The transmitter differential output comprises two identical CMOS push-pull structures on the two output pins. The NMOS output transistor in Renesas' process sources current when the output pin is taken below ground, so a diode is utilized to block the current. Adding the diode raises the low output voltage to approximately 1V, which has caused problems in some applications that tried to use RS-485 transmitters as single-ended line drivers. The PMOS device is able to function properly over the full -7V to +12V signal range, therefore no blocking diode is needed. The result is a better differential output voltage compared with transmitters that require both high- and low-side blocking diodes. Driver ESD cells are the same as those used on the receiver pins.