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partfinder:vreg [2012/04/08 17:07]
gregham [LM2931-XX series]
partfinder:vreg [2016/01/28 18:05] (current)
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-Voltage regulators are used for turning input voltage to the desired output voltage to run a circuit ​off of.+Voltage regulators are used for providing a stable supply ​voltage, free of noise and AC ripple, ​to power a circuit.
  
 Different types include: Different types include:
-   ​* ​linear '​dropout' ​regulators: ​also called LDO regulators, these take high voltage and create a '​dropout'​ to set the output to be some lower voltage. ​For example, 9V down to 5V the regulator creates a 4V drop. That drop is dissipated ​as heat. They are low cost, have varying input/output and dropout voltages as well as max current capability. +   ​* ​Linear ​regulators: ​Starting with a higher than required input voltage, these provide ​stable, ​lower output ​voltage. ​The regulator heats up as it dissipates ​the voltage ​drop times the current ​as heat. Low-dropout (LDO) versions can regulate their output ​voltage up to close to the input voltage, whereas regular ones require 2-3V headroom over and above the desired output voltageLinear ​regulators ​are the lowest-cost types.
-   * switching ​regulators +
-   * DC/DC converters+
  
-====== Linear ​'​dropout' ​regulators ======+   * Switching regulators: These use a PWM approach to rapidly '​chop'​ or '​buck'​ the input voltage, which after smoothing provides a lower output voltage. These don't warm up as much because there is essentially no voltage drop in the regulator; it is either on or off, not somewhere in between. Switching regs can be small (many are surface-mount) and provide relatively high current for their size, but they do require a few external components to function. 
 + 
 +   * DC/DC converters: This category includes step-up or '​boost'​ converters which can actually provide a higher output than the input voltage. These are similar in basic operation to the switching '​buck'​ converter just mentioned. Some are classified as buck-boost converters, meaning that they can provide an output of 5V (say) from an input of anywhere from 3V to 9V. Pretty handy stuff. 
 + 
 +====== Linear regulators ======
  
  
 ==== 78xx, 79xx ==== ==== 78xx, 79xx ====
-The simplest and best known regulators are the 78xx and 79xx series, where xx is the desired output voltage. They have three pins: input, output and ground. 7805 will get you 5V on the output pin, as long as you supply an input voltage of at 2-3V higher. 79xx Series are for negative output voltages, but they work the same.+The simplest and best known regulators are the 78xx and 79xx series, where xx is the desired output voltage. They have three pins: input, output and ground. 7805 will get you 5V on the output pin, as long as you supply an input voltage of at least 2-3V more. 79xx Series are for negative output voltages, but they work the same.
 These "​building blocks"​ are great for making a simple and stable power supply. These "​building blocks"​ are great for making a simple and stable power supply.
    
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   * Current: 800mA (assuming that the power dissipation isnt too high for the package)   * Current: 800mA (assuming that the power dissipation isnt too high for the package)
  
-The following table has links for the 1117-3.3 and 5.0 only, since those are the most popular. [[http://​www.st.com/​internet/​com/​TECHNICAL_RESOURCES/​TECHNICAL_LITERATURE/​DATASHEET/​CD00002116.pdf|1117 Datasheet]] ​+The following table has links for the 1117-3.3 and 5.0 only, since those are the most popular. [[http://​www.st.com/​internet/​com/​TECHNICAL_RESOURCES/​TECHNICAL_LITERATURE/​DATASHEET/​CD00000544.pdf|1117 Datasheet]] ​
  
 ^ Image ^  Package ​ ^  Vout @ Iout  ^  Distributors ​ ^ ^ Image ^  Package ​ ^  Vout @ Iout  ^  Distributors ​ ^
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 |  " ​ |  TO-220 ​ | 5.0V @ 0.8 amp | [[http://​mouser.com/​ProductDetail/​STMicroelectronics/​LD1117V50C/?​qs=sGAEpiMZZMsGz1a6aV8DcCwRipvt0X3PXDVXWaOVWAU%3d|Mouser]] [[http://​search.digikey.com/​scripts/​DkSearch/​dksus.dll?​Detail&​name=AP1117T50L-UDI-ND|Digikey]] | |  " ​ |  TO-220 ​ | 5.0V @ 0.8 amp | [[http://​mouser.com/​ProductDetail/​STMicroelectronics/​LD1117V50C/?​qs=sGAEpiMZZMsGz1a6aV8DcCwRipvt0X3PXDVXWaOVWAU%3d|Mouser]] [[http://​search.digikey.com/​scripts/​DkSearch/​dksus.dll?​Detail&​name=AP1117T50L-UDI-ND|Digikey]] |
 |  " ​ |  TO-220 ​ | 1.25+ adjustable @ 0.8 A \\ Works similar to LM317 but lower dropout ​ |  [[http://​www.mouser.com/​Search/​ProductDetail.aspx?​R=LD1117Vvirtualkey51120000virtualkey511-LD1117V|Mouser]] [[http://​search.digikey.com/​scripts/​DkSearch/​dksus.dll?​Detail&​name=497-7310-5-ND|Digikey]] | |  " ​ |  TO-220 ​ | 1.25+ adjustable @ 0.8 A \\ Works similar to LM317 but lower dropout ​ |  [[http://​www.mouser.com/​Search/​ProductDetail.aspx?​R=LD1117Vvirtualkey51120000virtualkey511-LD1117V|Mouser]] [[http://​search.digikey.com/​scripts/​DkSearch/​dksus.dll?​Detail&​name=497-7310-5-ND|Digikey]] |
- 
 ==== LM317, LM337 ==== ==== LM317, LM337 ====
 Basically the same as the 78xx regulator, but adjustable. It also has three pins: input, output, adjust. A voltage divider (2 resistors) is connected to the output pin and ground to create a reference voltage. This reference voltage is connected to the adjust pin. The regulator will adjust the output voltage, until the reference voltage is 1.25V. By altering one of the resistors of the voltage divider, you can adjust the output voltage. Basically the same as the 78xx regulator, but adjustable. It also has three pins: input, output, adjust. A voltage divider (2 resistors) is connected to the output pin and ground to create a reference voltage. This reference voltage is connected to the adjust pin. The regulator will adjust the output voltage, until the reference voltage is 1.25V. By altering one of the resistors of the voltage divider, you can adjust the output voltage.
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 ====== Switching regulators ====== ====== Switching regulators ======
 +==== 7660 Switched Capacitor Voltage Converter ====
  
-7660 | Charge pump based step-up/​voltage inverting chip. \\ Provides a low-current voltage at either -Vin or \\ 2Vin, using only capacitors. ​ Suitable for \\ providing a negative rail for low-power op-amp circuits, or \\ a low-current stepped-up supply for programming \\ voltages on flash-based microcontrollers. | Available in MSOP-8, PDIP-8, SOP-8. | Widely available from many \\ suppliers and manufacturers. |+The 7660 is a voltage converter capable of converting a positive voltage in the range of +1.5V to +10V to a negative voltage of −1.5V to −10V 
 + 
 +^ Image ^ Part # & Datasheet ​ ^  Description ​  ​^ ​  ​Package notes  ^  Distributor ​ ^ 
 +| . | [[http://​www.ti.com/​lit/​ds/​symlink/​lmc7660.pdf|LCM7660]] ​| Charge pump based step-up/​voltage inverting chip. \\ Provides a low-current voltage at either -Vin or \\ 2Vin, using only capacitors. ​ Suitable for \\ providing a negative rail for low-power op-amp circuits, or \\ a low-current stepped-up supply for programming \\ voltages on flash-based microcontrollers. ​ | Available in MSOP-8, PDIP-8, SOP-8. | Widely available from many \\ suppliers and manufacturers. |
  
 ====== DC/DC converters ====== ====== DC/DC converters ======
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