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  • Converts low-swing AC coupled differential input to HDMI 1.4a compliant open-drain current steering Rx terminated differential output.

  • HDMI TMDS level shifting operation up to 1.65Gb/s per lane (165MHz pixel clock).

  • Enable feature to turn off TMDS inputs and outputs and to enter low-power state.

  • Transparent operation: no re-timing or configuration required.

  • Inter-Pair added skew < 250ps

  • Intra-Pair added skew < 10ps

  • Switching power only from a single 3.3V supply.

  • Integrated 50-ohm termination resistors for AC coupled differential Inputs.

  • Pass-gate voltage limiters allow 3.3V termination on GMCH pins, 5V DDC termination on HDMI connector pins.

  • Human Body Model ESD protection: 8kV for all output pins and 2kV for all other pins.

  • Level shifter for HDMI 1.4a HPD.

  • Integrated pull-down resistor on HPD_SINK input guarantees “input low” when no display is plugged in.

  • Driver’s current adjustment +10%.

  • Inverting buffer for HPD signal

  • Configurable pre-emphasis level (0dB, 2.0dB, 4.0 dB, & 6.0dB)

  • Offered in a 48-Pin QFN Package.


CH7318C is a high speed HDMI level shifter that converts low-swing AC coupled differential input to HDMI 1.4a compliant open-drain current steering Rx terminated differential output.

The CH7318C features integrated parallel termination resistors (50-ohm), which eliminate the requirement for external termination resistors on the TMDS differential output pins. This device has incorporated a ESD protection for DDC channels as well as TMDS signal lines. In addition, the DDC_EN pin controls bias voltage to enable or disable the DDC passgate level shifter gates. The OE* pin is a two- state output enable control for the differential input and the TMDS signal output. It can activate IN_Dx pins and OUT_Dx pins or switch them into high impedance. A unique pre-emphasis control is also implemented into CH7318C; this feature has four-level adjustment to increase rise and fall times which are degraded during the transmission over a long trace on PCB.

The device operates from a single +3.3V supply, and is characterized the operation temperature range from 0 °C to 70 °C (ambient temperature). The CH7318C is available in a 48-Pin QFN package.

Structure diagram

Data sheet

Application Desc

  •   PCB Layout and Design Considerations for CH7318C, AN-B003

Technical Report



Input Interface  HDMI, DVI

Output Interface  HDMI, DVI

Audio Interface  No

Other features  No

Package Type  QFN48


Part Number Package Type Number of Pins Voltage Supply

CH7318C-BF Lead Free - QFN483.3V

CH7318C-BF-TR Lead Free - QFN in Tape & Reel483.3V




About Chrontel Overview Chrontel, headquartered in San Jose, California, is a privately-held company with over 130 employees worldwide. Incorporated in 1986, the company develops and markets mixed-signal integrated circuits for the PC, display and consumer mark...


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