1 description lt c2325/lt c2324/lt c2320 quad/octal 16-bit/14-bit/12-bit, 5msps/2msps/1.5msps, serial, high speed sar adcs demonstration circuit 2395a features the lt c ? 2325/ LTC2324/ltc2320 family. with up to 5msps, these differ - ential, multiple channel, 16-bit, serial, high speed succes - sive approximation register (sar) adcs are available in a 52- lead qfn package. each adc has an internal 20ppm/c maximum drift reference and an spi-compatible serial interface that supports cmos and lvds logic. note the demo board is configured for cmos operation by default; see the note under jp8 for lvds operation. the following text refers to the ltc2325 , but applies to all members of the family, the only difference being the number of channels, l , lt, ltc, ltm, linear technology and the linear logo are registered trademarks and pscope is a trademark of linear technology corporation. all other trademarks are the property of their respective owners. the sample rate and/or the number of bits. the dc2395a demonstrates the dc and ac performance of the ltc2325 in conjunction with the dc890 pscope? data collection board. alternatively, by connecting the dc2395a into a customer application, the performance of the ltc2325 can be evaluated directly in that circuit. design files for this circuit board are available at http://www.linear.com/demo/dc2395a assembly o ptions table 1. dc2395a assembly options version u1 part number max conversion rate # of bits max clock frequency dc2395a-a ltc2320cukg-16#pbf 1.5msps 16 52.5mhz dc2395a-b LTC2324cukg-16#pbf 2msps 16 110mhz dc2395a-c ltc2325cukg-16#pbf 5msps 16 110mhz dc2395a-d ltc2320cukg-14#pbf 1.5msps 14 52.5mhz dc2395a-e LTC2324cukg-14#pbf 2msps 14 110mhz dc2395a-f ltc2325cukg-14#pbf 5msps 14 110mhz dc2395a-g ltc2320cukg-12#pbf 1.5msps 12 52.5mhz dc2395a-h LTC2324cukg-12#pbf 2msps 12 110mhz dc2395a-i ltc2325cukg-12#pbf 5msps 12 110mhz dc2395af demo manual dc2395a
2 b o a r d p hoto figure 1. dc2395a connection diagram signal generator clock signal from generator to dc890b 7v dc power supply ?7v dc power supply dc2395af demo manual dc2395a
3 quick s t a rt p roce d ure demonstration circuit 2395a is easy to set up and evaluate for performance. refer to figure 1 and follow the proce - dure below. n connect the dc2395a to a dc890 usb high speed data collection board using edge connector p1. n connect the dc890 to a host pc with a standard usb a/b cable. n apply a low jitter signal source to j11 to test channel?1. note that the dc2395 a is capable of accepting a differential input signal as well as a single-ended signal. see the hardware setup section for the jumper positions that correspond to these configurations. n as a clock source, apply a low jitter 10dbm sine wave or square wave to connector j9. see table 1 for maximum clock frequencies. note that j9 has a 50 termination resistor to ground. n run the pscope software (pscope.exe version k73, or later) supplied with the dc890 or download it from www.linear.com/software. complete software doc- umentation is available from the help menu. updates can be downloaded from the tools menu. check for updates periodically, as new features may be added. the pscope software should recognize the dc2395a and configure itself automatically. n click the collect button (figure 2) to begin acquiring data. the collect button then changes to pause, which can be used to stop data acquisition. d rive o p tions there are several ways to drive the ltc2325 on the dc2395 a. it can be driven with a true differential source, or a single-ended source in either pseudo-differential bipolar or unipolar mode. for details on how to configure the dc2395a for any of these see table 2. an example input circuit for channel 1 is shown in figure 3. table 2. resistor values for different input configurations input configuration r32, 52, 72, 104, 146, 179, 202, 222 r17, 37, 57, 88, 125, 163, 187, 207 r15, 35, 55, 75, 122, 159, 185, 205 r16, 36, 56, 76, 123, 160, 186, 206 r24, 44, 64, 100, 143, 173, 194, 214 differential 0? dni dni 0? dni single-ended differential adc drive 0? dni 301? 301? dni single-ended bipolar adc drive 0? dni dni 0? 0? unipolar adc drive dni 0? 301? 301? 0? *dni = do not install dc2395af demo manual dc2395a
4 figure 2. dc2395a pscope screenshot quick s t a rt p roce d ure dc2395af demo manual dc2395a
5 figure 3. example input circuit, single-ended differential adc drive 2 2 1 1 d d c c b b a a ??????????? ????? ??????????? ????? +6v -6v vcm_bias1 ain1- ref_out1 ain1+ r217 0 c124 dni c206 10uf r212 dni r222 0 r218 dni r207 dni r206 301 c203 dni + - u21b lt1819cms8 5 6 7 8 4 r213 49.9 c123 10uf r214 1k r209 dni c126 220pf r210 150 r216 dni c125 dni j11a bnc 1 4 3 r208 49.9 r221 dni r205 301 r203 0 r219 0 + - u21a lt1819cms8 3 2 1 8 4 j11b bnc 2 6 5 c127 dni r220 1k r211 0 r215 0 c129 10uf c207 10uf c128 dni c204 0.1uf r204 dni c2080.1uf quick s t a rt p roce d ure dc2395af demo manual dc2395a
6 signal c onnections j2 fpga program: factory use only. j4 jtag: factory use only. j11 ch1 input: in the single-ended configuration, use the upper bnc connector as the signal input. for differential operation, use the upper bnc as the ch1 + input, and the lower bnc as the ch1 C input. j10 ch2 input: in the single-ended configuration, use the upper bnc connector as the signal input. for differential operation, use the upper bnc as the ch2 + input, and the lower bnc as the ch2 C input. j8 ch3 input: in the single-ended configuration, use the upper bnc connector as the signal input. for differential operation, use the upper bnc as the ch3 + input, and the lower bnc as the ch3 C input. j7 ch4 input: in the single-ended configuration, use the upper bnc connector as the signal input. for differential operation, use the upper bnc as the ch4 + input, and the lower bnc as the ch4 C input. j6 ch5 input: in the single-ended configuration, use the upper bnc connector as the signal input. for differential operation, use the upper bnc as the ch5 + input, and the lower bnc as the ch5 C input. j5 ch6 input: in the single-ended configuration, use the upper bnc connector as the signal input. for differential operation, use the upper bnc as the ch6 + input, and the lower bnc as the ch6 C input. j3 ch7 input: in the single-ended configuration, use the upper bnc connector as the signal input. for differential operation, use the upper bnc as the ch7 + input, and the lower bnc as the ch7 C input. j1 ch8 input: in the single-ended configuration, use the upper bnc connector as the signal input. for differential operation, use the upper bnc as the ch8+ input, and the lower bnc as the ch8 C input. j9 clk: this input has a 50 termination resistor, and is intended to be driven by a low jitter 10dbm sine or square wave. to achieve the full ac performance of this part, the clock jitter should be kept under 2ps. this input is capacitively coupled so that the input clock can be either 0v to 2.5v or 1.25v . this eliminates the need for level shifting. to run at the maximum conversion rate, apply the frequency specified in the table 1. jp1 vccio: use this jumper to select the vccio supply voltage. the default setting is 2.5v. the 1.8v setting selects a 1.8v supply voltage. jp2 vdd: use this jumper to select the vdd supply volt - age. the default setting is 5v. the 3.3v setting selects a 3.3v supply voltage. j p5 ref int : set for int when using the internal reference. set for ext to disable the internal refout1-4 buffers for use with external voltage references. jp11 ref1: set for onb to use onboard voltage reference. set for ext to use external reference applied at e14. jp10 ref2: set for onb to use onboard voltage reference. set for ext to use external reference applied at e13. jp4 ref3: set for onb to use onboard voltage reference. set for ext to use external reference applied at e12. jp3 ref4: set for onb to use onboard voltage reference. set for ext to use external reference applied at e11. ha r d w a re s etup dc2395af demo manual dc2395a
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. jp8 sdr/ddr: set for sdr for single data rate operation. set for ddr for double data rate operation. jp6 cmos/lvds: use this jumper to select the data output format from the ltc2325. the default setting is cmos. the output data will not be valid if the jumper is moved to the lvds position unless the following changes have been made: install 100 s0402 resistors at r113, 114, 117, 118, 124, 239 reprogram the cpld through j2 using the program - ming file ltc2325_lvds.pof found at: http ://www .linear.com/demo/dc2395a move jp6 to the lvds position. jp7 eeprom : factory use only. jp9 osc: use this jumper to enable the onboard encode clock source. the default setting is off. the on setting energizes this source. refer to the dc2395a schematic for additional passive elements required to use the onboard source. ha r d w a re s etup dc2395af demo manual dc2395a
8 linear technology corporation 1630 mccarthy blvd., milpitas, ca 95035-7417 (408) 432-1900 fax : (408) 434-0507 www.linear.com ? linear technology corporation 2016 lt 0916 ? 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 whatsoeve r. 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 dc2395af demo manual dc2395a
|
