To enter programming mode or use external clock synchronization, J3 is used. To program the TPS542A50, the SYNC pin must be brought high while keeping the EN pin low. The device is then programmed via the I²C pins, SCL (J6-9) and SDA (J6-10). If J6 is used to program the TPS542A50 via a TI USB-TO-GPIO programmer, a jumper should be placed between J3-1 and J3-2. After the device is enabled, all registers are read-only. Details on the valid I²C registers and instructions are provided in the TPS542A50 data sheet.

An external signal (recommended 0-V to 3.3-V) can be used as an external clock synchronization source. To use this feature, the TPS542A50 must be enabled, either by pulling the EN pin high or leaving it floating as described in Section 3.1.2. A jumper should be placed between J3-2 and J3-3, and the external clock signal should be applied to the SYNC_CLK (TP12) test point, referenced to AGND. The external clock synchronization signal applied to the SYNC pin must also be within -10% to +10% of the configured switching frequency. This is true whether the switching frequency is selected using a resistor from FSEL to AGND (R10), or selected via I²C.