InterChip USB (IC-USB), sometimes referred to as USB-IC or Inter-chip USB, is an addendum to the USB Implementers Forum (USB-IF) USB 2.0 specification. IC-USB is intended as a low-power variant of the standard physical USB interface, intended for direct chip-to-chip communications. The IC-USB bus's maximum length of 10 cm results in a lower inductance and capacitance and therefore allows lower power requirements. IC-USB is used primarily in embedded systems; for example, ETSI (in specification TS 102 600) has standardized on IC-USB as the official high-speed interface for connections between the main chipset of a smartphone and the SIM card or UICC card.
High-Speed Inter-Chip (HSIC) is a chip-to-chip variant of USB 2.0 that eliminates the conventional analog transceivers found in normal USB. It was adopted as a standard by the USB-IF in 2007. The HSIC physical layer uses about 50% less power and 75% less board area compared to traditional USB 2.0. HSIC uses two signals at 1.2 V and has a throughput of 480 Mbit/s. Maximum PCB trace length for HSIC is 10 cm. It does not have low enough latency to support RAM sharing between two chips. The USB 3.0 successor of HSIC is called SuperSpeed Inter-Chip (SSIC).
The USB-IF Inter-Chip USB Supplement was released in March 2006. ETSI TS 102 600, which is ETSI's USB implementation requirements specification, was first released in December 2007.
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