Controlled Load Current Gate Scan - Electricity and Electronic Circuits Step by Step

A controlled-load gate scan separates the threshold decision from the current calculation, so Ohm's law applies only after the ideal switch is closed. The open and closed rows are exact only for the declared control voltage, threshold, source, load resistance, and ideal gate model; real switches have finite thresholds, hysteresis, leakage, contact or on-resistance, source sag, heating, parasitics, and voltage/current measurement uncertainty.

A strict threshold scan separates the control decision from the load-current calculation. Exact arithmetic here means exact results for the stated model inputs; measured inputs still carry uncertainty and significant-figure limits.

highlighted = computed this step

The control voltage must be above the threshold

The ideal control rule is strict. Equal to the threshold is not above the threshold, so the boundary row stays open.

V_{\text{control}} > V_{\text{threshold}}

The load current appears only after the switch closes

The source and load resistor are fixed in every row. The only input that changes is the control voltage, and current appears only in the row above threshold.

\begin{array}{c|c|c|c|c}V_c&V_{\text{th}}&V_s&R_L&I_L\\3\ \text{V}&6\ \text{V}&12\ \text{V}&4\ \text{ohm}&0\ \text{A}\\6\ \text{V}&6\ \text{V}&12\ \text{V}&4\ \text{ohm}&0\ \text{A}\\9\ \text{V}&6\ \text{V}&12\ \text{V}&4\ \text{ohm}&3\ \text{A}\\\end{array}

The closed row is still Ohm's law

Once the controlled switch closes, the load current is not a separate rule. It is the source voltage divided by the load resistance.

I_L = \frac{V_s}{R_L} = 12\ \text{V}/4\ \text{ohm}=3\ \text{A}

The boundary row prevents a hidden rounding rule

The scan includes below, equal, and above threshold. That makes the switching rule visible before the current calculation starts.

0\ \text{A},\quad 0\ \text{A},\quad 3\ \text{A}