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42 DESIGN007 MAGAZINE I MAY 2021 • ere may be le out or missing informa- tion. Here you should seek a second or third source to find the information you need. • Misprinted information. is one is quite common. Frequently the datasheet itself was translated from its original language and as we all know, this can result in sentences that make no sense, with some that are downright hilarious. • ere could be measured data that was misinterpreted and therefore useless to anyone looking to use that information. Due diligence on the part of the designer is always required. Know what you want, what your customer wants, and how to get it. is requires amassing information about your design's purpose. At Monsoon Solutions, we do this in a "kick- off " meeting with the customer to ask specific questions. We cover things like power needs, mechanical constraints, fixed components, and thermal considerations, just to name a few, Even the best laid plans do not always cover everything you need to know about your design in the kick-off meeting, and follow-up conversations are usually necessary. Do not be afraid of asking more questions (within rea- son) to get your design right. I also encourage you to learn and read more. Of course, be careful not to believe everything you read, either online or in print. Testing everything you read to prove the concept to yourself sometimes means you will also have to prove it to the customer. Be ready for that. #5: Large PMICs A power management IC is a power IC solid- state component that distributes the required measure of voltage to all other parts, which is usually accomplished using a low on-resistance MOSFET placed between the source and the load. e PMIC controls the MOSFET and thus its resistance. e PMIC manages the turn on/off rate by timing these MOSFETS, one per rail. It's typically used in battery operated devices such as cellphones, laptops, and por- table media players to decrease the amount of space required due to limited board real estate. About this, Jeff Reinhold said: "e reason I put PMICs above other circuits is we typically get a lot of information on how to lay out certain circuits (not just PMICs), includ- ing impedance, length, matching , clearance, and placement info. In addition, there may be pic- tures of completed placement/routing and even reference boards. e more complicated the cir- cuit, the more information we might get. Very oen, the parts and connections we have don't match the input(s) exactly. It may just be that parts are sized differently, but very oen the cir- cuit is slightly different as well. "For anything that isn't a large PMIC, if I fol- low the input well, there is a good chance I won't have to change anything aer it gets reviewed and/or simulated. If I do, it's typically minor. at has never happened with a large PMIC (small ones are easier to get right on the first try). I had one instance where I was able to follow the reference/input very closely and I thought it would be good, but it still needed some difficult work to get it right. Adding or moving caps and trying to squeeze more copper area or vias is oen not easy to do in crowded areas." #4: 'Scale' or Available Space for Design Many times as designers, we run into restric- tions on available space and board real estate issues, based on a number of things, such as the number and size of components needed for a given design. I can tell you that looking at Due diligence on the part of the designer is always required. Know what you want, what your customer wants, and how to get it.

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