TPS54A24: RT/CKL Sink/Source Current Spec.

The RT/CLK pin will only source current when it is in RT mode. In RT mode, the pin regulates to ~0.5V and the current through the resistor sets the switching frequency. This current being sourced is quite small as with the minimum RT/CLK resistance of 30.1 kΩ results in only 16.6 µA. As soon as CLK source pulls the RT/CLK pin high, the circuit sourcing current to regulate the pin voltage turns off and the pin is high impedance. A source with +/-4 mA shouldn't have any issue driving the pin. External components should be the only thing that loads the CLK source.

Let me know if you have any further questions.