- Texas Instraments Digital-To-Analog Converter Model DAC7741EVM User's Guide

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DAC7741EVM

October 2002 DAP EVMs

User’s Guide

SLAU093

Summary of content (28 pages)

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DAC7741EVM User’s Guide October 2002 DAP EVMs SLAU093
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IMPORTANT NOTICE Texas Instruments Incorporated and its subsidiaries (TI) reserve the right to make corrections, modifications, enhancements, improvements, and other changes to its products and services at any time and to discontinue any product or service without notice. Customers should obtain the latest relevant information before placing orders and should verify that such information is current and complete.
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EVM IMPORTANT NOTICE Texas Instruments (TI) provides the enclosed product(s) under the following conditions: This evaluation kit being sold by TI is intended for use for ENGINEERING DEVELOPMENT OR EVALUATION PURPOSES ONLY and is not considered by TI to be fit for commercial use.
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EVM WARNINGS AND RESTRICTIONS It is important to operate this EVM within the input voltage range of ±15 V and the output voltage range of ±10 V. Exceeding the specified input range may cause unexpected operation and/or irreversible damage to the EVM. If there are questions concerning the input range, please contact a TI field representative prior to connecting the input power. Applying loads outside of the specified output range may result in unintended operation and/or possible permanent damage to the EVM.
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Information About Cautions and Warnings Preface Read This First About This Manual This user’s guide describes the characteristics, operation, and the use of the DA7741 evaluation module. It covers all pertinent areas involved to properly use this EVM board along with the devices that it supports. The physical PCB layout, schematic diagram and circuit descriptions are included.
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Trademarks Related Documentation From Texas Instruments To obtain a copy of any of the following TI documents, call the Texas Instruments Literature Response Center at (800) 477 – 8924 or the Product Information Center (PIC) at (972) 644 – 5580. When ordering, identify this manual by its title and literature number. Updated documents can also be obtained through our website at www.ti.com.
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Contents Contents 1 EVM Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.1 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.2 Power Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.2.1 Supply Voltage . . . . . . . . . . . . . . . . . . . . .
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Contents Tables 2-1 3-1 3-2 3-3 3-4 3-5 vi Parts List . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Factory Default Jumper Setting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Unity Gain Output Jumper Settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Gain of Two Output Jumper Settings . . . . . . . . . . . . . . .
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Chapter 1 EVM Overview This chapter gives a general overview of the DAC7741 evaluation module (EVM), and describes some of the factors that must be considered in using this module. Topic Page 1.1 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2 1.2 Power Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2 1.3 EVM Basic Functions . . . . . . . . . . . . . . . . . . . . . . . . . . .
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Features 1.1 Features This EVM features the DAC7741 digital-to-analog converter. The DAC7741 EVM is a simple evaluation module designed for a quick and easy way to evaluate the functionality of the high resolution, single-channel, and parallel input DAC. This EVM features a parallel interface to communicate to any host processor base system. 1.2 Power Requirements The following sections describe the power requirements of this EVM. 1.2.
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EVM Basic Functions The REF102 precision reference derives its power of ±15-V supply through J10 or J7 terminal. The (plus) 15 V connects through J10-1 or J7-2 terminals, while the (minus) -15 V connects through J10-3 or J7-4 terminals. They are both referenced to analog ground through J10-2 and J7-1. The DAC7741 has a REFEN pin to enable the internal reference circuit or disable it and select an external reference source. The REFEN pin can be hardware driven through W2 jumper.
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EVM Basic Functions A block diagram of the EVM is shown below in the Figure 1-1. Figure 1-1.
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Chapter 2 Physical Description This chapter describes the physical characteristics and PCB layout of the EVM and lists the components used on the module. Topic Page 2.1 PCB Layout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2 2.2 Bill of Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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PCB Layout 2.1 PCB Layout The EVM is constructed on a four-layer printed-circuit board using a copper-clad FR-4 laminate material. The printed-circuit board has a dimension of 99,06 mm (3.90 inch) × 104,14 mm (4.10 inch), and the board thickness is 1,57 mm (0.062 inch). Figures 2-1 through 2-6 show the individual artwork layers. Figure 2-1.
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PCB Layout Figure 2-2.
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PCB Layout Figure 2-3.
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PCB Layout Figure 2-4.
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PCB Layout Figure 2-5.
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Bill of Materials 2.2 Bill of Materials Table 2-1. Parts List Item # 1 Qty 1 Designator C8 Manufacturer Panasonic Part Number ECJ3VB1C105K Description 1 µF, 1206 multilayer ceramic capacitor 2 2 C9 C10 Panasonic ECUV1H103KBM 0.01 µF, 1206 multilayer ceramic capacitor 3 5 C1 C2 C3 C7 C13 Panasonic ECJ3VB1C104K 0.
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Bill of Materials (This page has been left blank intentionally.
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Chapter 3 EVM Operation This chapter covers in detail the operation of the EVM to provide guidance to the user in evaluating the onboard DAC and how to interface the EVM to a specific host processor. Refer to the DAC7741 data sheet, SBAS248, for information about its parallel interface and other related topics. The EVM board is factory tested and configured to operate in the bipolar output mode. Topic Page 3.1 Factory Default Setting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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Factory Default Setting 3.1 Factory Default Setting The EVM board is set to its default configuration from factory as described on the table below to operate in bipolar ±10V mode of operation using the internal reference. Table 3-1. Factory Default Jumper Setting Reference Jumper Position W1 OPEN VREF output pin is floated and not used for offset adjustment. W2 2-3 REFEN pin is tied to AGND to enable 10 V internal reference.
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Host Processor Operation 3.2 Host Processor Operation The host processor basically drives the DAC, so the DACs proper operation depends on the successful configuration between the host processor and the EVM board. In addition, a properly written code is also required to operate the DAC. A custom cable can be made specific to the host interface platform. The EVM allows interface to the host processor through J2 and J3 header connectors for the control signals, and J1 header connector for the data input.
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Host Processor Operation 3.2.2 Output Gain of Two This configuration allows the DAC output with a gain of two, but is limited to the effective rails of the operational amplifier. When the DAC7741 is configured to operate in bipolar mode, the DAC output must be within the range of 12 VP- P or less. Anywhere above the range of 12 VP- P would clip the output of the op-amp. Likewise, when operating the DAC in unipolar mode, the DAC output must not exceed 6 VP- P.
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Jumper Setting 3.3 Jumper Setting The figures in Table 3-5 will show the function of each jumper on the EVM. Table 3-5. Jumper Setting Function Reference W1 W2 W3 W4 W5 Jumper Setting Function 1 3 ROFFSET is strapped to VREF to set VSJ (summing junction) to VREF/2. Refer to the data sheet for offset adjustment. 1 3 ROFFSET is not connected to set VSJ (summing junction) to VREF/3. Refer to the data sheet for offset adjustment.
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Jumper Setting Table 3-5. Jumper Setting Function (Continued) Reference Jumper Setting Function Disconnects AGND from DGND. W11 W12 Connects AGND and DGND together. 1 3 Positive supply rail of op-amp is powered by +15V. 1 3 Positive supply rail of op-amp is powered by VCC. 2 46 Routes the raw output of the DAC7741 to J4-2 and J5 output terminals. 1 35 2 46 W13 Routes the output of U2 to J4-2 and J5 output terminals. Used for unipolar and bipolar modes of operation.
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Schematic 3.4 Schematic A schematic of the DAC7741 is found on the following page.
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1 2 3 4 5 6 Revision History REV VCC J1 32 30 28 26 24 22 20 18 16 14 12 10 8 6 4 2 D 31 29 27 25 23 21 19 17 15 13 11 9 7 5 3 1 ECN Number Approved VSS D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0 D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0 VDD 35 34 33 32 31 30 29 28 27 22 21 20 19 18 17 16 U1 DB15 DB14 DB13 DB12 DB11 DB10 DB9 DB8 DB7 DB6 DB5 DB4 DB3 DB2 DB1 DB0 38 W9 Sum_Junc C2 0.1µF RST RSTSEL VCC 10 RST RSTSEL C1 0.