ADS8371EVM User’s Guide August 2004 Data Acquistion SLAU137A
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.
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.
EVM WARNINGS AND RESTRICTIONS It is important to operate this EVM within the input voltage range of ±6 V and the output voltage range of 0 V and 5.5 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.
Preface Read This First About This Manual This users guide describes the characteristics, operation, and use of the ADS8371 16-bit, 750-kHz, parallel interface, analog-to-digital converter evaluation board. A complete circuit description, schematic diagram, and bill of materials are included.
FCC Warning This equipment is intended for use in a laboratory test environment only. It generates, uses, and can radiate radio frequency energy and has not been tested for compliance with the limits of computing devices pursuant to subpart J of part 15 of FCC rules, which are designed to provide reasonable protection against radio frequency interference.
Contents 1 EVM Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1 1.1 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2 2 Analog Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1 2.1 Signal Conditioning . . . . . . . . . . . . .
Figures 2−1 6−1 6−2 6−3 6−4 Input Buffer Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Top Layer—Layer 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ground Plane—Layer 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Power Plane—Layer 3 . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Chapter 1 EVM Overview This chapter contains the features of the ADS8371EVM. Topic 1.1 Page Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Features 1.1 Features - Full-featured evaluation board for the high-speed ADS8371 16-bit, single channel, parallel interface, SAR-type analog-to-digital converters.
Chapter 2 Analog Interface The ADS8371 analog-to-digital converter has both a positive and negative analog input pin. Ground for the negative input is provided on the EVM (via SJP7) close the device, or a user-furnished ground wire may be attached. The negative input pin has a range of –200 mV up to 200 mV, and is shorted on the EVM via SJP7. A signal for the positive input pin can be applied at connector P1, pin 2 (shown in Table 2−1 ), or applied to the center pin of SMA connector J1. Table 2−1.
Signal Conditioning 2.1 Signal Conditioning The factory recommends the analog input to any SAR-type converter be buffered and low-pass filtered. It is important to note that the input buffer circuit of the ADS8371EVM, shown in Figure 2−1, uses the THS4031 in an inverting gain-of-one configuration. The amplifier is not stable in a conventional gain-of-one configuration. The THS4031 was selected for its low noise, high slew rate, and fast settling time.
Reference 2.2 Reference The ADS8371EVM allows users to select from two reference sources: - an onboard (REF1004−2.5) - a user supplied reference voltage via P1 pin 20 Both the user supplied reference and the onboard reference voltage can be amplified and filtered using reference amplifier, U2. The ADS8371EVM ships with the reference amplifier, U2, set for a gain of 1.6 V. The onboard reference (U10) is a 2.5-V reference.
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Chapter 3 Digital Interface The ADS8371EVM is designed for easy interfacing to multiple platforms. Samtec part numbers SSW−110−22−F−D−VS−K and TSM−110−01−T−DV−P provide a convenient dual-row-header/socket combination at P2 and P3. Consult Samtec at www.samtec.com or 1−800−SAMTEC−9 for a variety of mating connector options. Table 3−1. Pinout for Parallel Control Connector P2 Connector.Pin Signal P2.1 DC_CS Description Daughtercard Board Select pin P2.3 P2.5 P2.7 A0 Address line from processor P2.
Table 3−2. Jumper Settings Jumper Settings Reference Designator Description 1−2 Connect +5 VD from connector to +BVDD W1 Connect +3.3 VD from connector to +BVDD Installed † Set A[2..0] = 0x1 to generate RD pulse W2 Set A[2..0] = 0x2 to generate RD pulse Installed † Set A[2..0] = 0x3 to generate convst pulse W3 W4 † 2−3 Installed † Set A[2..
Chapter 4 Power Supply Requirements The EVM accepts four power supplies. - A dual ±Vs DC supply for the dual supply op amps. Recommend a ±6-VDC supply. - A single +5.0-VDC supply for analog section of the board (A/D + Refer- ence). - A single +5.0-V or +3.3-VDC supply for digital section of the board (A/D + address decoder + buffers). There are two ways to provide these voltages. 1) Wire in the voltages at test points on the EVM. See Table 4−1. Table 4−1.
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Chapter 5 Using the EVM The ADS8371EVM serves three functions 1) As a reference design 2) As a prototype board and 3) As software test platform Topic Page 5.1 As a Reference Board . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-2 5.2 As a Prototype Board . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-2 5.3 As a Software Test Platform . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
As a Reference Board 5.1 As a Reference Board As a reference design, the ADS8371EVM contains the essential circuitry to showcase the analog-to-digital converter. This essential circuitry includes the input amplifier, reference circuit, and buffers. The EVM analog input circuit is optimized for a 100-kHz sine wave; therefore, users may need to adjust the resistor and capacitor values of the A/D input RC circuit.
Chapter 6 ADS8371EVM BOM, Layout, and Schematic This chapter contains the ADS8371EVM bill of materials, the layouts, and the schematic. Topic Page 6.1 ADS8371EVM Bill of Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-2 6.2 ADS8371EVM Layout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-5 6.3 ADS8371EVM Schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
ADS8371EVM Bill of Materials 6.1 ADS8371EVM Bill of Materials Table 6−1 contains a complete bill of materials for the ADS8371EVM. The schematic diagram also is provided for reference. Contact the Product Information Center or send an e-mail to dataconvapps@list.ti.com for questions regarding this EVM. Table 6−1.
ADS8371EVM Bill of Materials QTY Value Reference Designators Footprint Mfg Mfg’s Part Number Description 1 10 µF C11 3528 Kemet or Alternate T491B106K016AS Capacitor TANT 10 µF 16V 10% SMT 13 0.1 µF C12 C13 C14 C19 C21 C22 C23 C26 C50 C53 C60 C61 C62 603 Kemet or Alternate C0603C104K3RACTU CAP 0.1 µF 25 V ceramic X7R 0603 1 0.47 µF C15 603 Panasonic − ECG or Alternate ECJ-1VF1C474Z CAP 0.47 µF 16 V ceramic Y5V 0603 2 0.
ADS8371EVM Bill of Materials QTY Value Reference Designators Footprint Mfg Mfg’s Part Number Description 1 6X2X.1 J2 6X2X.1_SMT_PL UG_&_SOCKET Samtec TSM-106-01-T-D-V-P 0.025” SMT plug − top side of PWB 1 5X2X.1 J3 5X2X.1_SMT_SO CKET Samtec SSW-105-22-S-D-VS 0.025” SMT socket − bottom side of PWB Samtec TSM-105-01-T-D-V-P 0.025” SMT plug − top side of PWB Samtec SSW-110-22-S-D-VS 0.025” SMT socket − bottom side of PWB Samtec TSM-110-01-T-D-V-P 0.
ADS8371EVM Layout 6.2 ADS8371EVM Layout Figure 6−1.
ADS8371EVM Layout Figure 6−2.
ADS8371EVM Layout Figure 6−3.
ADS8371EVM Layout Figure 6−4.
ADS8371EVM Schematic 6.3 ADS8371EVM Schematic The schematic follows this page.
1 2 3 4 5 6 Revision History REV ECN Number Approved D D J1 Analog-to-Digital Converter P1 EXT_REF DB[15...0] +IN BUSY 2 4 6 8 10 12 14 16 18 20 B_CS B_RD B_CONVST B_BYTE B_BUS18/16 1 3 5 7 9 11 13 15 17 19 DB[15..0] Analog Input Power & Digital Buffer C C +VA +VA TP3 AGND TP4 +5VD W1 TP12 +BVDD A0 A1 A2 INTc 2 4 6 8 10 -VA -VA DC_CS +3.3VD 1 3 5 7 9 B_DB[15...0] B_BUSY +VA +5VA DGND -VA ADC_CS ADC_RD ADC_CONVST BYTE TP10 J3 DB[15...
1 2 3 4 5 6 Revision History REV ECN Number Approved EXT_REF D 3 D 2 +5VCC SJP6 1 +VCC +5VCC C15 0.47uF C41 1uF U3 IN 1 C40 0.1uF 0.1uF 0.1uF C20 2 SJP5 0.01uF 7 R14 TP8 3 NI 3 C42 3 R13 2 R10 6 47uF 0.01uF U2 5 50 SJP4 2 +VBD 0 100 1 1 OPA627 + 2 4 0.01uF U4 C52 0.1uF C7 1 2 3 4 5 6 7 8 9 10 11 12 0.01uF 50k U10 +5VCC 2 C46 NI C47 3 NI 4 NI NC NC +VIN NC EN VREF GND NC R11 8 768 7 +5VCC 6 5 C12 R7 REF1004-2.5 2 1 0.
1 2 3 4 5 6 Revision History TP11 +5VA REV +5VCC L4 +5VA ECN Number Approved BLM21AJ601SN1L + C44 C48 10uF C43 C45 C49 0.1uF 10uF 0.01uF 1nF TP6 D D TP15 +VBD L1 +BVDD +BVDD BLM21AJ601SN1L + C55 C16 C58 10uF 10uF C59 C57 0.1uF 0.01uF 1nF TP16 +VBD +VBD U9 B_RD TP7 +VA +VA +VCC L3 DB[15...0] C61 0.1uF RP3 + C35 C39 10uF C38 VCC DIR BLM21AJ601SN1L 1uF C36 C37 0.01uF 1nF DB0 DB1 DB2 DB3 DB4 DB5 DB6 DB7 10uF C /OE DB[15...
