DEMO MANUAL DC1792A LTC2756 Serial 18-Bit SoftSpan IOUT DAC Description Demonstration circuit 1792A features the LTC2756 18-bit SoftSpan™, IOUT DAC. The digital interface is a simple, 4-wire Serial Peripheral Interface (SPI) interface, augmented with separate CLEAR and LDAC pins that reset the output to zero and load the DAC code, respectively. This device features six output ranges: 0V to 5V, 0V to 10V, ±5V, ±10V, ±2.5V, and –2.5V to 7.5V. These ranges are programmable through the SPI interface or through Board Photo separate span control pins if SoftSpan operation is not needed. Voltage input offset and gain adjustment pins facilitate trimming of residual DC errors without impacting the excellent temperature stability of this device. Design files for this circuit board are available at http://www.linear.com/demo L, LT, LTC, LTM, µModule, Linear Technology and the Linear logo are registered trademarks and SoftSpan and QuikEval are trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. RIBBON CABLE TO DC590 CONTROLLER ANALOG POWER SUPPLY (NORMALLY ±15V) DAC OUTPUT Figure 1. Connection Diagram Quick Start Procedure Connect a low noise ±15V power supply to the AMPV+ and AMPV– turret posts at the left side of the DC1792A board. Connect J1 to a DC590 USB serial controller using the supplied 14-conductor ribbon cable. Connect DC590 to a host PC with a standard USB A/B cable. Run the evaluation software supplied with the DC590, or download it from www.linear.com/software. The correct control panel will be loaded automatically, shown in Figure 2. The software automatically sets the LTC2756 outputs according to the entries in the control panel. A square wave option is available to test settling time. MSPAN jumper should be set to 0 if software span control is desired. Setting MSPAN high (1) causes the S2, S1, S0 pins to set the span according to the table printed on the board, and the corresponding span should be selected in software to ensure that the calculated DAC code is correct. dc1792af 1 DEMO MANUAL DC1792A quick start procedure Additional software documentation may be available from the Help menu item, as features may be added periodically. VCC: Select source for 5V VCC supply. Set to 5V for supply by onboard LTC6655 reference (recommended). Set to REG to be supplied by regulated supply from DC590 Controller and remove the jumper to supply externally. VREF: Select source for reference. Set to 5V to use onboard LTC6655 reference or select EXT to drive externally through the VREF jumper. CLR: Asynchronous Clear Input. Tie to 0 to set all DAC outputs to 0V. LDAC: Asynchronous DAC Load Input. Tie to 0 to update all DACS if _CS is high. RFLAG: Reset Flag Output. Remove jumper and probe middle pin for RFLAG status. Figure 2. Software Screenshot HARDWARE SET-UP Analog Connections (Turret Posts) Jumpers VOUT: DAC Voltage Output. MSPAN: Manual Span Control Pin. MSPAN is used to configure the LTC2756 for operation in a single, fixed output range. If MSPAN is 1 (high) it will be configured for single span use. If MSPAN is low it will be set through the QuikEval™ Software. Default position is 0 (low). S0, S1, S2: Used to set the fixed output range if MSPAN is 1 (high). Table 1. MSPAN Configuration S2 S1 S0 SPAN 0 0 0 0V to 5V 0 0 1 0V to 10V 0 1 0 ±5V 0 1 1 ±10V 1 0 0 ±2.5V 1 0 1 –2.5V to 7.5V GEADJ: Gain Adjust Pin. If no adjustments are required, select GND. Selecting EXT. connects the pin to the turret allowing external adjustment to null gain error or compensate for reference errors. VOSADJ: Offset Adjustment Selection for DAC. If no offset adjustment is required, select GND. Selecting EXT connects the offset pin to the turret allowing external adjustment of offset. VREF: DAC Reference Voltage. If the onboard LTC6655 reference is selected, the voltage may be measured at these points. If a remote reference is selected, then an external reference must be applied to these points. VOSADJ: DAC offset adjust input, use only if VOSA jumper set to EXT. Nominal input range is ±5V, which will provide ±2048LSB of offset adjustment. GEADJ: Gain Adjust Pin. This voltage control pin can be used to null gain error or to compensate for reference errors. The gain error change expressed in LSB is the same for any output range. Nominal range is ±5V, which will provide ±2048LSB of gain adjustment. Power and Ground Connections Analog Power: AMPV+, AMPV–, and GND turret posts are the analog supplies for the onboard DAC amplifiers. These should be connected to a well regulated, low noise ±15V power supply. VCC: Connection to VCC. See schematic and description for VCC jumper. Grounding: Separate power and signal grounds are provided. Signal GND is the turret closest to VOUT, use this for measurement ground and output return. Power GND is between AMPV+ and AMPV– turrets. dc1792af 2 DEMO MANUAL DC1792A Parts List ITEM QTY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER Required Circuit Components 1 11 C1, C2, C3, C5, C6, C11, C13, C15, C18, C19, C20 CAP., X7R, 10µF, 10V, 20% 1206 TDK, C3216X5R1A106M 2 5 C4, C36, C37, C40, C41 CAP., X7R, 0.1µF, 10V, 10% 0603 AVX, 0603ZC104KAT2A 3 3 C7, C10, C21 CAP., X7R, 0.01µF, 10V, 10% 0603 AVX, 0603ZC103KAT2A 4 0 C34(OPT.) CAP., 0603 5 1 C31 CAP., C0G, 100pF, 10V, 10% 0603 6 0 C29, C35(OPT.) CAP., 1206 7 1 C30 CAP., C0G, 100pF, 10V, 10% 1206 AVX, 1206ZC101KAT 8 2 C32, C33 CAP., X7R, 1µF, 10V, 10% 1206 AVX, 1206ZC105KAT2A 9 3 D1, D2, D3 DIODE, BAT54C, SOT23 DIODE/ZETEX, BAT54CTA AVX, 06033A101KAT2A 10 1 J1 CONNECTOR, HD2X7-079 MOLEX, 87831-1420 11 11 JP1–JP11 3-PIN 0.079 SINGLE ROW HEADER SAMTEC, TMM103-02-L-S 12 14 XJP1–XJP11 SHUNT, .079" CENTER SAMTEC, 2SN-BK-G 13 1 JP12 0.1" JUMPER SHUNT, SOLDER DOWN SAMTEC, JL-100-25-T 14 1 R1 RES., CHIP, 88.7k, 1/16W, 1% 0603 VISHAY, CRCW060388K7KFEA 15 1 R2 RES., CHIP, 10.0k, 1/16W, 1% 0603 NIC, NRC06F1002TRF 16 3 R3, R4, R5 RES., CHIP, 4.99k, 1/16W, 1% 0603 NIC, NRC06F4991TRF 17 3 R22, R25, R30 RES., CHIP, 1k, 1/16W, 5% 0603 VISHAY, CRCW06031K00JNEA 18 9 R11–R17, R23, R24 RES., CHIP, 10k, 1/16W, 5% 0603 NIC, NRC06J1002TRF 19 0 R26, R29, R31–R34(OPT.) RES., CHIP, 0603 20 1 R27 RES., CHIP, 4.02k, 1/16W, 1% 0603 VISHAY, CRCW06034K02KFEA 21 1 R28 RES., CHIP, 10, 1/16W, 5% 0603 VISHAY, CRCW060310R0JNEA 22 11 E1–E11 Turret, Testpoint MILL-MAX, 2308-2-00-44 23 1 U1 IC., LTC2756ACG, SSOP28 LINEAR, LTC2756ACG#TRPBF 24 1 U2 IC., LTC6655CHMS8-5, MSOP-8 LINEAR, LTC6655CHMS8-5#TRPBF 25 0 U3(OPT) IC., SO-8 26 1 U4 IC., 24LC025, TSSOP-8 MICROCHIP, 24LC025 I /ST 27 1 U5 IC., LT1761ES5-5, SOT23-5 LINEAR, LT1761ES5-5#TRPBF 28 1 U6 IC., LT1964ES5-5, SOT23-5 LINEAR, LT1964ES5-5#TRPBF 29 1 U7 IC., LT1012ACS8, SO-8 LINEAR, LT1012ACS8#TRPBF 30 1 U9 IC., LT1360CS8, SO-8 LINEAR, LT1360CS8#TRPBF 31 1 U8 IC., LTC2054CS5, TSOT23-5 LINEAR, LTC2054CS5#TRPBF 32 1 U10 IC., LT1761ES5-BYP, SOT23-5 LINEAR, LT1761ES5-BYP#TRPBF 33 1 U11 IC., LTC6244CDD, 8-PIN 3 × 3, DD LINEAR, LTC6244CDD#TRPBF 34 4 MH1–MH4 STAND-OFF, NYLON 0.25" KEYSTONE, 8831(SNAP ON) dc1792af 3 A B C 5 D 4 - + - + 3 2 2 V- V+ 3 1 TECHNOLOGY 1 4 4 5 A B C D DEMO MANUAL DC1792A Schematic Diagram dc1792af 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. A B C 5 D 4 3 3 2 2 4 TECHNOLOGY 1 1 5 A B C D DEMO MANUAL DC1792A Schematic Diagram dc1792af 5 DEMO MANUAL DC1792A 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 dc1792af 6 Linear Technology Corporation LT 0412 • PRINTED IN USA 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com LINEAR TECHNOLOGY CORPORATION 2012