We will begin today's call with the legal disclaimers and Safe Harbor statement. All material contained in the webcast is the sole property and copyright of Micrel Incorporated with all rights reserved. Certain statements in this conference call, which are not historical facts, may be considered forward-looking statements that involve risks and uncertainties. Forward-looking statements include statements regarding future business results, future levels of sales and profitability, future customer demand and economic and industry projections. Various factors could cause actual results to differ materially from what is set forth in such forward-looking statements. Some of the factors that could affect the company's results have been set forth in our press release dated July 22, 2010 and are also described in detail in the company's SEC filings, including but not limited to our Annual Report on Form 10-K for the year ended December 31, 2009.
Listeners who do not have a copy of the second quarter earnings press release may view the press release on the company's website at www.micrel.com. We will review the financial results for the second quarter ending June 30, 2010 and then discuss our outlook for the third quarter of 2010. Our prepared remarks will then be followed by a question-and-answer session with the financial community.
Let's begin with Micrel second quarter financial and operational highlights. Second quarter revenues increased by 10% on a sequential quarter basis but fell slightly short of our expected sequential quarter growth range of 12% to 15%. A major reasons for this short fall was supply chain delinquencies at right from of our scheduled product shipments in the quarter. However, we currently expect these supply chain issues will be resolved during the third quarter and will not impact our results in the second half of 2010.
Despite a short-term challenge, our second quarter results was solid and we are pleased with our operational execution. Finance from customer serving the communication, computer and industrial end-markets was strong, resulting in a book-to-bill ratio well above one along with a robust ending backlog. In addition, our second quarter gross margin was better than expected, an increase on sequential quarter basis for the fifth quarter in a row.