I have a TomTom and happen to have discussed the operating voltage with TomTom themselves because I do not have an original TomTom charger: It is 4.8 Volts DC although the equipment will operate happily anywhere between 4.5 and 4.9 Volts - under no circumstances exceed 5.0 Volts plugged into the TomTom. This voltage is thus the range for any AC/DC converter's output, except that below 4.8 Volts the battery is not likely to be fully charged. The only way to be safe is to have a stabilised converter which does not, as unstabilised ones do, exceed 5 volts under next-to-no-load conditions (i.e. for example toward the end of charging), or else know that at no load the output voltage it is within 5 volts. The TomTom charger is a multi-voltage charger/converter and it will automatically cope with anything in the range 110-250V AC. All you need to make sure of is that the one you have has input requirements that match your mains voltage (220-230V in the UK and rest of Europe, 110V in North America). Short answer,for charger converter figures (in Europe): Input 230V AC, output 4.8V DC.