the internal circuit schematic of any typical bus transceiver shows that input A is buffered to output B. My question is: if my Vcc is 5V and my input to A is 3.3V, will my output B be 5V? If not then is there an IC that does level translation to Vcc as well? thank you.

 

Buffer does not alter input. 5 goes in, 5 comes out.

Level translators exist. They are commonly called level shifter.

 

The input of a digital bus transceiver has low-to-high and high-to-low switching thresholds. Once those thresholds are met the output will switch according to the supply levels (i.e. between Vcc and GND.)

Hence the 0-3.3V input will translate to GND to Vcc output, 0 to 5V in your case.

The opposite is not necessarily true. If you are driving 0-5V input into a 3.3V device you have to make sure that the device is protected from the over voltage at the input.