Regulator Headroom Boundary Three-Row Scan - Electronic Circuits XIII: Power, Rectification, and Regulation Step by Step

The same input minimum can pass, touch, or fail as headroom grows. Exact arithmetic here means exact results for the stated model inputs; measured inputs still carry uncertainty and significant-figure limits.

highlighted = computed this step

Headroom 1 V sets acceptance

Input minimum stays 7 V and output stays 5 V. Headroom 1 V requires 6 V, leaving margin 1 V.

7\ \text{V}\mathbin{-}\bigl(5\ \text{V}+1\ \text{V}\bigr)=1\ \text{V}\Rightarrow\text{pass}

Headroom 2 V sets acceptance

Input minimum stays 7 V and output stays 5 V. Headroom 2 V requires 7 V, leaving margin 0 V.

7\ \text{V}\mathbin{-}\bigl(5\ \text{V}+2\ \text{V}\bigr)=0\ \text{V}\Rightarrow\text{pass}

Headroom 3 V sets acceptance

Input minimum stays 7 V and output stays 5 V. Headroom 3 V requires 8 V, leaving margin negative 1 V.

7\ \text{V}\mathbin{-}\bigl(5\ \text{V}+3\ \text{V}\bigr)=-1\ \text{V}\Rightarrow\text{fail}