1 MHz I²C bus buffer with near-zero standby draw
The PCA9646PW,118 is a 4-channel I²C bus buffer and reDriver from NXP, rated for a 1 MHz maximum data rate. That covers standard-mode (100 kHz), fast-mode (400 kHz), and fast-mode plus (1 MHz) I²C buses — the full speed range for most multi-drop sensor and memory buses. Supply current is 1 µA typical, so the buffer's own draw is negligible on an always-powered bus. Each of the four channels isolates one bus segment, letting the designer split a heavily loaded I²C bus into independent branches. The 100 ns propagation delay through the buffer adds about one bit time at 1 MHz — tight but workable for most multi-master arbitration windows.