1 description lt 3790 60v four-switch synchronous buck-boost controller the dc2123 a is a 60 v four- switch synchronous buck- boost controller that demonstrates the high power capability of? the lt ? 3790 . the output is 24 v and the maximum output current is 5 a. the switching frequency is 200 khz and efficiency is as high as 98% for a 24v input. the LT3790 is capable of high power operation. dc2123a can be altered for either lower input voltage operation with the same output power or for increased output power with higher minimum input voltage. v in can be reduced to 8v in minimum and still deliver 120 w output by changing rs1 to 2 m, rin1 to 1.5 m, and r3 ( uvlo) to 88.7 k. if v in remains always above 20 v, i out can be increased to 12a + (for 290 w output) with the above changes, and an additional change of rout to 4m. the operating input voltage range of dc2123a is from 12v to 57 v. the output voltage, en/uvlo, and ovlo are all programmed by resistor dividers. en/uvlo is set so the circuit will turn off when the input voltage falls below 11.9v and will turn on when the input voltage rises above 13.4v. ovlo is set to engage for input voltages above 57 v. current sense resistors program input and output current limits and also determine the monitoring voltages that indicate input and output current. ivinmon provides a 60mv/1a voltage that is used to monitor the input cur - rent. input current limit occurs at 16.7 a and is set by rin1. ismon provides a 160 mv/1a voltage that is used to monitor the output current. the output current limit is 7.5a and is set by rs2. the demo circuit features mosfets that compliment the 5v gate drive of the LT3790 to achieve high efficiency . 60v mosfets are used on the input side of the four-switch topology while 40 v mosfets are used on the output side. ceramic capacitors are used at both the circuit input and output because of their small size and high ripple current capability. in addition to ceramic capacitors, there is an aluminum polymer capacitor on the output that assures feedback loop stability, even at low temperatures. the input has an aluminum electrolytic capacitor in addition l , lt, ltc, ltm, linear technology and the linear logo are registered trademarks of linear technology corporation. all other trademarks are the property of their respective owners. to ceramic capacitors. a two-stage l-c input filter can easily be added for electro-magnetic compatibility. the pcb has large copper planes and extensive vias for thermal performance. the clkout output and the sync input can be used to synchronize switching between two or more dc2123a circuits. a resistor from sync to ground must be removed prior to using the sync input. short and c /10 are open- collector status flag outputs and are pulled up to the intv cc pin voltage. a resistor shorts the ccm pin to c/10 and causes the circuit to change to discontinuous conduction mode ( dcm) when c /10 is active at light load currents. ccm can also be connected with a resistor to intv cc instead of c/10 for continuous conduc- tion mode (ccm) operation over the entire load range. the ctrl input is pulled up to the v ref pin through a 0? resistor to set the output current limit to its maximum, and an external voltage on ctrl can be used to lower the current limit if the resistor is removed. a capacitor at the ss pin programs soft-start and additionally ss is pulled up to the v ref pin through a 100 k resistor. the switching frequency is adjustable with a resistor. the demo circuit is designed to be easily reconfigured to many other applications, including the example schemat - ics in the data sheet. consult the factory for assistance. high power operation, four-switch buck-boost topology, fault protection and full monitoring make the LT3790 attractive for high power voltage regulator circuits and also circuits that require output current regulation such as battery chargers. the LT3790efe is available in a thermally enhanced 38- lead tssop package. the LT3790 data sheet must be read in conjunction with this demo manual to properly use or modify demo circuit dc2123a. design files for this circuit board are available at http://www .linear.com/demo/dc2123a dc2123af demo manual dc2123a
2 quick start procedure it is easy to set up demonstration circuit dc2123a to evaluate the performance of the LT3790. refer to figure ?1 for the proper measurement equipment setup and follow the procedure below: note: make sure that the voltage applied to pv in does not exceed the absolute maximum voltage rating of 60v for the LT3790. 1. connect the en/uvlo terminal to ground with a clip-on lead. connect the power supply ( with power off), load, and meters as shown. 2. after all connections are made, turn on the input power and verify that the input voltage is between 12 v and ?5 7 v . 3. remove the clip-on lead from en/uvlo. verify that the output voltage is 24v. note: if the output voltage is low, temporarily disconnect the load to make sure that it is not set too high. 4. once the proper output voltage is established, adjust the input voltage and load within the operating ranges and observe the output voltage regulation, ripple volt - age, efficiency and other parameters. performance summary specifications are at t a = 25c parameter conditions min typ max units minimum input voltage, v pvin v out = 24v i out 4.5a 12 v maximum input voltage, v pvin v out = 24v i out 5a 57 v maximum output current 13.3v < v pvin < 57v, ctrl = v ref v pvin = 12v, ctrl = v ref 5 4.5 a a input en v oltage, v pvin(en) r3 = 56.2k, r4 = 499k, v pvin rising 13.4 v input uvlo voltage, v pvin(uvlo) r3 = 56.2k, r4 = 499k, v pvin falling 11.9 v input ovlo turn-off voltage, v pvin(ovlo turn-off) r11 = 27.4k, r1 = 499k, v pvin rising 57.6 v input ovlo turn-on voltage, v pvin(ovlo turn-on) r11 = 27.4k, r1 = 499k, v pvin falling 56.2 v output voltage v out r19 = 71.5k, r34 = 1.37k, r20 = 3.83k 23.5 24.5 v efficiency v pvin = 24v, i out = 5a 98 % switching frequency r18 = 147k 200 khz input current limit rin1 = 0.003 16.7 a output current limit rs2 = 0.008 7.5 a dc2123af demo manual dc2123a
3 quick start procedure figure 1. proper measurement equipment setup for dc2123a figure 2. efficiency load current (a) 0 80 efficiency (%) 85 90 95 100 1 2 3 4 5 dc2123a f02 v in = 24v v in = 12v dc2123af demo manual dc2123a
4 quick start procedure figure 3. output voltage ripple at 5a output current, v out = 24v, 25mhz bandwidth figure 4. output voltage load transient response, v out = 24v, i out = 2.5a to 5a to 2.5a, 25mhz bandwidth v in = 14v v in = 24v v in = 54v v in = 14v v in = 24v v in = 54v dc2123af demo manual dc2123a
5 quick start procedure figure 5. v out in current limit, v in = 24v i out (a) 0 0 v out (v) 5 15 10 25 20 30 1 2 3 4 5 6 87 dc2009a f05 the LT3790 is an improved version of the lt3791-1 and is recommended for use in new designs. some external component values may change, but otherwise, the LT3790 is functionally equivalent to the lt3791-1. the differences between the two products are: 1. the LT3790 has a 60mv ( typical) full-scale v (isp-isn) current sense voltage, compared to 100mv ( typical) for the lt3791-1. this change allows lower power current sense resistors to be used for most applications. 2. the LT3790 ctrl pin linear range is from 0 v to 1.1v, and has a turn- off threshold of 50mv( typical), compared to a 200 mv to 1.1 v linear range and 175mv (typical) turn-off threshold for the lt3791-1. these changes make it easier to parallel two or more LT3790 ics for higher power levels. 3. the LT3790 c /10 pin pulls low when the v ( isp- isn) voltage is less than 1/10 full scale, compared to the lt3791-1, where c/10 pulls low when both v (isp-isn) is less than 1/10 full scale and v fb is greater than 1.15v(typical). since the c/10 pin is used to allow dcm mode for some applications, this change ensures that negative current does not occur at light loads for a broader range of applications. differences between LT3790 and lt3791-1 dc2123af demo manual dc2123a
6 parts list item qty reference part description manufacturer/ part number required electrical components 1 1 cc1 cap., x7r 0.01f 25v 10% 0603 avx 06033c103 kat 2a 2 1 cc2 cap., npo 1000pf 25v 10% 0603 avx 06033a102 kat 1a 3 1 css1 cap., x7r 33nf 25v 10% 0603 avx 06033c333 kat 1a 4 1 c1 cap., x5r 0.47f 16v 20% 0402 tdk c1005x5r1c474mt 5 3 c2, c12, c13 cap., x5r 0.1f 16v 10% 0402 tdk c1005x5r1c104kt 6 1 c3 cap., x5r 1f 100v 10% 1206 taiyo yuden hmk316bj105kl-t 7 1 c4 cap., x5r 4.7f 10v 10% 0603 taiyo yuden lmk107bj475ka 8 2 c6, c7 cap., x7s 4.7f 100v 10% 1210 tdk c3225x7s2a475k200ab 9 1 c10 cap., alum. elect. 47f 80v 20% united chemi-con emza800ada470mja0g 10 2 c14, c15 cap., x5r 4.7f 50v 20% 1210 taiyo yuden umk325bj475mm-t 11 2 c20, c30 cap., hybrid cond. polymer 220f 35v 20% sun electronic industries 35hvp220m 12 1 c29 cap., x7r 0.033f 16v 10% 0402 tdk c1005x7r1c333k 13 2 d1, d2 schottky barrier 100v sod323 (sc-90) nxp semi. bat 46wj 14 1 l1 inductor, 10h ser2900 coilcraft ser2918h-103kl 15 2 m1, m2 mosfet-n channel, 60v/25a lfpak renesas rjk0651dpb-00-j5 16 2 m3, m4 mosfet -n channel, 40v/35a lfpak renesas rjk0451dpb-00-j5 17 1 rc1 res., chip 15k 0.06w 5% 0402 vishay crcw040215k0jned 18 1 rin1 res., 0.003 1w 1% 2512 vishay wsl25123l000fea 19 1 rs1 res., 0.004 1/2w 1% 2010 vishay wsl20104l000fea 20 1 rs2 res., 0.008 1w 1% 2512 panasonic erj-m1wsf8m0u 21 2 r1, r4 res., chip 499k 0.06w 1% 0603 vishay crcw0603499kfkea 22 1 r3 res., chip 56.2k 0.06w 1% 0402 vishay crcw040256k2fked 23 1 r5 res., chip 51 0.06w 5% 0402 nic nrc04f51r0trf 24 2 r6, r10 res., chip 200k 0.06w 5% 0603 vishay crcw0603200kjnea 25 1 r11 res., chip 27.4k 0.06w 1% 0402 vishay crcw040227k4fked 26 1 r16 res., chip 200k 0.06w 5% 0402 vishay crcw0402200kjned 27 1 r17 res., chip 100k 0.06w 5% 0402 vishay crcw0402100kjned 28 1 r18 res., chip 147k 0.06w 1% 0402 vishay crcw0402147kfked 29 1 r19 res., chip 71.5k 0.06w 1% 0603 vishay crcw060371k5fkea 30 1 r20 res., chip 3.83k 0.06w 1% 0402 vishay crcw04023k83fked 31 1 u1 i.c., 60v buck-boost volt. reg. linear tech. corp. LT3790efe#pbf dc2123af demo manual dc2123a
7 parts list item qty reference part description manufacturer/ part number optional electrical components 1 0 c5, c8, c9, c16, c17, c18 (opt) cap., 1210 2 0 c11, c19 (opt) optional 3 0 c21, c22, c28 cap., 0603 4 0 c23 optional 5 0 c24, c25, c26, c27 (opt) optional 6 0 d3, d4 (opt) schottky diode, smb 7 0 d5, d6 (opt) diode, sod-123 8 0 d7 (opt) diode, sod-523 9 0 l2, l3 (opt) optional 10 0 m5, m6, m7, m8, m12 (opt) optional 11 0 m9, m10, m11 (opt) optional 12 0 r2, r23, r24, r26-r32 res., 0603 optional 13 1 r7 res.,chip 0? 1206 yageo rc1206fr-070rl 14 0 r8, r9, r25 res., 0402 optional 15 3 r12, r14, r22 res., chip 0? 0402 vishay crcw04020000z0ed 16 2 r13, r21 res., chip 0? 0603 vishay crcw06030000z0ea 17 1 r34 res., chip 1.37k 0.06w 1% 0603 panasonic erj-3ekf1371v hardware 1 4 e1, e2, e19, e20 connector, banana jack keystone 575-4 2 13 e3, e5, e6, e7, e8, e9, e10, e11, e12, e13, e14, e21, e22 turret, testpoint mill max 2308-2-00-80-00-00-07-0 3 5 e4, e15, e16, e17, e24 turret, testpoint mill max 2501-2-00-80-00-00-07-0 4 0 e18 (opt) optional 5 0 e23 (opt) optional 6 4 mh1-mh4 standoff nylon 0.50" keystone, 8833 (snap-on) dc2123af demo manual dc2123a
8 schematic diagram note: unless otherwise specified. all capacitors 0603. all resistors 0402 1%. snsp isp sw2 fb pwmout pwm ss *short tg2 bg2 bg1 tg1 sw1 *c/10 fb pwmout snsp bg1 sw1 tg1 tg2 sw2 bg2 isp *c/10 pwm intvcc vref ss *short intvcc intvcc vref pvin intvcc vin intvcc vref pvin vout ivinn tp6 tp6 r11 27.4k r11 27.4k r21 0 ohm 0603 r21 0 ohm 0603 tp2 tp2 m3 rjk0451dpb m3 rjk0451dpb r4 499k 0603 r4 499k 0603 m2 rjk0651dpb m2 rjk0651dpb c17 (opt) 1210 c17 (opt) 1210 tp4 tp4 e7 ctrl e7 ctrl c9 (opt) 1210 c9 (opt) 1210 c14 4.7f 50v 1210 c14 4.7f 50v 1210 r16 200k 5% r16 200k 5% m1 rjk0651dpb m1 rjk0651dpb r10 200k 0603 5% r10 200k 0603 5% r8 (opt) r8 (opt) c8 (opt) 1210 c8 (opt) 1210 e8 short e8 short e13 sync e13 sync r1 499k 0603 r1 499k 0603 + c30 220f 35v + c30 220f 35v c21 (opt) c21 (opt) d3 (opt) smb d3 (opt) smb c4 4.7f 10v c4 4.7f 10v c18 (opt) 1210 c18 (opt) 1210 c15 4.7f 50v 1210 c15 4.7f 50v 1210 r17 100k 5% r17 100k 5% u1 LT3790efe u1 LT3790efe en/uvlo 9 short 5 c/10 4 ivinn 11 ctrl 1 pwm 3 isp 25 sync 34 ss 2 pwmout 31 vc 36 rt 35 ivinmon 8 ismon 7 ivinp 10 clkout 33 vref 6 ovlo 38 snsn 28 snsp 27 isn 26 pgnd 17 pgnd 20 fb 37 tg2 24 sw2 21 bg2 19 bg1 18 sw1 16 tg1 14 bst1 15 bst2 22 ccm 32 vin 12 intvcc 13 sgnd 30 sgnd 39 test1 29 e20 gnd e20 gnd css1 33nf css1 33nf r12 0 ohm r12 0 ohm + c20 220f 35v + c20 220f 35v e12 clkout e12 clkout rs1 0.004 1% 2010 rs1 0.004 1% 2010 + c19 (opt) 12.5mm?dia. thru \hole + c19 (opt) 12.5mm?dia. thru \hole e9 c/10 e9 c/10 r34 1.37k 0603 r34 1.37k 0603 cc1 0.01f cc1 0.01f r3 56.2k r3 56.2k c5 (opt) 1210 c5 (opt) 1210 l1 10h ser2918h-103kl l1 10h ser2918h-103kl 1 2 3 c7 4.7uf 100v 1210 c7 4.7uf 100v 1210 e1 pvin 12v - 57v e1 pvin 12v - 57v e16 gnd e16 gnd e10 ivinmon e10 ivinmon c12 0.1f 0402 c12 0.1f 0402 r13 0 ohm 0603 r13 0 ohm 0603 r6 200k 0603 5% r6 200k 0603 5% tp5 tp5 e2 gnd e2 gnd c2 0.1f 0402 c2 0.1f 0402 + c11 (opt) 12.5mm?dia. thru \hole + c11 (opt) 12.5mm?dia. thru \hole c1 0.47f 0402 c1 0.47f 0402 e15 gnd e15 gnd tp3 tp3 e5 en/uvlo e5 en/uvlo r14 0 ohm r14 0 ohm e14 gnd e14 gnd e18 out (opt) e18 out (opt) r20 3.83k r20 3.83k c6 4.7uf 100v 1210 c6 4.7uf 100v 1210 + c10 47f 80v + c10 47f 80v m4 rjk0451dpb m4 rjk0451dpb rs2 0.008 2512 rs2 0.008 2512 e3 vin 12v - 57v e3 vin 12v - 57v r19 71.5k 0603 r19 71.5k 0603 c13 0.1f 0402 c13 0.1f 0402 c29 0.033f 0402 c29 0.033f 0402 r22 0 ohm r22 0 ohm e6 ovlo e6 ovlo c3 1f 100v 1206 c3 1f 100v 1206 rin1 0.003 1% 2512 rin1 0.003 1% 2512 d2 bat46wj d2 bat46wj rc1 15k 5% rc1 15k 5% r9 (opt) r9 (opt) c16 (opt) 1210 c16 (opt) 1210 r18 147k 200khz r18 147k 200khz e4 gnd e4 gnd r2 (opt) 0603 r2 (opt) 0603 cc2 1000pf cc2 1000pf e11 ismon e11 ismon e19 vout 24v 5a e19 vout 24v 5a d4 (opt) smb d4 (opt) smb r5 51 5% r5 51 5% d1 bat46wj d1 bat46wj tp1 tp1 r7 0 ohm 1206 r7 0 ohm 1206 e17 gnd e17 gnd dc2123af demo manual dc2123a
9 information furnished by linear technology corporation is believed to be accurate and reliable. however, no responsibility is assumed for its use. linear technology corporation makes no representa- tion that the interconnection of its circuits as described herein will not infringe on existing patent rights. schematic diagram isp sw1 sw2 *c/10 tg1 bg1 tg2 bg2 sw1 sw2 snsp snsp pwmout isp intvcc pwm *short ss fb isp sw2 bg2 isp fb pwmout snsp bg1 sw1 tg1 tg2 *c/10 intvcc pwm *short vref ss vin ivinn ivinn pvin pvin pvin vref vref + c23 47f 80v (opt) 10mm dia. surface mount + c23 47f 80v (opt) 10mm dia. surface mount m9 sot-23 (opt) m9 sot-23 (opt) l2 4.7h 7443551470 wurth electronik (opt) l2 4.7h 7443551470 wurth electronik (opt) e21 pwm e21 pwm m10 sot-23 (opt) m10 sot-23 (opt) m12 (opt) lfpak m12 (opt) lfpak c28 (opt) c28 (opt) r30 (opt) 0603 r30 (opt) 0603 c24 4.7f 100v 1210 (opt) c24 4.7f 100v 1210 (opt) e22 intvcc e22 intvcc r27 (opt) 0603 r27 (opt) 0603 d6 (opt) sod-123 d6 (opt) sod-123 r26 (opt) 0603 r26 (opt) 0603 m7 (opt) lfpak m7 (opt) lfpak r23 (opt) 0603 r23 (opt) 0603 c22 (opt) c22 (opt) r31 (opt) 0603 r31 (opt) 0603 c26 4.7f 100v 1210 (opt) c26 4.7f 100v 1210 (opt) m8 (opt) lfpak m8 (opt) lfpak d7 sod-523 (opt) d7 sod-523 (opt) c25 4.7f 100v 1210 (opt) c25 4.7f 100v 1210 (opt) r32 (opt) 0603 r32 (opt) 0603 d5 (opt) sod-123 d5 (opt) sod-123 c27 4.7f 100v 1210 (opt) c27 4.7f 100v 1210 (opt) r24 (opt) 0603 r24 (opt) 0603 r29 (opt) 0603 r29 (opt) 0603 l3 4.7h 7443551470 wurth electronik (opt) l3 4.7h 7443551470 wurth electronik (opt) m6 (opt) lfpak m6 (opt) lfpak m5 (opt) lfpak m5 (opt) lfpak e23 led- (opt) e23 led- (opt) r28 (opt) 0603 r28 (opt) 0603 r25 (opt) r25 (opt) e24 gnd e24 gnd m11 sot-23 (opt) m11 sot-23 (opt) dc2123af demo manual dc2123a
10 linear technology corporation 1630 mccarthy blvd., milpitas, ca 95035-7417 (408) 432-1900 fax : (408) 434-0507 www.linear.com ? linear technology corporation 2014 lt 1214 ? printed in usa demonstration board important notice linear technology corporation (ltc) provides the enclosed product(s) under the following as is conditions: this demonstration board ( demo board) kit being sold or provided by linear technology is intended for use for engineering development or evaluation purposes only and is not provided by ltc for commercial use. as such, the demo board herein may not be complete in terms of required design-, marketing-, and/or manufacturing-related protective considerations, including but not limited to product safety measures typically found in finished commercial goods. as a prototype, this product does not fall within the scope of the european union directive on electromagnetic compatibility and therefore may or may not meet the technical requirements of the directive, or other regulations. if this evaluation kit does not meet the specifications recited in the demo board manual the kit may be returned within 30 days from the date of delivery for a full refund. the foregoing warranty is the exclusive warranty made by the seller to buyer and is in lieu of all other warranties, expressed, implied, or statutory, including any warranty of merchantability or fitness for any particular purpose. except to the extent of this indemnity, neither party shall be liable to the other for any indirect, special, incidental, or consequential damages. the user assumes all responsibility and liability for proper and safe handling of the goods. further, the user releases ltc from all claims arising from the handling or use of the goods. due to the open construction of the product, it is the users responsibility to take any and all appropriate precautions with regard to electrostatic discharge. also be aware that the products herein may not be regulatory compliant or agency certified (fcc, ul, ce, etc.). no license is granted under any patent right or other intellectual property whatsoever. ltc assumes no liability for applications assistance, customer product design, software performance, or infringement of patents or any other intellectual property rights of any kind. ltc currently services a variety of customers for products around the world, and therefore this transaction is not exclusive. please read the demo board manual prior to handling the product . persons handling this product must have electronics training and observe good laboratory practice standards. common sense is encouraged. this notice contains important safety information about temperatures and voltages. for further safety concerns, please contact a ltc application engineer. mailing address: linear technology 1630 mccarthy blvd. milpitas, ca 95035 copyright ? 2004, linear technology corporation dc2123af demo manual dc2123a
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