SLVSIL5 Data sheet

SLVSIL5A May 2025 – September 2025 UCC25661-Q1

PRODUCTION DATA

8.2.2.6 LLC Primary-Side Currents

The primary-side currents are calculated to understand the sizing and ratings necessary during component selection purposes. The currents are calculated based on a 110% overload condition.

The primary side RMS load current is calculated by:

Equation 31.

I_{O E} = \frac{π}{2 \sqrt{2}} \times \frac{I_{O}}{n} = \frac{π}{2 \sqrt{2}} \times \frac{1.1 \times 15 A}{16.5} = 1.111 A

Where I_o is the maximum load current times the allowable overload condition, for UCC25661EVM-128 10% was chosen as the allowable output current overload condition.

The RMS magnetizing current at minimum switching frequency is calculated using:

Equation 32.

I_{M} = \frac{π}{2 \sqrt{2}} \times \frac{N_{P S} V_{O U T}}{{ω L}_{M}} = \frac{π}{2 \sqrt{2}} \times \frac{16.5 \times 12}{2 π \times 64.8 k H z \times 510 μ H} = 0.797 A

The total current in resonant tank is calculated using Equation 33.

Equation 33.

I_{R} = \sqrt{{I_{M}}^{2} + {I_{O E}}^{2}} = \sqrt{{(1.111 A)}^{2} + {(0.797 A)}^{2} = 1.367 A}