[Moved]: Looking for cheaper LDO

[pkaras]

Manufacturer recommends using the following LDO to power its module - LT1764AEQ. But this part is rather expensive. I am looking for a cheaper alternative. The main requirements are:
- Low dropout (5V_in, 4.2V_out)
- 1A max avg load, 2.5A bursts (hence fast response to load transients is required)
- Low output voltage ripple
- Little output voltage under/over shoots
- No soft start (full switch on in less than 1 ms)
- Protection against reverse current
- Reverse polarity protection would be an advantage
- SMD, low θ_J-A

I have picked MIC39302 (θ_J-A figure is not provided) and LP38501-ADJ (no reverse polarity protection). Can you please advice me if my choice is right?

 

[BradtheRad]

Re: Looking for cheaper LDO

This simple transistor regulator can deliver most of your specs.



Values need to be carefully adjusted to provide desired performance.

Reverse current is prevented by adding a diode and zener. Or as an alternate, string together the right combination of diodes or led's.

 

[malli_1729]

Re: Looking for cheaper LDO

generally selecting power solutions for GSM/GPS applications will have same requirements.
Very good Transient response with little Under and Over voltage overshoots.

Check these links..

http://www.maximintegrated.com/en/app-notes/index.mvp/id/898
**broken link removed**

Micrel good app note and gives possible solutions.

I am not sure about your target price...You can get Cheaper DC-DC (Buck) converters also based on your price range. Search them also.... I doubt Simple transistor regulator may not give good transient response with less Undershoot /overshoot....
check