ZTM
H-Bridge dead time
Abstract: Software configurable H-Bridge dead time.
Details
The C12 booster can be set how long the H-bridge remains in the tri-state (dead time). In RTB this is called Z-time or ZTM. By default, the integrated H-bridge has a dead time of around 150 ns, which is considered short compared to many other bridges. To facilitate mixing different bridge types, assuming the current chip will one day become obsolete, the signal generator allows the dead time to be extended in 500ns increments. For this purpose, the H-bridge is forced into tri-state before each state transition.
Below are some examples of signal traces for different Z-time settings. During recording, one locomotive (Mtx V160) ran at medium speed to ensure a load condition. DCC track voltage was set to 15V on the this booster.
Caution: RTB allows the Z-time to be set up as high as 7500 ns. This should only be done for booster compatibility troubleshooting. According to RCN-210, the DCC rise/fall time should be >2.5V per microsecond, which corresponds to Z time <= 1000ns.
The recording shown was carried out for Z-time set to 7500 ns with 10 active locomotives on the tracks. As we can see, the DCC voltage retracts to ~0V within 500ns and stays that way until the Z-time expires. Like mentioned before, this setting would violate the RCN-210 requirements.
