TEXAS INSTRUMENTS THS0842 Technical data
查询THS0842EVM供应商
User’s Guide
September 2000 AAP Data Conversion
SLAU043C
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Copyright 2000, Texas Instruments Incorporated
About This Manual
How to Use This Manual
Preface
Read This First
This document presents a description of the THS0842 evaluation module.
How to Use This Manual
This document contains the following chapters:
- Chapter 1 – Overview
- Chapter 2 – Circuit Functionality
- Chapter 3 – Layout, Decoupling, and Grounding Considerations
- Chapter 4 – PC Board and Bill of Materials
- Appendix A – Schematics
Read This First
iii
iv
Running Title—Attribute Reference
Contents
1 Overview 1-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.1 Purpose 1-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.2 EVM Basic Function 1-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.3 Power Requirements 1-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.3.1 Voltage Limits 1-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.4 THS0842 EVM Operational Procedure 1-4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2 Circuit Functionality 2-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2.1 Circuit Function 2-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2.2 Analog Inputs 2-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2.2.1 Single-Ended Transformer Coupled Interface 2-2. . . . . . . . . . . . . . . . . . . . . . . . . . .
2.2.2 Differential Interface 2-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2.3 Digital Inputs 2-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2.3.1 Internal Clock 2-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2.3.2 External Clock 2-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2.4 Analog Output 2-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2.5 Digital Output 2-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2.6 References 2-4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2.7 Power 2-5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3 Layout, Decoupling, and Grounding Considerations 3-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4 PC Board and Bill of Materials 4-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.1 Printed-Circuit Board 4-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.2 Bill of Materials 4-10. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
A Schematics A-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Chapter Title—Attribute Reference
v
Running Title—Attribute Reference
Figures
1–1 Block Diagram 1-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4–1 Printed-Circuit Board (Top) 4-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4–2 Printed-Circuit Board Layer 1 4-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4–3 Printed-Circuit Board Layer 2 4-4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4–4 Printed-Circuit Board Layer 3 4-5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4–5 Printed-Circuit Board Layer 4 4-6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4–6 Printed-Circuit Board Layer 5 4-7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4–7 Printed-Circuit Board Layer 6 4-8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4–8 Printed-Circuit Board (Bottom) 4-9. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
T ables
1–1 Jumper List Table 1-4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1–2 Default Jumper Positions 1-4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2–1 Daughtercard Connector J2 2-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2–2 Daughtercard Connector J5 2-4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2–3 Minimum/Maximum Reference Input Levels 2-5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
vi
Chapter 1
Overview
This chapter gives a general overview of the THS0842 evaluation module
(EVM), and describes some of the factors that must be considered in using the
module.
T opic Page
1.1 Purpose 1-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.2 EVM Basic Function 1-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.3 Power Requirements 1-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.4 THS0842 EVM Operational Procedure 1-4. . . . . . . . . . . . . . . . . . . . . . . . . . .
Overview
1-1
Purpose
T
T
1.1 Purpose
The THS0842 evaluation module (EVM) provides a platform for evaluating the
THS0842 analog-to-digital converter (ADC) under various signal, reference,
and supply conditions. The system block diagram is shown below. This illustration provides a general indication of the features and functions available. It
should be read in combination with the circuit schematic supplied.
Figure 1–1.Block Diagram
AIN+
AIN–
1:1
Xfmr
A
IN
1:1
Xfmr
A
IN
IIN+
IIN–
CML
QIN+
QIN–
THS0842
DA7
DA0
COUT
COUT
I
THS5651A
Buffer
8
J2 – I OUT
OU
AIN–
AIN+
Clock
80 MHz
Osc
Optional
External
Reference
CLK
REFT
REFB
DB7
DB0
8
Buffer
THS5651A
J5 – Q OUT
I
OU
1-2
1.2 EVM Basic Function
Analog inputs to the ADC are provided via six external SMB connectors. Two
pairs of SMB connectors provide true differential inputs, or two individual SMB
connectors provide single-ended transformer-coupled signals to the inputs of
the device.
The EVM provides an external SMB connection for input of the ADC clock. A
crystal oscillator is provided on the board to perform this function and can be
used when required. Refer to the section on clocking for correct provisioning.
Digital output from the EVM is via two 25-pin connectors. The digital lines from
the ADC are buffered before going to the connectors. More information on
these connectors can be found in the ADC output section.
Analog output from the EVM is via two SMB connectors (J1 and J3). A pair of
THS5651 10-bit DACS are used to recreate the analog signal from the ADC’s
digital data. More information on this can be found in the ADC analog output
section.
Power connections to the EVM are via a pair of screw-down connectors.
Separate input connectors are provided for the analog and digital supplies.
EVM Basic Function
1.3 Power Requirements
The EVM is powered directly through independent 3.3-V analog and digital
supplies.
1.3.1 Voltage Limits
Exceeding the 3.3-V maximum can damage EVM components. Under voltage
may cause improper operation of some or all of the EVM components.
Overview
1-3
THS0842 EVM Operational Procedure
1.4 THS0842 EVM Operational Procedure
The THS0842 EVM provides a flexible means of evaluating the THS0842 in
a number of modes of operation. A basic setup procedure that can be used as
a board confidence check follows:
1) Verify all jumper settings against the schematic jumper list in Table 1–1:
Table 1–1.Jumper List Table
Jumper Function Installed Removed Default
W1 Reserved for future use Required Do not use Installed
W2 Reserved for future use Required Do not use Installed
W3 Oscillator power down Power down Active Installed
W4 Reference select Internal External Installed
W5 THS0842 standby Active Power down Installed
W6 Select clock source Onboard Offboard Removed
W7 Digital bus output enable 3-state bus Active Removed
W8 Single/dual bus mode Dual mode Single mode Installed
W9 External REFB source 1–2 onboard 2–3 offboard 1–2
W10 External REFB feed External Internal Removed
W1 1 External REFT feed External Internal Removed
W12 Q+ Input select 1–2 differential 2–3 single-ended 2–3
W13 Q– Input select 1–2 differential 2–3 single-ended 2–3
W14 I+ Input select 1–2 differential 2–3 single-ended 2–3
W15 I– Input select 1–2 differential 2–3 single-ended 2–3
W16 External REFT source 1–2 onboard 2–3 offboard 1–2
Table 1–2.Default Jumper Positions
EVM Jumper Table (connection)
THS0842 W1, W2, W3, W4, W5, W7, W9 (1–2), W12 (2–3), W13 (2–3), W14(2–3), W15 (2–3), W16(1–2)
1) Set both dc power supplies to read 3.3 V at the output terminals. Connect
GND of the first power supply to the AGND(J6–2) terminal on the EVM,
and GND of the other power supply to the DGND(J7–2) terminal on the
EVM. Then connect the first power supply’s 3.3-V output to the A VDD power (J6–1) terminal of the EVM, and the other power supply’s 3.3-V output
to the DVDD(J7–1) terminal of the EVM.
1-4
2) Switch power supplies on.
3) Set function generator number one to output a square wave at a frequency
of 80 MHz, 0-V offset, and an amplitude of 3.3 V on the 50-Ω output.
4) Use a 50-Ω coaxial cable with BNC/SMB connectors to connect generator
number 1 to J4 (clock input).
THS0842 EVM Operational Procedure
5) Set function generator number 2 to output a sine wave at a frequency of
1 MHz, 0-V offset, and an amplitude of 0.8 Vp-p on the 50-Ω output.
6) Use a 50-Ω coaxial cable with BNC/SMB connectors to connect generator
number 2 to J8 (Q input). Use a T-splitter to connect the test signal to channel 1 of the oscilloscope.
7) Use a 50-Ω coaxial cable with BNC/SMB connectors to connect the second channel of the oscilloscope to J3 (Q-output). The two sine waves
should have the same period (their amplitudes may differ).
8) Repeat Step 5 with the SMB connected to J11 (I-input).
9) Repeat Step 6, except connect to J1 (I-output).
Overview
1-5
1-6
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