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Description
3
SLUUBJ1A – February 2017 – Revised June 2017
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TPS2373-4EVM-758 Evaluation Module
3
Description
The TPS2373-4EVM-758 enables full evaluation of the TPS2373-4 device. Refer to the schematic shown
in
Figure 1
and
Figure 2
. Ethernet power is applied from J1 and is dropped to the FET bridge rectifier. At
the output of the FET bridge is the EMI and EMC filter and transient protection for the TPS2373-4.
Input power can also be applied at J3 from a DC source when power at J1 is not present or when the
DC/DC converter is being evaluated and not the PoE front end.
The TPS2373-4 (U1) PD controller is shown in
Figure 1
. R30 provides the detection signature while J7
and J10 allow user selection of the classification signature and desired power level. To the right of U1 is
the switched side of the PD controller. The TPS2373-4 RTN pin provides inrush, current limited turn on,
and charge of the bulk capacitor C28 and C62.
The DC/DC converter is a high-efficiency, active clamp-forward converter. The primary (Q16) switching
MOSFET is driven from the U2 OUT pin and the secondary (Q13/Q15) synch switching MOSFET is in a
self-driven configuration.
Output voltage feedback is provided with U3 and associated error amplifier (U4) circuitry. R55 provides a
means for error injection to measure the frequency response of the converter. This feedback circuit drives
the U2 FB pin which provides a voltage proportional to the output load current. As the output load current
decreases, the FB pin voltage decreases.