The RXD output structure is an open-drain output stage which allows the TLIN2021A-Q1 to be used with 3.3-V and 5-V controllers. If the RXD pin of the controller does not have an integrated pull-up, an external pull-up resistor to the controller's IO voltage is required. The external pull-up resistor value should be between 1-kΩ to 10-kΩ. The V_SUP pin of the device should be decoupled with a 100-nF capacitor by placing it close to the V_SUP supply pin. The system should include additional decoupling on the V_SUP line as needed per the application requirements.