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THVD1410: Requirement for external fail safe circuit

Part Number: THVD1410

Hi team,

Could you give me comment on customer question?

<Customer question>

THVD1410 has receiver fail safe, but can it always work even when connecting termination resistor? It seems termination resistor can cause the input signal voltage level to input indeterminate range. For the case of using termination resistor, the customer should add external resistor network to prevent input indeterminate range in fail cases. 

Best regards,

Takeshi Sasaki

  • Hi Takeshi-san,

    THVD1410 is designed to function normally in a terminated system. The receiver failsafe for this device not not bias the bus above the input threshold Vth+, but rather internally biases the receiver so that when the input differential is within indeterminate ranges near 0V, the receiver output will be high. This ensures the receiver will be in a known state in open bus, shorted bus, or idle bus conditions.

    An external failsafe biasing network may be used to bias the bus to a  logic high state when not actively being driven to provide more robustness to device with internal failsafe biasing like THVD1410 as well as accommodate nodes that may not have this feature. 

    Let me know if this makes sense or if you have any more questions.