AND8242/D 19 V, 3.0 A Universal Input AC-DC Adaptor Using NCP1271 Prepared by: Jon Kraft and Kahou Wong ON Semiconductor http://onsemi.com APPLICATION NOTE INTRODUCTION This application note presents an example circuit (Figure 1) using the NCP1271 (65 kHz version) in a flyback topology. The design steps and subsequent measurements are also included. An Excel based design worksheet is available at www.onsemi.com. The measurements show that the 19 V, 3.0 A circuit delivers above 85% across a universal input (85 to 265 Vac). The no load standby consumption is 83 mW at 230 Vac and the light load operation is greater than 75% efficient. The NCP1271 is one of the latest fixed-frequency current-mode PWM switching controllers with (1) adjustable Soft-Skipt standby operation for low-level audible noise, (2) integrated high-voltage startup for saving standby power, (3) timer based overload fault detection, and (4) internal latch protection features. Table 1 summarizes all the features of an NCP1271 based power supply. 19 V / 3 A - D10 MZP4746A (18V) IC4 TL431 R11 15.8k R9 1.69k C12 0.15 uF R12 2.37k R8 0.25 / 1W R10 1.69k R7 511 IC3 SFH615AA-X007 C13 100uF C4 100uF R6 10 C7 1.2 nF C6 1.2 nF R5 30.1k R2 10 Flyback transformer : Cooper CTX22-17179 Lp = 180uH, leakage 2.5uH max np : ns : naux = 30 : 6 : 5 Hi-pot 3600Vac for 1 sec, primary to secondary Hi-pot 8500Vac for 1 sec, winding to core C10 2200 uF C9 2200 uF D5 MMSZ914 R1 100k / 2W IC1 NCP1271A + D8 MBR3100 D7 MURS160 Q1 SPP06N80C3 T1 E3506-A C5 10 nF D6 MRA4005T3 C2 0.1 uF Common Mode Choke C1 0.1 uF 85 to 265 Vac C3 82uF / 400V D1 - D4 1N5406 x 4 Fuse 2A C11 1nF/ 1000V Figure 1. Application Circuit Schematic © Semiconductor Components Industries, LLC, 2007 July, 2007 - Rev. 3 1 Publication Order Number: AND8242/D AND8242/D Table 1. Features of Power Supply Using NCP1271 Operation Mode Features Topology CCM/DCM Flyback • • • • • Standby Condition Soft-Skip Operation • Adjustable skip level for optimal standby power consumption. • Proprietary Soft-Skip to reduce the risk of low-frequency audible noise. • Soft-Skip operation is automatically disabled if an abrupt transient load is applied from standby operation. This improves the output response to a transient load. Fault Condition Double Hiccup Restart Latch Protection Activated Latch Off Fixed-frequency current-mode control with inherent primary current limitation. Frequency jittering to soften the EMI signature. Built-in soft-start. Output short-circuit fault detection independent of the auxiliary winding. Integrated high voltage startup that minimizes standby power loss. • Double Hiccup operation minimizes the power dissipation in a fault mode and allows the application to auto-recover when the fault is removed. • An internal latch makes it easy to add overtemperature protection (OTP) or overvoltage protection (OVP) to any applications. • Latch is reset by unplugging the AC input and allowing VCC to drop below 4 V (typ). The Demo Board Specification Input 85 to 265 Vac, 50 Hz Output 19 Vdc, 3.0 A, Isolated Features • • • • • Based on the results from the NCP1271 design spreadsheet, the final values for this adapter's key flyback parameters were calculated to be: Np:Ns = 5:1 Lp = 180 mH RCS = 0.3 Ohms Ipeak(full load) = 3.5 A Switch Rating = 6 A, 800 V Diode Rating = 3 A, 100 V Rsnubber = 100 kW Csnubber = 10 nF < 100 mW Input Power at 230 Vac Excellent Light Load Performance No Audible Noise > 85% Full Load Efficiency Short Circuit Protection Activates at < 100W for Any Input Voltage A Discontinuous Conduction Mode (DCM) flyback was selected for this application. DCM gives very good stability, small inductor size (lower leakage inductance), and good transient response. Setting the Short Circuit Protection Level The current sense resistor (RCS or R8), provides two functions. First it senses the primary current for current- mode PWM operation. Secondly, it provides the maximum primary current limitation according to equation 1: Flyback Calculations Several resources are available at www.onsemi.com to calculate the necessary component values for a flyback supply. In particular, an Excel based design spreadsheet can be found at: www.onsemi.com/collateral/NCP1271SHEET.xls Additionally, most of the other NCP12xx application notes also apply to the NCP1271. For detailed information on designing a flyback power supply, please visit AND8076/D. Other app notes which may also aid in the design include: AND8069/D Tips and Tricks to Build Efficient Circuits With the NCP1200 AND8205/D How to Choose a Switching Controller for Design AND8023/D Implementing the NCP1200 in Low-Cost AC/DC Converters AND8032/D Conducted EMI Filter Design for the NCP1200 AND8076/D A 70 W Low Standby Power Supply with the NCP12xx Series Ip(max) + 1V RCS (eq. 1) The short circuit protection activates when the Ip(max) current is reached for more than 130 ms (typ). This also corresponds to VFB being greater than or equal to 3 V for 130 ms. Therefore, RCS must be set large enough to ensure that the required peak current can always be delivered, but small enough to meet the short circuit protection requirements. A DCM flyback converter has the following relationship: Pout + 1ń2 Lp Ip2 FSW h (eq. 2) Therefore, for an assumed efficiency of 80%, a peak current of 4 A should trigger the short circuit protection circuitry at 80 W. This corresponds to an RCS value of 0.25 W. This change in RCS may also require that the snubber and transformer be re-calculated to handle this level of peak current during the short circuit fault time. A few iterations of the Excel based NCP1271 design spreadsheet should produce a good starting point for the application's design. http://onsemi.com 2 AND8242/D Over Power Compensation input voltage is due to the propagation delay (Tprop) of the NCP1271. This propagation delay has a more pronounced effect on the power delivered at high line than at low line as shown in Figure 2. For this demo board, the short circuit protection is activated with an output load of 76 W at 85 Vac and 93 W at 265 Vac. The variation in short circuit power level with Peak Primary Current Additional Power Delivered due to Prop Delay Ip(max) 230 Vac 120 Vac Slope = Vbulk/Lp 0 time Tprop Tprop Figure 2. Effect of Propagation Delay on the Maximum Power Delivered at High Line and Low Line NCP1271 This effect is called “Over Power” because it delivers more power than what is requested by the feedback loop. Specifically, for a DCM flyback system, the total power delivered to the output including the prop delay effect is: Aux CS DRV ROPP Pout + 1 @ Lp @ (Ip(max) ) VbulkńLp @ Tprop) 2 @ Fsw @ h 2 RCOMP (eq. 3) The NCP1271 has been designed with a very low Tprop (50 ns typ). This minimizes the over power effect. However, if reduced variation is required, then over power compensation can be easily implemented by using one of the circuits shown in Figures 3 and 4. Figure 4. Over Power Compensation by Modifying the Auxiliary Winding Topology The circuit in Figure 3 simply modifies the CS setpoint proportional to the HV bulk level. This creates an offset which compensates for the propagation delay. However, this does increase the standby power dissipation. Figure 4 gives another option which results in much lower power dissipation. By altering the position of the Aux winding diode, a new point is created whose voltage is proportional to Vin. The power dissipation is now reduced by a factor of (Np:Naux)2. Values for Ropp are best found experimentally to give suitable precision for the activation of the short circuit protection. VBULK ROPP NCP1271 CS DRV RCOMP RCS RCS Figure 3. Over Power Compensation by means of a Resistor to the Bulk Voltage http://onsemi.com 3 AND8242/D Biasing the Controller bunch of skip pulses. To address this need, the NCP1271 has a proprietary Soft-Skip feature which ramps each bunch of pulses. This dramatically lowers acoustic noise and allows a higher skip level to be set for greater power savings. The NCP1271 also allows the designer to select the optimal level of the peak current during skip through a simple resistor from pin 1 to GND. This skip resistor sets the skip level according to equation 4: The NCP1271 includes a high voltage (HV) startup pin (Pin 8) which charges VCC to its operating level. This pin can be directly connected to the high voltage DC bus. Once the device is powered up, an auxiliary winding powers VCC as shown in Figure 5. Rectified Input Vskip + Iskip Output 19V / 3A HV Rskip (eq. 4) where Iskip = 43 mA (typ) The peak current when skip mode is activated can be calculated with equation 5: VCC 16 V V Ipeak(skip) + skip 3V Ipeak(max) (eq. 5) For this demo board, Vskip was set to 1.3 V (Rskip = 30.1 kW). And Ipeak(max) is 1 V / 0.25 W = 4 A. Therefore, Ipeak(skip) = 1.7 A. NCP1271 Minimum On Time Limitation Figure 5. VCC Biasing Scheme The NCP1271 includes a current sense (CS) Leading Edge Blanking (LEB) filter. The LEB filter blanks out the first 180 ns (typ) of the CS voltage at the beginning of each drive pulse. This helps to prevent a premature reset of the output due to noise. However, this also results in a minimum on time of the device. The duration is equal to the LEB time (180 ns typical) and the propagation delay of logic (50 ns typical). If the application circuit is configured for 0% skip (by connecting Pin 1 to Ground), then that minimum on time duration may result in an abnormally high output voltage during no load conditions. Therefore, it is recommended to set skip to some small value rather than disable it completely. The range of VCC is from 10 V (min) to 20 V (max). Therefore, the auxiliary winding should be designed to give a level of VCC within this range over all output loads. When the circuit is in standby mode, very few pulses are delivered and the auxiliary level decreases. To provide enough voltage range, a nominal VCC level of 16 V was selected for this application. Additionally, an 18 V (±5%) Zener diode was added externally to protect the controller from abnormally high auxiliary levels. The 16 V bias supply is constructed from a 6:5 turns ratio (19 V:16 V) between the main output and the auxiliary winding. Figure 6 shows the auxiliary supply circuit. A resistor is included to provide the flexibility to redesign the circuit for higher output voltages. Any extra bias voltage greater than 18 V is simply dissipated across the resistor. Ramp Compensation The NCP1271 also incorporates a feature called “ramp compensation.” Ramp compensation is a known mean to cure subharmonic oscillations. These oscillations take place at half the switching frequency and occur only during continuous conduction mode (CCM) with a duty-cycle greater than 50%. To prevent these oscillations, one usually injects between 50 and 75% of the inductor down slope into the CS pin. The NCP1271 generates an internal current ramp that is synchronized with the clock. This current ramp is then routed to the CS pin. Since the flyback design in this app note is well within DCM operation, ramp compensation is not necessary. However, for designs that do run in CCM with the NCP1271, ramp compensation is easy to implement. It only requires one external resistor between Rcs and the CS pin. The value of the ramp resistor to obtain 50% inductor down slope injection can be calculated with the following equation: NCP1271 C4 100uF 18 V C13 100uF Figure 6. Auxiliary Supply Soft-Skip Adjustment When the load current drops, the compensation network responds by reducing the peak current. When the peak current reaches the skip peak current level, the NCP1271 enters skip operation to reduce the power consumption. The peak current level at which skip is entered should be set high for good standby power dissipation. However, it also needs to be set low enough that no audible noise occurs during each Rramp + 0.50 http://onsemi.com 4 RCS ǒ(Vout ) Vf) ǒLp Fsw NP NS Ǔ 100mA 0.80 Ǔ (eq. 6) AND8242/D Maximum Duty Cycle and Ramp Compensation If the ramp resistor is set too high, the maximum duty cycle will be reduced. But as a long as Rramp is below 10 kW, this will not be a problem. A typical graph of the maximum duty cycle verses Rramp is shown in Figure 7. However, it is not recommended to try to reduce the maximum duty cycle by the Rramp value because this relationship is not guaranteed by the production tests of the device. NTC resistor R limit 2 90 80 70 MAXIMUM DUTY (%) 8 1 3 6 4 5 NCP1271 60 Figure 9. Overtemperature Protection Latch with a NTC Thermistor 50 40 30 20 10 0 0 5 10 15 20 25 30 35 40 45 50 R limit RRAMP, RESISTOR (kW) OVP Figure 7. Maximum Duty Cycle Characteristics 8 1 2 Optional Output OVP Latch The NCP1271 includes a feature where if Pin 1 is brought above 8.0 V (typ), the part will safely latch off the controller. The controller is reset by unplugging the AC input. This allows for easy implementation of overvoltage (OVP) or overtemperature (OTP) protection. In order to pull the Pin 1 voltage above the latch threshold, a greater than 8.0 V source is needed. That is usually the bias supply voltage VCC. Therefore, to protect Pin 1, a resistor (Rlimit) is connected to limit the current below the maximum allowed level. In addition, the internal ESD diode will limit the maximum voltage on Pin 1 to about 10 V. This latch off feature can be configured in a variety of ways. Some of the most popular include using the auxiliary winding to detect an overvoltage and using an NTC resistor to detect an overtemperature condition. A few variations of these circuits are listed in Figures 8 to 11. 3 6 4 5 NCP1271 Figure 10. Output Overvoltage Protection Using the Auxiliary Winding V out R limit 8 1 2 opto coupler 3 6 4 5 NCP1271 Figure 11. Output Overvoltage Protection Using an Optocoupler R limit 8 1 latch off 2 3 6 4 5 NCP1271 Figure 8. Simple Latchoff Circuit by Bipolar Transistors http://onsemi.com 5 AND8242/D Layout Consideration It is important to note that when Pin 1 is open it sets the default skip level to 1.2 V. However, in this mode, pin 1 is internally pulled high to the Vskip-reset level (6.5 V typ). This only leaves about 1.5 V of noise margin before the part latches off. Therefore, if a skip level of 1.2 V is desired, then instead of leaving pin 1 open, it is always recommended to place a 28 kW resistor from pin 1 to GND. Then the skip level becomes 1.2 V (28 kW x 43 mA = 1.2 V), and the pin 1 voltage is also 1.2 V. This gives much better noise immunity and reduces the chance of falsely triggering the latch due to noise or leakage current from the external latch circuitry. Additionally, a small capacitor should be added to pin 1 to further increase the noise immunity. Figures 9-10 show the layout of the design. It is a single-layer PCB. As with any power converter, some care must be exercised with the design and layout. The following are some important guidelines. 1. Minimize the high-current loop and locate the IC controller outside the high-current loop to prevent malfunctioning of the IC internal logic due to strong magnetic fields from the high current. 2. Locate the decoupling capacitors close to the device to improve noise immunity. 3. Locate the VCC capacitor very close to the device to prevent the circuit from entering a UVLO fault condition because of noise. 4. Locate the output voltage sense resistor close to the output load points. 5. Minimize the current sense trace. It can become easily polluted with noise. 6. Minimize the distance between the feedback opto-coupler and controller because this trace is also easily polluted. 7. Minimize the distance between the MOSFET and controller because the PCB trace is high frequency and high current so it can easily pollute other parts of the circuit. Additionally, there are three pins in the NCP1271 that may need external decoupling capacitors. 1. Skip/latch pin (Pin 1) – If the voltage on this pin is above 8.0 V, the circuit enters latch-off protection mode. Hence, a decoupling capacitor on this pin is essential to improve noise immunity. Additionally, a resistor should always be placed from this pin to GND to prevent noise from causing the pin 1 level from exceeding the latch-off level. 2. Feedback pin (Pin 2) – A small capacitor may be necessary here for improved stability and noise immunity. 3. VCC pin (Pin 6) – The NCP1271 maintains normal operation when VCC is above VCC(off) (9.1 V typical). If VCC drops below VCC(off), then the circuit enters UVLO protection and restarts after a double hiccup. Therefore, if VCC inadvertently drops below VCC(off) due to switching noise, then the circuit will recognize it as a fault condition. Hence, it is important to locate the VCC capacitor and a ceramic decoupling capacitor as close as possible to the NCP1271. HV Pin Protection Circuit When the main power is interrupted in the application, the high voltage DC bus may potentially go negative in a short transient period. Since this is directly connected to pin 8, it could create a reverse current out of the HV Pin and could potentially damage the device. There are two easy solutions to this problem. The first is demonstrated in Figure 12. The inserted diode turns on when the HV Pin voltage goes below the VCC biasing voltage. This eliminates the chance of negative voltage on the HV pin. A second method is shown in Figure 13. Here, the inserted resistor limits the negative current to a low level and protects the HV pin. Either option works well, but for this demo board, a diode between VCC and HV was used. HV 8 1 2 1N4005 Vcc 3 6 4 5 NCP1271 Figure 12. Protection Diode for HV Pin >4.7 kW HV 1 8 2 Vcc 3 6 4 5 NCP1271 Figure 13. Protection Resistor on HV Pin http://onsemi.com 6 AND8242/D Measurements Figure 16 shows the go-to-standby transition from full load operation. The output voltage (yellow trace) does not consume current and remains at 19 V, but the VCC voltage drops from 16 V to 15 V because the VCC auxiliary winding is not supplying current to the controller. The minimum VCC voltage in the transition can be as low as 12 V. This is why the 16 V biasing voltage was selected to maintain VCC above VCC(off) and prevent a VCC reset. Standby Performance Thanks to the features in the NCP1271, the demo board power supply offers excellent no load and light load standby performance. The 230 Vac power consumption of the 57 W circuit is only 83 mW. And the input power at 230 Vac with 500 mW load is only 710 mW. Figure 14 shows the efficiency with output loads from 500 mW to 60 W at 120 Vac and 230 Vac. 95 EFFICIENCY (%) 90 120 Vac Vout 85 230 Vac VCC 80 75 70 VCS 65 60 0 10 20 30 40 50 Figure 16. Operating to Standby 60 Pout (W) Short Circuit Protection Measurements Figure 14. Efficiency of the NCP1271 Demo Board at Nominal Line Voltages Figure 17 details the operation of the short circuit protection . The load steps from 60 W to 100 W, causing the peak current to increase to its maximum (1 V) as shown by the blue CS voltage. After approximately 130 ms, the controller shuts the power supply down and enters double hiccup fault operation (Figure 18). This provides very low power dissipation and protects the power components. When the short circuit fault is removed, the application recovers by executing a soft start and bringing the output back to 19 V. Dynamic Study Figure 15 shows the startup transient waveforms of the circuit when the input is 110 Vac. A 4 ms soft-start is observed in the drain current. The VFB drops below 3.0 V after 32 ms. Since this is shorter than the 130 ms fault validation time, the circuit does not enter fault condition and starts up normally. Vfb VCC Vout VCC Vout VCS VCS Figure 15. Startup Transient Figure 17. Short Circuit Protection is Activated When the Output Load Increases to about 100 W http://onsemi.com 7 AND8242/D Conclusion A 57 W flyback power supply featuring over voltage and short circuit protection using the NCP1271 was demonstrated to have excellent light load power dissipation and active mode efficiency. The NCP1271's proprietary Soft-Skip t operation offers low-audible-noise and excellent standby performance. The NCP1271 design worksheet, as well as other design aid resources, are available at www.onsemi.com. VCC Vout VCS Figure 18. The Controller Enters Double Hiccup Fault Operation during a Continuous Short Circuit Event http://onsemi.com 8 AND8242/D Appendix I: Bill of Materials for the NCP1271 19 V/3.0 A Example Circuit Designator Qty Part Number Description T1 1 E3506-A 3.0 A 508 mH Common-Mode Filter Coilcraft T2 1 CTX22-17179 Custom Transformer 180 mH 30:6:5, 2.5 mH Max Leakage Cooper/Coiltronics IC1 1 NCP1271D65R2 65 kHz Flyback PWM Controller, SO-7 ON Semiconductor IC2 1 TL431AID 2.5 V 1% Voltage Reference, SO-8 ON Semiconductor IC3–IC4 2 SFH615AA-X007 D1–D4 4 1N5406 D5 1 MMSZ914 D6 1 MRA4005T3 D7 1 D8 1 D10 1 Q1 1 SPP06N80C3 6.0 A 800 V N-MOSFET, TO-220AB R1 1 P100KW-2BK 100 kW 2.0 W, Axial 5% R2 1 CFR-25JB-10R 10 W, 1/4 W Axial Yageo R5 1 CRCW12063012F 30.1 kW, 1206 Vishay R6 1 CRCW120610R0F 10 W, 1206 Vishay R7 1 CRCW12065110F 511 W 1206 Vishay Optocoupler Manufacturer Vishay 3.0 A 600 V Diode, Axial 267-05 ON Semiconductor 1.0 A 100 V Diode, SOD-123 ON Semiconductor 1.0 A 600 V Diode, SMA ON Semiconductor MURS160 1.0 A 600 V Diode, SMB ON Semiconductor MBR3100 3.0 A 100 V Schottky Diode, Axial 267-05 ON Semiconductor MZP4746A 18 V @ 14 mA Zener Diode ON Semiconductor Infineon - R8 1 WSL2512R2500FEA 0.25 W 1.0 W 1% Vishay R9, R10 1 CRCW12061691F 1.69 kW, 1206 Vishay R11 1 CRCW12061582F 15.8 kW, 1206 Vishay R12 1 CRCW12062371F 2.37 kW, 1206 Vishay C1-C2 2 PHE840MA6100MA04 C3 1 C4, C13 2 0.1 mF X2 Cap 10 mm Pitch Evox Rifa ECOS2GP820BA, EETED2G820BA, or EETXB2G820BA 82 mF 400 V Electrolytic Panasonic ECA1EM101 100 mF 25 V Electrolytic Panasonic 10 nF 630 V Film Cap C5 1 630MMB103J C6-C7 1 VJ1206Y122KXXA C9–C10 3 025YXG220M12.5X30 2200 mF 25 V Electrolytic Rubycon C11 1 ERO610RJ4100M 1.0 nF 1.0 kV 5.0 mm Pitch Y2 Cap Evox Rifa 0.15 mF 25 V Ceramic C12 1 VJ1206Y154KXXA Fuse 1 1025TD2-R 1.2 nF 25 V, 1206 250 V 2.0 A Tie Delay Fuse Heatsink for TO-220 Package Rubycon Vishay Vishay Cooper Fuse Heatsink 1 590302B03600 Heatsink Insulation 1 4672 TO-220 Mica Insulation Keystone Aavid IEC60320 C8 Connector Qualtek AC Connector 1 770W-X2/10 DC Connector 1 26- 60- 4030 or 009652038 Standoff 4 4804 K Standoff M/F Hex 4-40 Nyl 0.750” - Heatsink Mechanic 1 30F698 4-40 1/4 Inch Screw - Heatsink/Standoff Mechanic 5 31F2106 4-40 Screw Nuts - Nylon Washer 1 3049 Nylon Shoulder Washer #4 - 3-T erminal 3.96 mm Pitch Male Header http://onsemi.com 9 Molex AND8242/D Appendix II: NCP1271 57 W Adaptor Layout Figure 19. Top View Figure 20. Bottom View Soft-Skip is a trademark of Semiconductor Components Industries, LLC (SCILLC). ON Semiconductor and are registered trademarks of Semiconductor Components Industries, LLC (SCILLC). SCILLC reserves the right to make changes without further notice to any products herein. SCILLC makes no warranty, representation or guarantee regarding the suitability of its products for any particular purpose, nor does SCILLC assume any liability arising out of the application or use of any product or circuit, and specifically disclaims any and all liability, including without limitation special, consequential or incidental damages. “Typical” parameters which may be provided in SCILLC data sheets and/or specifications can and do vary in different applications and actual performance may vary over time. All operating parameters, including “Typicals” must be validated for each customer application by customer's technical experts. SCILLC does not convey any license under its patent rights nor the rights of others. SCILLC products are not designed, intended, or authorized for use as components in systems intended for surgical implant into the body, or other applications intended to support or sustain life, or for any other application in which the failure of the SCILLC product could create a situation where personal injury or death may occur. Should Buyer purchase or use SCILLC products for any such unintended or unauthorized application, Buyer shall indemnify and hold SCILLC and its officers, employees, subsidiaries, affiliates, and distributors harmless against all claims, costs, damages, and expenses, and reasonable attorney fees arising out of, directly or indirectly, any claim of personal injury or death associated with such unintended or unauthorized use, even if such claim alleges that SCILLC was negligent regarding the design or manufacture of the part. SCILLC is an Equal Opportunity/Affirmative Action Employer. This literature is subject to all applicable copyright laws and is not for resale in any manner. PUBLICATION ORDERING INFORMATION LITERATURE FULFILLMENT: Literature Distribution Center for ON Semiconductor P.O. Box 5163, Denver, Colorado 80217 USA Phone: 303-675-2175 or 800-344-3860 Toll Free USA/Canada Fax: 303-675-2176 or 800-344-3867 Toll Free USA/Canada Email: [email protected] N. American Technical Support: 800-282-9855 Toll Free USA/Canada Europe, Middle East and Africa Technical Support: Phone: 421 33 790 2910 Japan Customer Focus Center Phone: 81-3-5773-3850 http://onsemi.com 10 ON Semiconductor Website: www.onsemi.com Order Literature: http://www.onsemi.com/orderlit For additional information, please contact your local Sales Representative AND8242/D