partfinder:vreg

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 partfinder:vreg [2012/04/08 17:34]gregham [7660 Switched Capacitor Voltage Converter] partfinder:vreg [2016/01/28 18:05] (current) Both sides previous revision Previous revision 2012/10/27 10:17 porkrhombus meaning of LDO was incorrect; redrafted reg defns2012/04/08 17:38 gregham [Switching regulators] 2012/04/08 17:34 gregham [7660 Switched Capacitor Voltage Converter] 2012/04/08 17:32 gregham [Switching regulators] 2012/04/08 17:13 gregham ['1117-XX series] 2012/04/08 17:07 gregham [LM2931-XX series] 2012/04/08 17:05 gregham [LM2931-XX series] 2012/04/08 16:23 gregham [LM317, LM337] 2012/04/08 16:22 gregham ['1117-XX series] 2010/12/03 15:38 scottinnh Added Mouser link for Max7562010/10/02 17:44 external edit Next revision Previous revision 2012/10/27 10:17 porkrhombus meaning of LDO was incorrect; redrafted reg defns2012/04/08 17:38 gregham [Switching regulators] 2012/04/08 17:34 gregham [7660 Switched Capacitor Voltage Converter] 2012/04/08 17:32 gregham [Switching regulators] 2012/04/08 17:13 gregham ['1117-XX series] 2012/04/08 17:07 gregham [LM2931-XX series] 2012/04/08 17:05 gregham [LM2931-XX series] 2012/04/08 16:23 gregham [LM317, LM337] 2012/04/08 16:22 gregham ['1117-XX series] 2010/12/03 15:38 scottinnh Added Mouser link for Max7562010/10/02 17:44 external edit Line 1: Line 1: - 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 a 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 ​a 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 voltage. Linear ​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. Line 71: Line 73: ====== Switching regulators ====== ====== Switching regulators ====== - - | 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. | - ==== 7660 Switched Capacitor Voltage Converter ==== ==== 7660 Switched Capacitor Voltage Converter ====