ZHCS901E May 2012 – September 2021 TPS55340
PRODUCTION DATA
With an estimated 85% efficiency, the input current is calculated with Equation 9 to be 2.35 A. With KIND of 0.3 and the maximum 18-V input voltage, the minimum inductance is calculated to be 10.5 µH using Equation 41. The nearest standard value of 12 µH is used. As mentioned previously, this equation assumes a coupled inductor is used.
The inductor ripple current is recalculated to be 615 mA with Equation 42. The peak current is calculated to be
3.69 A. The typical current limit is used as the saturation rating for the inductor used. The RMS current for La is approximately the average input current of 2.35 A. The RMS current for Lb is approximately the output current of 1 A. For this design, a CoilCraft MSD1260-123 is used with 6.86-A saturation, 74-mΩ DCR, and 3.12-A RMS current rating for one winding.