Adapters < 75 W Agenda • New ENERGY STAR® requirements • Needed features to meet the new specification • New controllers • Practical examples • Conclusion www.onsemi.com 2 EPA 2.0 (External Power Supplies) (was > 0.84 in previous version 1.1) (< 0.5 W in 1.1) (< 0.75 W in 1.1) www.onsemi.com 3 Agenda • New ENERGY STAR® requirements • Needed features to meet the new specification • New controllers • Practical examples • Conclusion www.onsemi.com 4 Improving Efficiency • Sources of loss: – Switching losses: Ploss ( switching ) = 1 2 ⋅ C DRAIN ⋅ VDRAIN ( turn−off ) ⋅ FSW 2 – Gate charge losses: Ploss ( gate ) = Vgate ( high) ⋅ Qgate ⋅ FSW • Ways to improve efficiency: – Lower the switching frequency FSW Î frequency foldback at light loads – Lower the Drain voltage at turn-off Î valley switching www.onsemi.com 5 Reducing No-load Input Power • Static losses in the start-up circuit: – Start-up resistor permanently drawing current from the bulk capacitor • Ways to lower the start-up circuit losses – With external start-up resistor Î Extremely low start-up current – Integrated start-up current source Î Extremely low leakage when off – Connect the start-up circuit to the half-wave rectified ac input HV rail Start-up resistors NCP1351 1 8 2 7 3 6 4 5 Vcc www.onsemi.com 6 Agenda • New ENERGY STAR® requirements • Needed features to meet the new specification • New controllers • Practical examples • Conclusion www.onsemi.com 7 The Right Controllers • Two new families of controllers implement features to increase efficiency and lower no-load input power: – NCP1237/38/87/88: fixed-frequency controllers with integrated start-up current source, frequency foldback and skip mode Æ Increased efficiency at light load and standby – NCP1379/80 valley switching controllers with extremely low start-up current and frequency foldback Æ Increased efficiency at all load levels www.onsemi.com 8 NCP1237/38/87/88 Value Proposition The NCP12X7/X8 series represents the next generation of fixed frequency PWM controllers. It targets applications where cost-effectiveness, reliability, design flexibility and low standby power are compulsory. Unique Features High-voltage current source with built-in Brown-out and mains OVP Freq. reduction in light load conditions and skip mode Adjustable Over Power Protection Benefits Application Data Fewer components and rugged design Extremely low no-load standby power Simple option to alter the max. peak current set point at high line DSS NCP1237A NCP1237B NCP1238A NCP1238B NCP1287A NCP1287B NCP1288A NCP1288B Others Features Latch-off input for severe fault conditions, allowing direct connection of NTC Timer-based protection: auto-recovery or latched Dual OCP option available Built-in ramp compensation Frequency jittering for a softened EMI signature Vcc operation up to 30 V Market & Applications AC-DC adapters for notebooks, LCD monitor, game console, printers CE applications (DVD, STB) www.onsemi.com 9 Yes Yes Yes Yes HV only HV only HV only HV only Dual OCP Yes Yes No No Yes Yes No No Latch Auto Recovery Yes Yes Yes Yes Yes Yes Yes Yes Various options available depending upon end applications needs Ordering & Package Information NCP1237/38xDR2G - NCP1287/88xDR2G SOIC-7 2500p per reel Pb O, DW NCP1237/38/87/88 – Brown-out and Mains OVP HV Detection independent of Ripple on HV pin www.onsemi.com 10 Can be connected to the half-wave rectified ac line NCP1237/38/87/88 – Brown-out and Mains OVP Timer-based detection www.onsemi.com 11 Passes full line cycle drop-out NCP1237/38/87/88 – Over Power Protection Need to compensate for the effect of the propagation delay Over Power Protection www.onsemi.com 12 The compensation current creates an offset on the Current Sense signal Maximum output power clamped NCP1237/38/87/88 – Frequency Foldback Switching frequency lowered at light load Increased efficiency Switching frequency clamped at 25 kHz No audible noise www.onsemi.com 13 NCP1237/38/87/88 – Latch-off Protection Vcc VLATCH OVP Latch! LATCH OK Latch! OTP time An NTC thermistor can be directly connected to the IC Less external components needed www.onsemi.com 14 NCP1379/80 Value Proposition The NCP1380 is a high-performance circuitry aimed to powering QR converters. Capitalizing on a novel valley-lockout system, the controller shifts gears and reduces the switching frequency as the power loading becomes lighter. Unique Features Valley switching operation with valley-lockout Freq. reduction in light load condition Adjustable Over Power Protection Benefits Application Data Excellent efficiency over a wide range and noise free operation Extremely low no-load standby power Simple option to alter the max. peak current set point at high line HV-bulk Vout Chrono A/B ZCD / OPP 1 Others Features Auto-recovery or latched internal output short-circuit protection Fixed 80 ms timer for short-circuit protection Combined Over-voltage and over-temperature protection (A and B versions) Combined OVP & brown-out (C and D versions) 3 µs blanking delay to ignore leakage ringing at turn-off Market & Applications AC-DC adapters for notebooks, LCD monitor, game console Auxiliary power for Flat TVs CE applications (DVD, STB) www.onsemi.com 15 Gnd OVP 8 2 7 3 6 4 5 OTP Gnd Design flexibility Ordering & Package Information NCP1380xDR2G SOIC-8 2500p per reel Pb O, DW NCP1379/80 - QR Mode with Valley Lockout • • As the load decreases, the controller changes valley (1st to 4th valley) The controller stays locked in a valley until the output power changes significantly. ¾ No valley jumping noise ¾ Natural switching frequency limitation 80000 SWITCHING FREQUENCY (Hz) 70000 60000 50000 4th 3rd 2nd 1st 40000 30000 20000 QR operation 10000 0 0 10 VCO mode www.onsemi.com 16 20 30 OUTPUT POWER (W) 40 50 60 NCP1379/80 - Frequency Foldback • • Occurs when VFB < 0.8 V (POUT decreasing) or VFB < 1.6 V (POUT increasing) Fixed peak current (25% of Ipk,max), variable frequency set by the FB loop. Ipk max Constant peak current (25% of Ipk max) Fsw1 @ Pout1 www.onsemi.com 17 Fsw2 @ Pout2 Pout1 > Pout2 NCP1379/80 - Frequency Foldback • • The switching frequency is set by the end of charge of Ct capacitor The end of charge of Ct capacitor is controlled by the FB loop Vdd Load Rpullup FB Enable VCO mode Ct 6.5-(10/3)Vfb VFBth ICt VCO - Vdd Ct + Ct discharge Controlled by FB loop S DRV Q Q R CS comparator (Timing capacitor voltage) www.onsemi.com 18 NCP1379/80 - Overpower Protection • • • Laux with flyback polarity swings to –NVIN during the on time. Adjust amount of OPP voltage with Ropu // Ropl. VCS,max = 0.8 V + VOPP Ropu CS ZCD/OPP OPP Peak current set point IpFlag 1 Aux Ropl ESD protection V ILIMIT 100% + - Demag 60% Vth leakage blanking DRV Tblank 370 Non dissipative OPP ! www.onsemi.com 19 VIN (V) Agenda • New ENERGY STAR® requirements • Needed features to meet the new specification • New controllers • Practical examples • Conclusion www.onsemi.com 20 Fixed-Frequency Example: Schematic 10k 10k 2.7k 57.4k 120k/0.5W A typical 65 W notebook adapter (19 V output) (not optimized for EPS 2.0) www.onsemi.com 21 Fixed-Frequency Example: Efficiency • EPS 2.0 efficiency (compared to NCP1271, from a previous generation) VIN % of POUTnom 100 % (65 W) 75 % (49 W) 50 % (32 W) 25 % (16 W) 115 Vac 230 Vac NCP1271 NCP1271 88.5 % 88.7 % 88.4 % 88.2 % 89.2 % 89.1 % 88.2 % 88.3 % 88.9 % 88.9 % 86.8 % 87.0 % 88.2 % 88.4 % 87.3 % Average at 230 Vac: 87.7 % www.onsemi.com 22 84.3 % Effect of the frequency foldback Fixed-Frequency Example: Standby Power • Light load and no load input power with the NCP1237 (compared to NCP1271, from a previous generation) VIN POUT 230 Vac NCP1271 NCP1271 10.7 W 12.0 W (88.7 %) 12.2 W (87.5 %) 12.5 W (85.1 %) 13.2 W (80.76 %) 1.3 W 1.67 W (78.0 %) 1.77 W (72.9 %) 1.75 W (74.2 %) 2.46 W (52.4 %) 0.5 W 0.74 W (69.0 %) 0.81 W (62.6 %) 0.76 W (66.0 %) 1.34 W (37.3 %) No load 71 mW 76 mW 97 mW 121 mW www.onsemi.com 23 115 Vac Fixed-Frequency Example: Summary 95 Efficiency (%) 85 75 – 115 Vac - NCP1237 – 230 Vac - NCP1237 65 – 115 Vac - NCP1271 – 230 Vac - NCP1271 55 45 35 0 10 20 30 40 Ouput power (W) www.onsemi.com 24 50 60 70 Valley Switching Example: Efficiency • EPS 2.0 efficiency with the NCP1380, valley switching controller VIN 115 Vac 230 Vac 100 % 88.7 % 91.1 % 75 % 88.8 % 90.9 % 50 % 89.2 % 89.1 % 25 % 88.2 % 87.9 % % of POUTnom Average at 115 Vac: 88.7 % www.onsemi.com 25 Valley Switching Example: Standby Power • Light load and no load input power with the NCP1380 VIN 115 Vac 230 Vac 10.7 W 12.37 W (86.5 %) 12.44 W (86 %) 1.3 W 1.85 W (70.3 %) 1.82 W ( 71.4 %) 0.5 W 0.82 W (61 %) 0.78 W (64.1 %) No load 122 mW 210 mW POUT No-load standby power meets ENERGY STAR® with a start-up resistor! www.onsemi.com 26 Agenda • New ENERGY STAR® requirements • Needed features to meet the new specification • New controllers • Practical examples • Conclusion www.onsemi.com 27 Adapters < 75 W: Conclusion • Meeting the most recent requirements from ENERGY STAR® or IEC is possible with the classical Flyback converter • Two new controllers sharing the same concept of frequency foldback at light load make it possible: – Fixed-frequency: NCP1238 family – Valley-switching (Quasi-resonant, QR): NCP1380 family • Average efficiencies above 87% are possible • No-load input power below 300 mW is possible, even with a start-up resistor • No-load input power below 100 mW is achievable, although the controller alone cannot ensure this. The whole power supply must be designed to reduce power waste. www.onsemi.com 28 For More Information • View the extensive portfolio of power management products from ON Semiconductor at www.onsemi.com • View reference designs, design notes, and other material supporting the design of highly efficient power supplies at www.onsemi.com/powersupplies www.onsemi.com 29