ZHCS352E August 2011 – October 2024 TCA9509
PRODUCTION DATA
VCCB and VCCA can be applied in any sequence at power up. The TCA9509 includes a power-up circuit that keeps the output drivers turned off until VCCB is above 2.5 V and the VCCA is above 0.8 V. After power up and with the EN high, a low level on the B-side (below 0.3 × VCCB) turns the corresponding A-side driver (either SDA or SCL) on and drives the A-side down to approximately 0.2 V. When the B-side rises above 0.3 × VCCB, the A-side pull-down driver is turned off and the external pull-up resistor pulls the pin high. When the A-side falls first and goes below 0.3 × VCCA, the B-side driver is turned on and the B-side pulls down to 0 V. The A-side pull-down is not enabled unless the A-side voltage goes below 0.4 V. If the A-side low voltage does not go below 0.5 V, the B-side driver turns off when the A-side voltage is above 0.7 × VCCA. If the A-side low voltage goes below 0.4 V, the A-side pull-down driver is enabled, and the A-side is able to rise to only 0.5 V until the B-side rises above 0.3 × VCCB.
A 100 nF a decoupling capacitor should be placed as close to the VCCA and VCCB pins in order to provide proper filtering of supply noise.