Apple (NASDAQ:AAPL) investors have thrown a fit since the company's fiscal year 2018 fourth-quarter report. Indications point to a slowdown in iPhone unit sales, a metric that will become less clear starting in 2019 as the company stops reporting specific sales numbers in lieu of more transparency on its services business.

The uncertainty surrounding Apple has wreaked havoc for many of the company's hardware suppliers too. Many that rely heavily upon the iPhone, Watch, and other products for revenue have suffered as of late due to the expected slowdown in device sales in the coming year. Nevertheless, that weakness has set up a buying opportunity for some supplier stocks, especially those that don't rely solely on Apple as the tech giant weens investors off hardware numbers.

All about connectivity

Skyworks Solutions (NASDAQ:SWKS) has been riding Apple's coattails for the last decade, but as iPhone sales have tapered, so has Skyworks' stock. Slowing smartphone sales have pressured demand for the company's chips that enable internet network connectivity. During the company's fiscal 2018 fourth quarter, for example, year-over-year revenue rose a mere 2%, and management expects sales to be down 4% in the first quarter of 2019. That has sent shares spiraling over 40% from their high point reached in early 2018.

All is not hopeless for Skyworks, though. The company continues to develop non-smartphone connectivity solutions, everything from auto solutions to wearable devices and smart home products. The up-and-coming 5G mobile network could be a big boost too, as the company has released a portfolio of 5G antennas, infrastructure materials, and 5G connection-enabling equipment.

Paired with an expected uptick in smartphone sales later in 2019, the growth in new connectivity chip uses -- known as the Internet of Things -- makes the sell-off in Skyworks' stock look overdone. The company's trailing 12-month price to free cash flow (money left over after basic operations and capital expenditures are paid for) ratio rests at 14.4 as of this writing. Skywork's forward price to earnings based on Wall Street estimates is 8.9, implying a big jump in the bottom line in the year ahead.

Memory chips on the ebb... for now

Micron Technology (NASDAQ:MU) shares capitulated during 2018 as Wall Street analysts predicted a slowdown in the memory chip sector this year. Since peaking in the late spring, the stock has lost half of its value. The reason? Management has confirmed that the company is in fact in the midst of a digital memory demand contraction. Year-over-year revenue is expected to fall 14% to 22% during the company's fiscal 2019 second quarter, and profit is slated to fall even further.

Micron sells products to a diverse group of customers, so the blame can't be laid solely on the iPhone. Nevertheless, memory chip oversupply at device manufacturers, automakers, and data center operators will take some time to work down. Plus there's no telling how far demand will fall, or how long it will last. This puts an unknown amount of near-term pressure on Micron's top- and bottom-lines, so more share price declines could be in order.

However, while the company's management says its outlook remains cloudy, things are expected to start picking up again by the second half of 2019. As Micron issues more certain language surrounding an expected rebound for its memory products, its stock will show signs of life once again. In the meantime, investors interested in Micron should buy the stock a little bit at a time.

An artist's illustration of everyday objects getting connected to the internet. Pictures of cars, phones, watches, and appliances are depicted inside honey-comb shaped cells.

Image source: Getty Images.

Power management solutions for all

ON Semiconductor (NASDAQ:ON), a maker of power management and sensor chips, is also on Apple's official supplier list. Despite headwinds in consumer electronics like smartphones, the company has been executing well in the auto industry and expanding power management solutions for other industrial applications. Year-over-year sales and earnings per share in the third quarter of 2018 were up 11% and 52%, respectively.

Sales in the fourth quarter are expected to increase at least another 7% over 2017, and ON's bottom line should be up even higher as profit margins improve. In spite of the rosy outlook, sluggish performance in some of ON's end-markets and a slowdown in earnings growth after the acquisition and integration of a competitor in 2016 have caused shares to drop over 40% from their high reached early in 2018.

That steep drop and ON management's overall positive outlook make the stock look like a value heading into the new year. Trailing 12-month price to free cash flow is 13.7, and one-year forward price to earnings is only 8.3. Much like Skyworks and other diversified Apple suppliers, this implies a much more profitable company next year as new uses for ON's product portfolio continue to propel business results higher.

The high-growth days driven by Apple's iPhone might be coming to a close for the time being, but that doesn't mean the company's suppliers are doomed. After an ugly end to 2018, some of those supplier stocks look like real bargains in 2019 -- not to mention for the long-term -- as the growth of the digital economy continues to expand at a rapid pace.

Nicholas Rossolillo and his clients own shares of Apple, Micron Technology, ON Semiconductor, and Skyworks Solutions. The Motley Fool owns shares of and recommends Apple and Skyworks Solutions. The Motley Fool has the following options: long January 2020 $150 calls on Apple and short January 2020 $155 calls on Apple. The Motley Fool has a disclosure policy.