1 description ltc 3624edd high efficiency synchronous step-down regulator with ultralow quiescent current demonstration circuit dc2005a is a synchronous step- down regulator using an lt c ? 3624 monolithic buck regulator. the dc2005a operates from an input voltage range of 2.7 v to 17 v and provides an adjustable output voltage range from 1.2 v to 5v (v out < v in ) at 2 a of output current. a user-selectable mode input is provided to allow the user to trade off ripple noise for light load efficiency. burst mode ? operation provides the highest efficiency at light load, while pulse-skipping mode provides the lowest voltage ripple. the mode pin can also be used to sync the switching frequency to an external clock. the switching frequency is fixed at 1 mhz or 2.25mhz with a 40% synchronizing range. the regulator features ultralow quiescent current and high efficiency over a wide v out range. l , lt, ltc, ltm, linear technology, the linear logo and burst mode are registered trademarks of linear technology corporation. all other trademarks are the property of their respective owners. the dc2005a uses very low profile surface mount com- ponents and all ceramic output capacitors. the compact 8-lead dfn (3mm 3 mm) package makes the ltc3624 an excellent choice for battery-powered equipment, general purpose step-down power supply, and emergency radio applications. it is recommended to read the data sheet and demo manual of the ltc3624 prior using or making any changes to dc2005a. design files for this circuit board are available at http://www .linear.com/demo performance summary specifications are at t a = 25c parameter conditions value input voltage range 2.7v to 17v onboard user selectable output voltages v in = 2.7v to 17v, i out = 2a (v out v in ) 1.2v, 1.8v, 2.5v, 3.3v and 5v default mode setting jp2 burst mode operation (bm) default switching frequency 1mhz default output voltage, v out v in = 12v, v out = 5v, i out = 0a to 2a 5v 2% maximum continuous output current, i out 2a output voltage ripples (peak-to-peak) v in = 12v, v out = 5v, i out = 2a 9.4mv (see figure 5) load transient response v in = 12v, v out = 5v, i out = 1a to 2a see figure 6 thermal image v in = 12v, v out = 5v, i out = 2a, 1mhz see figure 7 efficiency v in = 12v, v out = 5v, i out = 2a, bm, 1mhz 90.4% (see figure 3 ) dc2005af demo manual dc2005a
2 quick start procedure demonstration circuit dc2005 a is easy to set up to evaluate the performance of the ltc3624. please refer to figure1 for proper measurement equipment setup and follow the procedure below: 1. place jumpers in the following positions for a typical 5v output application: table 1. typical 5v output voltage jumper selection jp1 jp2 jp7 run mode/sync vout on bm 5.0v 2. with power off, connect the input power supply at vin (e1) and gnd (e2). 3. connect the load between vout ( e8) and gnd (e9). preset the load to 0a. 4. connect the dmms to the input and output to monitor the input voltage and output voltage. 5. turn on the power supply at the input. the run pin jumper should be at on position. measure and make sure the input supply voltage is 12 v. the output voltage should be 5v 2%. 6. once the input and output voltages are properly es - tablished adjust the loads within the operating range (0a to 2 a max) and observe the output voltage regula- tion, output ripple voltage, switch node waveform and other parameters. refer to figure 2 for proper input/ output voltage ripple measurement. 7. to select other output voltages, use the on board user selectable output voltage jumpers. shutting down ltc3624 by placing run pin jumper ( jp1) to the off position or turn off the input power supply. refer to the following table ( table 2) for the output voltage selection and repeat steps 2 to 6: table 2. output voltage jumper selection jp3 jp4 jp5 jp6 jp7 jp8 1.2v 1.8v 2.5v 3.3v 5v *user select * note: if jp8 is selected, r6 needs to be calculated and inserted to obtain the desired output voltage. note 1: to measure the input/output voltage ripple prop- erly, do not use the long ground lead on the oscilloscope probe. see figure 2 for the proper scope probe technique. short, stiff leads need to be soldered to the (+) and (C) terminals of an output capacitor. the probes ground ring needs to touch the (C) lead and the probe tip needs to touch the (+) lead. note 2: the dc2005 a can also be used to evalu - ate ltc 3624 - 2 (2.25 mhz) by simply changing u1 to ltc3624 - 2 and l1 to 1.5h ( coilcraft xal4020-152me). dc2005af demo manual dc2005a
3 quick start procedure figure 1. proper equipment measurement setup figure 2. scope probe placements for measuring input or output ripple dc2005af demo manual dc2005a
4 quick start procedure load current (a) 60 efficiency (%) 70 80 90 100 0.01 1 2 50 0.1 1.2v out 1.8v out 2.5v out 3.3v out 5.0v out v in = 12v i out = 0a to 2a f sw = 1mhz load current (a) 0 efficiency (%) 70 80 2 60 50 0.5 1 1.5 100 90 1.2v out 1.8v out 2.5v out 3.3v out 5.0v out v in = 12v i out = 0a to 2a f sw = 1mhz v out 20mv/div v sw 10v/div 20mhz bw limit v in = 12v v out = 5v i out = 2a f sw = 1mhz 1s/div v out 200mv/div i out 1a/div v p-p = 250mv 1a to 2a v in = 12v v out = 5v i out = 1a 100s/div figure 3. measured efficiency in burst mode operation (bm) figure 4. measured efficiency in forced continuous mode (fcm) figure 5. measured output voltage ripple figure 6. load transient response dc2005af demo manual dc2005a
5 quick start procedure no forced airflow t a = 24c v in = 12v v out = 5v i out = 2a f sw = 1mhz figure 7. thermal performance dc2005af demo manual dc2005a
6 parts list item qty reference part description manufacturer/ part number required circuit components 1 1 cff cap, 0402 15pf 5% 50v npo avx 04025a150 jat 2a 2 1 cin cap, 47f 20% 20v 33m panasonic oscon 20svpa47m 3 2 c2,c3 cap, 1206 22f10% 25v x5r murata grm31cr61e226ke15l 4 1 c4 cap, 1206 47f 20% 6.3v x5r taiyo yuden jmk316bj476ml-t 5 1 c8 cap, 0603 2.2f 10% 10v x5r murata grm188r61a225ke34p 6 1 l1 ind, 3.3h coilcraft xal4030-332me 7 2 r1, rset res, 0402 619k 1% 1/16w vishay crcw0402619kfked 8 1 r2 res, 0402 309k 1% 1/16w vishay crcw0402309kfked 9 1 r3 res, 0402 196k 1% 1/16w vishay crcw0402196kfkea 10 1 r4 res, 0402 137k 1% 1/16w vishay crcw0402137kfked 11 1 r5 res, 0402 84.5k 1% 1/16w vishay crcw040284k5fked 12 2 r7, r12 res, 0402 0 jumper vishay crcw04020000z0ed 13 1 r11 res, 0402 1m 5% 1/16w vishay crcw04021m00jned 14 1 u1 ic, monolithic synchronous buck regulator linear tech LTC3624EDD additional demo board circuit components 1 0 c5 cap, 1206 22f 20% 6.3v x5r option taiyo yuden emk316bj226ml-t option 2 0 c6 cap, 1210 option option 3 0 c7 cap, 0402 option option 4 0 r6, r8 res, 0402 option option 5 0 r9, r10 res, 0402 1m 5% 1/16w option vishay crcw04021m00jned option hardware 1 10 e1, e2, e3, e4, e5, e6, e7, e8, e9, e10 turret mill-max 2501-2-00-80-00-00-07-0 2 1 jp1 header, 3-pin, 2mm samtec tmm-103-02-l-s 3 1 jp2 header, 4-pin, 2mm samtec tmm-104-02-l-s 4 6 jp3, jp4, jp5, jp6, jp7, jp8 header, 2-pin, 2mm samtec tmm 102-02-l-s 5 4 mh1, mh2, mh3, mh4 standoff, snap on keystone_8833 6 3 jp1, jp2, jp3 shunt, 2mm samtec 2sn-bk-g dc2005af demo manual dc2005a
7 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 5 5 4 4 3 3 2 2 1 1 d d c c b b a a [1] cin is an optional capacitor. it is inserted on the dc2005a to dampen the (possible) ringing voltage due to the long input leads. on a normal, typical pcb, with short traces, the capacitor is not needed. notes: [2] for fcm operation, stuff r9 and r10 with 1meg ohm resistor. [2] [2] [2] vout intvcc intvcc size date: ic no. rev. sheet of title: approvals pcb des. app eng. technology fax: (408)434-0507 milpitas, ca 95035 phone: (408)432-1900 1630 mccarthy blvd. ltc confidential-for customer use only customer notice linear technology has made a best effort to design a circuit that meets customer-supplied specifications; however, it remains the customer's responsibility to verify proper and reliable operation in the actual application. component substitution and printed circuit board layout may significantly affect circuit performance or reliability. contact linear technology applications engineering for assistance. this circuit is proprietary to linear technology and schematic supplied for use with linear technology parts. scale = none www.linear.com 2 tuesday, january 07, 2014 11 monolithic synchronous buck regulator mi g le n/a LTC3624EDD demo circuit 2005a with ultra-low quiescent current size date: ic no. rev. sheet of title: approvals pcb des. app eng. technology fax: (408)434-0507 milpitas, ca 95035 phone: (408)432-1900 1630 mccarthy blvd. ltc confidential-for customer use only customer notice linear technology has made a best effort to design a circuit that meets customer-supplied specifications; however, it remains the customer's responsibility to verify proper and reliable operation in the actual application. component substitution and printed circuit board layout may significantly affect circuit performance or reliability. contact linear technology applications engineering for assistance. this circuit is proprietary to linear technology and schematic supplied for use with linear technology parts. scale = none www.linear.com 2 tuesday, january 07, 2014 11 monolithic synchronous buck regulator mi g le n/a LTC3624EDD demo circuit 2005a with ultra-low quiescent current size date: ic no. rev. sheet of title: approvals pcb des. app eng. technology fax: (408)434-0507 milpitas, ca 95035 phone: (408)432-1900 1630 mccarthy blvd. ltc confidential-for customer use only customer notice linear technology has made a best effort to design a circuit that meets customer-supplied specifications; however, it remains the customer's responsibility to verify proper and reliable operation in the actual application. component substitution and printed circuit board layout may significantly affect circuit performance or reliability. contact linear technology applications engineering for assistance. this circuit is proprietary to linear technology and schematic supplied for use with linear technology parts. scale = none www.linear.com 2 tuesday, january 07, 2014 11 monolithic synchronous buck regulator mi g le n/a LTC3624EDD demo circuit 2005a with ultra-low quiescent current jp8 user select jp8 user select 15pf cff 15pf cff r7 0 r7 0 e6 pgood e6 pgood 47uf c4 6.3v 1206 47uf c4 6.3v 1206 e8 vout 2a e8 vout 2a c7 opt c7 opt jp1 on off run jp1 on off run 1 3 2 r5 84.5k 1% r5 84.5k 1% jp4 1.8v jp4 1.8v u1 LTC3624EDD (1mhz) u1 LTC3624EDD (1mhz) vin 2 run 3 intvcc 6 mode/sync 7 pgood 4 fb 5 sw 1 8 gnd 9 gnd r3 196k 1% r3 196k 1% jp7 5.0v jp7 5.0v c8 2.2uf 10v 0603 c8 2.2uf 10v 0603 22uf c3 25v 1206 22uf c3 25v 1206 e10 gnd e10 gnd c6 opt 1210 c6 opt 1210 e2 gnd e2 gnd rset 619k 1% rset 619k 1% e3 intvcc e3 intvcc r1 619k 1% r1 619k 1% r11 1m r11 1m opt c5 1206 opt c5 1206 r10 opt r10 opt e7 run e7 run l1 3.3uh l1 3.3uh r2 309k 1% r2 309k 1% e5 gnd e5 gnd e9 gnd e9 gnd e1 vin 2.7v - 17v e1 vin 2.7v - 17v r4 137k 1% r4 137k 1% 22uf c2 25v 1206 22uf c2 25v 1206 jp3 1.2v jp3 1.2v jp2 bm fcm / sync mode ps jp2 bm fcm / sync mode ps 1 3 2 4 + cin 47uf 20v [1] + cin 47uf 20v [1] e4 sync e4 sync r8 opt r8 opt r6 opt r6 opt r12 0 r12 0 jp5 2.5v jp5 2.5v jp6 3.3v jp6 3.3v r9 opt r9 opt dc2005af demo manual dc2005a
8 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 0114 ? printed in usa demonstration board important notice linear technology corporation ( lt c ) 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 lt c 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 p arty 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 lt c 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. lt c assumes no liability for applications assistance, customer product design, software performance, or infringement of patents or any other intellectual property rights of any kind. lt c 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 lt c applica- tion engineer. mailing address: linear technology 1630 mccarthy blvd. milpitas, ca 95035 copyright ? 2004, linear technology corporation dc2005af demo manual dc2005a
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