One Driver Can Feed a Limited Number of Bases - Electronic Circuits XI: Transistor Switching and Device Regions Step by Step

Base currents add, and equality to the driver limit still passes. Exact arithmetic here means exact results for the stated model inputs; measured inputs still carry uncertainty and significant-figure limits.

highlighted = computed this step

Four half-ampere bases need two amperes

Four transistor bases at 1/2 A each sum to 2 A, below the 3 A driver limit.

4\cdot {1\over 2}\ \text{A}=2\ \text{A}\le 3\ \text{A}

Equality also passes by the stated convention

Six half-ampere bases sum exactly to the 3 A limit, and equality is accepted.

6\cdot {1\over 2}\ \text{A}=3\ \text{A}