SLVUCQ2A july 2023 – july 2023 TPSF12C1 , TPSF12C1-Q1
The TPSF12C1EVM-FILTER can be used for evaluation and for system development of an EMI filter circuit and application. Figure 3-2 presents typical schematics of equivalent single-phase passive and active filter designs – with the active circuit component values corresponding to this EVM. Terminals designated L, N and PE refer to live, neutral and protective earth, respectively. Comparing the passive and active circuits in this example, the CM inductance of chokes LCM1 and LCM2 reduces from 12 mH to 2 mH by virtue of the higher effective Y-capacitance with AEF.
The AEF circuit uses a capacitive multiplier circuit in place of the two Y-capacitors normally placed between the CM chokes in a conventional two-stage passive filter design. The TPSF12C1 senses the high-frequency CM disturbance on the two power lines using two Y-rated sense capacitors and injects a noise-canceling current back into the power lines using a Y-rated inject capacitor. The X-capacitor placed between the two CM chokes provides a low-impedance path between the power lines from a CM standpoint, typically up to low-MHz frequencies. This allows current injection onto one power line (neutral in this case) using only one inject capacitor.
Acting as a complete filter with features such as surge immunity protection and X-capacitor resistive discharge, the EVM uses a recommended PCB layout to minimize the overall noise signature and required board area. If required, the user can add external components for inrush limiting and fuse protection.