The holding current (I_H) of an SCR is defined as the minimum anode current required to keep the SCR in its conduction (ON) state. Once the device has latched on, the regenerative internal feedback of its P-N-P-N structure sustains conduction only as long as the anode current stays at or above this minimum.

Behaviour around I_H:

• While anode current ≥ I_H, the SCR remains ON with the gate having no further control.
• If the load or supply reduces the anode current below I_H, the internal regeneration can no longer sustain itself and the SCR turns OFF, reverting to the forward blocking state.
• I_H is a small value — typically a few milliamperes in low-power SCRs, rising to tens of milliamperes in larger devices.

It is important to distinguish I_H from the closely related latching current (I_L), which is the minimum anode current needed to latch the device fully ON at the moment of triggering, before the gate pulse is removed. For a given SCR, I_L is always greater than I_H (typically 2–3 times).

The other definitions describe different parameters. The minimum current needed to turn the SCR on is governed by the gate trigger and latching current, not the holding current, which concerns maintaining rather than establishing conduction. A gate current to turn the SCR off does not exist for a conventional SCR — the gate cannot commutate it off. And the maximum current the device can withstand is its forward current rating (or surge rating), an entirely separate thermal limit unrelated to I_H.