Circuit forms constant-current SCR

摘要

Atypical SCR (silicon-controlled rectifier) requires a trigger current, which causes the SCR structure to latch on. Once the device latches, the current through the SCR is solely a function of external component values. The SCR has no inherent ability to limit the current flow once it latches on. Current continues to flow, as long as the current exceeds a minimal value known as the holding current. The circuit in Figure 1 is similar to an SCR, because it also requires a trigger current to latch into its on state.