Texas Instruments ADS8402 User manual

User's GuideSLAU126A – December 2003 – Revised September 2004
ADS8402/ADS8406/ADS8412 EVM User's Guide
This user's guide describes the characteristics, operation, and use of theADS8402/ADS8406/ADS8412 16-bit, high-speed, parallel interface, analog-to-digital converterevaluation board. A complete circuit description, schematic diagram, and bill of materials areincluded.
Contents1 EVM Overview .............................................................................................. 22 Analog Interface ............................................................................................ 23 Digital Interface ............................................................................................. 44 Power Supplies ............................................................................................. 65 Using the EVM .............................................................................................. 76 ADS8402/ADS8406/ADS8412EVM BOM ................................................................ 87 ADS8402/ADS8406/ADS8412EVM Layouts .......................................................... 108 ADS8402/ADS8406/ADS8412EVM Schematic ....................................................... 13
List of Figures
1Input Buffer Circuit ........................................................................................ 32Top - Layer 1 ............................................................................................... 103Ground Plane - Layer 2 .................................................................................. 114Power Plane - Layer 3 ................................................................................... 125Bottom - Layer 4 .......................................................................................... 13
List of Tables
1Analog Input Connector .................................................................................. 22Solder Short Jumper Setting ............................................................................ 43Pinout for Parallel Control Connector P2 ............................................................. 44Jumper Settings for Decoder Outputs ................................................................. 55Data Bus Connector P3 ................................................................................... 56Pinout for Converter Control Connector J3 .......................................................... 67Power Supply Test Points ................................................................................ 68Power Connector, J1, Pinout ............................................................................ 69Bill of Materials ............................................................................................. 8
TMS320C5000, TMS320C6000 are trademarks of Texas Instruments.
ADS8402/ADS8406/ADS8412 EVM User's GuideSLAU126A – December 2003 – Revised September 2004 1

www.ti.com
1 EVM Overview
1.1 Features
2 Analog Interface
EVM Overview
•Full-featured evaluation board for the ADS8402 (1.25 MHz), ADS8406 (1.25 MHz), and ADS8412(2 MHz) high-speed 16-bit, single channel, parallel interface SAR-type analog-to-digital converters.•Onboard Signal Conditioning•Onboard Reference•Input and Output Digital Buffers•Onboard Decoding for Stacking Multiple EVMs
The ADS8402/ADS8406/ADS8412EVM analog-to-digital converter has pseudo-bipolar differential input. Apseudo-bipolar differential input is a differential signal (inverting and noninverting input is 180 degrees outof phase) that is level shifted such that the signals levels are always equal to or above zero volts. Thepeak-to-peak amplitude on each input pin can be as large as the reference voltage. See the respectiveproduct data sheet for more information.
The ADS8402/ADS8406/ADS8412EVM comes installed with the unity gain buffer (U2) wired forsingle-ended into differential-out configuration. The common-mode voltage is derived from REF3040reference IC and adjustable using a potentiometer (R9). The common mode voltage pin of the THS4503 isset to 2.0 V on the evaluation module. A single-ended input signal can be applied at pin-connector P1 orvia SMA connectors J2 (noninverting input). The buffer circuit can be reconfigured for a differential inputby installing resistor R6 and R8 and removing R1. The inverting leg of the differential signal should beapplied
to either connector P1 pin 1 or SMA connector J4 (inverting input). See Table 1for pinout ofanalog
connector, P1. See Section 8for the EVM schematic.
Table 1. Analog Input Connector
Description Signal Name Connector.pin# Signal Name Description
Inverting Input (–) P1.1 P1.2 (+) Noninverting InputReserved N/A P1.3 P1.4 N/A ReservedReserved N/A P1.5 P1.6 N/A ReservedReserved N/A P1.7 P1.8 N/A ReservedPin tied to Ground AGND P1.9 P1.10 N/A ReservedPin tied to Ground AGND P1.11 P1.12 N/A ReservedReserved N/A P1.13 P1.14 N/A ReservedPin tied to Ground AGND P1.15 P1.16 N/A ReservedPin tied to Ground AGND P1.17 P1.18 N/A ReservedReserved N/A P1.19 P1.20 REF+ External Reference Input
ADS8402/ADS8406/ADS8412 EVM User's Guide2 SLAU126A – December 2003 – Revised September 2004

www.ti.com
2.1 Signal Conditioning
1 kΩ
1 kΩ
+VCC
VI
0.1 µF
1 µF
25 Ω(+) IN
(−) IN
6800 pF
1 µF
0.1 µF
1 kΩ
−VCC
−
+
68 pF
1 kΩ
68 pF
VOCM 25 Ω
−
+
THS4503
+2.048 V
Analog Interface
It is recommended that the analog input to any SAR-type converter be buffered. The amplifier circuit inFigure 1 is the buffer circuit used on the ADS8402/ADS8406/ADS8412EVM. This circuit consists of theTHS4503, a high-speed fully differential amplifier configured as a single-ended into differential-out, unitygain buffer. The circuit shown in Figure 1 was optimized to achieve the ac (i.e., SNR, THD, SFDR, etc)specifications listed in the ADS8402, ADS8406, and ADS8412 data sheets. The 68-pF and 6800-pFcapacitors in the signal path are polypropylene type, manufactured by WIMA Corporation. Polypropylenecapacitors cause the least distortion of the input signal; therefore, they provide good dynamic performancefrom the converter. A low-cost alternative for the polypropylene type are C0G capacitors by TDKCorporation.
Figure 1. Input Buffer Circuit
ADS8402/ADS8406/ADS8412 EVM User's GuideSLAU126A – December 2003 – Revised September 2004 3

www.ti.com
2.2 Reference
3 Digital Interface
Digital Interface
The EVM allows users to select from three reference sources. The ADS8402/ADS8406/ADS8412EVMprovides an onboard 4.096-V reference, U3. The EVM also has the provision for users to supply areference voltage via connector P1 pin 20. The user reference voltage and onboard reference voltagescan be filtered by installing amplifier U1. The ADS8402, ADS8406, and ADS8412 analog-to-digitalconverters have a integrated onboard reference buffer; therefore, it is not necessary to buffer the voltageexternally. The reference buffer circuit on the EVM is not populated with an amplifier for this reason. TheEVM comes installed with on-chip internal reference tied directly to the reference pin of the converter. SeeSection 8 for a full schematic.
Table 2. Solder Short Jumper Setting
(1)
Jumper SettingsReference
DescriptionDesignator
1-2 2-3
On-chip internal reference applied to A/D reference pin Installed
(2)SJP2
Apply reference voltage from external source InstalledSJP3 Apply voltage to amplifier, U2, common-mode voltage pin Installed
(2)
N/ABuffer onboard reference, REF3040 Installed Not installedSJP4
Buffer user reference voltage applied at P1 pin 20 Not installed installedSelect REF3040 for reference voltage Installed Not installedSJP5
Select buffered reference voltage Not Installed Installed
(1) Designator SJP1 is not used on the EVM.(2) Factory installed
The ADS8402/ADS8406/ADS8412 EVM is designed for easy interfacing to multiple platforms. Samtec partnumbers SSW-110-22-F-D-VS-K and TSM-110-01-T-DV-P provide a convenient dual-row header/socketcombination at P2 and P3. Consult Samtec at www.samtec.com or 1-800-SAMTEC-9 for a variety ofmating connector options.
Table 3. Pinout for Parallel Control Connector P2
(1)
Connector.Pin Signal Description
P2.1 DC_CS Daughtercard board-select pinP2.3
P2.5
P2.7 A0 Address line from processorP2.9 A1 Address line from processorP2.11 A2 Address line from processorP2.13
P2.15
P2.17
P2.19 INTc Set jumper to select BUSY or inverted signal to be applied to this pin.
(1) All even numbered pins of P2 are tied to DGND.
4ADS8402/ADS8406/ADS8412 EVM User's Guide SLAU126A – December 2003 – Revised September 2004

www.ti.com
Digital Interface
Read ( RD), conversion start ( CONVST) and reset ( RESET) signals to the converter can be assigned totwo different addresses in memory via jumper settings. This allows for the stacking of up to twoADS8402EVM, ADS8406EVM, and/or ADS8412EVMs into processor memory. See Table 4 for jumpersettings. Note that the evaluation module does not allow the chip select ( CS) line of the converter to beassigned to different memory locations. It is therefore suggested that the CS line be grounded or wired toan appropriate signal of the processor.
Table 4. Jumper Settings for Decoder Outputs
Reference Description Jumper SettingsDesignator
1-2 2-3
Set A[2..0]= 0x1 to generate RD pulse Installed
(1)W2
Set A[2..0]=0x2 to generate RD pulse InstalledSet A[2..0]=0x3 to generate convst pulse Installed
(1)W5
Set A[2..0]=0x4 to generate convst pulse InstalledSet A[2..0]=0x5 to generate RESET pulse Installed
(1)W4
Set A[2..0]=0x6 to generate RESET pulse Installed
The data bus is available at connector P3; see Table 5 for pinout information.(1) Factory Installed
Table 5. Data Bus Connector P3
(1)
Connector.Pin Signal Description
P3.1 D0 Buffered Data Bit 0 (LSB)P3.3 D1 Buffered Data Bit 1P3.5 D2 Buffered Data Bit 2P3.7 D3 Buffered Data Bit 3P3.9 D4 Buffered Data Bit 4P3.11 D5 Buffered Data Bit 5P3.13 D6 Buffered Data Bit 6P3.15 D7 Buffered Data Bit 7P3.17 D8 Buffered Data Bit 8P3.19 D9 Buffered Data Bit 9P3.21 D10 Buffered Data Bit 10P3.23 D11 Buffered Data Bit 11P3.25 D12 Buffered Data Bit 12P3.27 D13 Buffered Data Bit 13P3.29 D14 Buffered Data Bit 14P3.31 D15 Buffered Data Bit 15
This evaluation module provides direct access to all the analog-to-digital converter control signals viaconnector J3; see Table 6 .(1) All even-numbered pins of P3 are tied to DGND.
SLAU126A – December 2003 – Revised September 2004 ADS8402/ADS8406/ADS8412 EVM User's Guide 5

www.ti.com
4 Power Supplies
Power Supplies
Table 6. Pinout for Converter Control Connector J3
(1)
Connector.Pin Signal Description
J3.1 CS Chip Select pin. Active LowJ3.3 RD Read Pin. Active LowJ3.5 CONVST Convert start pin. Active LowJ3.7 BYTE BYTE mode pin. Used for 8-bit busesJ3.9 RESET Reset pin. Active LowJ3.11 BUSY
(2)
Converter Status Output. High when a conversion is in progress
(1) All even-numbered pins of J3 are tied to DGND.(2) Error on silkscreen of Rev A evaluation module. J3 pin 11 reads BUS16/18. The signal connected isBUSY, as shown in Section 8 .
The EVM accepts four power supplies.•A dual ±Vs dc supply for the dual supply operational amplifiers. Maximum voltage recommended is ±7VDC
•A single 5-V dc supply for analog section of the board (A/D + Reference).•A single 5-V or 3.3-V dc supply for digital section of the board (A/D + address decoder + buffers).
There are two ways to provide these voltages.1. Wire in voltages at test points on the EVM. See Table 7
Table 7. Power Supply Test Points
Test Point Signal Description
TP14 +BVDD Apply 3.3 VDC or 5 VDC. See ADC data sheet for full range.TP11 +AVCC Apply 5 VDCTP12 +VA Apply 7 VDC. Positive supply for amplifierTP13 –VA Apply -7 VDC. Negative supply for amplifier
2. Use the power connector J1, and derive the voltages elsewhere. The pinout for this connector isshown in Table 8 . If using this connector, then set W1 jumper to connect 3.3 VD or 5 VD from theconnector to +BVDD. Short between pins 1-2 to select 5 VD, or short between pins 2-3 to select 3.3VD as the source for the digital buffer voltage supply (+BVDD).
Table 8. Power Connector, J1, Pinout
Signal Power Connector - J1 Signal
+VA (7 V) 1 2 –VA (–7V)5 VA 3 4 N/CDGND 5 6 AGNDN/C 7 8 N/C3.3 VD 9 10 5 VD
6 SLAU126A – December 2003 – Revised September 2004ADS8402/ADS8406/ADS8412 EVM User's Guide

www.ti.com
5 Using the EVM
5.1 As a Reference Board
5.2 As a Prototype Board
5.3 As a Software Test Platform
Using the EVM
The ADS8402/ADS8406/ADS8412 EVM serves three functions1. As a reference design2. As a prototype board and3. As software test platform
As a reference design, the ADS8402/ ADS8406/ADS8412EVM contains the essential circuitry toshowcase the analog-to-digital converter. This essential circuitry includes the input amplifier, referencecircuit, and buffers. The EVM analog input circuit is optimized for 100-kHz sine wave; therefore, users mayneed to adjust the resistor and capacitor values of the A/D input circuit. In ac-type applications wheresignal distortion is concern, polypropylene capacitors should be used in the signal path.
As a prototype board, the buffer circuit consists of resistor pads for configuring the input as eithersingle-ended or differential input. The input circuit can be modified to accommodate user prototype needs,whether it be evaluating another differential amplifier or limiting noise for best performance. The analog,power, and digital connectors can be made to plug into a standard 0.1-inch breadboard or cables made upto interface direct to a FPGA or processor.
As a software test platform, connectors P1, P2, and P3 plug into the parallel interface connectors of the5-6K interface card. The 5-6K interface card sits on the TMS320C5000 ™ and TMS320C6000 ™ DSPPlatform starter kit (DSK). The ADS8402/ADS8406/ADS8412EVM is then mapped into the processor'smemory space. This card also provides an area for signal conditioning. This area can be used to installapplication circuit(s) for digitization by the ADS8402/ADS8406/ADS8412 analog-to-digital converter. Seethe 5-6K interface card user’s guide ( SLAU104 ) for more information.
The ADS8402/ADS8406/ADS8412EVM provides a simple platform for interfacing to the converter. TheEVM provides standard 0.1-inch headers and sockets to wire into prototype boards. The user need onlyprovide 3 address lines (A2, A1, A0) and address valid line (DC_ CS) to connector P2. To choose whichaddress combinations generates RD, CONVST, and RESET, set jumpers as shown in Table 5 . Recall thatthe chip select ( CS) signal is not memory mapped or tied to P2; therefore, it must be controlled via ageneral-purpose pin or shorted to ground at J3 pin 1. If address decoding is not required, the EVMprovides direct access to converter data bus via P3 and control via J3.
SLAU126A – December 2003 – Revised September 2004 7ADS8402/ADS8406/ADS8412 EVM User's Guide

www.ti.com
6 ADS8402/ADS8406/ADS8412EVM BOM
ADS8402/ADS8406/ADS8412EVM BOM
Table 9 contains a complete bill of materials for the ADS8402/ ADS8406/ADS8412 EVM. The schematicdiagram is also provided for reference. Contact the Product Information Center or e-mail[email protected] for questions regarding this EVM.
Table 9. Bill of Materials
Used Part Type Designator Footprint MFG MFG's Part Number Description
Panasonic - ECG2 0 R15 R21 805 ERJ-6GEY0R00V Resistor 0.0 Ω1/8W 5% 0805 SMDor Alternate
Panasonic - ECG2 24.9 R12 R13 805 ERJ-6ENF24R9V Resistor 24.9 Ω1/10W 1% 0805 SMDor Alternate
Panasonic - ECG3 100 R5 R14 R25 805 ERJ-6ENF1000V Resistor 100 Ω1/10W 1% 0805 SMDor Alternate
Panasonic - ECG1 910 R4 805 ERJ-6GEYJ911V Resistor 910 Ω1/8W 5% 0805 SMDor Alternate
Panasonic - ECG Resistor 1.00 k Ω1/10W 1% 08053 1k R1 R7 R10 805 ERJ-6ENF1001Vor Alternate SMD
R16 R17 R18 Panasonic - ECG Resistor 10.0 k Ω1/16W 1% 06035 10k 603 ERJ-3EKF1002VR19 R20 or Alternate SMD
Panasonic - ECG Resistor 10.0 k Ω1/10W 1% 08051 10k R24 805 ERJ-6ENF1002Vor Alternate SMD
R6 R8 R11 R26 NI 805 Not Installed Not InstalledR3 R22
Panasonic - ECG1 49.9 R23 805 ERJ-6ENF49R9V Resistor 49.9 Ω1/10W 1% 0805 SMDor Alternate
C3 C5 C11 TDK Corporation Capacitor 1000 pF 50V ceramic NPO4 1 nF 1206 C3216C0G1H102JTC23 or Alternate 1206
2 68 pF C34 C35 TH WIMA FKP2 68/100/1 68 pF Polypropylene capacitor
1 6800 pF C17 TH WIMA FKP2 6800/100/1 6800 pF Polypropylene capacitor
C13 C21 C41C44 C46 C48 TDK Corporation Capacitor 10000 pF 50V ceramic X7R10 0.01 µF 603 C1608X7R1H103JTC53 C56 C65 or Alternate 0603C50
C10 C18 C20 TDK Corporation Capacitor 10000 pF 50V ceramic X7R4 0.01 µF 805 C2012X7R1H103KTC66 or Alternate 0805
TDK Corporation Capacitor 10000 pF 50V ceramic X7R2 0.01 µF C4 C26 1206 C3216X7R1H103JTor Alternate 1206
C8 C25 C40C42 C43 C47
TDK Corporation Capacitor 0.1 µF 25V ceramic X7R15 0.1 µF C51 C52 C54 603 C1608X7R1E104KTor Alternate 0603C55 C57 C58C62 C63 C64
C7 C9 C15
TDK Corporation Capacitor 0.10 µF 50V ceramic X7R7 0.1 µF C22 C32 C36 805 C2012X7R1H104JTor Alternate 0805C45
C16 C31 C33 TDK Corporation6 1 µF 805 C2012X7R1C105KT Capacitor 1 µF 16V ceramic X7R 0805C37 C59 C60 or Alternate
TDK Corporation Capacitor 1.0 µF 25V ceramic X7R2 1 µF C2 C28 1206 C3216X7R1E105KTor Alternate 1206
C1 C6 C12 TDK Corporation Capacitor 10 µF 16V ceramic X5R4 10 µF 1206 C3216X5R1C106MTC19 or Alternate 1206
Capacitor tantalum 10 µF 16V 10%1 10 µF C49 3528 Kemet or Alternate T491B106K016AS
SMT
C14 C24 C27 Panasonic - ECG Capacitor 10 µF 25V tantalum TE4 10 µF 6032 ECS-T1EC106RC29 or Alternate SMD
TDK Corporation1 22 µF C30 805 C2012X5R0J226MT Capacitor CER 22 µF 6.3V X5R 20%or Alternate
3 NI C38 C39 C61 805
Resistor array 1 k Ω16TERM 8RES2 1K RP1 RP3 CTS_742 CTS Corporation 742C163102JTR
SMD
ADS8402/ADS8406/ADS8412 EVM User's Guide8 SLAU126A – December 2003 – Revised September 2004

www.ti.com
ADS8402/ADS8406/ADS8412EVM BOM
Table 9. Bill of Materials (continued)Used Part Type Designator Footprint MFG MFG's Part Number Description
Resistor array 100 Ω16TRM 8RES1 100 RP2 CTS_742 CTS Corporation 742C163101JTR
SMD
BOURNS_1 10k R9 Bourns 3214W-1-103E Trimpot 10 k Ω4 mm Top ADJ SMD32X4W
4 BLM21AJ601SN1L L1 L2 L3 L4 1206 TDK Corporation MPZ2012S601AT Chip ferrite beads - 600 Ωat 100 MHz
REF3040 50 ppm/ °C, 50 µA in2 REF3040 U1 U3 3-SOT-23 Texas Instruments REF3040AIDBZT
SOT23-3 CMOS voltage reference
1 THS4503 U2 8-SOP(D) Texas Instruments THS4503ID High-speed fully-differential amplifiers
SOCKET_1 ADS8402 U4 Texas Instruments ADS8402IPFBT
(1)
ADS8402 16-bit 1.25 MSPS48QFP
1 OPA627AU U8 8-SOP(D) NOT INSTALLED NOT INSTALLED Amplifier
Footprint for 8 pin SOIC reference that1 NI U9 8-SOP(D)
operates from 5 V
1 SN74AHC1G04DBV U10 5-SOT(DBV) Texas Instruments SN74AHC1G04DBVR Single inverter gate
1 SN74AHC138PWR U11 16-TSSOP(PW) Texas Instruments SN74AHC138PWR 3-line to 8-line decoder / demultiplexer
3 SN74AHC245PWR U5 U6 U7 20-TSSOP(PW) Texas Instruments SN74AHC245PWR Octal bus transceiver, 3-state
5X2X.1_SMT_1 5X2X.1 J1 Samtec TSM-105-01-T-D-V-P 0.025" SMT plug - top side of PWBSOCKET
6X2X.1_SMT_
0.025" SMT socket - bottom side of1 6X2X.1 J3 PLUG_&_ Samtec SSW-106-22-S-D-VS
PWBSOCKET
Samtec TSM-106-01-T-D-V-P 0.025" SMT plug - top side of PWB
MaCom #5002-5003-10 /2 SMA_PCB_MT J2 J4 SMA_JACK AMPHENOL 901-144-4
Amphenol #901-144
10X2X.1_SMT_
0.025" SMT socket - bottom side of2 10X2X.1 P1 P2 PLUG_&_ Samtec SSW-110-22-S-D-VS
PWBSOCKET
Samtec TSM-110-01-T-D-V-P 0.025" SMT plug - top side of PWB
16X2X.1_SMT_16X2X.1_SMT_PLU 0.025" SMT socket - bottom side of1 P3 PLUG_&_ Samtec SSW-116-22-S-D-VSG_&_SOCKET PWBSOCKET
Samtec TSM-116-01-T-D-V-P 0.025" SMT plug - top side of PWB
1 SJP2 SJP3 SJP2 NOT INSTALLED NOT INSTALLED Pad 2 position Jumper
SJP2 SJP43 SJP3 SJP3 NOT INSTALLED NOT INSTALLED Pad 3 Postion JumperSJP5
1 SW-PB S1 EVQ-PJ Panasonic EVQ-PJU04K Switch
W1 W2 W35 3POS_JUMPER 3pos_jump Samtec TSW-103-07-L-S 3 Position Jumper _0.1" spacingW4 W5
TP1 TP2 TP3TP4 TP5 TP6TP7 TP8 TP9 Keystone Elec-14 TP_0.025 test_point2 5000K–ND Test Point - Single 0.025" PinTP10 TP11 tronicsTP12 TP13TP14
(1) On ADS8412EVM, the ADS8412IPFBT is installed instead of ADS8402IPFBT. On ADS8406EVM, theADS8406IPFBT is installed instead of ADS8402IPFBT.
ADS8402/ADS8406/ADS8412 EVM User's GuideSLAU126A – December 2003 – Revised September 2004 9

www.ti.com
7 ADS8402/ADS8406/ADS8412EVM Layouts
ADS8402/ADS8406/ADS8412EVM Layouts
This section contains the EVM layouts.
Figure 2. Top - Layer 1
ADS8402/ADS8406/ADS8412 EVM User's Guide10 SLAU126A – December 2003 – Revised September 2004