TP45 is a higher-permeability MnZn power ferrite with an initial permeability (μi) of 2500, a saturation flux density (Bs) of 500 mT at 25 °C (400 mT at 100 °C) and a Curie temperature above 210 °C. A μi 25 % above TP40/TP44 reduces the number of turns for a given magnetising inductance, so flyback and adapter transformers require fewer winding layers and exhibit lower leakage, without a loss penalty: 600 → 300 kW/m³ at 100 kHz / 200 mT, equivalent to TP44; 620 → 420 kW/m³ at 300 kHz / 100 mT; and 270 → 200 kW/m³ at 500 kHz / 50 mT, so the usable band extends to low-flux operating points around 500 kHz; at 100 °C the coercivity (Hc) is 7 A/m and the remanence (Br) 70 mT. Typical applications are flyback transformers for adapters and chargers, telecom supplies and 300 kHz-class half-bridge/LLC transformers. Among the six mid-frequency grades TP45 is distinguished by μi: it is recommended where turns and leakage are the design constraint, TP44 where an existing μi 2000 turns design is retained and loss must be reduced, and TP40 for large general-purpose cores. Its Bs retention at 100 °C is 80 %, the same as TP44; the hot-state saturation margin should be calculated at 400 mT.