I recently added three stocks to my portfolio, so I know for a fact that I wouldn't hesitate to buy Medtronic (MDT 0.89%), Texas Instruments (TXN 1.25%), and Unilever (UL -0.17%). The real question is: Why did I buy these three dividend stocks? Here's the backstory.

1. Medtronic: No need to be a doctor

My main investment in the healthcare sector is a closed-end fund because, honestly, there are so many things I don't know about this highly technical industry. But when I saw medical-device giant Medtronic trading at a historically high yield, I jumped at the opportunity to buy it.

On a simple level, it has a diversified business spanning medical devices (e.g., pacemakers; 37% of sales), surgical tools and devices (e.g., robotic surgery; 28%), neuroscience (e.g., brain stimulation; 28%), and diabetes (glucose monitors; 7%). I know that diversification is good for my portfolio, and I'm confident it's good for Medtronic, too. 

The proof of that is Medtronic's history of annual dividend increases, which is more than four decades long. That makes it an elite Dividend Aristocrat. The average annual dividend increase over the past decade, meanwhile, was a generous 10% or so.

A company can only create a record like this by being good at what it does on a consistent and long-term basis. It's also why I'm willing to trust that the company, which remains profitable, is capable of dealing with the product delays and a product recall that are helping to push down the stock. In fact, even given these headwinds, management is still looking for organic revenue growth of 4% to 5% in fiscal 2023.

I'm glad I jumped on this long-term healthcare success story while Mr. Market has pushed its dividend yield to a historically high 3%-plus. You might want to look at it, too, even if (like me) you aren't a doctor.

2. Texas Instruments: The long-term plan

Chipmaker Texas Instruments is also a little outside my sphere of confidence. But I understand that chips are increasingly important in a world that is becoming more and more digital.

Texas Instruments' chips, meanwhile, are predominantly simple and low cost (analog chips are around 75% of sales) and can be sold into a huge number of end markets. This is where the diversification comes in, with the company serving five key markets: industrial (41% of sales), personal electronics (24%), automotive (21%), communications equipment (6%), and enterprise systems (6%). It has roughly 80,000 products and over 100,000 customers spread across the globe. 

While I don't fully understand what the company's chips do, I know that it has increased its dividend for 18 straight years and, from what I can tell, it hasn't actually cut its dividend since it started paying one in the 1980s. The most recent increase was a pleasing 13%.

The current weak economic backdrop is one issue Texas Instruments is facing, as it could subdue demand. But it is also looking to build new chipmaking facilities (a long and costly process) to serve long-term demand growth. That sounds like a good plan, and I believe management has proved that it knows how to weather the chip industry's ups and downs while building long-term value for shareholders.

Meanwhile, Wall Street has pushed the stock price down, based on worries about near-term performance, raising the yield to a historically high 3%. I'll happily take that and wait for management to show that, once again, it can come out the other side of a rough patch as a stronger company.

3. Unilever: A real fixer-upper

European consumer staples giant Unilever is a lot simpler to understand; you probably use some of its iconic brands, such as Dove soap and Ben & Jerry's ice cream. That said, annualized revenue and earnings growth over the past 10 years have been pretty meager at 1.2% and 4.7%, respectively.

Dissident investors have suggested that the company needs an overhaul. On that front, Unilever recently added Nelson Peltz to its board. One of Peltz's claims to fame is helping to turn around peer Procter & Gamble (PG 0.60%), so his involvement is a good thing in my eyes.

That said, the weak business performance has resulted in a historically high dividend yield of 4.3%. I'm confident that management can get things moving in the right direction, or at least a better one.

A key factor backing up my thoughts here is that Unilever generates around 60% of its revenue from emerging markets, which have higher growth rates than developed ones. And with the big brands it owns, it really has a solid foundation to support the revamp effort it has already started. 

The dividend history here is a bit harder to parse, given that the company recently changed from a dual listing to a single one. But Unilever has a long track record of rewarding investors with reliable dividends. This is definitely more of a turnaround story than either of the two other names here, but I'm a small investor and I can wait for the story to play out.

Time is on my side

If you haven't figured it out yet, I like to buy historically strong companies when they have historically high yields. That is the story that I think supports my recent buys of Medtronic, Texas Instruments, and Unilever. Maybe they all take a little while to get back on track, but I'm fine collecting their dividend checks until they do. You might want to collect those checks, too.