UPDATE 2-Volterra posts Q1 net loss; sees improvement in Q2

* Q1 adj EPS $0.03 vs est. $0.00/shr

* Q1 rev down 21 pct to $18.3 mln vs est. $17.5 mln

* Sees Q2 adj EPS $0.02-$0.06 vs est. $0.02/shr

* Sees Q2 rev $20-$22 mln vs est. $18.70 mln (Adds outlook, details from conference call)

April 20 (Reuters) - Volterra Semiconductor Corp (VLTR.O), a low-voltage power supply chipmaker, swung to a first-quarter net loss as revenue fell 21 percent amid an overall weakness in demand in the semiconductor industry.

The company, however, forecast a better second quarter, citing an improved customer visibility, and said it is "cautiously optimistic" that its business will grow over the year as new product cycles continue to kick in.

"We believe first quarter was our bottom," Chief Executive Jeffrey Staszak said in a conference call with analysts.

Bellwether chipmaker Intel Corp (INTC.O) last week posted better-than-expected results and said the worst was over for the tech sector.

For the second quarter, Volterra forecast adjusted earnings of 2 cents to 6 cents a share, on revenue of $20 million to $22 million.