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Some doubt for SN74ABT541

Other Parts Discussed in Thread: SN74AHCT541

HI, My company have new project that need to use SN74ABT541 buffer IC ,our doubt is that how to design the SN74ABT541  OE1 pin pull high resistor ? because in datasheet  mention 

"OE should be tied to VCC through a pullup resistor;the minimum value of the resistor is determined by the current-sinking capability of the driver."  So, where we can find the sink current information to design the pull high resistor in datasheet ?

thanks .

  • Hi,

    You can refer to this FAQ on OE pin for information which also applies to this device. 

    It is not a requirement to have OE pull high resistor, but in case the requirement is to have tri state on the IO ports during power up or power down of supply, the OE can have pull high resistor. Else, it can be connected directly to gnd to enable the device for normal operation.

    Is there a specific reason why the SN74ABT541 device was considered? We have other newer devices in our portfolio like the SN74AHCT541 which consume lesser current than the ABT devices.

  • Hi, Our question is ,if we use pull high resistor to determine the clear state  that  how many current we have to design ,can driver the OE state, because we have to reference sink current to design pull high resistor but we don't know which parameter in SN74ABT541's datasheet is sink current parameter.

  • OE is the input pin which has input leakage spec of 1uA ( Ii). 

    For eg, when you have 10k pull high resistor to Vcc at 5.5V, then 5.5V/ 10k = 0.55mA is required to over drive (sink) the pullup to have a low level at the OE pin.

    Let me know if anything else.