Integrated circuits

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Op-Amps

Considerations are noise (matters for audio and high amplification circuits), offset voltage, slew-rate (matters for high frequency and pulse circuits), quiescent current (matters for battery-operated), operating voltage (matters for battery operated), single or dual supply (most modern circuits require single supply), rail-to-rail, output current.

"Rail-to-Rail" means that the output of the op-amp can swing to several millivolts of its positive and negative supply rail. Non rail-to-rail op-amps can only get to within about 1.5 V of their supplies. For example, if you supply a non R-to-R op-amp off 0 and 5 V supplies, the useable output swing will be 1.5 to 3.5 V which is not very useful. Note: When checking for R-to-R, check if spec'ed for input, output or both. Many R-to-R op-amps are R-to-R on the output only. For these, the input typically includes the minus rail, but only to 1.5 V less than the positive rail. For example, if you are using an R-to-R input only op-amp powered off 0 and +5 V, it's use as a unity gain voltage buffer will only be good from 0 to 3.5 V. Moral: read the data sheet.

TI has a useful site for comparing op-amps. Prices listed are for singles, DIP pkg, as of May, 2003 (more or less). Prices are from Digi-Key unless Jameco number listed. Jameco has lower prices than Digi-Key, but Digi-Key has wider selection...and is a Minnesota company.

Types

Recommendations

Pinouts

Voltage Regulator

Specs to look for: (1) line and load regulation which dictate how precisely the output is held; (2) ripple; (3) output current; (4) dropout voltage which is the minimum difference between input and output, handy to have low for battery powered applications.

Pinouts

Microcontrollers

Microchip PIC chip microcontrollers. Good choice for cost, ease-of-use. For development, use C compiler from CCS (http://www.ccsinfo.com/picc.shtml). Recommend purchasing their PCM 14-bit compiler ($125), Warp-13A device programmer ($99), and "PIC C Tutorial" book ($15).

The following table lists recommended flash-programmable PIC chip parts. Prices are for single quantity from Digi-Key.

Recommendations

• If you just need some i/o pins then: 16F628A (low-cost).
• If you need many pins, ADC and serial, then: 16F873A
• If you want ADC and very few pins, then: 12F675
• If you want ADC and no serial, then: 16F819

Notes: (1) 16F84 is outdated, go with 16F628 which costs less. (2) Sometimes Digi-Key has no stock on 16F630, 16F648A, 16F870. (3) Microchip is introducing new parts all the time so it is worth it to check their line up every 6 months or so.

Oscillators

The easiest way to clock a PIC chip is with a ceramic resonator. Cheap, small, and available from Digi-Key. Use 4 MHz unless speed is an issue. 20 MHz resonators may or may not work. For 20 MHz, can also use a TTL crystal oscillator, e.g. Jameco 27932CP, $1.79. Note that resonators do not have tight frequency specs.

Analog-to-Digital Converters

Lots to choose from. Main vendors are Maxim, Analog Devices, Texas Instruments (Burr-Brown), Linear Technologies.

Digital-to-Analog Converters

Same companies as for ADCs

Audio

Pre-amp circuits driven by low-noise, ease of use. Power amplifier circuits are all about power. Can find lots of hobby-level info with a good Google search.

Interesting ICs

A random collection of ICs that may prove useful.