Digitrax boosters have maximum output current limits of either 5 or 8 amps.
The actual continuous output current that your booster will provide to the layout depends on several factors including the input supply voltage, the ambient room temperature and air flow over the booster's heat sink.
Higher input voltages increase the amount of heat that must be dissipated by the booster's heat sink.
If the heat sink does not get enough air flow to allow for heat dissipation, the booster will eventually reach an over temperature state and shut down.
A small fan blowing across the heat sink on your booster will increase the maximum sustained current output capacity of your booster.
Each DCC company specifies the output capacity of its boosters according to their own internal standards.
Tests designed and performed by several model railroaders have shown wide variations in the actual output capacity of DCC boosters.
In most cases the tests were designed to overload boosters and cause them to shut down.
The conclusion based on these tests is that each manufacturer uses a different way of determining booster output capacity, Digitrax tends to be more conservative in stating booster output ratings.
The factor that is most important for achieving maximum output capacity is the booster’s heat sinking ability.
In these tests, Digitrax boosters have demonstrated excellent heat sinking capabilities and the ability to consistently output the advertised 5 or 8 amps when appropriate fans are added in high temperature situations.