Maintaining an identical I2C addressing scheme is especially important in automotive systems that employ multiple TCA9539-Q1 GPIO expanders on a shared bus, such as body electronics and zonal controller architectures. The TCA9539AQPWRQ1 can be introduced into these systems without requiring changes to I2C address maps or software configuration.

For applications requiring a larger number of unique I2C addresses, device also offers related device variant with orderable part number TCA9539BQPWRQ1 with expanded address capability allowing another four unique I²C addresses as shown in Table 2-2. This allows up to eight unique devices on the same I²C bus if using both TCA9539AQPWRQ1 and TCA9539BQPWRQ1 as shown in Figure 2-1

Although the TCA9539AQPWRQ1 is designed as a drop-in replacement, TI recommends validating system-level requirements such as supply voltage, GPIO loading, power-up behavior, and thermal margin when migrating any device.