A buffer stage turns one oversized fanout request into smaller current ledgers that each stay under the output limit. The arithmetic treats buffers and inputs as ideal loads with fixed current draws; real buffered handoffs also depend on propagation delay, output resistance, voltage margins, device variation, and measurement tolerance.
Buffers can make each stage's current budget small enough, while the helper still checks every stage. 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 direct handoff is too large
Driving 6 inputs directly asks for 6 amperes, above the output limit.
6A>5A
Buffers split the load
Two buffers are input loads for the first stage, so that stage supplies 2 amperes. Each buffer then supplies 3 amperes to its own group.