Sourcing an obsolete Littelfuse TVS
The 1.5SMC75 carries an Obsolete product status from Littelfuse — no longer recommended for new designs. No official successor is listed in this series for the 64.1 V standoff band.
Standoff, breakdown, and clamping — what the voltage ratings mean
The reverse standoff voltage of 64.1 V defines the working dc bias the protected node can carry without the TVS drawing significant leakage — the part sits in high-impedance standby below this level. Junction current begins at the minimum breakdown voltage of 67.55 V; above that threshold the TVS enters conduction and the clamped voltage waveform is what the downstream load actually sees during the event. At the rated peak pulse current of 14.8 A, the maximum clamping voltage is 108.15 V — this 108.15 V is the maximum stress voltage the downstream circuitry sees during a worst-case 10/1000 µs transient at rated amplitude, and it is the figure that drives downstream component selection.