The NCA9617-Q100 is a CMOS dual bidirectional buffer that provides level translation for Fast-mode Plus (Fm+) I²C-bus and SMBus applications. It supports voltage translation between a low-voltage port A operating from 0.8 V to 5.5 V and a higher-voltage port B operating from 2.2 V to 5.5 V. The device preserves all standard I²C operating modes while isolating bus capacitance and voltage domains.

Both SDA and SCL lines are buffered, allowing the connection of two I²C bus segments with up to 540 pF per segment at 1 MHz operation, or up to 4000 pF at lower frequencies. This buffering enables bus extension while maintaining signal integrity. The SDA and SCL pins are overvoltage tolerant and remain high-impedance when the device is unpowered.

Port B incorporates a static level offset architecture, whereas port A eliminates static offset. This ensures that a LOW level on port B is translated to a near 0 V LOW on port A, supporting reduced voltage swings required by low-voltage logic.

Due to the static offset implementation on port B, these pins must not be directly connected to other buffers that use static or incremental offset outputs on the same side. Port A pins of multiple NCA9617-Q100 devices may be connected together to form a common bus in star configurations. Cascaded connection of multiple devices from port A to port B is supported without cumulative offset buildup; only propagation delay must be considered.

The drivers are enabled only when V_CCA exceeds 0.8 V and V_CCB exceeds 2.2 V. The EN pin, referenced to V_CCB, provides system-level enable control and should be toggled only while the bus is idle.

On port B, the internal LOW-level output pull-down is approximately 0.54 V, with an input threshold set approximately 90 mV lower at 0.45 V to prevent internal latching. When port B is driven LOW internally, this level is not interpreted as a valid LOW at the input stage. Port A drives a hard LOW level, and its input threshold is defined at 0.35 × V_CCA to ensure reliable operation when V_CCA is as low as 0.8 V.