LM2940 DATASHEET PDF
The LM/LMC positive voltage regulator features the ability to source 1A of output current with a dropout volt- age of typically V and a maximum of. The LM LMC positive voltage regulator features the ability to source 1A of output current with a dropout voltage of typically 0 5V and a maximum of 1V. The LM positive-voltage regulator features the Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
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Now my confusion starts with ESR and capacitor type CuF is an SMD tant: This chip predates big cheap ceramic caps, I think. I was using datashet above to supply 5v to my Atmegap-pu project in my automotive environment for controlling the signal that datqsheet on some lights via Mosfet.
Email Required, but never shown. This capacitor must be rated over the same operating temperature range as the regulator and 2 the ESR is critical – see curve. Sign up using Email and Password.
What is the input voltage?
LM datasheet & applicatoin notes – Datasheet Archive
They need to be rated above my voltages also. Tom Wilson 68 7. Could that contribute to the oscillation?
Hi Russel, thanks for the feedback. Any advice or pointers will be much appreciated! Is your automotive environment 12V or 24V? The vishay datasheet shows change of ESR with frequency. I was reading it on my break and was in a hurry. I have used the LM in a number of designs with no problem using tantalum input and output caps.
Do you also have the input capacitor 0. Your oscillations are at 18 Mhz where the ESR is hopefully very low. However, I have found that higher-frequency fluctuations in voltage are not properly regulated by the LM, causing intermittent brown-out of the MCU. Whether the or Hz ESR is relevant is tbd BUT as you have a 2 x mains input ripple that the regulator is dealing with this may be the instability trigger.
JohnLincoln God Member Posts: I believe that I have conformed to the guidelines in the datasheet. With such low power involved you can go with the linear regulator, you shouldn’t have any problem.
I live in Lincoln. Russell McMahon k 9 This capacitor must be rated over the same operating temperature range as the regulator and.
Have you taken their compulsory advice re the output capacitor? If you look at page 18 in its datasheet the ESR for the uF, 6. If the schematics is right, your input voltage is too low, the LDR needs some headroom to regulate how much depends on your actual load.
Sorry, that was my mistake. Schematic of the regulation circuit. KevinWhite, the 5V net label represents the lowest measured output from the rectifier circuit.
Or offer an alternative regulator that is more linear at high frequency As suggested in this answer? Because they don’t list ESR on data sheets dahasheet at least the ones I’m looking at. The suggested solution in that dataheet, figure 7 vs. Sign up using Facebook. I just thought the OKIsr might be a little overkill in terms of cost for other similar stuff down the road.
Tying down what manufacturers really mean can be a challenge. Does anyone have any ideas how I might stabilize this output? Alas the data on minimum ESR is rather sketchy nothing for “C” case for exampleso you have to guesstimate from just these two graphs or datasyeet an ESR meter and measure it, or even just with your scope and a function gen that can hit those MHz frequencies where you see oscillation.
Post as a guest Name. The datasheet specifies the drop-out dztasheet as 0. For reference, this is the LM datasheet. I read the data sheet for the LM and understand I need two capacitors one on the input and one on the output.