Use coax or STP for in-car data, with high-speed deserialisers

June 14, 2016 // By Graham Prophet
Maxim Integrated has posted details of its MAX9276A/MAX9280A, which are 3.12 Gbps GMSL deserializers for coax or STP (shielded twisted pair) input, and parallel output. They have been designed to allow automotive data, especially for infotainment, to be routed on lighter-weight, lower cost cabling.

Use these parts, Maxim suggests, in high-resolution automotive navigation systems; megapixel camera systems; and rear-seat infotainment. The gigabit multimedia serial link (GMSL) deserializers receive data from a GMSL serializer over 50Ω coax or 100Ω shielded twisted-pair (STP) cable and output deserialized data on LVCMOS outputs. MAX9280A has HDCP content protection in addition to the feature set of the MAX9276A. The deserializers pair with any GMSL serializer capable of coax output including the MAX9293 HDMI/MHL serializer. When programmed for STP input they are backward compatible with any GMSL serializer.

An audio channel supports L-PCM I²S stereo and up to eight channels of L-PCM in TDM mode. Sample rates of 32 kHz to 192 kHz are supported with sample depth up to 32 bits.


The embedded control channel operates at 9.6 kbps to 1 Mbps in UART-to-UART and UART-to-I²C modes, and up to 1 Mbps in I²C-to-I²C mode. Using the control channel, a microcontroller can program serializer, deserializer, and peripheral device registers at any time, independent of video timing, and manage HDCP operation (MAX9280A). Two GPIO ports are included, allowing display power-up and switching of the backlight among other uses. A continuously sampled GPI input supports touch-screen controller interrupt requests in display applications.


For use with longer cables, the deserializers have a programmable cable equalizer. Programmable spread spectrum is available on the parallel output. The serial input meets ISO 10605 and IEC 61000-4-2 ESD standards. The core supply is 3.0V to 3.6V and the I/O supply is 1.7V to 3.6V. Packaging is 56-pin, 8 × 8 mm TQFN and QFND packages with exposed pad and 0.5 mm lead pitch.


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