des infos sur les alims adc ICI : http://focus.ti.com/lit/ds/symlink/pcm4201.pdf p11

Je me suis apercu qu'il y avait les :

• linear regulator
• reference

Le but semble le meme, fournir une tension. Les regulateurs semblent tourner a 200mA contre 1mA pour les references. J'en conclue que les applications ne sont pas les memes. Ceci dit pour un microphone, on peut peut etre utiliser une reference pour l'alimenter..

Documentation interessante sur le 7760 CPA :

• montageICL7660.doc:

Ceramic Capacitors Replace Tantalum Capacitors in LDOs :

• slva214a.pdf:

Analog : peu de produits (une vingtaine) (Refences -> Voltage References)

• page principale : http://www.analog.com/en/subCat/0,2879,769%255F838%255F0%255F%255F0%255F,00.html
• ADR440_441_443_444_445.pdf:

Explications :

• Wikipedia : voltage regulator : http://en.wikipedia.org/wiki/Voltage_regulator

DC voltage stabilizers

Many simple DC power supplies regulate the voltage using a shunt regulator such as a zener diode, avalanche breakdown diode, or voltage regulator tube. Each of these devices begins conducting at a specified voltage and will conduct as much current as required to hold its terminal voltage to that specified voltage. The power supply is designed to only supply a maximum amount of current that is within the safe operating capability of the shunt regulating device (commonly, by using a series resistor). In shunt regulators, the voltage reference is also the regulating device.

If the stabilizer must provide more power, the shunt regulator output is only used to provide the standard voltage reference for the electronic device, known as the voltage stabilizer. The voltage stabilizer is the electronic device, able to deliver much larger currents on demand.

Active regulators

Because they (essentially) dump the excess current not needed by the load, shunt regulators are inefficient and only used for low-power loads. When more power must be supplied, more sophisticated circuits are used. In general, these can be divided into several classes:

• Linear regulators
• Switching regulators

Linear regulators

Linear regulators are based on devices that operate in their linear region (in contrast, a switching regulator is based on a device forced to act as an on/off switch). Linear designs have the advantage of very "clean" output with little noise introduced into their DC output. Entire linear regulators are available as integrated circuits. These chips come in either fixed or variable voltage types.

Switching regulators

Switching regulators rapidly switch a series device on and off. The duty cycle of the switch sets how much charge is transferred to the load. This is controlled by a similar feedback mechanism as in a linear regulator. Because the series element is either fully conducting, or switched off, it dissipates almost no power; this is what gives the switching design its efficiency. Switching regulators are also able to generate output voltages which are higher than the input, or of opposite polarity - something not possible with a linear design.

Like linear regulators, nearly-complete switching regulators are also available as integrated circuits. Unlike linear regulators, these usually require one external component: an inductor that acts as the energy storage element. (Unfortunately, the inductor must be external because large-valued inductors tend to be physically large relative to almost all other kinds of componentry; because of this, they are impossible to fabricate within integrated circuits.) This may not be completely true. National Semiconductor was able to accomplish this feat with the LM2825 voltage regulator dip chip.

Comparing linear vs. switching regulators

Sometimes only one or the other will work:

• Linear regulators are best when low output noise is required
• Linear regulators are best when a fast response to input and output disturbances is required.
• Switching regulators are best when power efficiency is critical (such as in portable computers).
• Switching regulators are required when the only power supply is a DC voltage, and a higher output voltage is required.

In many cases either one would work. So the choice comes down to which costs less. At high levels of power (above a few watts), switching regulators are cheaper. At low levels of power, linear regulators are cheaper.

• Wikipedia : Linear Regulator : http://en.wikipedia.org/wiki/Linear_regulator

Fixed regulators "Fixed" three-terminal linear regulators are commonly available to generate fixed voltages of plus 3 V, and plus or minus 5 V, 9 V, 12 V, or 15 V when the load is less than about 7 amperes.

The "78" series (7805, 7812, etc.) regulate positive voltages while the "79" series (7905, 7912, etc.) regulate negative voltages. Often, the last two digits of the device number are the output voltage; eg, a 7805 is a +5 V regulator, while a 7915 is a -15 V regulator.

• 7805.jpg:
  

• 7805_good.jpg:
  

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