2 IRMS Discharge Current

Many times, the battery FET's maximum discharge current is given as root mean square current (ARMS). RMS discharge current for pulsed system load with duty cycle D is computed by the following equation.

Equation 1.

I_{DCHRG-RMS} = \sqrt{D} \times I_{DCHRG-PK}

As an example, if a charger’s RMS discharge current is 6 A, the charger can safely sustain the peak discharge current, clamped to 10 A, as a function of system load duty cycle as shown in Figure 5-3.

Figure 2-1 Peak Discharge Current vs. Duty Cycle

From the graph, if the system load duty cycle is only 40% at a fixed frequency, the internal battery FET’s peak discharge current can be as high as 9A.