DEMO MANUAL DC979A LTC2442 24-Bit High Speed 4-Channel DS ADC with Integrated Amplifier Description The LTC®2442 is a 2-/4-channel, high speed, 24-bit ΔΣ ADC with ten selectable speed/resolution modes from 6.9Hz/200nVRMS to 3.5kHz/25μVRMS. Key DC specifications include 4ppm maximum INL, 5μV offset, 10ppm fullscale error and 20nV/°C offset drift. In the 6.9Hz/200nVRMS mode, an input normal mode rejection of 50Hz and 60Hz noise is better than 87dB. The accuracy (offset, full-scale, linearity, drift) and power dissipation are independent of the speed selected. The LTC2442 incorporates rail-to-rail buffer amplifiers for true high impedance inputs. DC979A is a member of Linear Technology’s QuikEval™ family of demonstration boards. It is designed to allow easy evaluation of the LTC2442 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 evaluating with LTC’s software, the digital signals can be connected to the application’s processor/controller for development of the serial interface. Design files for this circuit board are available at http://www.linear.com/demo L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and QuikEval and SoftSpan are a trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. Board Photo Figure 1. DC979A Demonstration Board DC979Af 1 DEMO MANUAL DC979A Quick Start Procedure 1. Connect the DC979A to a DC590 USB serial controller using the supplied 14-conductor ribbon cable. 2. Connect the DC590 to the host PC with a standard USB A/B cable. 3. Run the QuikEval evaluation software supplied with the DC590 or download it from www.linear.com/software. The correct program will be loaded automatically. 5. Click the slider at the bottom of the strip chart display to change the oversample ratio (OSR) which will in turn change the data output rate. 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. 4. Click the COLLECT button to start reading the input voltage. Figure 2. QuikEval Software Hardware Setup Jumpers JP1, JP2: Select the source for REF + and REF –, respectively. REF + can be 5.00V from the onboard LT®1236 reference (default) or supplied externally. REF – can be ground (0V, default) or supplied externally. JP3: Select source for analog COM input, either tied to ground or supplied externally to the COM turret post. 2 JP6, JP7: Select the positive and negative supply voltages for the onboard amplifier. Supplies can be VCC and GND or +10 and –5V from the onboard LTC1983 charge pump. To use an external power supply, REMOVE JP6 and JP7 and connect the external supply to the V +, GND, and V – turrets. JP4: Trigger mode, either normal (default) or externally triggered (TRIG). DC979Af DEMO MANUAL DC979A Hardware Setup JP5: Enable/disable the LTC1983 charge pump power supply for onboard amplifier. See JP6, JP7 description. JP8: Trigger Input Signal. Pin 1 is a 5V logic input, Pin 2 is ground. When triggered mode is selected on JP4, a rising edge starts a new conversion. Note that since a conversion cannot be terminated once started, this signal can only be used to slow down the conversion rate. CONNECTION TO DC590 SERIAL CONTROLLER J1 is the power and digital interface connector. Connect to the DC590 serial controller with the 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 form a solid connection between grounds. GND: Ground turrets are connected directly to the internal analog ground plane. 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 the DC590. If the DC590 serial controller is being used, the voltage must be regulated 5V only, as the isolation circuitry will also be powered from this supply. See the DC590 Quick Start guide for details. REF+, REF –: These turrets are connected to the LTC2442 REF + and REF – pins. If the onboard reference is being used, the reference voltage may be monitored from this point. An external reference may be connected to these terminals if JP1 and JP2 are configured for external reference. Note: The REF + and REF – terminals are decoupled to ground with 0.01μF and 4.7μF capacitors in parallel. Thus, any source connected to these terminals must be able to drive a capacitive load and have very low impedance at DC. Examples are series references that require an output capacitor and C-load stable op amps, such as the LT1219 and LT1368/ CH0-CH3: These are the differential inputs to the LTC2442. They may be configured either as single-ended inputs with respect to the COM pin, or adjacent pairs may be configured as differential inputs (CH0-CH1, CH2-CH3.) Experiments INPUT NOISE COMMON MODE REJECTION Solder a short wire from CH0 to CH1. Ensure that the buffer amplifiers are in their active region of operation by either biasing the inputs to mid-supply with a 10kΩ to 10kΩ divider when the buffer amplifier is powered from VCC and ground, or tie the inputs to ground and select +10 and –5V for V + and V –. Tie the two inputs (still connected together from the previ ous experiment) to ground through a short wire and note the indicated voltage. Tie the inputs to REF +; the difference should be less than 5μV due to the 120dB CMRR of the LTC2442. Set the demo software to OSR32768 (6.8 samples per second) and check the 2X box. Noise should be approximately 0.04ppm of VREF (200nV.) Next, select different oversample ratios. Measured noise for each oversample ratio should be close to the values given in the LTC2442 data sheet. Select +10 and –5V for V + and V – for this experiment. If the common mode voltage is limited to GND + 0.25V to VCC – 0.25V, this test may be performed with the amplifier supplies set to ground and VCC. DC979Af 3 DEMO MANUAL DC979A Experiments INPUT NORMAL MODE REJECTION The LTC2442’s SINC4 digital filter is trimmed to strongly reject both 50Hz and 60Hz line noise when operated with the internal conversion clock and oversample ratio 32768 (6.8 samples per second.) To measure input normal mode rejection, connect COM to a 2.5V source such as an LT1790-2.5 reference or a power supply. Connect any other input (CH0-CH3) to the same supply through a 10k resistor. Apply a 10Hz, 2V peak-to-peak sine wave to the input through a 1µF capacitor. Select OSR32768 (6.8 samples per second) and 2X mode in the demo software and start taking data. The input noise will be quite large, and the graph of output vs time should show large variations. Next, slowly increase the frequency to 55Hz. The noise should be almost undetectable in the graph. Change the OSR to 16384 (13.75 samples per second) the noise will increase substantially, as the first notch at this OSR is at 110Hz. Increase the signal generator frequency to 110Hz, the noise will drop again. Parts List ITEM QTY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER CAP., X7R, 0.1µF, 16V, 20%, 0402 TDK, C1005X7R1C104M DC979A Required Circuit Components 1 7 C1, C4, C11-C15 2 8 C2, C5, C7, C8, C9, C16, C17, C21 CAP., X5R, 4.7µF, 10V, 20%, 0603 TDK, C1608X5R0J475M 3 3 C3, C6, C10 CAP., X7R, 0.01µF, 25V, 10%, 0402 AVX, 04023C103KAT1A 4 3 C18, C19, C20 CAP., X5R, 2.2µF, 10V, 20%, 0805 TDK, C2012X5R1A225M 5 3 D1, D2, D3 DIODE, SCHOTTKY, SOT23 DIODE INC., BAT54S 6 16 E1-E16 TESTPOINT, TURRET, 0.064" MILL-MAX, 2308-2 7 7 JP1-JP7 JMP, 3-PIN, 1 ROW, 0.079" SAMTEC, TMM-103-02-L-S 8 7 FOR JP1-JP7, PIN 1 AND PIN 2 SHUNT, 0.079" CENTER SAMTEC, 2SN-BK-G 9 0 JP8 JMP, 2-PIN, 1 ROW, 0.100" COMM CON., 3801S-02G2 10 1 J1 HEADER, 2×7 PIN, 0.079" MOLEX, 87831-1420 11 0 J2 CONN, 5-PIN, GOLD, STRAIGHT CONNEX, 132134 12 0 R1 RES., 0402 OPT 13 3 R2, R3, R4 RES., CHIP, 4.99k, 1/16W, 1%, 0402 AAC, CR05-4991FM 14 1 R5 RES., CHIP, 100, 1/16W, 5%, 0402 VISHAY, CRCW0402101J 15 2 R6, R13 RES., CHIP, 10k, 1/16W, 5%, 0402 AAC, CR05-103JM 16 1 R7 RES., CHIP, 51, 1/16W, 5%, 0402 AAC, CR05-510JM 17 4 R8, R9, R10, R12 RES., CHIP, 0, 1/16W, 5%, 0805 AAC, CJ10-000M 18 0 R11 RES., CHIP, 0, 1/16W, 5%, 0805 OPT 19 1 U1 I.C., LTC2442CG, SSOP36G LINEAR TECHNOLOGY, LTC2442CG 20 1 U2 I.C., LT1236ACS8-5, SO8 LINEAR TECHNOLOGY, LT1236ACS8-5 21 1 U3 I.C., 24LC025, TSSOP8 MICROCHIP, 24LC025-I/ST 22 1 U4 IC, NON-INVERTING MULTIPLEXER, SC70 FAIRCHILD, NC7SZ157P6X 23 1 U5 IC, SINGLE D, FLIP-FLOP, US8 ON SEMI., NL17SZ74US 24 1 U6 I.C., LTC1983ES6-5, SOT23-6 LINEAR TECHNOLOGY, LTC1983ES6-5 4 DC979Af A B C D COM CH3 CH2 CH1 CH0 REF- REF+ C16 4.7UF,10V 0603 VCC OFF 1 2 VCC 1 2 VCC 5 D2 BAT54S D1 BAT54S C9 4.7UF,10V 0603 R12 0 0805 D3 BAT54S 0805 C18 2.2UF,10V 6 CH0 7 CH1 18 -INB 17 OUTB 12 OUTA 13 -INA 10 ADCINB 11 ADCINA 28 COM 8 CH2 9 CH3 30 REF+ 31 REF- VCC C2 4.7UF,10V 0603 VCC C20 2.2UF,10V 0805 R11 OPT 0 0805 R8 0 0805 COM CH3 CH2 CH1 CH0 REF- REF+ EXT JP2 REFEXT GND JP3 COM EXT GND JP1 REF+ 5V 1 VCC VOUT 2 6 SHDN GND 5 3 C+ C- 4 U6 LTC1983ES6-5 C14 0.1UF C12 0.1UF C19 2.2UF,10V 0805 3 3 C10 0.01UF C6 0.01UF NC 8 NC 7 VOUT 6 TRIM 5 C5 4.7UF,10V 0603 JP5 AMP SUPPLY ON E7 E6 E5 E4 E3 E2 E1 3 NC C1 0.1UF 4 GND 1 NC 2 VIN 4 MUXOUTA V- E15 +10V E14 GND E11 -5V C15 0.1UF +INB R10 0 0805 MUXOUTB +INB 19 +10V -5V 10K CS +INA R6 MISO BUSY SCK +INA 25 MUXOUTB 26 MUXOUTA 27 INT-EXT/ 3 BUSY 2 FO 34 SDI 33 CS/ 35 SCK 1 SDO 36 R9 0 0805 C4 0.1UF U1 LTC2442CG V+ MOSI R7 51 1 FO OPT JP8 C13 0.1UF R13 10K 2 D 1 CP VCC 3 I0 1 I1 2 GND Z 4 VCC Q 5 Q 3 U5 NL17SZ74US S 6 VCC 5 3 THIS CIRCUIT IS PROPRIETARY TO LINEAR TECHNOLOGY AND SUPPLIED FOR USE WITH LINEAR TECHNOLOGY PARTS. LINEAR TECHNOLOGY HAS MADE A BEST EFFORT TO DESIGN A CIRCUIT THAT MEETS CUSTOMER-SUPPLIED SPECIFICATIONS; HOWEVER, IT REMAINS THE CUSTOMER'S RESPONSIBILITY TO VERIFY PROPER AND RELIABLE OPERATION IN THE ACTUAL APPLICATION. COMPONENT SUBSTITUTION AND PRINTED CIRUIT BOARD LAYOUT MAY SIGNIFICANTLY AFFECT CIRCUIT PERFORMANCE OR RELIABILITY. CONTACT LINEAR TECHNOLOGY APPLICATIONS ENGINEERING FOR ASSISTANCE. CUSTOMER NOTICE FO OPT U4 NC7SZ157P6X R1 2 DESIGNER: KIM T. ENGINEER: MARK T. APPROVED: CHECKED: DRAWN: APPROVALS CONTRACT NO. GND -5V +10V VCC R2 4.99K 1% -5V +10V VCC R4 4.99K 1% J1 HD2X7-079-MOLEX 14 NC 11 EESCL 12 EEGND 10 EEVCC 9 EESDA 5 MISO 7 MOSI 6 CS 4 SCK 1 V+ 2 5V V- V+ VCC VIN E13 V- E12 GND E10 V+ E9 GND E8 VCC E16 VIN 1630 McCarthy Blvd. Milpitas, CA 95035 Phone: (408)432-1900 Fax: (408)434-0507 LTC Confidential-For Customer Use Only JP7 V- JP6 V+ R3 4.99K 1% 0603 C7 VIN 4.7UF,10V 1 DATE: A SIZE 1 SHEET DC979A-LTC2442CG Monday, September 26, 2005 DWG NO. 1 OF 1 A REV 4-CHANNEL, HIGH SPEED, 24-BIT ADC WITH BUFFER TITLE: C11 0.1UF 0603 C8 4.7UF,10V VCC TECHNOLOGY SCHEMATIC 3 A2 SCL 6 4 VSS SDA 5 VCC 8 WP 7 U3 24LC025 1 A0 2 A1 JP4 TRIG. MODE TRIG. NORMAL R5 100 2. INSTALL SHUNTS ON JP1-JP7 PIN 1 AND 2. 1. ALL RESISTORS ARE IN OHMS, 0402. ALL CAPACITORS ARE IN MICROFARADS, 0402. MOSI OPT J2 2 NOTES: UNLESS OTHERWISE SPECIFIED MISO SCK CS 3 Figure 3. DC979A 4-Channel, High Speed, 24-Bit ADC with Buffer C21 4.7UF,10V 0603 C17 4.7UF,10V 0603 V+ C3 0.01UF VCC GND 32 VIN V24 VCC 29 GND 4 V+ 21 4 2 3 4 5 5 3 1 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 representation that the interconnection of its circuits as described herein will not infringe on existing patent rights. 2 GND 4 GND 5 VCC 8 PR 7 CLR 6 GND 13 GND 8 GND 3 U2 LT1236ACS8-5 A B C D DEMO MANUAL DC979A Schematic Diagram DC979Af 5 DEMO MANUAL DC979A 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 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. 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 6 DC979Af Linear Technology Corporation LT 0613 • PRINTED IN USA 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com LINEAR TECHNOLOGY CORPORATION 2013