LTC2411 LINER [Linear Technology], LTC2411 Datasheet
LTC2411
Available stocks
Related parts for LTC2411
LTC2411 Summary of contents
Page 1
... INL and 0.29ppm RMS noise. They use delta-sigma technology and provide single cycle settling time for multiplexed applications. Through a single pin, the LTC2411 can be configured for better than 110dB differential mode rejection at 50Hz or 60Hz 2%, and the LTC2411-1 can provide better than 87dB input differential mode rejection over the range of 49Hz to 61 ...
Page 2
... GND .................................... – 0. Digital Input Voltage to GND ........ – 0. Digital Output Voltage to GND ..... – 0. Operating Temperature Range LTC2411C ............................................... LTC2411I ............................................ – Storage Temperature Range ................. – 150 C Lead Temperature (Soldering, 10 sec).................. 300 C ELECTRICAL CHARACTERISTICS temperature range, otherwise specifications are at T ...
Page 3
... REF 49Hz to 61.2Hz (LTC2411-1) GND < IN Input Normal Mode Rejection (Note 7) 60Hz 2% (LTC2411) Input Normal Mode Rejection (Note 8) 50Hz 2% (LTC2411) Input Normal Mode Rejection (Note 15) 49Hz to 61.2Hz (LTC2411-1) Reference Common Mode 2.5V REF Rejection 2.5V, IN REF + Power Supply Rejection, DC REF = 2.5V, REF ...
Page 4
... LTC2411/LTC2411 DIGITAL I PUTS A D DIGITAL OUTPUTS operating temperature range, otherwise specifications are at T SYMBOL PARAMETER V High Level Input Voltage IH CS Low Level Input Voltage IL CS High Level Input Voltage IH SCK V Low Level Input Voltage IL SCK I Digital Input Current ...
Page 5
... O External Oscillator (Note 11) Internal Oscillator (LTC2411) (Note 10) Internal Oscillator (LTC2411-1) (Note 10) External Oscillator (Notes 10, 11) (Note 10) (Note 9) (Note 9) (Note 9) Internal Oscillator (LTC2411) (Notes 10, 12) Internal Oscillator (LTC2411-1) (Notes 10, 12) External Oscillator (Notes 10, 11) (Note 10) (Note 9) (Note 5) Note (external oscillator). ...
Page 6
... LTC2411/LTC2411 TYPICAL PERFOR A CE CHARACTERISTICS Total Unadjusted Error ( 5V) CC REF – – REF = 5V – REF = GND – 2.5V INCM F = GND O –3 –2.5 –2 –1.5 –1 –0.5 0 0.5 1 1.5 2 2.5 V (V) IN 2411 G01 Integral Nonlinearity ...
Page 7
... CC 0.8 REF– = GND 0 GND INCM F = GND 0 0.2 0 –0.2 –0.4 –0.6 –0.8 –1 (V) REF 2411 G17 LTC2411/LTC2411-1 RMS Noise 1.60 + REF = 2.5V – REF = GND 1. GND 1.50 1.45 1.40 1.35 1.30 4.3 5.1 2.7 3.1 3.5 3.9 4.7 V (V) CC Offset Error vs Temperature ...
Page 8
... REF = GND – GND – 1.25V – GND O –5 –45 –30 – TEMPERATURE ( C) 2411 G21 PSRR vs Frequency (LTC2411 4.1V DC 0.7V CC P-P + REF = 2.5V –20 – REF = GND + IN = GND – – GND F = GND –60 –80 –100 –120 – ...
Page 9
... REF CC more positive than the reference negative input, REF at least 0.1V. + – IN (Pin 4), IN (Pin 5): Differential Analog Input. The voltage on these pins can have any value between LTC2411/LTC2411-1 Conversion Current vs Output Data Rate 650 + REF = V CC – 600 ...
Page 10
... O CC digital filter first null is located at 50Hz. When the F connected to GND (F oscillator and the digital filter first null is located at 60Hz. For the LTC2411-1, the converter provides simultaneous 50Hz/60Hz rejection with the F When F O frequency f system clock and the digital filter first null is located at a ...
Page 11
... Clocked by the on-chip oscillator, the LTC2411 achieves a minimum of 110dB rejection at the line fre- quency (50Hz or 60Hz 2%) and the LTC2411-1 achieves a minimum of 87dB rejection over 49Hz to 61.2Hz. Ease of Use The LTC2411/LTC2411-1 data output has no latency, filter settling delay or redundant data associated with the conversion cycle ...
Page 12
... Output Data Format – pins covers the The LTC2411/LTC2411-1 serial output data stream is 32 bits long. The first 3 bits represent status information in- dicating the sign and conversion state. The next 24 bits are the conversion result, MSB first. The remaining 5 bits are sub LSBs beyond the 24-bit level that may be included in averaging or discarded without loss of resolution ...
Page 13
... Bit 5 is the least significant bit (LSB). Bits 4-0 are sub LSBs below the 24-bit level. Bits 4-0 may be included in averaging or discarded without loss of resolution. CS BIT 31 SDO EOC Hi-Z SCK 1 SLEEP Table 2. LTC2411/LTC2411-1 Output Data Format Differential Input Voltage 0.5 • REF 0.5 • – 1LSB REF 0.25 • ...
Page 14
... The LTC2411-1 internal oscillator provides better than 87dB normal mode rejection over the range of 49Hz to 61.2Hz. For this simultaneous 50/60Hz rejection connected to GND. The performance of the LTC2411-1 is the same as the LTC2411 when driven by an external conversion clock at F /2560 EOSC ...
Page 15
... SDO pin on the falling edge of the serial clock. In the Internal SCK mode of operation, the SCK pin is an output and the LTC2411/LTC2411-1 create their own se- rial clock by dividing the internal conversion clock the External SCK mode of operation, the SCK pin is used as input ...
Page 16
... Grounding CS will force the ADC to continuously convert at the maximum output rate selected by F SERIAL INTERFACE TIMING MODES The LTC2411/LTC2411-1’s 3-wire interface is SPI and MICROWIRE compatible. This interface offers several flexible modes of operation. These include internal/exter- nal serial clock 3-wire I/O, single cycle conversion. ...
Page 17
... GND BIT 31 BIT 30 BIT 29 BIT 28 EOC SIG MSB Hi-Z SLEEP DATA OUTPUT LTC2411/LTC2411-1 exceeds 1.9V. The level 50Hz REJECTION (LTC2411) = EXTERNAL OSCILLATOR = 60Hz REJECTION (LTC2411) = SIMULTANEOUS 50Hz/60Hz REJECTION (LTC2411-1) 3-WIRE SPI INTERFACE TEST EOC BIT 27 BIT 9 BIT 8 Hi-Z CONVERSION 2411 F06 17 ...
Page 18
... BIT 29 BIT 28 BIT 27 BIT 26 SIG MSB DATA OUTPUT Figure 8. Internal Serial Clock, Single Cycle Operation 50Hz REJECTION (LTC2411) = EXTERNAL OSCILLATOR = 60Hz REJECTION (LTC2411) = SIMULTANEOUS 50Hz/60Hz REJECTION (LTC2411-1) 2-WIRE I/O BIT 5 BIT 0 LSB 24 CONVERSION 50Hz REJECTION (LTC2411) = EXTERNAL OSCILLATOR = 60Hz REJECTION (LTC2411) ...
Page 19
... CONVERSION DATA OUTPUT Figure 9. Internal Serial Clock, Reduced Data Output Length the device is using its internal oscillator for the LTC2411 (F = logic LOW or HIGH) and 26 s for the LTC2411 logic LOW frequency f HIGH before time t state. The conversion result is held in the internal static shift register ...
Page 20
... CS. This can be avoided by adding an external 10k pull-up resistor to the SCK pin or by never pulling CS HIGH when SCK is LOW. Whenever SCK is LOW, the LTC2411/LTC2411-1’s inter- nal pull-up at pin SCK is disabled. Normally, SCK is not externally driven if the device is in the internal SCK timing mode ...
Page 21
... OH CC During the conversion period, the undershoot and/or overshoot of a fast digital signal connected to the LTC2411/ LTC2411-1 pins may severely disturb the analog to digital conversion process. Undershoot and overshoot can oc- cur because of the impedance mismatch at the converter pin when the transition time of an external control signal is less than twice the propagation delay from the driver to LTC2411/LTC2411-1 ...
Page 22
... U APPLICATIO S I FOR ATIO Particular attention must be given to the connection of the F signal when the LTC2411/LTC2411-1 are used with an O external conversion clock. This clock is active during the conversion time and the normal mode rejection provided by the internal digital filter is not very high at this fre- quency ...
Page 23
... PAR than the one predicted by Figures 13 and 14. The effect of the input dynamic current is almost the same for the LTC2411 and the LTC2411-1 and measurements of the LTC2411 with F = GND are plotted out as a typical case. O For simplicity, two distinct situations can be considered. ...
Page 24
... For the + LTC2411-1, when internal oscillator is used (F every 1 (external conversion full-scale common mode input signal into a differential mode input signal of 0.084ppm. When F external oscillator with a frequency f – ...
Page 25
... This current, nominally 1nA ( 10nA max), results in a small offset shift. A 100 source resistance will create a 0.1 V typical and 1 V maximum offset voltage. Reference Current In a similar fashion, the LTC2411/LTC2411-1 sample the + differential reference pins REF and REF amount of charge to and from the external driving circuits thus producing a dynamic reference current ...
Page 26
... INL error. When F = HIGH (internal oscillator and 50Hz notch), O every 100 of source resistance driving REF translates into about 0.37ppm additional INL error. For the LTC2411-1, when F = LOW, every 100 O + – resistance driving REF or REF 0.41ppm additional INL error. When F ...
Page 27
... A 100 source resistance will create a 0.05 V typical and 0.5 V maxi- mum full-scale error. Output Data Rate When using its internal oscillator, the LTC2411 can pro- duce up to 7.5 readings per second with a notch frequency of 60Hz (F = LOW) and 6.25 readings per second with a ...
Page 28
... LTC2411/LTC2411 APPLICATIO S I FOR ATIO 120 REF V = 2.5V 80 INCM EXT OSC – –80 –120 OUTPUT DATA RATE (READINGS/SEC) Figure 20. Offset Error vs Output Data Rate and Temperature 100 ...
Page 29
... LTC2411/LTC2411-1 input bandwidth is shown in Figure 28. When an external oscillator of fre- quency f is used, the shape of the LTC2411/LTC2411-1 EOSC input bandwidth can be derived from Figure 28, F curve of the LTC2411 in which the horizontal axis is scaled by f /153600. EOSC The conversion noise (1.45 V RMS can be modeled as a white noise source connected to a noise free converter ...
Page 30
... Figure 29 can still be used for noise calculation if the EOSC x-axis is scaled by f /153600. For large values of the EOSC ratio f /153600, the Figure 29 plot accuracy begins to EOSC decrease, but in the same time the LTC2411/LTC2411-1 1000 100 F = LOW HIGH O 1 ...
Page 31
... The user can expect to achieve in practice this level of performance using the internal oscillator demon- strated by Figures 34 to 36. Typical measured values of the normal mode rejection of the LTC2411 operating with an internal oscillator and a 60Hz notch setting are shown in Figure 34 superimposed over the theoretical calculated curve ...
Page 32
... REF LTC2411-1 have a full-scale differential input range of 5V peak-to-peak. Figures 37 and 38 show measurement re- sults for the LTC2411 normal mode rejection ratio with a 7.5V peak-to-peak (150% of full scale) input signal super- imposed over the more traditional normal mode rejection ratio results obtained with a 5V peak-to-peak (full scale) input signal and Figure 39 shows the corresponding mea- surement result for the LTC2411-1 ...
Page 33
... The mathematical summation of the output of multiple LTC2411/LTC2411-1’s provide the benefit of a root square reduction in noise. The low power consumption of the LTC2411/LTC2411-1 make it attractive for multidrop communication schemes where the ADC is located within the load-cell housing. A direct connection to a load cell is perhaps best incorpo- ...
Page 34
... A gain of 34 may seem low, when compared to common practice in earlier generations of load-cell interfaces, how- ever the accuracy of the LTC2411/LTC2411-1 changes the rationale. Achieving high gain accuracy and linearity at higher gains may prove difficult, while providing little benefit in terms of noise reduction ...
Page 35
... S 2. REF R1 25.5k 3 0.1% – REF LTC2411/ LTC2411 PLATINUM 100 5 RTD – GND 6 2411 F43 Figure 43. Remote Half Bridge Interface 0 REF 3 – REF 20k LTC2411/ LTC2411-1 20k 5 – IN GND 6 2411 F42 , REF 35 ...
Page 36
... U APPLICATIO S I FOR ATIO bridge output can be eliminated completely; if the refer- ence arm of the bridge is used as the reference to the ADC, as shown in Figure 43. The LTC2411/LTC2411-1 can accept inputs Hence, the reference resistor REF R1 must be at least 2 the highest value of the variable resistor. In the case of 100 platinum RTD’ ...
Page 37
... F FILM 12 200 14 –10V LTC2411/LTC2411-1 15V LT1236 0 0 LTC2411/ LTC2411 REF 3 – REF – IN GND *FLYING CAPACITORS ARE 1 F FILM (MKP OR EQUIVALENT SEE LTC1043 DATA SHEET FOR DETAILS ON UNUSED HALF ...
Page 38
... LTC2411/LTC2411-1, via an inexpensive multiplexer such as the 74HC4052. Figure 46 shows the use of an LTC2411/LTC2411-1 with a differential multiplexer. This is an inexpensive multi- plexer that will contribute some error due to leakage if used directly with the output from the bridge resistors are inserted as a protection mechanism from overvoltage ...
Page 39
... Plastic MSOP (Reference LTC DWG # 05-08-1661) 0.118 0.004* (3.00 0.102) 0.193 0.006 (4.90 0.15) 0.043 (1.10) MAX 0 – 6 TYP SEATING PLANE 0.007 – 0.011 0.021 0.006 (0.17 – 0.27) (0.53 0.015) LTC2411/LTC2411 0.118 0.004** (3.00 0.102 0.034 (0.86) REF 0.005 0.002 (0.13 0.05) 0.0197 MSOP (MS10) 1100 (0.50) ...
Page 40
... Pin Compatible with the LTC2410 ADC in SO-8 1.2ppm Noise, 8ppm INL, Pin Compatible with LTC2400 ADC 1.2ppm Noise, Pin Compatible with LTC2404/LTC2408 www.linear.com 5V LT1236 0 LTC2411/ LTC2411 REF 3 – REF – IN RN1 GND 10k 6 RN1 IS CADDOCK T914 10K-010-02 ...