SLUSAE5G August 2011 – April 2021 TPS53355
PRODUCTION DATA
Refer to the PDF data sheet for device specific package drawings
Refer to Section 8.2.1.2.3 for guidelines for this design with all ceramic output capacitors.
The external components selection is a simple process when using organic semiconductors or special polymer output capacitors.
Select operation mode and soft-start time using Table 7-3.
Select the switching frequency from 250 kHz to 1 MHz using Table 7-1.
The inductance value should be determined to give the ripple current of approximately 1/4 to 1/2 of maximum output current. Larger ripple current increases output ripple voltage and improves signal-to-noise ratio and helps ensure stable operation, but increases inductor core loss. Using 1/3 ripple current to maximum output current ratio, the inductance can be determined by Equation 17.
The inductor requires a low DCR to achieve good efficiency. It also requires enough room above peak inductor current before saturation. The peak inductor current can be estimated in Equation 9.
When organic semiconductor capacitor(s) or specialty polymer capacitor(s) are used, for loop stability, capacitance and ESR should satisfy Equation 7. For jitter performance, Equation 19 is a good starting point to determine ESR.
where
The output voltage is programmed by the voltage-divider resistor, R1 and R2 shown in Figure 8-1. R1 is connected between VFB pin and the output, and R2 is connected between the VFB pin and GND. Recommended R2 value is from 1 kΩ to 20 kΩ. Determine R1 using Equation 20.
The overcurrent setting resistor, R_{TRIP}, can be determined by Equation 10.
where
Use an R_{DS(on)} value of 1.5 mΩ for an overcurrent level of approximately 30 A. Use an R_{DS(on)} value of 1.7 mΩ for overcurrent level of approximately 10 A.