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jh24628
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I was going to use a +5V Fixed-Voltage Regulator 7805, for a project until I noticed that I need 2 amps and the 7805 can supply at max 1 amp. what can I do?
ranger said:The datasheet for the respective regulators will tell you all that info.
http://www.google.com/search?hl=en&q=7805+datasheet&btnG=Google+Search
Learning how to read datasheets is a good thing.
berkeman said:I agree, datasheets are our friends. Also, google can be useful if you know a couple keywords... I just googled heatsink tutorial, and got lots of good hits. This is one of the first ones on the hit list:
http://sound.westhost.com/heatsinks.htm
It describes the concepts of thermal resistance and heatsink sizing, plus gives some useful tips for how to use heatsinks.
jh24628 said:yes I know, but you did not read my question. my question was how does heat impact its performance, I know the hotter the chip is the lower the current output will be. do I need to worry about a heatsink on it at all? according to this at 25 degrees Celsius, it will output 1 amp ( http://www.national.com/mpf/LM/LM78M05.html [Broken] )
berkeman said:I agree, datasheets are our friends.
jh24628 said:I guess for the current question i should have rephrased it. I need the regulator to output one amp, would I be safe putting more than one amp to the input of the regulator?
jh24628 said:(maybe this is why I'm not an EE major) but if you are supplying the 7805 with power from a DC power supply, how can the 7805 only have voltage as an input when the dc power supply has both a voltage and current output?
berkeman said:... The input current equals the output current (the current all just flows through the linear regulator), and the input voltage is determined by the voltage setting on the source power supply.
jh24628 said:I have a couple more questions. is it absolutely necessary to have the two capacitors in the circuit
"*Required if regulator input is more than 4 inches from input filter capacitor
(or if no input filter capacitor is used). <- ON INPUT
**Optional for improved transient response." <-ON OUTPUT
and is there a recommended input current? I know the higher the current the more heat made.
TheAnalogKid83 said:It may help you to understand that your load draws the current and that determines how much current your regulator "passes" and not the regulator or power supply themselves necessarily; their current spec is a max rating rather than a given constant so it means they can go up to 1A for example, but they will only ever supply as much current as the load is drawing which could be anything less than 1A. The regulator just varies how much current it takes from the input voltage, your power supply for example, and passes to the output voltage so that no matter the variation of current your load takes, the voltage will remain at a constant regulated level (just remember ohm's law and power equation to see the relationships your regulator is trying to control). Your heat will be generated by how much internal resistance is present in the switching or passive components of your regulator. The bigger drop in voltage across the regulator (a bigger difference between input voltage and output voltage), the more power you will dissipate with the regulator for a given current (because current is determined by the load) by the equation of Power = I*V.
Mike Phan said:If you regulator MAX output current is 1A, your load should be equal or less than 1A. Otherwise, the regulator will be burnt.
Base on you choice of using 7805, there are several ways to design a regulator higher than the max current using "your" 7805 IC.
1. Pick uA7805 type that provides 3A (there have 1A and 3A), or
2. Since your design is not too high power (5V * 3A = 15W), you can find other regulator from linear technology or analog devices
3. Use a shunt circuit with the 7805 to increase the output current.
A voltage regulator is an electronic component that controls the voltage output of a power supply. It takes in a varying voltage input and maintains a steady output voltage by adjusting the resistance or using a feedback mechanism.
The main purpose of a voltage regulator is to provide a stable and consistent voltage output to power electronic devices. This ensures that the devices receive the correct amount of power and prevents damage from voltage fluctuations.
The amperage rating of a voltage regulator refers to the maximum current it can handle without overheating or malfunctioning. If your electronic device requires 2 amps of current, you will need a voltage regulator that can safely provide this amount of current to power the device.
If your voltage regulator is not providing enough amps for your device, you can either replace it with a higher amperage regulator or use a separate power supply to supplement the current. It is important to always use a voltage regulator that can handle the required amperage to avoid damaging your device.
Yes, there are voltage regulators that can work for both AC and DC circuits. However, it is important to make sure that the voltage regulator is compatible with the type of circuit you are using it for. Some regulators may only work for either AC or DC, so it is important to check the specifications before use.