Texas Instruments LSF-EVM User manual

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LSF-EVM Hardware User's Guide
User's Guide
SLVUB53–July 2017
LSF-EVM Hardware User's Guide
Contents
1 Introduction ................................................................................................................... 2
2 Hardware Description ....................................................................................................... 2
2.1 Board View and Supported Devices ............................................................................. 2
2.2 Board Overview..................................................................................................... 3
2.3 Board Component Descriptions................................................................................... 4
3 Setup .......................................................................................................................... 6
3.1 LSF0108 Setup (Out of Box Setup) .............................................................................. 6
3.2 LSF0204 Setup ..................................................................................................... 7
3.3 Operating Modes.................................................................................................... 7
4 Additional Information ...................................................................................................... 9
4.1 Hardware Change Log............................................................................................. 9
4.2 Schematic .......................................................................................................... 10
4.3 Bill of Materials .................................................................................................... 11
List of Figures
1 LSF-EVM With LSF0108PW Populated .................................................................................. 2
2 LSF-EVM With LSF0101 Populated....................................................................................... 3
3 LSF-EVM With LSF0102 Populated....................................................................................... 3
4 LSF-EVM With LSF0204 Populated....................................................................................... 3
5 LSF-EVM Board Overview ................................................................................................. 3
6 Jumper and Supply Connections for Multi-Voltage Level Translation (Zoom for High Resolution)............... 4
7 LSF Pass Transistor LOW-State Operation.............................................................................. 5
8 Typical LSF-EVM Setup .................................................................................................... 6
9 LSF0204 Board Setup ...................................................................................................... 7
10 LSF0102 Single-Supply Operation Setup ................................................................................ 8
11 LSF-EVM Without Single-Supply Resistors.............................................................................. 8
12 LSF-EVM With Single-Supply Resistors Populated..................................................................... 8
13 LSF-EVM Schematic (Zoom for Higher Resolution)................................................................... 10
14 Bill of Materials ............................................................................................................. 11
List of Tables
1 Compatible Parts and Packages for LSF-EVM .......................................................................... 2
2 Allowable Operating Voltages.............................................................................................. 4
3 Pullup Resistor Values...................................................................................................... 5
4 Description of Hardware Changes......................................................................................... 9
Trademarks
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LSF-EVM Hardware User's Guide
1 Introduction
The Texas Instruments' LSF-EVM aids in the evaluation of the operation and performance of the LSF
family of auto-bidirectional multi-voltage level translators. The LSF family of devices are level translators
that support a voltage range of 0.95 V to 5.5 V and provide multi-voltage bidirectional translation without
the need for a direction pin.
The LSF-EVM comes populated with the LSF0108PWR device and has landing patterns that are
compatible with the LSF0101DRYR, LSF0102DCTR, and LSF0204PWR devices.
The LSF-EVM is optimized for high-speed translation by reducing reflections for data rates greater than
100 MHz. Additionally, the design of the board enables simple evaluation as multiple connection interfaces
are available and pullups are populated which is easily connected or disconnected by using shunt
jumpers.
2 Hardware Description
2.1 Board View and Supported Devices
The LSF-EVM comes populated with the LSF0108 device in the PW (TSSOP) package; however, this
EVM can evaluate additional devices as well. Figure 1 shows the EVM populated with the LSF0108PWR
device, and Table 1 lists all of the part numbers and packages that are compatible with the LSF-EVM.
Figure 1. LSF-EVM With LSF0108PW Populated
Table 1. Compatible Parts and Packages for LSF-EVM
Part Number Packages
LSF0101DRYR SON (DRY) - See Figure 2 for device pad location
LSF0102DCTR SSOP (DCT) - See Figure 3 for device pad location
LSF0204PWR TSSOP (PW) - See Figure 4 for device pad location
LSF0204DPWR TSSOP (PW) - See Figure 4 for device pad location
LSF0108PWR TSSOP (PW) - default populated device

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Figure 2. LSF-EVM With LSF0101
Populated Figure 3. LSF-EVM With LSF0102 Populated Figure 4. LSF-EVM With LSF0204 Populated
NOTE: The location of pin 1 of the LSF0204 and LSF0204D is not the same as the LSF0108 which
comes pre-populated on the board. Please note the location of the LSF0204 device in
Figure 4 carefully, as pin 1 of the LSF0204 is located on the LSF0108 pin 2 landing pad.
2.2 Board Overview
Figure 5 shows an overview of the LSF-EVM. The main features, such as connectors, pullups, and
headers are highlighted. A more detailed description of the board is given in Section 2.3, and a schematic
is provided in the Section 4.2 section.
Figure 5. LSF-EVM Board Overview
NOTE: Two sections of the board are labeled as LSF0204*. The LSF0204 has a different pinout,
and additional jumpers are required for proper operation. See Section 3.2 for additional
information regarding evaluation of the LSF0204 and LSF0204D devices.

Jumper to pull up line B1
to V_PU through R8
Additional Supply for Second Pull-up voltage
Jumper to pull up line A4 to
VREF_A through R3
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2.3 Board Component Descriptions
This section describes the components on the LSF-EVM to aid in configuration of the EVM prior to
evaluation of the selected LSF device.
2.3.1 J1, J2 - A Supply (Vref_A), B Supply (V_PU)
These jumpers provide connections for the A side and B side supplies for the LSF device. The grounds of
each jumper are shorted, with two positions provided for convenience. Be sure that the two supplies share
the same ground.
Refer to Table 2 for allowable supply voltages.
Table 2. Allowable Operating Voltages
PARAMETER MIN MAX UNIT
V_PU Pullup supply voltage Vref_A + 0.85 5.5 V
Vref_A A side reference voltage 0.95 5.5 V
VI(EN) Enable pin input voltage Vref_A + 0.85 5.5 V
2.3.2 J3, J4 - A Side and B Side Pullup Headers
These jumpers are provided to be able to quickly connect or disconnect the pullup resistors connected to
the A side supply (Vref_A) or the B side supply (V_PU). Additionally for multi-supply voltage level
translation, a separate supply voltage could be connected to the side of the header that is directly
connected to the resistor. See Figure 6 for an example of this additional supply.
Figure 6. Jumper and Supply Connections for Multi-Voltage Level Translation (Zoom for High Resolution)

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Figure 7. LSF Pass Transistor LOW-State Operation
The pullup resistors that come populated on the board are 310 Ω.
The pullup resistor must be selected to limit the current through the pass transistor to 64 mA maximum.
To ensure a pass voltage of 260 mV to 350 mV, the pullup resistor should be sized to limit the current
through the pass transistor to 15 mA, see Figure 7. To set the current through each pass transistor at 15
mA, calculate the pullup resistor value using Equation 1:
Rpu = (Vpu – 0.35 V) / 0.015 A (1)
Table 3 summarizes resistor values, reference voltages, and currents at 15 mA, 10 mA, and 3 mA. The
resistor value shown in the +10% column (or a larger value) must be used to ensure that the pass voltage
of the transistor is 350 mV or less.
(1) Calculated for VOL = 0.35 V
(2) Assumes output driver VOL = 0.175 V at stated current
(3) +10% to compensate for VDD range and resistor tolerance
Table 3. Pullup Resistor Values(1)(2)
VPU 15 mA 10 mA 3 mA
NOMINAL (Ω) +10%(3) (Ω) NOMINAL (Ω) +10%(3) (Ω) NOMINAL (Ω) +10%(3) (Ω)
5 V 310 (Populated
Resistance) 341 465 512 1550 1705
3.3 V 197 217 295 325 983 1082
2.5 V 143 158 215 237 717 788
1.8 V 97 106 145 160 483 532
1.5 V 77 85 115 127 383 422
1.2 V 57 63 85 94 283 312
2.3.3 J5 - J8 - Channel 1-2 Edge-Mounted SMB Connectors
Connectors J5 and J6 are provided for channel 1 of the device to enable optimal conditions for high-speed
operation of the LSF devices. J7 and J8 are spaces left for additional edge-mount connectors to connect
channel 2. See Section 4.3 for orderable part numbers.
For input signals that are being driven by a 50-Ωsource, TI recommends to have a 50-Ωtermination
either at the device, see Figure 8.
2.3.4 J9, J10 - Channel 3-8 Header Connectors
Connectors J9 and J10 are provided for channels 3-8 of the device to enable the remaining connections
for the LSF0108 device. Each output has a corresponding ground connection to enable measurement of
the output using a differential probe for optimal signal integrity.
2.3.5 J11, J12 - Additional Headers for LSF0204 and LSF0204D Operation
J11 and J12 are provided as connectors for use when the LSF0204 device is populated. See Section 3.2
for additional information.

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3 Setup
The following sections describe the jumpers and connectors on the EVM as well as how to properly
connect, setup, and use the LSF-EVM.
3.1 LSF0108 Setup (Out of Box Setup)
Figure 8 shows a typical setup of the LSF-EVM. Note the following connections:
• VREF_A is connected to J1
• V_PU is connected to J2
• A high-speed signal is connected into the SMA Connector on the A side with a 50-Ωtermination
impedance to reduce line reflections
• An SMA cable is connected from the B side to a high-impedance oscilloscope input to monitor the
output waveform
• The yellow cable on the left is connected to A3 on the A side to provide an input signal
• The yellow cable on the right is connected to B3 on the B side to monitor the output waveform
• Two red boxes indicate the positions for shunt jumpers placed on J4 which connect pullups for
channels 1 and 3 on the B side for up-translation.
Figure 8. Typical LSF-EVM Setup

SH1
SH3
SH2
SH4
LSF
0204
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3.2 LSF0204 Setup
Figure 9 shows a typical setup of the LSF-EVM with the LSF0204 device populated. Note the following
connections:
• VREF_A is connected to J1
• V_PU is connected to J2
• A high-speed signal can be connected into the SMA Connector on the A side with a 50-Ωtermination
impedance to reduce line reflections
• An SMA cable is connected from the B side to a high-impedance oscilloscope input to monitor the
output waveform
• Four red boxes indicate the positions for shunt jumpers, refer to the following descriptions:
– SH1: This shunt jumper is populated to pull up the B3 line to up translate the signal from the A side
– SH2: This shunt jumper is populated to pull up the B1 line to up translate the signal from the A side
– SH3: This shunt jumper is populated to short/bypass the R7 200-kΩresistor. This resistor is not
required for operation with the LSF0204 devices, as the 200-kΩresistor is integrated.
– SH4: This shunt jumper is populated to connect the EN pin of the LSF0204 to VREF_A to enable
the device. For the LSF0204D device, this shunt/jumper should be connected to GND to enable the
device (shifting the shunt/jumper up one position pulls this line to ground).
Figure 9. LSF0204 Board Setup
3.3 Operating Modes
There are two operating modes of the LSF-EVM: dual-supply operation and single-supply operation.
3.3.1 Dual Supply Operation (Typical operating mode)
This is the typical mode of operation for this EVM. Two supplies are used as shown in Figure 8. With two
supplies connected, the device is able to up or down translate bidirectionally between the A and B side
when the corresponding pullup resistors are connected.

R2= (R7+R1)(VPU-VREFA) - R1VTH
R7 R1 VREFA
3.3V
Vref_AVref_B
EN
A1
A2
B1
B2 GND
LSF0102
200 k
3.3V 1 M1.8-5.5V
379 k
3.3V
Device 1.8-5.5V Device
This node sets
~1.8V threshold
R1 R2
R7
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3.3.2 Single-Supply Operation
Single-supply operation enables the use of a single supply to bias the LSF to enable translation. The
primary application for this setup is when the A side has a variable supply. Because the VREF_A voltage
must be 0.8 V less than the VREF_B voltage, this setup enables the user to bias the device and allow for
a wider range of voltages on the A side.
NOTE: One limitation of this setup is that it does not allow for a pullup to be placed between the A
side output and the VREF_A pin. A separate supply is required for up translation on the A
side.
Figure 10. LSF0102 Single-Supply Operation Setup
To enable single-supply operation, resistors R1and R2must be populated, see Figure 12.
Use Equation 2 to determine the value of R1to set the threshold of the device:
where
• VREFA is the lowest voltage that is desired on the A side.
• VPU is the supply voltage provided at the J2 jumper and must be 0.85 V higher than VREFA.
• VTH is the threshold drop of the device, assumed to be 0.85 V.
• R7 is the pullup resistor between VREFB and VPU, typically 200 kΩ.
• R1 is the resistor that connects VPU to VREFA, recommended 1 MΩ.
• R2 is the resistor that connects VREFA to ground. (2)
Figure 11. LSF-EVM Without Single-Supply Resistors Figure 12. LSF-EVM With Single-Supply Resistors
Populated

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4 Additional Information
4.1 Hardware Change Log
Table 4. Description of Hardware Changes
PCB Revision Description of Changes
Rev 1.0 Initial Release

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4.2 Schematic
Figure 13. LSF-EVM Schematic (Zoom for Higher Resolution)
NOTE: DNP is an abbreviation for do not populate. Components highlighted as DNP in the schematic are not populated out of the box.