quick start guide for demonstration circuit 438 triple phase, single ou tput step-down converter 1 ltc3731cg description demonstration circuit 438 is a triple phase single output synchronous buck converter featuring the ltc ? 3731cg. this circuit can be used for desktop computers and servers, notebook computers and other high output curren t dc/dc converters. the output voltage can be configured for either 2.5v or 1.8v and the maximum load current is 60a. the input voltage range of dc438 is 9v to 14v. the ltc3731cg requires a separate supply for its internal control circuits and for its gate drivers. dc438 is populated with a 5v lt1761 linear regulator for this purpo se. to obtain a higher bias/gate drive supply voltage, the user can apply an external dc source to the ?+5v? terminal on dc438. the maximum voltage for this input is 7.0v. dc438 also features an on-board high di/dt dynamic load circuit to measure the load step response. refer to the ?dynamic load testing? section for operating instructions. design files for this circuit board are available. call the ltc factory. ltc is a trademark of linear technology corporation table 1. performance summary parameter condition value minimum input voltage 9v maximum input voltage 14v v out v in = 9v to 14v, i out = 0a to 60a 2.5v 3% 1.8v 3% airflow 100% load 100 lfm quick start procedure demonstration circuit 438 is easy to set up to evaluate the performance of the ltc3731cg. refer to figure 1 for proper measure ment equipment setup and follow the procedure below: 1. with power off, connect the input voltage source and the load. the input cables should be sized for 20a and the load cables should be sized for 60a. 2. if an external bias supply is connected to ?+5v?, then the ?5v select? jumper should be in the ?ext? position. the external bias supply should be able to supply at least 100ma. 3. the jumpers should be in their default positions as shown in figure 1. 4. if a constant current load is used, preset the load current to about 5a or less before applying power to the input. otherwise, the foldback current limit function of the ltc3731 will be triggered during startup. 5. apply power to the input and set the input voltage to 12v. the output voltage should be 2.5v 3%. increase the load to 60a. the output voltage should still be within regulation. 6. keep the input voltage at 12.0v and the load at 60a. measure the dc input current. it should be less than 15.2a. 7. remove input power from the converter. set the voltage to 1.8v using ju mper jp3. apply 12v to the input and 60a to the output. the voltage should be 1.8v 3%. 8. for operation at 100% load and room tempera- ture ambient, use 100 lfm airflow or greater.
quick start guide for demonstration circuit 438 triple phase, single ou tput step-down converter 2 9. adjust the input voltage and load current to the desired levels within their limits and observe the regulation, output ripple, load step response, efficiency and other parameters. note: the bnc connectors labeled ?vout+? and ?load step? can be used to monitor the output voltage and load step waveforms, respectively, on an oscilloscope. dynamic load testing dc438 is populated with a high di/dt dynamic load circuit that is capable of applying a 0a to 60a load step to the output. the lowe r level of the step is fixed at 0a. to test this circuit, follow the instructions below: 1) put both the ?dlc? jumper and the ?dlc bias? jumper in the ?on? position. 2) turn-on the converter and set the external load to the low level of the load step. 3) adjust potentiometers r38, r34 and r33 to set the height, up slope and down slope of the load step respectively. 4) monitor the load step cu rrent and output volt- age. for the load step current, 5mv = 1a. figure 1. proper measurement equipment setup
quick start guide for demonstration circuit 438 triple phase, single ou tput step-down converter 3
quick start guide for demonstration circuit 438 triple phase, single ou tput step-down converter 4
linear technology corporation ltc3731cg 3-phase high efficiency 60a power supply bill of materials DC438A-3 item qty reference part description manufacture / part # 1 1 cin1 cap., trh hole 270uf 16v,c200d420 oscon, 16sp270m 2 0 cin2,cin3 cap., trh hole 270uf 16v,c200d420 oscon, 16sp270m 3 6 cin4,cin5,cin6,c16,c18,c20 cap., x5r 10uf 16v, 20%, 1210 taiyo yuden, emk325bj106mnt 4 0 cin7,cin8,cin9 cap., 1210 tbd 5 0 cout1,cout2,cout9,cout10 cap., 7343 opt 6 6 cout3-cout8 cap., 330uf 4v,7343 sanyo, 4tpd330m 7 4 c1,c11,c44,c47 cap., x5r 1uf 10v,0603 taiyo yuden, jmk107bj105ma 8 4 c2,c23,c29,c35 cap., x7r 0.01uf 16v 10% avx, 0603yc103kat1a 9 5 c3,c4,c5,c6,c53 cap., x7r 1000pf 50v 10% avx, 06035c102kat1a 10 8 c7,c26,c28,c32-c34,c37,c45 cap., x7r 0.1uf 16v 10% avx, 0603yc104kat1a 11 1 c8 cap., x7r 1500pf 50v 10% avx, 06035c152kat1a 12 2 c9,c36 cap., npo 100pf 50v 10% avx, 06035a101kat1a 13 3 c10,c13,c14 cap., x7r 0.22uf 10v 10% avx, 0603zc224kat1a 14 7 c12,c25,c27,c39,c42,c43,c46 cap., x7r 4.7uf 16v, 20%, 1206 taiyo yuden, emk316bj475mlt 15 4 c15,c17,c19,c38 cap., x7r 1uf 16v,0805 taiyo yuden, emk212bj105mg 16 0 c21 cap., 0603 tbd 17 1 c22 cap., npo 47pf 50v 10% avx, 06035a470kat1a 18 5 c30,c31,c54,c55,c56 cap., x7r 22uf 6.3v, 20%, 1206 taiyo yuden, jmk316bj226mlt 19 1 c40 cap., x7r 1uf 25v 80% avx, 12063c105zat1a 20 1 c41 cap., npo 10pf 50v 10% avx, 06035a100kat1a 21 5 c48-c52 cap., x5r 47uf 6.3v, 20%, 1812 taiyo yuden, jmk432bj476mm 22 1 d1 diode,schottky, sot23 diodes, bat54a 23 3 d2,d4,d5 diode, schottky 40v 3a, sma-diode diodes inc., b340a-13 24 1 d3 diode,schottky, sot23 diodes, bat54 25 2 d6,d8 diode, schottky rectifier 0.5a,sod123 diodes inc., b0540w 26 1 d7 diode, mmbz5231blt1, sot23 on semi., mmbz5231blt1 27 2 d9,d10 diode, cmdsh-3, sod323 central, cmdsh-3 28 9 e1-e9 testpoint, turret, .094" mill-max, 2501-2 29 7 jp1-jp7 jmp, 1x3 pins, .079" comm, 2802s-03g2 30 7 shunts for jp1-jp7 shunt, 2 pins, .079" comm con., ccij2mm-138g 31 4 j1,j2,j3,j4 stud, test pin pem kfh-032-10 32 8 for j1-j4 nut, brass nuts # 10-32 any #10-32 33 4 for j1-j4 ring, lug ring # 10 keystone #10 34 4 for j1-j4 washer, tin plated brass any #10 35 2 j5,j6 conn, bnc, 5 pins connex, 112404 page 1 - of - 2
linear technology corporation ltc3731cg 3-phase high efficiency 60a power supply bill of materials DC438A-3 item qty reference part description manufacture / part # 36 3 l1,l2,l3 ind, 0.8uh,l-cep125 sumida, cep125-0r8nc-u 37 1 l4 ind power, 10uh, l-cmd4d08 sumida, cmd4d08-100 38 1 l5 ind, 10uh, l-cls62 sumida, cls62-100 (6328-to64) 39 3 q1,q6,q10 trans, n-channel, so8-powerpak siliconix, si7860dp 40 0 q2,q5,q9 trans, opt, so8-powerpak opt 41 6 q3,q4,q7,q8,q11,q12 trans, n-channel, so8-powerpak siliconix, si7892dp 42 1 q13 trans, sud50n03-07,dpak-to252aa sil iconix, sud50n03-07 43 7 r1,r10-r15 res., chip 10 1/16w 5% aac cr16-100jm 44 2 r2,r36 res., chip 1k 1/16w 5% aac cr16-102jm 45 1 r3 res., chip 7.50k 1/16w 5% aac cr16-752jm 46 1 r4 res., chip 2.43k 1/16w 1% aac cr16-2431fm 47 4 r5,r6,r35,r43 res., chip 10.0k 1/16w 1% aac cr16-1002fm 48 1 r7 res., chip 20.0k 1/16w 1% aac cr16-2002fm 49 1 r8 res., chip 16.9k 1/16w 1% aac cr16-1692fm 50 1 r9 res., chip 13.3k 1/16w 1% aac cr16-1332fm 51 1 r16 res., chip 4.75k 1/16w 1% aac cr16-4751fm 52 1 r17 res., chip 121k 1/16w 1% aac cr16-1213fm 53 1 r18 res., chip 357k 1/16w 1% aac cr16-3573fm 54 0 r19,r31 res., 0603 tbd 55 1 r20 res., chip 1 1/16w 5% aac cr16-1r0jm 56 1 r21 res., chip 100k 1/16w 1% aac cr16-1003fm 57 0 r22,r24,r26 res., 2512 tbd 58 3 r23,r25,r27 res., 0.002 1w 5%, 2512 panasonic erjm1wtj2m0u 59 2 r28,r29 res., chip 51.1 1/16w 1% aac cr16-51r1fm 60 1 r30 res., chip 499k 1/16w 1% aac cr16-4993fm 61 1 r32 res., chip 1.5k 1/16w 5% aac cr16-152jm 62 3 r33,r34,r38 pot, 50k, 1turn, g3a bi, 22ar50k 63 1 r37 res., chip 15k 1/16w 5% aac cr16-153jm 64 1 r39 res., chip 2k 1/16w 5% aac cr16-202jm 65 2 r40,r42 res., lrf 0.01 1w 5% irc lrf2512-01-r010-j 66 1 r41 res., chip 39k 1/16w 5% aac cr16-393jm 67 1 r44 res., chip 115k 1/16w 1% aac cr16-1153fm 68 1 u1 i.c., ltc3731cg, ssop36g linear tech., ltc3731cg 69 1 u2 i.c., tlc555cd, so8 texas inst., tlc555cd 70 1 u3 i.c., lt1361cs8, so8 linear tech., lt1361cs8 71 1 u4 i.c., lt1210cr, ddpak-r-7p linear tech., lt1210cr 72 1 u5 i.c., lt1460hcs3-2.5, sot23 linear tech., lt1460hcs3-2.5 73 1 u6 i.c., lt1930es5, sot23-5 linear tech., lt1930es5 74 1 u7 i.c., lt1761es5-5, sot23-5 linear tech., lt1761es5-5 75 4 for mtgs at 4 corners screw, #4-40, 1/4" any 76 4 for mtgs at 4 corners standoff, nylon hex #4-40 1/2" microplastics, 14htsp003 notes: unless otherwise specified 1. all resistors are in ohms, 0603. 2. install shunts on jp1-jp7 pin 2 and 3. page 2 - of - 2
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