Reservoir Capacitors Bound Ripple

capacitor-ripple-is-charge-balance

Reservoir ripple comes from load current, time, and capacitance. Exact arithmetic here means exact results for the stated model inputs; measured inputs still carry uncertainty and significant-figure limits.

highlighted = computed this step

Ripple starts as charge divided by capacitance

The reservoir feeds 2 A for 3 s before the next recharge. The capacitance converts that charge draw into voltage droop.

ΔQ=IΔt,ΔV=ΔQC\Delta Q=I\Delta t,\qquad \Delta V={\Delta Q\over C}
Reservoir charge-balance setupCurrent, time, and capacitance are checked before ripple is named.Iload 2 Adt 3 sC 2 FdV 3 V

More load current makes more ripple

The interval and capacitance stay fixed, so the ripple rows move only with load current.

IΔtCΔV1 A3 s2 F32 V2 A3 s2 F3 V3 A3 s2 F92 V\begin{array}{c|c|c|c}I&\Delta t&C&\Delta V\\1\ \text{A}&3\ \text{s}&2\ \text{F}&\tfrac{3}{2}\ \text{V}\\2\ \text{A}&3\ \text{s}&2\ \text{F}&3\ \text{V}\\3\ \text{A}&3\ \text{s}&2\ \text{F}&\tfrac{9}{2}\ \text{V}\\\end{array}

Ripple is charge balance over the recharge interval

The reservoir gives the load current for a declared interval. The checked ripple is not a waveform guess.

ΔV=IΔtC=2 A⋅3 s/2 F=3 V\Delta V = {I\Delta t \over C} = 2\ \text{A}\cdot3\ \text{s}/2\ \text{F}=3\ \text{V}
Reservoir ripple ledgerCharge balance sets the voltage drop.Iload 2 Adt 3 sC 2 FdV 3 V