ZHCSM06C december 2020 – may 2023 TPS272C45
PRODUCTION DATA
In many situations, modules like to allow the current limit to be set programmatically from an MCU. This action enables a module to set current limits to fit the load after determining what load is plugged in. As described, the TPS272C45 current limits are set by RILIMx. However, the RILIMx that is seen by the device can be configured through small external FETs as shown in Figure 9-5.
For example, RILIM1_1 can set the device to 500-mA ILIM while RILIM1_2 can set the device at 2-A ILIM. After the MCU realizes how much current draw is required by the load, the MCU can drive one of the series FET's to set the ILIM to be ideal for the specific load. The current limit (ILIM1 and ILIM2) thresholds can be changed dynamically, but the inrush current limit delay set with the ILIMD resistor cannot be changed after powerup.
The external FET switches used to dynamically adjust the current limit must be chosen with a minimum capacitance (Coss) from the drain the ground. The total capacitance to PCB ground at the ILMx pins including from traces must be limited to less than 100 pF.