4 MP157 –SMALLEST ENERGY EFFICIENT OFF-LINE REGULATOR WITH EXTENDED POWER RANGE TYPICAL CHARACTERISTICS Feedback Threshold vs. Temperature 2.58 2.57 610 1.6 2.56 600 1.4 2.55 590 1.2 2.54 580 1.0 570 0.8 560 0.6 2.51 550 0.4 2.50 540 0.2 2.49 530 -40-25 -10 5 20 35 50 65 80 95 110125 0.0 -40 -25-10 5 20 35 50 65 80 95110 125 2.48 -40 -25-10 5 20 35 50 65 80 95110 125 VCC Increasing Level at which the internal regulator stops vs. Temperature 4.62 VFB (V) 1.8 4.86 VCC Decreasing Level at which the internal regulator Turns-On vs. Temperature 2.53 2.52 VCC Decreasing Level at which the protection Phase Ends vs. Temperature 2.60 4.60 2.55 4.82 4.58 2.50 4.80 4.56 2.45 4.78 4.76 4.74 4.72 VCCPRO (V) 4.84 4.54 4.52 4.50 4.48 2.40 2.35 2.30 2.25 4.70 4.46 2.20 4.68 4.44 2.15 4.66 -40-25 -10 5 20 35 50 65 80 95 110125 4.42 -40-25 -10 5 20 35 50 65 80 95 110125 2.10 -40-25-10 5 20 35 50 65 80 95 110125 Minimum Off Time vs. Temperature Peak Current Limit vs. Temperature SCP Point vs. Temperature 1200 680 13.7 670 1100 13.6 660 1000 13.5 650 900 640 800 ILIMIT (mA) 13.8 13.4 13.3 13.2 630 620 ISCP (mA) VCCOFF (V) 2.0 On-State Resistance vs. Temperature 620 VCCON (V) VBVDSS (V) 630 Break Down Voltage vs. Temperature 700 600 13.1 610 500 13.0 600 400 12.9 590 300 12.8 -40-25 -10 5 20 35 50 65 80 95110 125 580 -40-25 -10 5 20 35 50 65 80 95110125 200 -40-25-10 5 20 35 50 65 80 95110125 MP157 Rev. 1.03 11/17/2015 www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2015 MPS. All Rights Reserved. 5 MP157 –SMALLEST ENERGY EFFICIENT OFF-LINE REGULATOR WITH EXTENDED POWER RANGE TYPICAL PERFORMANCE CHARACTERISTICS VIN = 265VAC, VOUT = 12V, IOUT = 350mA, L = 1.2mH, COUT = 100μF, TA = +25°C, unless otherwise noted. Start Up Normal Operation SCP VDS 100V/div. VDS 100V/div. VDS 100V/div. IL 200mA/div. IL 200mA/div. IL 200mA/div. Open Loop VDS 100V/div. IL 200mA/div. MP157 Rev. 1.03 11/17/2015 www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2015 MPS. All Rights Reserved. 6 MP157 –SMALLEST ENERGY EFFICIENT OFF-LINE REGULATOR WITH EXTENDED POWER RANGE TYPICAL PERFORMANCE CHARACTERISTICS VIN = 230VAC, VOUT = 12V, IOUT = 350mA, L = 1.2mH, COUT = 100μF, TA = +25°C, unless otherwise noted. Input Power Start Up Input Power Shut Down SCP Entry VDS 100V/div. VDS 100V/div. VDS 100V/div. IL 200mA/div. IL 200mA/div. IL 200mA/div. SCP Recovery Open Loop Entry Open Loop Recovery VDS 100V/div. VDS 100V/div. VDS 100V/div. IL 200mA/div. IL 200mA/div. IL 200mA/div. Output Voltage Ripple VRIPPLE 50mV/div. Load Transient VRIPPLE 100mV/div. IOUT 200mA/div. MP157 Rev. 1.03 11/17/2015 www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2015 MPS. All Rights Reserved. 7 MP157 –SMALLEST ENERGY EFFICIENT OFF-LINE REGULATOR WITH EXTENDED POWER RANGE PIN FUNCTIONS Pin # TSOT23-5 1 2 3,4 5 MP157 Rev. 1.03 11/17/2015 Pin# Name SOIC8 1 VCC 2 FB 3,4 SOURCE 7 DRAIN 5,6,8 N/C Description Power supply of all the control circuit. Feedback of the regulator. Source of internal power MOSFET. Ground reference for VCC and FB pins. Drain of internal power MOSFET. Input of high voltage current source. Not connected. www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2015 MPS. All Rights Reserved. 8 MP157 –SMALLEST ENERGY EFFICIENT OFF-LINE REGULATOR WITH EXTENDED POWER RANGE FUNCTIONAL BLOCK DIAGRAM Vcc Drain Start up unit Power Management Driving Signal Management Feedback control Peak current Limitation FB Protection Unit Source Figure 1: Functional Block Diagram MP157 Rev. 1.03 11/17/2015 www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2015 MPS. All Rights Reserved. 9 MP157 –SMALLEST ENERGY EFFICIENT OFF-LINE REGULATOR WITH EXTENDED POWER RANGE OPERATION MP157 is a green mode operation regulator. With the load decreasing, the peak current and the switching frequency will both decreasing with the load. As a result, it still offers excellent efficiency performance at light load, thus better average efficiency is achieved. As shown in the typical application diagram, the regulator is designed to operate with a minimum number of external components. It incorporates the following features as described in the following sections. Start-up and Under Voltage Lock-out The internal high voltage regulator self-supplies the IC from the Drain pin. The IC starts switching and the internal high voltage regulator turns off as soon as the voltage on pin VCC reaches VCCOFF (4.6V, typical). the internal high voltage regulator turns on to charge the external Vcc capacitor When the Vcc voltage decreases below VCCON (4.45V, typical). So a small capacitor such as several uF capacitor is enough to hold on the voltage of Vcc and this can lower the cost by decreasing the value of the capacitor. When the voltage on Pin Vcc drops blow VCCstop (3.3V, typical), the IC stops working, then the internal high voltage regulator charges the Vcc capacitor again. When fault conditions happen, such as OLP, SCP, and OTP, the IC stops working and an internal current source, around 16uA, will discharge the Vcc capacitor, before the Vcc drops below VCCpro (2.4V, typical), the internal high voltage regulator will not start to charge the Vcc capacitor again. So when the fault conditions happen, the restart time can be calculated by the following equation, t restart = C VCC × VCC VCCOFF=4.6V VCCON =4.45V VCCStop=3.3V ON Internal Current Source OFF Driving Signal Figure 2: VCC Under-Voltage Lock Out Constant Voltage Operation MP157 is a fully integrated regulator when used in the Buck solution, as shown in the typical application on page2. At the beginning of each cycle, the integrated MOSFET is turned ON when the feedback voltage is below the reference voltage — 2.5V, which indicates insufficient output voltage. The ON period is determined by the peak current limit. After the ON period elapses, the integrated MOSFET is turned OFF. The Freewheeling diode (D1) will not be turned ON until inductor (L1) charges the voltage of the sampling capacitor (C3) to equal the output voltage. The sampling capacitor voltage changes along with the output voltage. The sampling capacitor can sample and hold the output voltage to keep the output voltage regulated. The voltage of the sampling capacitor will decrease when the current of inductor is smaller than the output current. When the feedback voltage falls below the internal reference voltage — 2.5V, another switching cycle begins. The detail operation in CCM is shown as Figure 3. VCC − 2.4V 4.6V − 2.4V + CVCC × 16uA 3.5mA Figure 2 shows the typical waveform with VCC under voltage lock out. MP157 Rev. 1.03 11/17/2015 www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2015 MPS. All Rights Reserved. 10 MP157 –SMALLEST ENERGY EFFICIENT OFF-LINE REGULATOR WITH EXTENDED POWER RANGE Minimum off time limitation A minimum off time limitation is implemented. During the normal operation, the minimum off time limit is 13.1μs, and during the start up period, the minimum off time limit is shorten gradually from 52.4μs, 26.2μs to 13.1μs (Shown as Figure 4). Each minimum off time retains 128 switching cycle. This soft start function provides safe start-up. MOS Diode IL Ipeak Io Vo V FB 2.5V Driver Thus by monitoring the sampling capacitor, the output voltage can be regulated, and the output voltage is determined by the following equation: Vout = 2.5V × R1 + R2 R2 Frequency Foldback At the light load or no load conditions, the output drops very slowly. This makes the MOSFET OFF time increase. The frequency decreases as the load decreases. So MP157 can maintain a high efficiency under light load condition by reducing the switching frequency automatically. ≥ 52.4us ≥ 13.1us ≥ 26.2us 128 Switching cycle 128 Switching cycle Figure 4: tminoff at start-up EA Compensation FB Comparator + EA VFB + + M Figure 3: VFB Vs Vout Vramp + Vramp The switching frequency can be obtained as: fs = (Vin − Vo ) Vo ⋅ , For CCM 2L(Ipeak − Io ) Vin fs = 2(Vin − VO ) Io Vo ⋅ , for DCM LI2peak Vin At the same time, the peak current limit starts to decrease from 640mA as the off-time increases. At standby mode, the frequency and the peak current are both minimum, so smaller dummy load could be added. As a result, peak current compression function helps to save no load consumption. The peak current limit can be calculated by the following equation (Toff is the off time of the power module): Ipeak = 640mA − (3mA / μs) × (Toff − 13.1μs) MP157 Rev. 1.03 11/17/2015 + - Vref 2.5V Ipeak Figure 5: EA and Ramp Compensation To obtain a better load regulation, MP157 features EA (Error Amplifier) Compensation function (Shown as Figure 5). After 6μs delay of MOSFET turning off, MP157 samples the feedback voltage. So with the EA Compensation, the reference voltage— 2.5V can be regulated with the load. This can make better regulation of power module. Ramp Compensation To maintain the precise output voltage, an internal ramp compensation circuit is added --an exponential voltage sinking source will be added to pull down the reference voltage of the www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2015 MPS. All Rights Reserved. 11 MP157 –SMALLEST ENERGY EFFICIENT OFF-LINE REGULATOR WITH EXTENDED POWER RANGE feedback comparator which is also shown in Figure 5. The ramp compensation is related with the load conditions. At the full load conditions, the compensation is about the 3mV/μs. With the load decreases, the compensation increases exponentially. Over Load Protection (OLP) As the load increases, the peak current and the switching frequency both increase. When switching frequency and peak current reaches the maximum, output voltage decreases if the load continues to increase. So FB voltage drops below OLP point. By continuously monitoring the FB voltage, when FB voltage drops below 1.7V which is considered as an error flag, the timer starts counting. If the error flag removes, the timer resets. If the timer reaches its completion when it has counted to 150ms (Fs=37kHz), OLP takes place. This timer duration avoids triggering OLP function when the power supply is at start up or load transition phase. So power supply should start up in less than 150ms (Fs=37kHz). Different switching frequency (fs) leads to different over load protection delay time, as shown following equation: TDealy ≈ 150ms × Open Loop Detection If the FB voltage is lower than 60mV, IC will stop working and a re-start cycle will begin. During the start up, the open loop detection is blanked for 128 switching cycles. Leading Edge Blanking In order to avoid the premature termination of the switching pulse due to the parasitic capacitance, an internal leading edge blanking (LEB) unit is employed between the current sense resistor inside the IC and the current comparator input. During the blanking time, the current comparator is disabled and can not turn off the external MOSFET. Figure 6 shows the leading edge blanking. VLimit TLEB = 400nS t Figure 6: Leading Edge Blanking 37kHz fs Short Circuit Protection (SCP) The MP157 monitors the peak current, and shuts down when the peak current rises above 900mA, featuring a short circuit protection. As soon as the fault disappears, the power supply resumes operation. Thermal shutdown (TSD) To prevent from any lethal thermal damage, MP157 shuts down switching cycle when the inner temperature exceeds 150°C. During the thermal shutdown (TSD), the VCC will be discharged to 2.4V, and then be re-charged by the internal high voltage regulator. MP157 Rev. 1.03 11/17/2015 www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2015 MPS. All Rights Reserved. 12 MP157 –SMALLEST ENERGY EFFICIENT OFF-LINE REGULATOR WITH EXTENDED POWER RANGE APPLICATION INFORMATION Table 1. Common Topologies Using MP157 Topology High-Side Buck Circuit Schematic Features 1. 2. 3. 4. No-isolation, Positive output Low cost Direct feedback 1. No-isolation, 2. Negative output 3. Low cost High-Side Buck-Boost Boost 4. Direct feedback 1. 2. 3. 4. No-isolation, Positive output Low cost Direct feedback 1. 2. 3. 4. Isolation, Positive output Low cost Indirect feedback Flyback MP157 Rev. 1.03 11/17/2015 www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2015 MPS. All Rights Reserved. 13 MP157 –SMALLEST ENERGY EFFICIENT OFF-LINE REGULATOR WITH EXTENDED POWER RANGE Topology Options MP157 can be used in common topologies, such as Buck, Buck-Boost, Boost and Flyback. Please find the Table.1 for more information. COMPONENT SELECTION Input Capacitor The input capacitor is used to supply the DC input voltage for the converter. Figure 7 shows the typical DC bus voltage waveform with halfwave rectifier and full-wave rectifier. VDC(max) Vin DC input Voltage Po max = 1 2 1 LIpeak ⋅ , for DCM τmin off 2 To consider the parameter error of the converter such as peak current limit, minimum off time and so on, we can obtain the minimum value Pmin of the maximum power. The principle of choosing the inductor is that Pmin should be higher than the rated power. Take the output voltage 12V as examples, the curve of Pmin for 12V is shown as Figure 8, (Ipeak=0.64A, tminoff=13.1μs) 5 4.6 VDC(min) a) DC input with half-wave rectifier V DC(max) Vin DC input Voltage PMIN (W) 4.2 3.8 3.4 3 VDC(min) 2.6 0.4 0.5 0.6 0.7 0.8 INDUCTANCE(mH) 0.9 b) DC input with full-wave rectifier Figure 8: Pmin vs. L at 12V output Figure 7: Input voltage waveform For CCM operation, the selection of L should make the frequency of converter lower than 40kHz to reduce the turn-on switching loss cause by reverse recovery of free-wheeling diode at high line input. When the half-wave rectifier is used, the input capacitor is usually set as 3uF/W for the universal input condition. And when the full-wave rectifier is used, we could choose a smaller capacitor usually set as 1.5-2uF/W. Avoid the minimum DC voltage below 70V. Low DC input voltage will bring the problem of thermal shutdown. Half-wave rectifier is recommended for <2W output application and full-wave rectifier is recommended for >2W output application. Inductor MP157 has a minimum off time limit, and this decides the maximum power it can output. The maximum power increases as the inductor increases. Using a smaller inductor may fail output the full load. The maximum power can be obtained as: Po max = Vo (Ipeak − MP157 Rev. 1.03 11/17/2015 Freewheeling Diode The diode should have a maximum reverse voltage rating which is greater than the maximum input voltage, and the current rating of the diode is determined by the output current. The reverse recovery of freewheeling diode can affect the efficiency and the circuit operation. For CCM operation. ultra fast diode with Trr<35ns is used such as STTH2R06, STTH1R06, and UGC10JH. For DCM operation, diode with Trr<75ns is used. Vo t min off ) , For CCM 2L www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2015 MPS. All Rights Reserved. 14 MP157 –SMALLEST ENERGY EFFICIENT OFF-LINE REGULATOR WITH EXTENDED POWER RANGE Output Capacitor The output capacitor is required to maintain the DC output voltage. The output voltage ripple can be estimated by: VCCM _ ripple VDCM _ ripple = Δi = + Δi ⋅ RESR , for CCM 8fsCo Io fsCo Auxiliary VCC Supply R3 D3 D2 VCC C3 MP157 FB R1 C4 R2 SOURCE L1 SOURCE VOUT 2 ⎛I −I ⎞ ⋅ ⎜ pk o ⎟ + Ipk ⋅ RESR , for ⎜ I ⎟ ⎝ pk ⎠ DCM Ceramic, tantalum or low ESR electrolytic capacitors are used to reduce the output voltage ripple. Feedback Resistors The resistor divider determines the output voltage. Choose appropriate values for R1 and R2 to maintain VFB at 2.5V. Avoid large R2 value (typically 4kΩ to 10kΩ). Figure 9: Auxiliary VCC Supply Circuit If output voltage is higher than the voltage of Vcc, an auxiliary Vcc supply by connecting a diode (D3) and a resistor (R3) between C3 and C4 can be implemented to reduce overall power consumption. Then the voltage of Vcc can be clamped to 5V, and the internal regulator will be turned off all the times. For values above VO=7V, determine R3 as per the formula below. R≈ Vo − 5V 165μA Feedback Capacitor Surge Performance The feedback capacitor provides a sample and hold function. Small capacitors result in poor regulation at light loads, and large capacitors affect the circuit operation. Roughly estimate an optimal capacitor value using the following equation: Select an appropriate input capacitor value to obtain a good surge performance. With the input capacitors C4 (10μF) and C5 (10μF), the board can pass 1000V surge test. Table 2 shows the capacitance required under normal condition for different surge voltage. C Vo C 1 Vo ⋅ o ≤ CFB ≤ ⋅ o 2 R1 + R2 Io R1 + R 2 Io Table 2: Recommended Capacitance Surge 500V 1000V 2000V voltage Choose the nearest appropriate value. C4 3.3μF 10μF Dummy Load C5 3.3μF 10μF A dummy load is required to maintain the load regulation. This ensures sufficient inductor energy to charge the sample and hold capacitor to detect the output voltage. Normally a 3mA dummy load is needed and can be adjusted to the regulated voltage. Increasing the dummy load reduces the efficiency and no-load consumption. Use a zener diode if no-load regulation is not a concern. MP157 Rev. 1.03 11/17/2015 Shown in Figure 9 The board can pass 2kV surge test by using the circuit below. 1) Change the fuse resistor F1 (10ohm/1W) to SS-5-2A 2) Add a MOV RV1 (TVR14431) 3) Add a resistor R8 (39Ω) www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2015 MPS. All Rights Reserved. 15 MP157 –SMALLEST ENERGY EFFICIENT OFF-LINE REGULATOR WITH EXTENDED POWER RANGE L F1 R8 SS-5-2A 39 L1 D3 RV1 CX1 TVR14431 33nF D4 C4 10uF/400V D6 C5 10uF/400V D7 N Figure 10: Solution to Pass 2kV Surge Test Layout Guide a) Top layer PCB layout is very important for reliable operation, good EMI and thermal performance. Please follow these guidelines to optimize performance. 1) Minimize the loop area formed by the input capacitor, IC, freewheeling diode, inductor and output capacitor. 2) Place the power inductor far away from the input filter. 3) Place a capacitor valued at several nF between the FB pin and SOURCE as close to the IC as possible. 4) Connect the exposed pad with the DRAIN pin to a larger copper area to improve thermal performance. b) Bottom layer Figure 11: PCB layout Design Example Below is a design example following the application guidelines for the specifications: Table 3: Design Example 85VAC to 265VAC VIN 12V VOUT 350mA IOUT The detailed application schematic is shown in Figure 12. The typical performance and circuit waveforms have been shown in the Typical Performance Characteristics section. For more device applications, please refer to the related Evaluation Board Datasheets -- EV157-J00A_r1.0 or EV157-S-00A_r1.0. MP157 Rev. 1.03 11/17/2015 www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2015 MPS. All Rights Reserved. 16 MP157 –SMALLEST ENERGY EFFICIENT OFF-LINE REGULATOR WITH EXTENDED POWER RANGE TYPICAL APPLICATION CIRCUITS Figure 12 shows a typical application example of a 12V, 350mA non-isolated power supply using MP157. D1 D2 1N4007 1N4148WS F1 L1 10/1W 1mH R5 D3 D4 1N4007 1N4007 C4 10uF/400V 33nF Drain Vcc FB 4 85~265VAC C5 10uF/400V 24K 19.6K 1 C1 220nF NC CX1 R1 U1 5 L R2 Source Source 2 C3 3 C2 R3 R4 2.2uF NC 4.99K D7 1N4007 1N4007 12V/350mA VOUT MP157 D5 D6 L2 1.2mH 470pF STTH1R06 C6 100uF/25V C7 R7 1uF 3K GND N GND Figure 12: Typical Application at 12V, 350mA MP157 Rev. 1.03 11/17/2015 www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2015 MPS. All Rights Reserved. 17 MP157 –SMALLEST ENERGY EFFICIENT OFF-LINE REGULATOR WITH EXTENDED POWER RANGE PACKAGE INFORMATION TSOT23-5 0.60 TYP 2.80 3.00 5 4 1.20 TYP 1.50 1.70 1 0.95 BSC 2.60 3.00 2.60 TYP 3 TOP VIEW RECOMMENDED LAND PATTERN 0.70 0.90 1.00 MAX 0.09 0.20 SEATING PLANE 0.30 0.50 0.95 BSC 0.00 0.10 SEE DETAIL "A" FRONT VIEW SIDE VIEW NOTE: GAUGE PLANE 0.25 BSC 0o-8o 0.30 0.50 DETAIL “A” MP157 Rev. 1.03 11/17/2015 1) ALL DIMENSIONS ARE IN MILLIMETERS. 2) PACKAGE LENGTH DOES NOT INCLUDE MOLD FLASH , PROTRUSION OR GATE BURR. 3) PACKAGE WIDTH DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSION. 4) LEAD COPLANARITY(BOTTOM OF LEADS AFTER FORMING) SHALL BE 0.10 MILLIMETERS MAX. 5) DRAWING CONFORMS TO JEDEC MO-193, VARIATION AA. 6) DRAWING IS NOT TO SCALE. www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2015 MPS. All Rights Reserved. 18 MP157 –SMALLEST ENERGY EFFICIENT OFF-LINE REGULATOR WITH EXTENDED POWER RANGE PACKAGE INFORMATION SOIC8 0.189(4.80) 0.197(5.00) 8 0.050(1.27) 0.024(0.61) 5 0.063(1.60) 0.150(3.80) 0.157(4.00) PIN 1 ID 1 0.228(5.80) 0.244(6.20) 0.213(5.40) 4 TOP VIEW RECOMMENDED LAND PATTERN 0.053(1.35) 0.069(1.75) SEATING PLANE 0.004(0.10) 0.010(0.25) 0.013(0.33) 0.020(0.51) 0.0075(0.19) 0.0098(0.25) SEE DETAIL "A" 0.050(1.27) BSC SIDE VIEW FRONT VIEW 0.010(0.25) x 45o 0.020(0.50) GAUGE PLANE 0.010(0.25) BSC 0o-8o 0.016(0.41) 0.050(1.27) DETAIL "A" NOTE: 1) CONTROL DIMENSION IS IN INCHES. DIMENSION IN BRACKET IS IN MILLIMETERS. 2) PACKAGE LENGTH DOES NOT INCLUDE MOLD FLASH , PROTRUSIONS OR GATE BURRS. 3) PACKAGE WIDTH DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSIONS. 4) LEAD COPLANARITY(BOTTOM OF LEADS AFTER FORMING) SHALL BE 0.004" INCHES MAX. 5) DRAWING CONFORMS TO JEDEC MS-012, VARIATION AA. 6) DRAWING IS NOT TO SCALE. NOTICE: The information in this document is subject to change without notice. Please contact MPS for current specifications. 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. MP157 Rev. 1.03 11/17/2015 www.MonolithicPower.com MPS Proprietary Information. Patent Protected.. Unauthorized Photocopy and Duplication Prohibited. © 2015 MPS. All Rights Reserved. 19