InterChip USB

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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)[1] 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.[2][3] The USB 3.0 successor of HSIC is called SuperSpeed Inter-Chip (SSIC).[4]

The USB-IF Inter-Chip USB Supplement was released in March 2006. ETSI TS 102 600,[1] which is ETSI's USB implementation requirements specification, was first released in December 2007.


  1. ^ a b "ETSI TS 102 600 v10.1.0: Smart Cards; UICC-Terminal interface; Characteristics of the USB interface (Release 10)" (PDF). ETSI. September 2020. Retrieved October 7, 2021.
  2. ^ "Interchip Connectivity: HSIC, UniPro, HSI, C2C, LLI... oh my!". Archived from the original on June 19, 2011. Retrieved June 24, 2011.
  3. ^ "USB High Speed Inter-Chip Interface". Archived from the original on June 9, 2011. Retrieved June 24, 2011.
  4. ^ "Transitioning from USB 2.0 HSIC to USB 3.0 SSIC". Archived from the original on October 7, 2015. Retrieved August 7, 2015.