Spreadtrum raises second-quarter revenue estimates; shares rise Wed Jun 12, 2013 6:15pm EDT (Reuters) - Spreadtrum Communications Inc, a cellphone chip designer, raised its revenue estimates for the current quarter due to higher demand from low-cost smartphone makers, sending its shares up 23 percent in extended trading. The China-based company now expects revenue of between $270 million and $278 million for the quarter ending June 30, up from the $220 million to $228 million it forecast earlier. Analysts on average were expecting revenue of $224.1 million, according to Thomson Reuters I/B/E/S. Topeka Capital Markets analyst Suji De Silva said Spreadtrum is doing very well in the Chinese low-end smartphone market. Spreadtrum's U.S.-listed shares were up at $23.30 in post-market trading, after closing at $18.95 on the Nasdaq. Reporting By Lehar Maan and Aditya Kondalamahanty in Bangalore