? semiconductor components industries, llc, 2002 january, 2002 rev. 1 1 publication order number: cs51411demo/d cs51411demo/d demonstration note for cs51411/3 5.0 v-16 v to 3.3 v/1.0 a buck regulator description the cs51411 demonstration board is a 1.0 a/3.3 v buck regulator running at 260 khz (cs51411) or 520 khz (cs51413). the switching frequency can be synchronized to a higher frequency through feeding clock signals to the sync input. driving shdnb input low shuts down the converter output and minimizes the power consumption. the regulator has superior line and load regulation due to the use of v 2 ? control. this control method also enhances the load transient response. features ? v 2 control for superior line and load regulation ? small board space requiring only 1.0 0.7 in. 2 ? total of 11 components including ic ? shutdown mode disables the output and reduces the operating current ? frequency synchronization to higher frequency ? 1.5 a peak current protection which folds back 30% during overload conditions ? builtin soft start to eliminate any inrush current ? high energy transfer efficiency of 83% at 1.0 a load ? line regulation better than 0.1% ? load regulation better than 0.4% figure 1. cs51411/3 demonstration board http://onsemi.com demonstration note
cs51411demo/d http://onsemi.com 2 absolute maximum ratings pin name maximum voltage maximum current v in 16 v 2.0 a v o 16 v 2.0 a shdnb 7.0 v 1.0 ma sync 7.0 v 1.0 ma electrical characteristics (t a = 25 c, 5.0 v v in 16 v, 0.1 a i out 1.0 a, unless otherwise specified.) characteristic test conditions typ unit output voltage voltage accuracy 4.0 % line regulation i out = 1.0 a 0.1 % load regulation v in = 5.0 v 0.3 % minimum load 0.1 a transient response 3.0 % transient response time load toggle between 0.1 a and 1.0 a 10 m s startup time 5.0 ms input voltage start threshold 3.3 v sync and shutdown sync frequency cs51411 cs51413 290 to 470 575 to 900 khz khz minimum sync threshold voltage 1.0 v minimum shutdown threshold voltage 0.3 v maximum shutdown bias current 12 m a general switching frequency cs51411 cs51413 260 520 khz khz efficiency i load = 100 ma i load = 1.0 a 77.5 83 % % shutdown current 100 m a
cs51411demo/d http://onsemi.com 3 figure 2. application diagram v fb gnd v c boost v in sync v sw shdnb cs51411/3 876 21 5 3 4 c4 0.1 m f j6 sync j7 shdnb j8 gnd d3 b230dkt_nd c6 3300 pf r2 127 w r1 205 w c3 100 m f j5 gnd j4 v out 3.3 v j3 swnode l1 15 m h c1 0.1 m f d1 1n4148 c5 0.1 m f c2 100 m f j1 gnd j2 v in 416 v operation guidelines 1. connect input voltage between j2 and j1 on the left side of the board. the maximum input voltage is limited by the voltage rating of the input capacitor. 2. connect the load between j4 and j5. the regulator requires 100 ma as minimum load. without this minimum load, the output may exceed the regulation voltage. 3. connect shutdown signal between j7 and j8. when the voltage on this input is below 0.3 v, the regulator enters a sleep mode. pull this input high or leave it open if not used. 4. the sync signal can be applied between j6 and j8. the amplitude of the sync pulses needs to be greater than 1.0 v. the duty cycle can vary from 10% to 90%. leave it open if not used. theory of operation 1. boost strapping circuit: the boost strapping circuit, made of c1 and d1, provides a voltage higher than the input voltage to drive the power transistor (inside ic) into saturation. the operation of the boost strapping circuit works as follows. when the power transistor turns off, diode d3 turns on and pulls the v sw node to ground. diode d1 is forward biased, and the output voltage charges c1 to v o . when the power transistor turns on, the v sw node is pulled high and is approximately equal to v in . now the voltage of the boost pin, which connects to c1, is equal to v in + v o . diode d1 is reverse biased. the boost pin voltage provides adequate base current to the power transistor, which lowers v ce(sat) and improves the energy transfer efficiency. 2. soft start: the softstart is implemented on the v c pin. during the startup, the limited source current (25 m a) of the error amplifier charges the v c pin capacitor. the rising slope of the v c pin voltage clamps the duty cycle through the pwm comparator. the v c pin voltage eventually settles down to a voltage roughly equal to the reference voltage 1.27 v. therefore, the startup time can be easily calculated. 3. feedback network: v 2 control relies on the output ripple to provide pulse width modulation. when the output ripple is inadequate, pulse skipping or instability may be observed. adding a capacitor c6 in parallel with r1 provides a low impedance pass for the output ripple. therefore, the output ripple is not attenuated by the resistor divider. the use of this capacitor is optional. please see data sheet for more description on regulator operation and component selection (document number cs51411/d available through the literature distribution center or via our website at http://www.onsemi.com).
cs51411demo/d http://onsemi.com 4 typical performance characteristics 5 input voltage output current figure 3. line regulation figure 4. load regulation output current figure 5. efficiency vs. output current 3.300 0.10 output voltage output voltage efficiency 88 0.10 3.290 3.289 3.288 3.287 3.286 3.285 3.284 3.283 3.282 3.281 3.280 6 7 8 9 10111213141516 3.295 3.290 3.285 3.280 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90 1.0 0 87 86 85 84 83 82 81 80 79 78 77 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90 1.00 bill of materials ref. designator vendor part number type pc/board c1, c4, c5 digikey pcc1762ctnd 0.1 m f ceramic 3 c2, c3 avx taje107k016r 100 m f tantalum 2 c6 digikey pcc1778ctnd 3300 pf ceramic 1 d1 digikey ll4148ctnd diode 1 d3 digikey b230dictnd 2.0 a schottky 1 j1j8 digikey v1055 test point 8 l1 coiltronics up2.8b150 15 m h inductor 1 r1 digikey p205ctrnd 205 w resistor 1 r2 digikey p127ctrnd 127 w resistor 1 u1 on semiconductor cs51411/3 controller 1
cs51411demo/d http://onsemi.com 5 drawings of layers figure 6. top copper figure 7. bottom copper figure 8. top silk
cs51411demo/d http://onsemi.com 6 notes
cs51411demo/d http://onsemi.com 7 notes
cs51411demo/d http://onsemi.com 8 on semiconductor and are 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. atypicalo parameters which may be provided in scill c data sheets and/or specifications can and do vary in different applications and actual performance may vary over time. all operating parameters, including atypicalso 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 sit uation 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 unauthori zed 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. publication ordering information japan : on semiconductor, japan customer focus center 4321 nishigotanda, shinagawaku, tokyo, japan 1410031 phone : 81357402700 email : r14525@onsemi.com on semiconductor website : http://onsemi.com for additional information, please contact your local sales representative. cs51411demo/d v 2 is a trademark of switch power, inc. literature fulfillment : literature distribution center for on semiconductor p.o. box 5163, denver, colorado 80217 usa phone : 3036752175 or 8003443860 toll free usa/canada fax : 3036752176 or 8003443867 toll free usa/canada email : onlit@hibbertco.com n. american technical support : 8002829855 toll free usa/canada
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