Overview: NCA9511 Hot Swappable I2C Bus
and SMBus Buffer
Datasheet (EN) 1.2 Product Overview
The NCA9511 is a hot-swappable I2C bus buffer that supports I/O card insertion into a live backplane without corruption of the data and clock buses. Control circuitry prevents the backplane-side I2C lines (in) from being connected to the card-side I2C lines (out) until a stop mand or bus idle condition occurs on the backplane without bus contention on the card. When the connection is made, this device provides bidirectional buffering, keeping the backplane and card capacitances separated. During insertion, the SDA and SCL lines are pre-charged to 1 V to minimize the current required to charge the parasitic capacitance of the device.
When the I2C bus is idle, the NCA9511 can be put into shutdown mode by setting the EN pin low, reducing power consumption. When EN is pulled high, the NCA9511 resumes normal operation. It also includes an open drain READY output pin, which indicates that the backplane and card sides are connected together. When READY is high, the SDAIN and SCLIN are connected to SDAOUT and SCLOUT. When the two sides are disconnected, READY is low.
