I recently received an email from Texas Instruments (Disclaimer: with whom I have no connection other than being on their mailing list) entitled “Re: Problem solved: Download your guide to often-used design formulas ”. Now I have got to the age where the hair has stopped growing on my head and started growing in my nose and ears, and along with this comes an inability to remember stuff I thought I’d never forget. So I thought I would download a copy. It’s a 98-page PDF (7MB), and you can check it out online or download it here. The editors say they compiled it from an oft-referred to folder full of worn printouts. I have a couple of such folders which I refer to regularly, so the chance to look at someone else’s ‘Bible’ of info sounded good. I started paging through.
The first thing I came across was a table of physical constants on page 8. Here I found the rest mass of an electron (I thought electrons never rested?) and a proton. “These guys move in pretty esoteric circles” I thought to myself – I have never needed to know the rest mass of an electron though I am sure there are those to whom this would be an indispensable nugget of knowledge. But this is just me. From then on this gem of an e-book is loaded with very useful and practical information, from conversion factors to component information to basic DC and AC calculations to op-amp theory, PCB design stuff, ADC and DAC info….. in fact the best I can do here is reproduce the list of sections in the book:
- Key constants and conversions
- Discrete components
- AC and DC analog equations
- Op amp basic configurations
- OP amp bandwidth and stability
- Overview of sensors
- PCB trace R, L, C
- Wire L, R, C
- Binary, hex and decimal formats
- A/D and D/A conversions
Now the guys (and gals) on EEtimes are a pretty smart bunch in general and no doubt within those headings there would be those who could recite all these formulae or configurations off-pat. But to have all this information in one place is very useful, I think.
It’s entitled “Analog Engineer’s Pocket Reference” and most of the information is oriented towards the analog design side of things, but a lot of this is applicable across a wide array of disciplines, especially if you have to interface with the real world. Each section starts with the basics (for example basic AC conversion factors, color codes, preferred resistance and capacitance values, series and parallel calculations, Binary to Hex and Decimal conversions, etc) before moving on to the more complicated stuff. Equations are given where applicable and are numbered for easy reference
For example, after discussing the practical equivalent circuit for a capacitor, including ESR and ESL and parallel resistance, there is this diagram of capacitor impedance for various types:
A good reminder that aluminium electrolytics have their shortcomings when used for decoupling power rails. There’s also a good deal of information on various capacitor types and characteristics.
And for ADCs. there is a good collection of information that you’d use in designing with these, including binary, hex and decimal conversions (and those pesky 2’s complement numbers), LSB resolution in mV for various combinations of reference voltage and number of bits, and how to work out SNRs, THDs, ENOBs and settling times and the like. There’s a section on various temperature sensors (thermistors, RTDs, diodes and thermocouples) and how to calculate resistance from temperature or vice-versa. You can find the Inductance, capacitance and resistance of PCB traces, wire and coax cables. Lots of stuff on op-amps, including configurations, Spice models, noise calculations, responses and filter stuff.
It’s very difficult to find fault with anything in here. It would be nice to have velocity ratio information in the table of coax cable types, for example, but this is real nitpicking stuff. I am a fairly general, low level design kind of guy and I can see myself referring to this book a lot for basic information that I don’t have in my head. It’s certainly something that a lot of people would find useful to have in easy reach near their workbench.
There is so much information in the 98 pages of this book that it’s difficult to select other examples to show here. But here is a table of settling times vs number of bits of accuracy for an ADC – something that is very easy to get wrong, but easy to get right with a table like this:
I could go on showing you excerpts from the book, but it’s free to download or look at here, so suss it out and let us have your impressions of how useful this is in the comments below.