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THVD2442: Encoder Interface Diff <-> SE coversion

Brian Wang0928
Genius 15310 points

Part Number: THVD2442
Other Parts Discussed in Thread: AM26C31

Team,

Customer is designing the encoder signal interface for a servo drive. The signal flow requires two independent, simultaneous conversions using a single THVD2442: Please see below schematic and descriptions.

  • Incoming differential clock signal SCK+ / SCK− is converted to a single-ended signal SCK1, which is fed to the Sensor IC (encoder sensing chip).
  • The single-ended data signal SSD1 returned by the Sensor IC is converted to a differential signal SSD1+ / SSD1−, which is sent out to the customer's drive/controller.

This is a point-to-point, fixed-direction signal format converter (not a multi-drop RS-485 communication bus), operating full-duplex with no direction switching. RE and DE are statically biased (receiver permanently enabled, driver permanently enabled) via pull resistors — not dynamically controlled by an MCU. (Originally design using AM26C31/C32 RS422)

We would like TI's confirmation on whether THVD2442 is suitable for this application, and any design concerns we should address.

Let us know if this schematic is ok or not? thanks. 

THVD2442_Encoder.png

Information:

Cable length 80cm，Communication: SSI，Data Speed: 1MHz

Sensor MPS MA600A

monolithicpower.com/en/documentview/productdocument/index/version/2/document_type/Datasheet/lang/en/sku/MA600A/document_id/12989/

Regards

Brian

  • 0
    TI__Intellectual 1890 points

    Hi Brian,

    Your setup looks good. 

    You don't have termination resistors for your receive line (A &B). For your combination of speed and cable length that should be fine, but if either the speed or cable length of the system might change in the future it would be a good idea to add DNP spots for a termination resistor. There's also no harm in putting one in from the start (unless you need ultra low power operation). Here's a resource we have on termination: https://www.ti.com/document-viewer/lit/html/SSZTB23.

    -Ethan White