quick start guide for demonstration circuit dc573 24 bit micropower no latency delta sigma adc 1 ltc2400 description this demonstration board features the ltc2400, a 24 bit high performance ? analog-to-digital converter (adc). the ltc2400 combines exemplary dc accu- racy (inl +/-2ppm, 2.5 v offset, 0.3ppm noise) with an easy to use spi interface in a so-8 package. dc573 is a member of linear technology?s quickeval? family of demonstration boards. it is de- signed to allow easy evaluation of the ltc2400 and may be connected directly to the target application?s analog signals while using the dc590 usb serial controller board and supplied software to measure performance. the exposed ground planes allow proper grounding to prototype circuitry. after evalu- ating with ltc?s software, the digital signals can be connected to the end application?s processor / con- troller for development of the serial interface. design files for this circuit board are available. call the ltc factory.
quick start guide for demonstration circuit dc573 24 bit micropower no latency delta sigma adc 2 quick start procedure connect dc573 to a dc590 usb serial controller using the supplied 14 conductor ribbon cable. con- nect dc590 to host pc wit h a standard usb a/b ca- ble. run the evaluation software supplied with dc590 or downloaded from www.linear.com . the correct program will be loaded automatically. click the collect button to start r eading the input voltage. details on software features are documented in the control panel?s help menu. tools are available for logging data, changing refer- ence voltage, changing the number of points in the strip chart and histogram, and changing the number of points averaged for the dvm display.
quick start guide for demonstration circuit dc573 24 bit micropower no latency delta sigma adc 3 hardware set-up jumpers jp1 ? select the reference source, either external or 5.00 volts from the onboard lt1236 reference (de- fault.) jp2 ? select the line rejection frequency, either 50hz or 60hz (default.) thi s jumper must be re- moved if applying an exte rnal conversion clock to the fo turret post. jp3 ? trigger mode, either normal (default) or ex- ternally triggered. jp4 ? trigger input signal. pin 1 is a 5 volt logic signal, pin 2 is ground. when triggered mode is selected on jp3, a rising edge starts a new conver- sion. connection to dc590 serial controller j1 is the power and digital interface connector. connect to dc590 serial controller with supplied 14 conductor ribbon cable. analog connections analog signal connections are made via the row of turret posts along the edge of the board. also, if you are connecting the board to an existing circuit, the exposed ground planes along the edges of the board may be used to fo rm a solid connection be- tween grounds. gnd ? ground turrets are connected directly to the pcb?s ground planes. vcc ? this is the supply for the adc. do not draw any power from this point . external power may be applied to this point after disabling the switching supply on dc590. if the dc590 serial controller is being used, the voltage must be regulated 5 volts only, as the isolation circ uitry will also be powered from this supply. refer to the dc590 quick start guide for more details. vref - this turret is conne cted to the ltc2400 ref- erence pin. if the onboard re ference is being used, the reference voltage may be monitored from this point. an external ground re ferred reference may be connected to this terminal if jp1 is configured for external reference. vin ? input voltage to the ltc2400. the absolute range of the input volt age is gnd ? 0.3v to vcc + 0.3v. the range for a valid conversion is gnd ? 0.125*vref to 1.125 vref. see figure 1 . figure 1. ltc2400 input range
quick start guide for demonstration circuit dc573 24 bit micropower no latency delta sigma adc 4 experiments offset short vin to ground. the offset is typically less than 0.5ppm of vref, with a m aximum of 2ppm of vref (2.5 v typical and 10 v max when using a 5 volt reference.) full scale short vin to vref. the full-scale error is typically less than 4ppm, with a maximum of 10ppm of vref (20 v typical and 50 v max when using a 5 volt reference.) rms noise short vin to ground. the rms noise display indi- cates the rms noise based on a number of samples that can be set in the software options. with the input shorted to ground, th e indicated noise is the noise of the ltc2400 input. when another source is connected, the indicated noise is the total noise of the ltc2400 and the source. the usb controller powers the ltc2400 from an lt1761 low noise regulator. although this device has exceptionally low noise for a power regulator, it may still slightly elevate the noise floor of the ltc2400. for lowest noi se operation, the ltc2400 may be powered from the onboard lt1236 refer- ence by cutting the indi cated trace and connecting vref to vcc as shown in figure 3. figure 2. proper meas urement equipment setup figure 3. low-noise setup
quick start guide for demonstration circuit dc573 24 bit micropower no latency delta sigma adc 5
linear technology corporation ltc1592acg 16-bit softspan dac eng: mark thoren (25-30) bill of materials dc572a-1 qty-175 11/9/2004 10:35 am item qty referenc e part description manufacture / part # 1 2 c1,c2 cap., y5v 4.7uf 25v, 20%, 1206 taiyo yuden, tmk316f475zg 2 1 c3 cap., x5r 4.7uf 6.3v, 20%, 0805 taiyo yuden, jmk212bj475mgt 3 1 c4 cap., npo 220pf 50v 10%,1206 avx, 12065a221kat1a 4 5 c5,c7,c8,c9,c10 cap., x7r 0.1uf 16v,0603 avx, 0603yc104mat1a 5 1 c6 cap., npo 30pf 50v 10%,1206 avx, 12065a300kat1a 6 8 e1-e8 testpoint, turret, .064" mill-max, 2308-2 7 2 jp1,jp2 jmp, 3pin 1 row .079cc comm-con, 2802s-03-g1 8 2 shunts for jp1 & jp2 shunt, .079" center comm-con ccij2mm-138g 9 1 j1 header, 2x7pin, 0.079cc molex, 87331-142 10 0 j2 conn, 5 pin gold, straight opt 11 1 j3 conn, 5 pin, straight connex, 112404 12 3 r1,r2,r3 res., chip 4.99k 1/16w 1%,0603 aac, cr16-4991fm 13 2 r4,r7 res., chip 10k 1/16w 5%,0603 aac, cr16-103jm 14 1 r5 res., 0603 opt 15 1 r6 res., chip 100 1/16w 5%,0603 aac, cr16-101jm 16 1 r8 res., chip 0 1/16w 5%,0805 aac, cj10-000m 17 0 tp1,tp2 test point opt 18 1 u1 i.c., ltc1592acg,ssop16g linear tech., ltc1592acg 19 1 u2 i.c., lt1469cs8,so8 linear tech., lt1469cs8 20 1 u3 i.c., lt1236acs8-5,so8 linear tech., lt1236acs8-5 21 1 u4 i.c., nl17sz74us, us8 on semi., nl17sz74us 22 1 u5 i.c., 24lc025, tssop8 microchip, 24lc025 23 1 for inventory only cable, ca-2440 notes: unless otherwise specified 1. all resistors are in ohms. 2. install shunts on jp1 and jp2 pin 1 and 2. page 1 - of - 1
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