ZHCSCK0C June 2014 – September 2021 TPS55340-Q1
PRODUCTION DATA
The overcurrent limit for the integrated power MOSFET limits the maximum input current and thus the maximum input power for a given input voltage. Maximum output power is less than maximum input power because of power conversion losses. Therefore, the following can all change the maximum current output (IOmax):
The current limit clamps the peak inductor current, therefore, the ripple must be subtracted to derive maximum DC current. Decreasing the K(IND) value or designing for a higher efficiency increases the maximum output current. Use the selected inductance or the selected K(IND) value to calculate the maximum output current. Use Equation 19, the minimum input voltage, and minimum peak current limit (I(LIM)) of 5.25 A to calculate the maximum output current.
For this design, with a 5-V input boosted to 24-V output, a 10-μH inductor with an assumed Schottky forward voltage of 0.5 V, and estimated efficiency of 85%, the maximum output current is calculated to be 871 mA. With a 12-V input and an increased estimated efficiency of 90%, the maximum output current calculated value increases to 2.13 A. This circuit was evaluated to the maximum output currents with both the minimum and maximum input voltage.