1 dc2027af demo manual dc2027a description ltc 4364hde-1 , 2 12v surge stopper with ideal diode demonstration circuit 2027a showcases the lt c ? 4364 surge stopper with ideal diode in a 12v, 1a application. dc inputs of up to 80v and transients to 250v are limited to just 28.7v at the output. sagging and reverse-polarity inputs of up to C24v are isolated from the output by a reverse-blocking mosfet configured as an ideal diode. further, the output is protected against backfeeding. the output may be driven C20v to +30v without circuit damage or backfeeding into the input. a 4.7f timer capacitor and robust forward mosfet permit the load to operate through iso-7637-2 load dump 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. performance summary waveform 5 a . sustained overvoltage or overcurrent condi- tions cause the ltc4364 to turn off after a timer delay. the ltc4364-1 (dc2027a-a) latches off and is reset by pulling shdn low for at least 100s. the ltc4364-2 (dc2027a-b) automatically retries after a three minute cool down delay. start-up and retry are inhibited in the presence of an input overvoltage. design files for this circuit board are available at http://www .linear.com/demo parameter conditions min typ max units input voltage limits operating dc survival 1ms transient 6.6 C24 12 27 80 250 v v v output voltage limits regulation voltage dc backfeed protection 27.2 C20 28.7 30.3 30 v v output current capability operating current limit 2.125 2.5 1 2.875 a a specifications are at t a = 25c quick start procedure danger! high voltage testing should be performed by qualified personnel only. as a safety precaution at least two people should be present during high voltage testing. board layout dc2027a is a 2-layer board. there are planes for input, output and ground; these are replicated on each layer. the 93mil input and output connection turrets are not swaged and may be removed for attachment of up to 12 awg wire. banana jacks facilitate bench testing. there are exposed conductors on the bottom of the board, and any banana plugs present will protrude through the bottom of the board. the underlying surface should be nonconductive and clear of any wire, solder and other conductive debris. the input plane is designed to have at least 78mil (2mm) clearance to adjacent conductors. this is adequate for 100v dc standoff and transients to 250v . spikes and surges are withstood by rled1, qled1, rov1, ruv1, r4, q1 (if present), d3, m1, rsnub and csnub. these components are chosen for wide pad spacing, pulse power capability and voltage stand off, but ultimately limit the maximum transient input voltage to 250v. the time spent above 80v is limited by the pulse power capability of r4.
2 dc2027af demo manual dc2027a quick start procedure figure 1. remove rvcc and add q1 to withstand prolonged inputs of up to 250v. r4 is increased to 270k o peration dc2027a has been designed for 12v operation with a load of up to 1a. m1 limits surges, spikes and transients, such as are commonly encountered in automotive applications. for positive-going events, the output is regulated at 28.7v. spikes of up to 250v are permissible for 1ms, limited by the pulse capability of r 4. the load may continue operating during positive transients, including load dump, without interruption. reverse inputs of up to C24v dc are blocked from reaching the load by m2. beyond C24v, a 400w transient voltage suppressor, d4, clamps the input. consult the smaj24a data sheet for specific information about peak current and time duration for spikes exceeding C24v. dc2027a-a is fitted with the ltc4364-1. this device latches off after a sustained overcurrent or overvoltage fault. operation is resumed after cycling the supply, or after pulsing shdn low for at least 100s. dc2027a-b is fitted with the ltc4364-2, which also shuts off the output in the presence of a sustained fault condi- tion, but automatically retries after a cool-down delay of 180 seconds. the cool-down delay may be prematurely interrupted by pulsing shdn low for at least 100s. in both cases, retry is inhibited by the ov pin if the input is higher than 16.8v, as is start-up. while a maximum load current of 1a is permitted during start-up and overvoltage conditions, current limit is set to 2.5a. this higher current level is permissible during normal (12v) operation. in short- circuit conditions where v out = 0v, current limit folds back to 1.25a. the output is protected against backfeeding over a range of C20v to 30v. if the output is connected to a low imped- ance source of less voltage than the input, m1 will likely go into current limit and fault off. if the output is higher than the input, m2 will block backfeeding. in the case that the output is higher than the 28.7v regulation voltage, the timer will run and m1 will fault off. optional components the pulse power limitations of r4 may be avoided by adding q1. pads are located on the bottom of the board. remove rvcc (a 0 jumper) and increase r4 to 270k (see figure 1). remember that the board spacing is only 78mils, and that this is inadequate for creepage and clear - ance at 250v dc . pads are included on the bottom of the board for optional output capacitors cout3 and cout4, in the event additional bypassing is desired. through-hole pads are included for adapting dc2027a to an off-board power stage, as shown in figure 2. v cc ltc4364 dc2027a f01 c1 100nf 100v q1 pzta42 rvcc removed d1 cmz5945b 68v d4 smaj24a d3 es1g r4 270k 1206 input
3 dc2027af demo manual dc2027a quick start procedure figure 2. connections to an off-board power stage. remove m1, m2, rsns, rsnub and resr from board. keep wires short to avoid parasitic oscillations in m1 small turrets no connection to any of the small turrets is necessary to make the board operatethe ltc4364 defaults to the on state. shdn is pulled high internally. if this turret is left open, the board will turn on when power is applied. short this turret to ground to turn off the ltc4364. f lt is an open-drain output which pulls low after a tmr interval if there is a sustained input overvoltage , and does so 94ms before the output shuts down. in overcurrent there is a brief early warning delay, the exact time of which depends on the severity of the overload. there is no pull-up resistor for f lt ; it must be pulled up to an external logic supply or to the output with an external resistor. f lt can sink up to 2ma. enout is an open-drain output which goes high when the output rises to within 700mv of the vcc pin. enout is latched and does not pull low again until the ltc4364 output drops below 2.2v. there is no pull-up resistor for enout; it must be pulled up to an external logic supply or to the output with an external resistor. enout can sink up to 2ma. tmr is made available so that its operation may be ex- amined easily with an oscilloscope, by way of a 10m probe. do not load or short this turret to ground as the timer function will be defeated and an overload may de- stroy m 1. tmr normally sits at ground, and charges to 1.35v in a fault condition. this turret also finds use for connecting different values of ctmr: simply remove the existing ctmr and solder substitutes between the tmr and gnd turrets. r5 10 dc2027a f02 resr c out rsnub 100 high current output high current 12v input csnub 10nf m2 rsns m1
4 dc2027af demo manual dc2027a how to o perate dc2027a danger! high voltage testing should be performed by qualified personnel only. as a safety precaution at least two people should be present during high voltage testing. to operate dc2027a, connect a 12v supply to the in- put and a 1a load to the output, as shown in figure 3. the circuit will turn on automatically when power is applied. up to C24v dc may be applied to the input with- out damage to dc2027a or the load. the output may be backfed with C20v to 30v, without damage to dc2027a or backfeeding of the input. the preferred method of coupling a transient to the input without backfeeding the 12v supply is to simply isolate the sources with blocking diodes, as shown in figure 4. dc2027a f03 1a load (12 ) 12v supply figure 3. basic test setup quick start procedure
5 dc2027af demo manual dc2027a dc2027a f04 1a load (12 ) input from surge generator mur460 mur460 12v supply figure 4. simple means of coupling surges, transients and spikes quick start procedure
6 dc2027af demo manual dc2027a parts list item qty reference part description manufacturer / part number required circuit components 1 1 chg cap., x7r, 10nf, 100v, 20%, 0805 avx , 08051c103 mat 2a 2 2 cout1, cout2 cap., x7s, 10f, 50v, 20%, 1210 tdk, c3225x7s1h106m 3 0 cout3, cout4 cap., x7s, 10f, 50v, 10%, 1210 opt 4 1 cov cap., x7r, 1nf, 100v, 20%, 0805 avx , 08051c102 mat 2a 5 1 csnub cap., x5r, 10nf, 500v, 20%, 1812 avx , 18127c103 mat 2a 6 1 ctmr cap., x5r, 4.7f, 10v, 10%, 0805 tdk, c2012x5r1a475k 7 2 c1, cuv cap., x7r, 100nf, 100v, 20%, 0805 avx , 08051c104 mat 2a 8 2 dled1, dled4 led, green j- type, led-ln1351c-green panasonic , ln1351c-tr 9 2 dled2, dled5 led, red j- type, led-ln1251c-red panasonic , ln1251c-tr 10 2 d2, dled3 diode, 300v, 250ma, sod523 diodes/zetex, bas521-7 11 1 d1 diode, zener, 68v, 1.5w, sma-diode central semi., cmz5945b 12 1 d3 diode, rectifier, 400v, 1.0a, sma-diode diodes inc., es1g-13-f 13 1 d4 diode, tvs , 24v, 400w, sma-diode diodes inc., smaj24a-13-f 14 2 d6, d7 diode, ddz9702s, 15v, 200mw, sod323 diodes inc., ddz9702s-7 15 6 e2, e3, e4, e5, e6, e8 testpoint, turret, 0.094 mill-max, 2501-2-00-80-00-00-07-0 16 4 e10, e11, e12, e14 testpoint, turret, 0.064 mill-max, 2308-2-00-80-00-00-07-0 17 4 j1, j2, j3, j4 banana jack, non- insulated keystone, 575-4 18 1 m 1 mosfet, n-ch, 250v, d2- pak fairchild , fdb33n25tm 19 1 m2 mosfet, n-ch, pwr 100v, 7.5a, so8 fairchild , fds3672 20 1 qled1 transistor, npn, 300v, sot223 fairchild , pzta42 21 1 qled2 transistor, npn, 40v, sot-23 diodes/zetex, mmbt3904-7-f 22 0 q1 transistor, pzta42, npn, 300v, sot223 opt 23 1 resr res., sense, 0.1, 1/8w, 5%, 0805 nic, ncst10jr100htrf 24 3 ruv1, rov1, rled1 res., chip, 249k, 1/4w, 1%, 1206 nic, nrc12f2493trf 25 1 rled2 res., chip, 200, 1/8w, 5%, 0805 nic, nrc10j201trf 26 2 rled3, rled4 res., chip, 3.3k, 1/4w, 5%, 1206 nic, nrc12j332trf 27 2 rov2, r8 res., chip, 21k, 1/8w, 1%, 0805 nic, nrc10f2102trf 28 1 rsns res., sense, 0.02, 1/4w, 5% 1206 nic, ncst12jr020jtrf 29 1 rsnub res., chip, 100, 1/2w, 5%, 1210 nic, nrcp25j101trf 30 1 ruv2 res., chip, 66.5k, 1/8w, 1%, 0805 nic, nrc10f6652trf 31 1 rvcc res., chip, 0, 0805 nic, nrc10z0trf 32 1 r4 res., chip, 2.2k, 1/4w, 5%, 1206 nic, nrcp12j222trf 33 1 r5 res., chip, 10, 1/8w, 5%, 0805 nic, nrc10j100trf 34 1 r7 res., chip, 453k, 1/8w, 1%, 0805 nic, nrc10f4533trf 35 4 mh1, mh2, mh3, mh4 standoff , nylon 0.5" keystone, 8833 (snap-on) 36 1 u1 i.c., LTC4364HDE-1, dc2027a-a linear technology, LTC4364HDE-1 37 1 u1 i.c., ltc4364hde-2, dc2027a-b linear technology, ltc4364hde-2
7 dc2027af demo manual dc2027a 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
8 dc2027af demo manual dc2027a linear technology corporation 1630 mccarthy blvd., milpitas, ca 95035-7417 (408) 432-1900 fax : (408) 434-0507 www.linear.com ? linear technology corporation 2013 lt 0313 ? 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 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 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 user s 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
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