USB µModule Isolator With Power Protects Hubs, Peripheral Ports

Combining USB data communications and USB power, the LTM2884 USB µModule (micromodule) isolator guards against ground-to-ground differentials and large common-mode transients. It separates grounds by isolating a pair of USB signal transceivers using internal inductive signal isolation. Thus, the ruggedized device provides 2500-V rms isolation and common-mode transient rejection of less than 30 kV/µs. An integrated, low-EMI, external or bus-powered dc-dc converter that powers the isolated transceiver delivers up to 2.5 W of isolated power for USB peripherals or hub/host controllers. Implementation of an automated bus speed-detection feature allows the LTM2884 to be used in hub/host/bus isolation applications. Integrated downstream-facing pull-down resistors and upstream-facing pull-up resistors are automatically configured to match the speed of the downstream devices, making it possible to monitor and report bus speeds to the host. The ±15-kV transceivers operate at full 12-Mbit/s USB 2.0 speed and low 1.5-Mbit/s speed. A suspend mode monitors for inactivity and reduces V_BUS current to less than 2.0 mA. Its dc-dc converter can supply 2.5 W when connected to an external high-voltage supply or 1 W when connected to the USB V_BUS supply. The isolator comes in a 15- by 15- by 5-mm, surface-mount BGA package; all integrated circuits and passive components are housed in the µModule package.

LINEAR TECHNOLOGY CORP.