Interview #2: Apple Inc.. No longer Apple Computers..

As promised, i'm giving you guys an overview of another big interview that I went through. This one was with the infamous Apple Inc based out of Cupertino, California. The interview was for the iPhone Power/Performance team. Based on the description of the job, it seemed like a job that has both hardware and software elements to it. The job entailed hardware analysis to see ICs that drain a lot of power, and find software solutions to optimize the system to use less power. Sounds fun doesn't it. Plus, had I gotten the job, I would have been able to brag that I work on the most successful smartphone of the last few years.. I guess you guys can conclude that I didn't get the job.. but I did get the 2nd interview.. so that means I did some things right..

For those of you that don't know.. I did 2 internships with RIM and worked on Power Management which is probably why I got this interview in the first place so most of their questions revolved around my experience at RIM.

One thing I came to realize with Apple is that they are interested in people who know their stuff inside out.. They don't want someone who displays potential, they want someone who HAS potential and they're very picky.. They don't beat around the bush.. The recruiters don't use flowerly language or emails that are a full page long.. they use 3 sentences to get to the point..

Here's an example..

"I'm one of the recruiters on the iPhone performance/power team and was really interested in your resume. The work you've been doing is very interesting and I'm sure the team would like to chat with you. When might you be available?"

or..

"Sounds like your first chat went well. If you are interested we'd like to have you chat with another person from the iPhone perf team

When is the next best day? Friday?"

As you can see.. they cut to the chase.. which I really haven't been doing in this entry so i'll start now.. let's cut to the chase and get to the questions..

Apple Inc.
Interview 1
Question 1: I see you've worked at RIM's Power team.. What did you do there?
Answer: This is a very open ended question and they want to see how detailed you can get from a technical standpoint. I was very in-depth in my answers. "I worked mostly in the lab automating power measurement for BlackBerry devices. Measuring voltage and current of different components and identifying Power Management ICs to be used in Next Gen BlackBerries."

Question 2: So u've worked with PMICs.. why don't u tell me what some of the components in a PMIC are?
Answer: Linear Regulators (LDO), Switched Mode Power Supplies(SMPS), I2C communication interface.


Question 3: Ok, you also said you helped pick out PMICs for next gen devices.. what are some of the criteria for picking them?
Answer: Size (Because mobile applications ahve a scarcity when it comes to board space) and efficiency (because mobile applications run on batteries with limited power capability). but there's a tradeoff because the more efficient power supplies (SMPS) are bigger and the less efficient ones (LDOs) are smaller..

Question 4: Very good point.. so u talk about LDOs and SMPS. Why are LDOs less efficient and Why are SMPS units bigger..
Answer: LDOs use a resistive network to bring down voltages, so you have loss to environment and heat dissipation while SMPS devices work with transistors that switch on and off really fast to produce the voltage and could theoretically reach 100% efficiency. The problem is that SMPS units require an extra inductor, so space wise, that adds to the size of the unit.

Question 5: Ok, I see that you talk about bringing down voltages. Is that all you can do?
Answer: No, you can use buck regulators to bring down voltages and boost regulators to bring up voltages too. But they can only be done in SMPS devices not LDOs.

Question 6: You've been giving very good answers so far and giving lot more detail than I need. Now something more specific. What do you think are the 5 biggest power consuming elements in the iPhone.
Answer: Processor, LCD, Radio, GPS, and Audio Speakers and Microphone..

Question 7: Great.. now can u organize those 5 in terms of most and least power consuming..
Answer: I would think LCD, Processor, GPS, Radio and finally speakers
Interviewer: close but the LCD doesn't consume as much as you think. I mean. it does consume a lot when it's on but over a period of time, the processor and radio are the biggest consumers..

Question 8: Do you know what a bypass capacitor does?
Answer: I know the term sounds familiar but I can't quite rememember.

The interviewer the explained what it was, and I knew that I had the answer somewhere in me but couldn't come to a conclusion.

So i screwed up two out of eight questions, not too bad.. I knew i did well enough in the hardware interview.. and I was confident..

I noticed that the interview was mostly based on my resume so i strongly urge you to not put anything that you don't know inside out.. they grill you on it and they question every nook and cranny.. The interviewers know their stuff so don't try to bullshit your way through it. If you don't know an answer, say that you don't know it. Don't try to make a fool of the interviewer coz they will point it out to you..

The next day I got a request for the second chat.. and sure enuff this one was going to be software based..

Stay tuned and i'll tell you what was in store for me.. I'll give you a hint.. I didn't follow my own advice.. LOL.