I was browsing the internet for SD card module schematics for a board I am developing that should read and write data to an SD card. I realized that these modules use specific ICs to convert 5V logic levels to 3.3V. The logic level shifting circuit that I know and usually use looks like this:
For comparison here is a link to the adafruit sd card reader module:
What is the advantage of using a chip like "CD74HC4050" in certain designs? After a quick search it seems to me that using the IC over the Mosfet is also a couple of cents more expensive. Is it that the IC is faster? In that case the "CD74HC4050" has a typical propagation delay of 6ns at 5V Vcc while according to the datasheet of the BSS138 it has a turn on delay time of 2.5ns to 5ns and a turn off delay time of 26ns to 36ns. Is it the turn off time that makes it better to use the ICs? I checked 2N7002s datasheet too for comparison. It says that it has a max turn off time of 20ns. Is this a typical characteristic for most commercial NMOS Transistors, which makes them undesirable to use in such applications? I use the level shifter circuit above for all I2C 3.3V to 5V Communication Lines I put in my PCBs, so does Adafruit. So I dont really understand the difference to this case. I would appriciate any thoughts on the matter. Thanks in advance.
Datasheets Of BSS138, N7002, CD74HC4050: