SLUSF58A December 2023 – April 2024 UCC23525
ADVANCE INFORMATION
Refer to the PDF data sheet for device specific package drawings
The external gate-driver resistors, RG(ON) and RG(OFF) are used to:
The output stage has a pull up with a peak source current of 5 A. Use Equation 2 to estimate the peak source current as an example.
where
In this example, the peak source current is approximately 1.15A as calculated in Equation 3.
Similarly, use Equation 4 to calculate the peak sink current.
where
In this example, the peak sink current is the minimum of 5 A and Equation 5.
The diodes shown in series with RGOFF, in Figure 8-1 ensure the gate drive current flows through the intended path, respectively, during turn-on and turn-off. Note that the diode forward drop will reduce the voltage level at the gate of the power switch. To achieve rail-to-rail gate voltage levels, add a resistor from the VOUT pin to the power switch gate, with a resistance value approximately 20 times higher than RGOFF. For the examples described in this section, a good choice is 100 Ω to 200 Ω.
The estimated peak current is also influenced by PCB layout and load capacitance. Parasitic inductance in the gate-driver loop can slow down the peak gate-drive current and introduce overshoot and undershoot. Therefore, TI strongly recommends that the gate-driver loop should be minimized. Conversely, the peak source and sink current is dominated by loop parasitics when the input capacitance of the power transistor is very small (typically less than 1 nF) because the rising and falling time is too small and close to the parasitic ringing period.