Texas Instruments THVD1424 User manual

User’s Guide
THVD1424 Evaluation Module (EVM) User Guide
ABSTRACT
This document is the EVM User’s guide for the THVD1424EVM which provides a quick way to evaluate TI’s
THVD1424, a full duplex RS-485 traceiver with selectable data rate and switchable integrated termination
resistors, in the VSON (DRC) package.
Table of Contents
1 Introduction.............................................................................................................................................................................2
2 Information on Cautions and Warnings................................................................................................................................4
3 Board Description...................................................................................................................................................................5
3.1 Board Component Overview.............................................................................................................................................. 5
3.1.1 Powering the Boarde................................................................................................................................................... 7
3.1.1.1 Single Supply Operation....................................................................................................................................... 7
3.1.1.2 Dual Supply Operation (Separate Digital Logic and Driver supplies)................................................................... 8
3.1.1.3 Default Operation Mode........................................................................................................................................8
3.1.1.4 Single Ended Bus Modification Operational Modes............................................................................................10
4 Design Documents................................................................................................................................................................11
4.1 Schematics.......................................................................................................................................................................11
4.2 Board Layout....................................................................................................................................................................13
4.3 Bill Of Materials................................................................................................................................................................ 14
5 Revision History................................................................................................................................................................... 14
Trademarks
All trademarks are the property of their respective owners.
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1 Introduction
About This Manual
This User’s guide describes the THVD1424EVM and its intended use.
Figure 1-1. Top Side View of THVD1424EVM
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Figure 1-2. Bottom Side View of THVD1424EVM
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2 Information on Cautions and Warnings
The information in the warning statement is provided for personal protection and the information in the caution
statement is provided to protect the equipment from damage. Read each caution and warning statement
carefully.
This EVM contains components that can potentially be damaged by electrostatic discharge. Always transport
and store the EVM in its supplied ESD bag when not in use. Handle using an antistatic wristband. Operate on an
antistatic work surface. For more information on proper handling, see Electrostatic Discharge (ESD).
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3 Board Description
Features
• Ready to Use out of Box with THVD1424DRC Pre-Installed
• Separate Logic Voltage Supply Connection (J5) with Option to Short to VCC (J6) Through Jumper J7
• Two 10uF Decoupling Caps Pre-Installed on VCC to GND and GND to EARTH Connections
• Six 0603 Capacitor Pads for additional decoupling on VCC or VL Supplies.
• Two Resistor Pads to create resistive link between GND and EARTH
• One 10x2 Header Connection for Feature Control Signals
• External Termination Resistor and Capacitor Pads on TX and RX bus.
• Common mode Voltage connections on TX and RX Bus.
3.1 Board Component Overview
The THVD1424EVM is ready to operate directly out of Box with a THVD1424EVM installed at U1. All the Signal
and Power Jumpers/Inputs (J1 – J20) come pre-installed on board. See Table 3-1 for description for every pad
on the board and if it comes pre-installed by default.
Table 3-1. Component Overview
Jumper ID Function Package Comment Installed?
J1 “R” Pin output 4x2 Header N/A Y
J2 “/RE” Pin Input 4x2 Header N/A Y
J3 “DE” Pin Input 4x2 Header N/A Y
J4 “D” Pin Input 4x2 Header N/A Y
J5 VL Terminal Terminal Block N/A Y
J6 VCC Terminal Terminal Block N/A Y
J7 VL to VCC Jumper 2x1 Header N/A Y
J8 Control Signal Jumper 10x2 Header N/A Y
J9 RX Common Mode Input 4x1 Header N/A Y
J10 “A” Line Common Mode
Input
4x1 Header N/A Y
J11 “B” Line Common Mode
Input
4x1 Header N/A Y
J12 RX Header #1 4x1 Header Between Series Resistor
and IC
Y
J13 RX Header #2 4x1 Header Between Series Resistor
and Terminal
Y
J14 RX Terminal Terminal Block N/A Y
J15 TX Header #1 4x1 Header Between Series Resistor
and IC
Y
J16 TX Header #2 4x1 Header Between Series Resistor
and Terminal
Y
J17 TX Terminal Terminal Block N/A Y
J18 TX Common Mode Input 4x1 Header N/A Y
J19 “Y” Line Common Mode
Input
4x1 Header N/A Y
J20 “Z” Line Common Mode
Input
4x1 Header N/A Y
Resistor ID Function Package Comment Installed?
R1 0 Ohm Series Resistor 0603 N/A Y
R2 Pull-Up Resistor 0603 N/A N
R3 LED Current Limiting
Resistor
0603 N/A Y
R4 0 Ohm Series Resistor 0603 N/A Y
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Table 3-1. Component Overview (continued)
Jumper ID Function Package Comment Installed?
R5 Pull-Up Resistor 0603 N/A N
R6 Pull-Down Resistor 0603 N/A N
R7 0 Ohm Series Resistor 0603 N/A Y
R8 Pull-Up Resistor 0603 N/A N
R9 Pull-Down Resistor 0603 N/A N
R10 0 Ohm Series Resistor 0603 N/A Y
R11 Pull-Up Resistor 0603 N/A N
R12 Pull-Down Resistor 0603 N/A N
R13 LED Current Limiting
Resistor
0603 N/A Y
R14 GND to EARTH Resistor 0603 N/A N
R15 GND to EARTH Resistor 0603 N/A N
R16 LED Current Limiting
Resistor
0603 N/A Y
R17 0 Ohm Series Resistor 0603 N/A Y
R18 0 Ohm Series Resistor 0603 N/A Y
R19 “A” Common Mode
Resistor
0603 Must be >= 375 Ohms if
Installed
N
R20 “B” Common Mode
Resistor
0603 Must be >= 375 Ohms if
Installed
N
R21 0 Ohm Series Resistor 0603 N/A Y
R22 0 Ohm Series Resistor 0603 N/A Y
R23 “Y” Common Mode
Resistor
0603 Must be >= 375 Ohms if
Installed
N
R24 “Z” Common Mode
Resistor
0603 Must be >= 375 Ohms if
Installed
N
R25 External RX Termination 0805 Used for Short Bus Power
Consumption Test
N
R26 External TX Termination 0805 Used for Short Bus Power
Consumption Test
N
Capacitor ID Function Package Comment Installed?
C1 Capacitive Loading for “R”
pin
0603 N/A N
C2 VL Supply Decoupling
Cap
0805 N/A N
C3 VL Supply Decoupling
Cap
0805 N/A N
C4 VL Supply Decoupling
Cap
0805 N/A N
C5 VL Supply Decoupling
Cap
0805 N/A N
C6 VCC Supply Decoupling
Cap
0805 N/A N
C7 VCC Supply Decoupling
Cap
0805 N/A Y
C8 VCC Supply Decoupling
Cap
0805 N/A N
C9 VCC Supply Decoupling
Cap
0805 N/A Y
C10 VCC Supply Decoupling
Cap
0603 HF Decoupling – Close to
IC Package
Y
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Table 3-1. Component Overview (continued)
Jumper ID Function Package Comment Installed?
C11 VL Supply Decoupling
Cap
0603 HF Decoupling – Close to
IC Package
Y
C12 Common Mode
Decoupling Cap “A” Line
0805 N/A N
C13 Common Mode
Decoupling Cap “B” Line
0805 N/A N
C14 Termination Capacitor RX 0805 N/A N
C15 Termination Capacitor TX 0805 N/A N
C16 Common Mode
Decoupling Cap “Y” Line
0805 N/A N
C17 Common Mode
Decoupling Cap “Z” Line
0805 N/A N
LED ID Function Package Comment Installed?
D1 “R” Line LED – Red Non-Standard N/A Y
D2 “D” Line LED – Green Non-Standard N/A Y
D3 “VCC” LED – Blue Non-Standard N/A Y
IC ID Function Package Comment Installed?
U1 RS-485 Transceiver VSON (DRC) THVD1424 Y
The default setup is optimized to work with the THVD1424. Operating in a single supply mode without a common
mode voltage. By shorting header J7 (VL = VCC), with control signals being applied externally at J2-J4 and J8 or
by using the headers J2-J4 and J8 to shunt to associated pin to GND or VCC/VL. The board is ready to operate
in its default state. See Single Supply Operation and Dual Supply Operation for information on power supplies
and operational modes of the board respectively.
3.1.1 Powering the Boarde
3.1.1.1 Single Supply Operation
The THVD1424 has both a VCC pin (used for the RS-485 bus pins) and VL pin (Used for console facing pins). In
single supply operation mode for the THVD1424 the VL pin should be shorted to VCC by shorting the J7 header
pins, so that the digital logic circuits connected to the Logic supply are properly powered.
Table 3-2. Single Supply Operation Configuration Table
Component ID Comment
J5 Leave VL terminal Open
J6 Attach VCC (3 V to 5.5 V) to Terminal
J7 Short Jumper to make sure VL = VCC
C2, C3, C4, and C5 Leave Uninstalled
C6 and C8 If More Decoupling Capacitance is Desired Attach Capacitors to C6
and C8
R15 Install Resistor if Low impedance pathway between GND and
EARTH is desired
To apply power onto the board, VCC is applied through the J6 terminal. With the board oriented with J6 on
the top of the board, as shown in figure 1.1, the signals are, from right to left, EARTH, GND, and VCC. The
EARTH and GND distinction are used to help the end user determine operational qualities w.r.t. ground potential
differences. If testing methods on reducing ground loop current install a resistor on pad R15. Check data sheet
for proper powering considerations as this will either recommend 3.3V, 5V or 3.3V to 5V.
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3.1.1.2 Dual Supply Operation (Separate Digital Logic and Driver supplies)
In Dual Supply operation the digital circuit supply, the supply which supplies the R, D, /RE, DE, H/F, SLR,
TERM_RX, and TERM_TX, can be held at a lower level than the VCC voltage of 3 V to 5.5 V as it can go down
to 1.65V. Allowing a 3.3V - 5V RS-485 bus to interface with devices operating at 1.8 V or 2.5 V logic. See Table
3-3 for information on power supply components in dual operation mode.
The VL supply is located at J6 on the bottom of the board and VCC is J5 located at the top of the board.
Table 3-3. Dual Supply Operation Configuration Table
Component ID Comment
J5 Connect to VL source (1.65V to 5.5V) for Logic Supply
J6 Connect to VCC Source (3V to 5.5V)
J7 Leave Open
C2, C3, C4, and/or C5 Have Minimum of 1uF of Decoupling Capacitance on VL
C6 and/or C8 If More Decoupling Capacitance is Desired Attach Capacitors to C6
and C8
R14 and/or R15 Install Resistor if Low impedance pathway between GND and
EARTH is desired
3.1.1.3 Default Operation Mode
With an understanding of how the board is setup and how to power the board for both supply situations the next
topic is how to operate the board. Out of the box the board, when powered, can operate the THVD1424 as a
full or half duplex RS-485 transceiver. The devices pins can be broken down into 4 distinct groups: single ended
communication pins, differential communication pins, power pins, and control pins. Power pins are discussed
above in the previous section, section 3.3, details below for the other 3 categories.
The single ended communication pins are to be connected directly, through their respective jumpers, to a single
ended bus – these pins are the “R” and “D” pins and represent RX and TX single ended data respectively. R is
connected to J1 and D is connected to J4 – these are the console side signal connection points for the EVM.
The THVD1424 has six control pins that vary in function. Two signals are enable signals for the driver (DE –
active high) and receiver (/RE – active low) that are accessed through J3 and J2 respectively. The other four
control signals are TERM_TX, H/F, TERM_RX, and the SLR pins which can be accessed through J8 and have
internal pull-downs leaving a default state as logic low on these four pins. A jumper configuration for J1 – J4 and
J8 are shown in Figure 3-1 with board orientation having jumper J1 at the top left corner of the board. A function
table for the control signals are shown in Table 3-4
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Figure 3-1. Control Signal Jumper Configuration
Table 3-4. THVD1424EVM Control Signal Function Table
Pin Associated Jumper - Pin Input Level Function
RE J2-3 and J2-8 Hi Receiver Disabled
RE J2-3 and J2-8 Low Receiver Enabled
DE J3-4 and J3-7 Hi Driver Enabled
DE J3-4 and J3-7 Low Driver Disabled
TERM-TX J8-3 and J8-4 Hi Y-Z Termination Enabled
TERM-TX J8-3 and J8-4 Low Y-Z Termination Disabled
H/F J8-7 and J8-8 Hi Half Duplex Mode
H/F J8-7 and J8-8 Low Full Duplex Mode
TERM-RX J8-11 and J8-12 Hi A-B Termination Enabled
TERM-RX J8-11 and J8-12 Low A-B Termination Disabled
SLR J8-15 and J8-16 Hi 500Kbps Mode
SLR J8-15 and J8-16 Low 20Mbps Mode
Finally, the last group of signals are the differential bus pins A, B, Y, and Z. A and B are connected at terminal
J14 with Y and Z at terminal J17. In Half Duplex Mode Y and Z are both the TX and RX connections, in full
duplex mode A and B are receiver pins and Y and Z are transmission pins.
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3.1.1.4 Single Ended Bus Modification Operational Modes
There are a few options with respect to the single ended data and control signals for modification on this EVM.
Jumpers J1 through J4 all contain pads that are blank by default. For D, DE, and /RE signals there are 0603
sized pads for either pull-up or pull-down resistors to have a default logic on these pins with the added benefit of
still being able to external signals to this pin. The R pin also contains a pull-up resistor 0603 sized, as is common
in UART based applications, as well as a 0603 sized pad to ground for a capacitive load in case testing requires
capacitive loading on the R pin. A summary of possible single ended signal pathway modifications on the EVM
are in Table 3-5.
Table 3-5. Single Ended Pins Modification Table
Associated Jumper / Signal Pad ID Comment
J1 / R R2 Pull Up Resistor Pad
J1 / R C1 Capacitive Load Pad
J2 / /RE R5 Pull Up Resistor Pad
J2 / /RE R6 Pull Down Resistor Pad
J3 / DE R8 Pull Up Resistor Pad
J3 / DE R9 Pull Down Resistor Pad
J4 / D R11 Pull Up Resistor Pad
J4 / D R12 Pull Down Resistor Pad
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