Board Setup
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SLVUAU3 – January 2017
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TPD2S701-Q1 Evaluation Module
2.3
Bandwidth Evaluation
Devices U3 and U4 are configured to allow for precise bandwidth measurements. The two devices are in a
DSK and DGS package respectively, but otherwise are functionally identical. Each device has SMA
connectors on both the connector and system side of the USB 2.0 Data line pins that offer a low
attenuation way to connect a network analyzer and ensure that during typical operation the TPD2S701-Q1
capacitance and inductance do not impede signal speed past where the maximum line signal speed is. In
addition, when U3 and U4 are placed into a fault state the bandwidth can be measured to ensure that the
DC fault voltage is significantly attenuated. See
Figure 3
.
There is an additional bandwidth setup that is designed for calibration. The board and trace add some
parasitics and bandwidth loss that do not reflect how the TPD2S701-Q1 operates when designed into a
system. This additional pass-through allows for calibration to account for those and get a more accurate
picture of the bandwidth of the TPD2S701-Q1.
Figure 3. Bandwidth Evaluation Configuration
2.4
IEC ESD Evaluation
Device U5 is configured to be an optimal place to test the TPD2S701-Q1 IEC ESD strike response. This
configuration contains the TPD2S701-Q1 in only the DSK package as there is no difference in the
performance between the DSK and DGS packages. Test points VD+ and VD– offer strike points that can
targeted with an external ESD simulator on the protected data lines. By measuring with attenuated scope
probes on the SMB connecters labeled D+ and D– during an ESD strike, the user can capture a waveform
of what the protected system is exposed to during an ESD strike. Resistors R7 and R9 are 150-
Ω
resistors
in series with the ESD pulse to provide a 4x attenuation with the 50-
Ω
oscilloscope probe impedance. In
addition to this, to ensure that the oscilloscope is not harmed a 10x attenuation probe must be used. See
Figure 4
.
For more information about Texas Instruments recommended ESD test setup, see the application report,
IEC 61000-4-x Tests for TI’s Protection Devices
.