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Hi, Atthen,

For the I max calculation, here is the formula to calculate it.

I_total = I_dynamic + I_static

For I_static, you can find the value in the datasheet. 

 I_dynamic = (Cpd+Cload) x Vcc x freq. For Cpd, please check with the Datasheet, and find the value for your power supply.Here I use the Cload is 0 for output port open. you can add your load and redo below calculation. anything, please let me know. 

For TXS0108E:

Based on the Dataheet, I_static for  IccA is 2uA, I_static for IccB is 6uA.

IccA_dynamic calculation

- For A-B direction worst case(8 Data lines are all switching, 60Mbps is 30MHz):

ICCA_dynamic = Cpda_data_b x VccA x freq x8= 8pF x 3.3 x 8 data lines x 30M=6.336mA   

- For B-A driection worst case(8 Data lines are all switching, 60Mbps is 30MHz):

IccA_dynamic = Cpda_data_a x VccA x freqx8 = 9.8pF x 3.3 x 8 data lines x 30M=7.761mA  

IccB_dynamic calculation

- For A-B direction worst case(8 Data lines are all switching, 60Mbps is 30MHz):

IccB_dynamic = Cpdb_data_b x VccBx freq x8= 23pF x 5 x 8 data lines x 30M=27.6mA   

- For B-A driection worst case(8 Data lines are all switching, 60Mbps is 30MHz):

IccB_dynamic = Cpdb_data_a x VccBx freqx8 = 20.9pF x 5 x 8 data lines x 30M=25.08mA

IccA(max) =2uA+7.761mA =7.763mA  (I don't whether you direction is fixed, I chose the direction which has the maximum current)

IccB(max)=6uA+27.6mA =27.606mA. (I don't whether you direction is fixed, I chose the direction which has the maximum current)

For SN74AVC1T45, you can use the same method to calculate. anything, please let me know.

BR
junjie