Level translating Fm+ I²C bus repeater/accelerator

The NCA9701A is a dual-channel bidirectional repeater for I²C and SMBus/PMBus applications. It targets the Fast-mode Plus (Fm+) of the I²C protocol, making the true 1 MHz operation possible without violating I²C timing specifications. This is achieved by using edge accelerators added at all NCA9701A ports that speed up the LOW-to-HIGH transitions of I²C input and output signals.

The NCA9701A provides the buffering for both clock (SCL) and data (SDA) I²C signals with the voltage level translation possibility (up and down) at the same time. The unique feature of the IC is the same operating voltage range of 1.08 V to 3.6 V that can be applied at both port A and port B of the device. This offers more flexibility in how the device can be used in the target application. Multiple NCA9701As can be connected in series or in star, and their ports A and B can be exchanged. Only when the I²C clock stretching needs to be supported, the NCA9701A port A must be connected to the I²C Master side and the NCA9701A port B to the I²C Slave side.

The NCA9701A features integrated pull-up resistors of 4.3 kΩ at each I/O pin. This simplifies the system implementation and reduces BOM count. Though external pull-up resistors are not required, they might be added to shorten the rise times of I²C signals even further.

The NCA9701A provides true signal buffering as the device implementation does not use the pass-FET topology. No static or incremental offsets are needed either, and the lock-free operation is guaranteed by an innovative implementation of the buffers. The very low VOL levels on port A and B improve the noise margin in the application and the potential noise components of input signals are filtered out by Schmitt trigger inputs. To reduce EMI, the negative edges of output signals are slew-controlled.

The NCA9701A is well suited for high-performance low-power applications which use the I²C communication protocol.