UPDATE 1-Google buys 7.7% of Reliance's digital unit for $4.5 bln

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NEW DELHI, July 15 (Reuters) - India's Reliance Industries on Wednesday said Alphabet Inc's Google will buy a 7.7% stake in its digital unit for $4.5 billion, winning the backing of another U.S. tech giant after Facebook Inc in late April.

With Google's investment, strategic and financial investors have committed a total of 1.52 trillion rupees ($20.22 billion) in the last few months, Reliance chairman and billionaire tycoon Mukesh Ambani said at the company's annual shareholders meeting hosted via a webcast.

Google's investment in Jio Platforms is at a valuation of 4.36 trillion Indian rupees ($58.01 billion) for the digital platform, the company said in a statement.

The unit houses music and movie apps but its mainstay is telecoms firm Jio Infocomm - India's largest mobile carrier with more than 387 million users.

The Reliance-Google announcement comes just days after Alphabet CEO Sundar Pichai said his company would invest $10 billion in India over the next five to seven years through equity deals and tie-ups.

The deal with Google will bolster Reliance's lofty tech ambitions, such as building smart homes, using solutions similar to Amazon.com Inc's Alexa voice assistant, connected cars and security systems.

The investment arms of chipmakers Qualcomm Inc's and Intel Corp have also bought stakes in Jio Platforms this month, at a time India is preparing to auction 5G airwaves to telecoms service providers. ($1 = 75.1590 Indian rupees) (Reporting by Sankalp Phartiyal, editing by Louise Heavens)