DC-DC Buck converter ICs, with internal MOSFET and freewheeling diode ?

Jeferson Pehls

Other Parts Discussed in Thread: LMZ14201, TPS54060, TPS54061, LM2674, LMR14203, LMR14206

Hi.
I am looking for a buck converter IC available in a small SMD package like SOT-23 (or other small one) to a power supply with these parameters:

Vin = 16 to 30VDC
Vout = 4.4VDC
Iout = 250mA

The maximum output peak current is also 250mA. The 4,4V rail will be used to supply voltage to a constant current supply (to a Li-Ion battery charge management IC). If possible, a higher output current capability would be better, but 250mA is enough for me.

It would be much better a buck converter IC who meet the parameters above and doesn't require the use an external MOSFET and also not require an external freewheeling diode. I didn't found.

I'm using TPS63000 from Texas Instruments in some designs. It is a buck-boost converter that doesn't need an external MOSFET nor an external freewheeling diode when operates in buck mode. 

I have many 1A SMD inductors with values from 4.7uH to 68uH. I just need to define which IC to be used. If don't find an IC who meet the parameters above, I will need to use a LM2596-ADJ buck converter from National Semiconductors to do the buck conversion, but it requires much more PCB space than the IC I am looking for.

Somebody know some good ICs to meet the parameters above? 
Preferentially, ICs that doesn't require external MOSFET, freewheeling diode and is availabe in a small SMD package like SOT-23.

Or some other suggestions of ICs with bigger size package that doesn't require external MOSFET nor a freewheeling diode ????

over 12 years ago

0 CWilson over 12 years ago

Expert 1920 points

The LMZ14201 (all included) or TPS54060 (external diode and inductor) could do the trick.

0 JohnTucker over 12 years ago in reply to CWilson

TI__Guru**** 191445 points

TPS54061 will release soon. That device will have integrated low side FET, but rated current is 200 mA. It may possibly be able to output more at reduced temperature range. What is your need time frame?

0 Jeferson Pehls over 12 years ago in reply to JohnTucker

Expert 1140 points

Hi.

We will start production in about 3~5 months. But this IC should be not so expensive and I need to be able to find it easier on Digikey (high quantity should be available),

I always bought from Digikey.

0 JohnTucker over 12 years ago in reply to Jeferson Pehls

TI__Guru**** 191445 points

That part will be available on Digikey when it releases. Digikey prices are kind of high. What are your volumes?

0 Jeferson Pehls over 12 years ago in reply to JohnTucker

Expert 1140 points

We will need around 2000 pcs, for initial tests.

And after the product is OK and tested, we could buy directly from TI / National distribuitors here in Brazil, in high quantity and lower costs.

0 CWilson over 12 years ago in reply to Jeferson Pehls

Expert 1920 points

Why not use the LM2674? It handles up to 37V input.

Inductor and diode is external but total bill of materials (BOM) is below 1.99 USD.

0 Jeferson Pehls over 12 years ago in reply to CWilson

Expert 1140 points

I will study these ICs, please give me more alternative part numbers, if possible.
Thanks.

0 Ismail Jorio over 12 years ago in reply to Jeferson Pehls

TI__Intellectual 895 points

Hi Jeferson,

First I would recommend using Webench tool. It is a tool by National Semiconductor/TI that provides part numbers when you enter your parameters (Vin range, Vout, Iout, Switching freq). it is important to specify swithcing frequency when you choose a regulator !!!

If you choose not to, you can use :

LMR14210 which is uSMD regulator (no external diode or Mosfets) capable of 1A output and up to 42V input, up to 1MHz switching .

LMZ14201 is a module capable of 1A output with no external components (just input and output caps), up to 42V input, up to 1MHz switching frequency.

Regards,

Ismail

0 Stephen Ott over 12 years ago in reply to Jeferson Pehls

TI__Prodigy 165 points

Hi Jeferson,

The LMR14203X is another good IC to consider. It is from our "nano regulator" portfolio so it is really small. It is available now on DigiKey.

It is in a thin SOT23-6 package (2.97 x 1.65 x 1 mm) and requires only 7 external components. It does require an external freewheeling diode but it is very small. Plus, is is really easy to design with since the control loop compensation components are internal and you can use webench.

Check out the demo board it uses a 15uH inductor: http://www.ti.com/lit/an/snva502a/snva502a.pdf

I created a custom design for you using our webench tool with your input parameters.

Input parameters:

Vin = 16 to 30VDC
Vout = 4.4VDC
Iout = 250mA

5047.LMR14203X webench design.pdf

If you need to move up to higher output current you could easily do that with the LMR14206. It has a maximum output capability of 600mA and is pin-to-pin compatible with the LMR14203.

Hope this helps.

Regards,

Stephen Ott

Power management

Power management forum

DC-DC Buck converter ICs, with internal MOSFET and freewheeling diode ?