What's the difference between the MT3400SMI, MT5600SMI-34, MT5600SMI-L34 and MT5600SMI-XL34 (or MT5600SMI-92, MT5600SMI-L92 and MT5600SMI-XL92)?The 'L' in the model number stands for low voltage (3.3V), models with out the 'L' are 5V Socket Modems.
The 'X' in the model number stands for exclude LED driver pins.
The exact replacement model for each will be:
MT5600SMI ---- MT5600SMI-L92 or MT5600SMI-XL92
MT3400SMI ---- MT5600SMI-34, MT5600SMI-L34 or MT5600SMI-XL34