My customer is starting up the device with VccB first with no observed issues. What's the reasoning for startup sequence requirement, especially with the VCC isolation feature that hold the data pins in high-impedance when either Vcc is GND?
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My customer is starting up the device with VccB first with no observed issues. What's the reasoning for startup sequence requirement, especially with the VCC isolation feature that hold the data pins in high-impedance when either Vcc is GND?
Hi Neal,
The power-up considerations given in section 11.1 of the datasheet are not a requirement. Most TI translation devices, including SN74AVC1T45, do not specifically have any power sequencing requirements (power up and power down). Note that the power sequencing recommendations can be modified according to the needs of the application/system without any performance or reliability concerns to the device. For more information on this topic you may be interested in the FAQs What are the power sequencing requirements for the translation device? and What is the difference between IOFF and VCC isolation? What are the conditions to guarantee it?
Your customer may also be interested in the SN74AXC1T45, which is a pin-to-pin upgrade with a wider voltage range and improved performance. To learn more about the AXC family check out the application note Glitch Free Power Sequencing With AXC Level Translators.
Thanks,
Anthony