LM117 3.3V PDF

Buy LMMP – TEXAS INSTRUMENTS – Fixed LDO Voltage Regulator, 15V in, V Dropout, V/mA out, SOT at Farnell element order. The ohm resistor is only required for the V version of the LD to maintain minimum regulation, with a 10 mA minimum load. This is the basic LDV33 voltage regulator, a low drop positive regulator with a V fixed output voltage. This fixed regulator provides a great amount.

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See the V O spec on the datasheet, for the 3. Try a larger load like mA and check to see if the voltage is still within range.

Resistors values to use with LM Ask Question. Post as a guest Name. I know that ratio R1 to R2 determine the output voltage of LM When I remove the resistor, I am getting the expected Vout 3. The adjust pin current has a maximum of uA. The LM datasheet specifies 10 mA max, 3. Even a 20k here would cause a change of 0. If it’s not within range at a higher load up to mA it may be bad.

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There’s no resistor in your schematic. It’s given by the following equation:. Post Your Answer Discard By clicking “Post 3.v Answer”, you acknowledge that you have read our updated terms of serviceprivacy policy and cookie policyand that your continued use of the website is subject to these policies.


In practice the change in Iadj is typically much smaller.

3.3V Regulator Board Using LM1117-3.3V IC

You may need a larger input capacitor depending on how far away your power supply is. So efficiency must be lower than the maximum possible in most cases. Recalled that I’d said 5 mA. You’ve multiplied your resistors by 10, so this error term will also be multiplied by 10, going from 33 mV to mV, or 0.

V Regulator Board Using LMV IC – Circuit Ideas I Projects I Schematics I Robotics

Several people have correctly pointed out that the LM output voltage is affected by the Iadj current which flows in R2 see example circuit below. SO the ohm resistor shown 3.v3 R1 would not meet the LM minimum load requirement worst case.

However, if external load current can fall to below 10 mA then the design must provide a load 3.3 provide this 10 mA. I am actually getting this 3.v3 without using any capacitors or resistors. I am using ldv33 with Vin as 4. The datasheet has a spec section for multiple output voltages. As this remains constant at all times, but the I through R1 changes depending on it’s resistance, you need to make sure that the uA is not a large part of the program current.


As others have noted, R2 need to be small enough such that Iadj voltage drop in R2 can be ignored or it must be allowed for.

Russell McMahon k 9 At very low currents the minimum load current of 10 mA may be significant. JGord – Did your comment end up on the wrong post?

If it was then you should probably not be using a simple 3 terminal regulator, but that’s another story. No real differences of note except that typical value given for R1 in about every example circuit I’ve seen violates data sheet spec for minimum current at no load. What I am saying is that the specification allows a maximum change of 5 uA in Iadj for changes of load from minimum to maximum. A maximum minimum is a nice concept: Where Vin is more than about 2V above Vout it is the regulators job to drop the excess voltage.

Changed my answer to accomodate. Sign up using Facebook.

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