I have an ICs which has an operating voltage range from 3.35V up to 4.5V. It typically needs a 20-milliamps current but it can have 1.9-amps current peak. Moreover, my system will work with a battery and I therefore must keep the input voltage as little as possible. I do not know well the field of voltage regulators; I thought of using a classical linear voltage regulator or an LDO, but none of them seems to fit my need. Which kind of voltage regulator would you suggest for the above-mentioned design?


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    \$\begingroup\$ massive capacitors can supply the current. How long is "peak" current for? This helps you determine how much capacitance you need. \$\endgroup\$ – KyranF Oct 28 '14 at 11:02
  • \$\begingroup\$ It is a GSM modules. I am talking about "peak of current consumption through the VCC pads during a GSM 1-slot transmit burst" which shoud be used "to dimension maximum current capability of power supply" (quoted from the page 22 of DS). \$\endgroup\$ – user1553136 Oct 28 '14 at 11:19
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    \$\begingroup\$ it's very common for GSM modules, for example the Arduino GSM modem shield, to have a large tantalum or similar capacitor to handle the pulsed current \$\endgroup\$ – KyranF Oct 28 '14 at 11:25
  • \$\begingroup\$ Yes. But wouldn't it be safer to have a voltage regulator furnishing the right current ? \$\endgroup\$ – user1553136 Oct 28 '14 at 11:33
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    \$\begingroup\$ Well, the Arduino guys think that 100uF in a huge-ass surface mount capacitor is good enough, so you can try the same. If you wanted to work it out, i'd simulate a simple switched 1.9A load for the durations given and play with capacitor values until you find a match for good enough performance (not too much voltage drop, you dont want to drop more than 200-300mV on the power rail during the pulse \$\endgroup\$ – KyranF Oct 28 '14 at 12:04

You don't say exactly which GSM module you're using, but I used an idea (similar to that described by KyranF in the comments to your question) a few years ago with a GSM module when I had to deal with a very similar situation.

Similar to you I had to allow the module to draw bursts of current in the 1.5A to 2A range for short infrequent periods.

My module also had a fairly wide supply voltage range because it has its own internal voltage regulators, so I could tolerate a larger voltage droop over the course of the current pulse than would normally be acceptable - providing the voltage started off near the top of the module's acceptable range at the beginning of the pulse.

I experimented a bit with component values, and in the end settled on 3x470uF electrolytics in parallel and a 2.2ohm series resistor from my 5V 500mA supply.


simulate this circuit – Schematic created using CircuitLab

Of course in your case you'll have to use a 4.5V supply since that's the maximum your module is rated for.

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