quick start guide for demonstration circuit 571 8/16 channel differential 24 bit adc ltc2418 description the ltc2418 is a high resolution, 24- bit ? adc with 5ppm inl and 5 v off- set. channel selection is programmed through a simple serial interface. since there is no latency, each con- version is valid, even after a change in input channel. DC571A is a member of linear technol- ogy?s quickeval? family of demonstra- tion boards. it is designed to allow easy evalua- tion of the ltc2418 and may be con- nected directly to the target appli- cation?s analog signals while using the dc590 usb serial controller board and supplied software to measure per- formance. after evaluating with ltc?s software, the digital signals can be connected to the application?s proces- sor/controller for development of the serial interface. design files for this circuit board are available. call the ltc factory. quick start procedure connect dc571 to dc590 usb serial controller using the supplied 14- conductor ribbon cable. connect dc590 to host pc with a standard usb a/b cable. run the evaluation software supplied with dc590 or downloaded from www.linear.com . the correct pro- gram will be loaded automatically. figu re 1. dc590 program click the collect button to start reading the input voltage. click the slider at the bottom of the strip- chart display to change the input channel being displayed. for differ- ential measurements, even channel pos and odd channel pos correspond to 1
quick start guide for demonstration circuit 571 8/16 channel differential 24 bit adc even channels being positive inputs or odd channels being positive in- puts, respectively. see the ltc2418 data sheet for details of channel se- lection. tools are available for logging data, changing reference voltage, changing the number of points in the strip chart and histogram, and changing the number of points averaged for the dvm display. 2
quick start guide for demonstration circuit 571 8/16 channel differential 24 bit adc hardware set-up jumpers select the connection for jp1: the common pin, either ground or external connection. single ended measurements are taken with respect to this pin. select the source for differential reference. selecting 5v and gnd will use the onboard 5 volt reference. select ext to use an ex- ternal reference. select notch frequency, 60hz jp5: or 50hz. alternatively, this jumper may be removed and an external conversion clock applied to the center pin of jp5. connection to dc590 serial controller j1 is the power and digital interface connector. connect to dc590 serial controller with supplied 14 conductor ribbon cable. jp2 and jp3: analog connections analog signal connections are made via the turret posts along the edge of the board (ch0 to ch15.) also, if you are connecting the board to an existing circuit, make full use of the four ground connections at the corners of the board. experiments figure 2 shows a number of applica- tions for the ltc2418. ch0, ch1, ch2 channels 0 and 1 measure the differ- ential output of an intersema ms5401 absolute pressure sensor. the 6.8k resistor performs a first order tem- perature compensation of the bridge output. ch2 measures the bridge volt- age, which provides a convenient tem- perature measurement. this can also be used to perform further tempera- ture compensation in software. ch3 channel 3 measures the output of a thermistor in a half bridge circuit. many thermistors will work, the con- straints are that the bridge output must have an impedance of less than 20k and the voltage must not go above v ref /2. ch4 channel 4 measures the output of a type j thermocouple. the circuit shown for channel 3 can be used for cold junction compensation. the cold junction sensor should be close to the connections of the thermocouple to the board. ch5 channel 5 measures the output of an omega os36-01 infrared thermocouple. this can be used for remote tempera- ture measurement. ch6 channel 6 measures the photocurrent of a hamamatsu s1336-5bk photodiode. 3
quick start guide for demonstration circuit 571 8/16 channel differential 24 bit adc ch7 channel 7 measures the output of a resistive attenuator. ch8, 9 channels 8 and 9 measure the drop across a deltec swe-3000-50 current shunt. up to 3000 amps can be meas- ured, with a resolution of 60ma. with careful grounding, both positive and negative currents can be measured. care must be taken to ensure that both inputs stay more positive than gnd?0.3v. ch10 channel 10 is buffered with an lt1793 fet input amplifier suitable for very high source impedance measurements. ch11 channel 11 measures the output of a precision rectifier. ch12, 13 channels 12 and 13 measure a 3-wire rtd. the differential voltage is the output, and ch12 single ended reading is the ground lead compensation. ch14, 15 channels 14 and 15 measure the output of a 350 ? bridge. this is standard for a wide variety of sensors. typi- cally the full-scale output voltage is only 10mv. however, the ltc2418 still gives 13 effective bits of resolution with no amplification. 4
quick start guide for demonstration circuit 571 8/16 channel differential 24 bit adc + 0v to 5v electrometer input (ph, piezo) 5v guard ring dc voltmeter input 1mv to 1000v ? v r3, 10k 5v max c1, 0.1 f lt1793 3 2 6 4 7 + + 5v ? v ltc1050 2 3 6 7 4 r4 1k r9 1k 1% + r7 10k, 0.1% r5 5k, 1% r8 100 ? , 5% 3-wire r-pack r6 10k, 0.1% in914 in914 1 f ac input 60hz 60hz?f rf power r1 900k 0.1%, 1w, 1000 wvdc r2 4.7k 0.1% 50 ? r13 5k 0.1% 5v daylight hamamatsu photodiode s1336-5bk 100 ? pt rtd (3-wire) rt force sense infrared infrared thermocouple omega 0s36-01 ref+ 50 ? load bonded to rtd on insulated mounting r11 24.9k, 0.1% j1 j2 j3 ref+ thermistor 10k ? ntc local temp r12 24.9k, 0.1% r10 5k 1% 60mv to 4v 2.7v at 0 c 0.9v at 40 c 20mv to 80mv < 1mv intersema ms5401-bm 0? bar absolute 3 2 4 6.8k 50ppm/ c ref+ 350 ? strain gage (load cell, torsion cell, pressure gage, etc. type j thermocouple 0mv a t ambient , 42.3mv a t 750 c above ambient deltec swe-3000-50 0a?000a + (iron) (constantan) 5
5 5 4 4 3 3 2 2 1 1 d d c c b b a a 2. install shunt on jp1-jp5 pin 1 and 2. 1. all resistors are in ohms, 0603. all capacitors are in microfarads, 0603. notes: unless otherwise specified ext 5v ext gnd ext gnd 60hz 50hz normal triggered a DC571A-1 * ltc2418cgn thursday, january 09, 2003 11 8-channel differential 24-bit adc kim t. mark t. a schematic size date: dwg no. rev sheet of title: contract no. approvals drawn: chec ked: approved: engineer: designer: technology fax: (408)434-0507 milpitas, ca 95035 phone: (408)432-1900 1630 mcca rthy blvd. ltc confidential-for cust omer use only trig mosi cs mosi sck sck ch0 ch1 ch2 ch3 ch4 ch5 ch6 ch7 ch15 ch14 ch13 ch12 ch11 ch10 ch9 ch8 com com vout ref+ ref+ cs/ vin ref- ref- miso vcc fo sdo vcc vcc vcc vcc vcc e21 ref+ e10 gnd c6 0.1uf jp3 ref- 1 3 2 u5 lt1236acs8-5 1 2 3 4 5 6 7 8 nc vin nc gnd trim vout nc nc c3 4.7uf,6.3v 0805 jp2 ref+ 1 3 2 c4 0.1uf c5 0.1uf r4 4.99k 1% e25 gnd e12 ch6 e14 ch4 e1 gnd e15 ch3 e18 ch0 c2 0.01uf e16 ch2 u3 24lc025 5 8 1 2 3 4 7 6 sda vcc a0 a1 a2 vss wp scl jp1 com 1 3 2 e17 ch1 e13 ch5 r2 100 e11 ch7 e5 ch11 u2 nc7sz157p6x 3 5 4 1 2 6 i0 vcc z i1 gnd s c7 0.1uf e24 gnd e6 ch12 e20 com j1 hd2x7-079-molex 8 5 12 11 10 9 6 7 3 4 2 1 13 14 8 5 12 11 10 9 6 7 3 4 2 1 13 14 e19 vcc jp4 trig mode 1 3 2 e8 ch14 u4 nl17sz74us 1 6 7 2 3 5 8 4 cp clr pr d q q vcc gnd e4 ch10 e26 fo e3 ch9 e7 ch13 e9 ch15 e23 trig c8 0.1uf e2 ch8 jp5 fo 1 3 2 r5 10k r1 opt r3 4.99k 1% e22 ref- u1 ltc2418cgn 5 8 1 2 3 4 7 6 13 14 20 19 18 17 16 15 26 25 24 23 22 21 27 28 9 10 11 12 ch12 ch15 ch8 ch9 ch10 ch11 ch14 ch13 nc nc sdi fo sck sdo cs gnd ch5 ch4 ch3 ch2 ch1 ch0 ch6 ch7 vcc com ref+ ref- c1 10uf,6.3v 0805
linear technology corporation ltc2418cgn 8-channel differential 24-bit adc eng: mark t. (25-30) bill of materials DC571A-1 qty-175 11/9/2004 10:31 am item qty referenc e part description manufacture / part # 1 1 c1 cap., x5r, 10uf 6.3v, 20%, 0805 tdk, c2012x5r0j106m 2 1 c2 cap., x7r 0.01uf 16v 10%,0603 avx, 0603yc103kat1a 3 1 c3 cap., x5r 4.7uf 6.3v, 20%, 0805 taiyo yuden, jmk212bj475mgt 4 5 c4,c5,c6,c7,c8 cap., x7r 0.1uf 16v,0603 avx, 0603yc104mat1a 5 26 e1-e26 testpoint, turret, 0.064" mill-max, 2308-2 6 5 jp1,jp2,jp3,jp4,jp5 jmp, 3pin 1 row .079cc comm-con, 2802s-03-g1 7 5 shunts for jp1-jp5 shunt, .079" center comm-con ccij2mm-138g 8 1 j1 header, 2x7pin, 0.079cc molex, 87331-1420 9 0 r1 res., 0603 opt 10 1 r2 res., chip 100 1/16w 5%,0603 aac, cr16-101jm 11 2 r3,r4 res., chip 4.99k 1/16w 1%,0603 aac, cr16-4991fm 12 1 r5 res., chip 10k 1/16w 5%,0603 aac, cr16-103jm 13 1 u1 i.c., ltc2418cgn, ssop16gn linear tech., ltc2418cgn 14 1 u2 i.c., nc7sz157p6x, sc70-6p fairchild semi., nc7sz157p6x 15 1 u3 i.c., 24lc025, tssop8 microchip, 24lc025 16 1 u4 i.c., nl17sz74us, us8 on semi., nl17sz74us 17 1 u5 i.c., lt1236acs8-5, so8 linear tech., lt1236acs8-5 notes: unless otherwise specified 1. all resistors are in ohms. 2. install shunts on jp1-jp5 pin 1 and 2. page 1 - of - 1
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