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Texas Instruments TXB-EVM Evaluation Module Users User guides
User's Guide
SCEU021 – November 2019
TXB-EVM Evaluation Module User Guide
This user's guide describes the characteristics, operation, and use of the TXB-EVM Evaluation Module
(EVM). A complete printed-circuit board layout, schematic diagrams, and bill of materials are included in
this document.
1
2
3
Contents
Introduction ................................................................................................................... 2
Board Layout ................................................................................................................. 5
Schematic and Bill of Materials ............................................................................................ 6
List of Figures
....................................................................................................................
1
TXB-EVM
2
TXB-EVM Layout ............................................................................................................ 5
3
3
1-Channel TXB0101 ......................................................................................................... 6
4
2-Channel TXB0102 ......................................................................................................... 6
5
4-Channel TXB0104 ......................................................................................................... 7
6
8-Channel TXB0108 ......................................................................................................... 7
List of Tables
1
Auto-Bidirectional Families ................................................................................................. 2
2
TXB-EVM Packages and Devices supported ............................................................................ 3
3
TXB Device Voltage Supply Ranges
4
TXB-EVM Bill of Materials .................................................................................................. 8
.....................................................................................
4
Trademarks
All trademarks are the property of their respective owners.
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TXB-EVM Evaluation Module User Guide
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1
Introduction
1
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Introduction
The TXS and TXB auto bidirectional voltage translators are designed for interfacing between 1.2-V to 5.5V drivers. TXS translation devices specialize in open-drain applications such as I2C, One-Wire, and MMCcard interfacing, while TXB translation devices are suited for high-impedance push-pull driver interfacing.
Watch choosing the right auto-bidirectional translator for a brief comparison of TXB, TXS and LSF
families.
This evaluation module (EVM) supports the customizable evaluation of the one, two, four, and eight bit
devices of the TXB family. Refer to TXS-EVM for evaluating the TXS device family.
1.1
1.1.1
Features
TXB Family
The TXB family uses two separate configurable power supply rails VCCA and VCCB with A ports tracking the
VCCA supply and B ports tracking the VCCB supply. These devices are fully specified for partial-power-down
applications using IOFF. The IOFF circuitry (SCEA026) disables the outputs, preventing damaging current
backflow through the device when it is powered down. The VCC isolation feature ensures that if either VCC
supply is powered down (0V), then the I/O ports are in a high-impedance state. Refer to the application
note A guide to voltage translation with the TXB family for more on TXB family characteristics.
Weak driving capability is characteristic of auto-bidirectional translators, allowing the device output to be
overridden by the external driver during a direction change, without the need for a separate DIR control
pin. TXB devices are designed with buffered I/O architecture suitable for light load push-pull applications.
During an edge transition, the One-shot (O.S) circuitry becomes active and lowers the effective output
impedance. Once the transition is complete, the weak 4-kΩ buffer drives the output. During a DC state,
only the series resistor drives the output, thus allowing the port to be overridden externally. Consequently,
external pull-up or pull-down resistor values must be larger than 50-kΩ to avoid affecting VOH or VOL. Refer
to the application note Effects of pull-up and pull-down resistors on TXB devices for further information.
Table 1 shows the comparison between the TXB, TXS and LSF Auto-Bidirectional families of TI.
Table 1. Auto-Bidirectional Families
2
Metrics
TXB
TXS
LSF
Translation mechanism
Weak buffered translation
Passive translation with NMOS
and internal pull-up resistors
Passive translation with NMOS
and external pull-up resistors
Drive strength
Very low drive of 20ua due to
4K limiting buffer
No DC drive
No DC drive
Applications/ Interface
Push-pull applications
Open-drain applications
Push-pull and open-drain
applications
Speed
Up to 140Mbps
Up to 24Mbps
High speed up to 200Mbps
Translation flexibility
Buffered and fixed translation
on A and B ports
Integrated pull-up resistorsreduces BOM cost of the
system; Fixed translation on A
and B ports
Flexible translation due to
external pull-up resistors
Frequency vs load balance
trade-off
I/O ports
A ports referenced to Vcca and A ports referenced to Vcca and
B ports referenced to Vccb
B ports referenced to Vccb
A ports not referenced to Vcca,
B ports not referenced to Vccb;
allows multi-voltage translation
Edge- acceleration
Integrated one-shot edge
acceleration circuitry
Integrated one-shot edge
acceleration circuitry
No integrated one-shot
acceleration circuitry
Vih/Vil requirements
Datasheet spec has Vih/Vil
specifications
Has Vih /Vil spec but no RON for
the FET
No Vih / Vil conditions, has RON
specifications
Additional care-about
VCCA<=VCCB
VCCA<=VCCB
VCCB>VCCA+0.8 V
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Introduction
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TXB-EVM is shown in Figure 1. Table 2 shows the packages supported by the TXB-EVM.
Table 2. TXB-EVM Packages and Devices supported
Device
Package
Pins
Device Populated
TXB0101
DCK (SC-70)
6
Yes
TXB0102
DCU (VSSOP)
8
Yes
TXB0104 (TXB0104-Q1*) (1)
PW (TSSOP)
14
No
RUT (UQFN)
12
Yes
PW (TSSOP)
20
No
RGY (VQFN)
20
Yes
TXB0108
(1)
-Q1 devices are not populated but can be supported.
Figure 1. TXB-EVM
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Introduction
1.2
1.2.1
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Hardware Description
Headers
All headers on this EVM are 100-mil. Each EVM board has header arrays for connection to the A and B
side data pins, with ground oriented towards the device and the data headers closer to the board edges.
Data pins are marked A1..A8 and B1..B8 from top to bottom. All ground pins on the board are at the same
ground potential.
1.2.2
Voltage Supply
Supply headers are located at the top of each EVM for VCCA and VCCB. Table 3 denotes the operational
voltage ranges for TXB devices.
Table 3. TXB Device Voltage Supply Ranges
TXB0101, TXB0102, TXB0104, TXB0104-Q1, TXB0108
1.2.3
VCCA range
VCCB range
1.2 – 3.6 V
1.65 – 5.5 V
Bypass Capacitors
0.1 µF Surface Mount (SM) 0402 capacitors are populated near VCCA and VCCB device pins on each board
(C4, C5, C6, C7, C23, C24, C25, C26). These are in place to smooth transient voltage supply spikes
during start up and normal device operation.
1.2.4
OE Select
A 3x1 100 mil header provides access to the Output Enable (OE) pin on the device. The 100 mil jumper is
available for selecting a known state for the OE pin. The outer header pins access VCCA or GND through a
10 kΩ resistor. OE on TXB devices may be referenced to either VCCA or GND, although using a pull up
resistor on OE during device power-on is recommended to have the I/O ports at high-impedance before
the VCCA becomes stable. Output enable pin is the input for the device and should never be left floating.
The CMOS inputs must be held at a known state, either VCC or ground, to ensure proper device operation.
Refer to Implications of Slow or Floating CMOS Inputs (SCBA004).
1.2.5
RC Loading
Each data I/O trace connects to an 0805 surface mount (SM) pad with access to VCC for customizable pullup resistors and a 0805 SM pad with access to GND for a customizable load. Large pads were chosen for
ease of access and the option to compose a load out of multiple, smaller, SM components if desired (for
load tests, propagation delay, rise/fall time adjustments, etc.). Figure 1 shows the SM pad locations. Pull
down pads are marked with a ground symbol, pull up pads are marked with a power port symbol on the
board.
4
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Board Layout
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2
Board Layout
Figure 2 illustrates the TXB-EVM layout.
Figure 2. TXB-EVM Layout
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Schematic and Bill of Materials
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3
Schematic and Bill of Materials
3.1
Schematic
Figure 3, Figure 4, Figure 5 and Figure 6 illustrates the TXB-EVM schematic.
Figure 3. 1-Channel TXB0101
Figure 4. 2-Channel TXB0102
6
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Schematic and Bill of Materials
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Figure 5. 4-Channel TXB0104
Figure 6. 8-Channel TXB0108
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Schematic and Bill of Materials
3.2
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Bill of Materials
Table 4 lists the TXB-EVM bill of materials.
Table 4. TXB-EVM Bill of Materials
Designator
Quantity Description
C4, C5, C6, C7, C23, C24,
C25, C26
8
CAP, CERM, 0.1 uF, 16 V, +/- 10%, X7R, 0402 0402YC104KAT2A
AVX
J1, J3, J12, J15
4
Header, 100mil, 3x1, Gold, TH
HTSW-103-07-G-S
Samtec
J2, J5, J6, J7, J9, J13, J14,
J18, J19, J20
10
Header, 100mil, 2x1, Gold, TH
HTSW-102-07-G-S
Samtec
J4, J8
2
Header, 100mil, 2x2, Gold, TH
TSW-102-07-G-D
Samtec
J10, J16
2
Header, 100mil, 8x2, Gold, TH
TSW-108-07-G-D
Samtec
J11, J17
2
Header, 100mil, 4x2, Gold, TH
TSW-104-07-G-D
Samtec
R1, R2, R3, R5, R20, R21,
R27, R29
8
RES, 10.0 k, 1%, 0.063 W, AEC-Q200 Grade
0, 0402
RMCF0402FT10K0
Stackpole Electronics
SH-J1, SH-J3, SH-J12, SHJ15
4
Shunt, 100mil, Flash Gold, Black
SPC02SYAN
Sullins Connector
U1
1
1-Bit Bidirectional Voltage-Level Shifter With
Auto Direction Sensing and +/-15-kV ESD
Protect, DCK0006A (SOT-SC70-6)
TXB0101DCKR
Texas Instruments
U2
1
2-Bit Bidirectional Voltage-Level Shifter with
Auto Direction Sensing and +/-15-kV ESD
Protect, DCU0008A (VSSOP-8)
TXB0102DCUR
Texas Instruments
U5
1
4-Bit Bidirectional Voltage-Level Shifter with
Auto Direction Sensing and +/-15 kV ESD
Protect, RUT0012A (UQFN-12)
TXB0104RUTR
Texas Instruments
U6
1
8-Bit Bidirectional Voltage-Level Shifter with
Auto Direction Sensing and +/-15-kV ESD
Protect, RGY0020A (VQFN-20)
TXB0108RGYR
Texas Instruments
C1, C2, C3, C8, C9, C10,
C11, C12, C13, C14, C15,
C16, C17, C18, C19, C20,
C21, C22, C27, C28, C29,
C30, C31, C32, C33, C34,
C35, C36, C37, C38
0
CAP, CERM, 0.1 uF, 50 V, +/- 5%, X7R, 0805
08055C104JAT2A
AVX
R4, R6, R7, R8, R9, R10,
R11, R12, R13, R14, R15,
R16, R17, R18, R19, R22,
R23, R24, R25, R26, R28,
R30, R31, R32, R33, R34,
R35, R36, R37, R38
0
RES, 10.0 k, 0.5%, 0.125 W, 0805
RT0805DRE0710KL
Yageo America
U3
0
8-Bit Bidirectional Voltage-Level Shifter For
Open-Drain And Push-Pull Application,
PW0020A (TSSOP-20)
TXS0108EPWR
Texas Instruments
U4
0
4-Bit Bidirectional Voltage-Level Shifter for
Open-Drain and Push-Pull Applications,
PW0014A (TSSOP-14)
TXS0104EPWR
Texas Instruments
8
TXB-EVM Evaluation Module User Guide
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Part Number
Manufacturer
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