TOKYO, Feb 3 - Japan's Nikkei average <.N225> ended at a five-week low on Tuesday as investors ditched Sharp Corp <6753.T> and other makers of digital products. Traders said large-lot selling in the futures market also weighed on the average. The Nikkei fell 1.25 percent to 10,641.92, after earlier falling more than two percent to 10,507.93, a five-week intraday low. Market players now see the 10,500 level, where the 75-day moving average stood, as a key support. The broader TOPIX index <.TOPX> slid 0.59 percent to 1,043.28.//