LDO application question

Kuo John

Other Parts Discussed in Thread: TPS7A7200, TPS7A85, TPS7A85A

Hi Team,

I have LDO application question.

ANPEC device APL5950can support 5A (@0.15V drop voltage) and internal current limit up to 8A. package is SOIC(8) with power pad.
I calculate ANPEC maximum power dissipation up to 3W.( juction temp150 degree / 50 degree per watt).
if output current 2A @1.5V drop voltage.

APL5950%2fA.pdf

Looks TI device. I not found same device compare APL5950, why?
I just can survey TPS7A7200??

over 8 years ago

0 Kyle Van Renterghem over 8 years ago

TI__Genius 14245 points

Hi Kuo,

We have a number of 5A devices and you can use the parametric search to find such devices:

http://www.ti.com/lsds/ti/power-management/single-channel-ldo-products.page#p451max=5;12

If you only need 2A-3A then you can change the search parameters to show those devices:

http://www.ti.com/lsds/ti/power-management/single-channel-ldo-products.page#p451max=2;3

-Kyle

0 Kuo John over 8 years ago in reply to Kyle Van Renterghem

Expert 1075 points

Hi Sir,

You not answer my question, please help.
I already survey TI device by web.

Thanks!
John

0 Kyle Van Renterghem over 8 years ago in reply to Kuo John

TI__Genius 14245 points

Hi John,

Unfortunately I misinterpreted what your question was, I thought you were looking for help finding a 5A LDO. If you are looking for something more specific then we will need more information (such as key spec/functionality) to find a part that better suites your application. However, the parametric search contains all of TI's LDOs so if it is not there then we do not have it at this time.

-Kyle

0 JCHK over 8 years ago in reply to Kuo John

TI__Guru 50090 points

HI John,

Maybe I can try to answer your question. The TPS7A7200 does have a nice low drop-out but this is rated at 2A. At 2A, the dropout when VOUT is <= 3.3V is only 180mV. For the same pass element, if the current limit allowed 4A, the drop-out voltage would be ~double this value. Our Flagship higher current LDO is the TPS7A85 which has a drop-out of only 240mV at 1.1VOUT.

Another thing to consider in high current devices is the thermal performance. The TPS7A85 has a TJA of 35.5 C/W vs. the APL5950's TJA of 50/60 C/W depending on package.

Does this answer your question?

0 Kuo John over 8 years ago in reply to JCHK

Expert 1075 points

Hi all,

Thanks for your help.
last question. May I know general LDO design input 3.3VDC and output 3.15VDC/5A for what application? or just special function?
looks ANPEC current limit 7A can shut down and thermal also can shun down(I guess when over loading)

Regards,
John

0 JCHK over 8 years ago in reply to Kuo John

TI__Guru 50090 points

HI John,

I am not aware of any applications that require 3.15VOUT. However, using any LDO in drop-out, there is no effective PSRR. While in Drop-out the pass element is fully enhanced so there is no real attenuation of any ripple on VIN.

The most common application I have seen for high current LDO's is for DSP or FPGA VCORE power. These devices typically require precision regulation (i.e. <1% accuracy), and a fast load transient response. If you compare the Anpec device to the TPS7A85A, both have an N-Channel pass element so they both should have a fast load transient response. While slightly lower current. the TPS7A85A has Any-Out(TM) technology which allows you to set VOUT without external Feed-back resistors. This gives a real 0.75% accuracy over line/load/temp whereas the Anpec device's 1% accuracy does not include the tolerance of the external resistors required to set VOUT.

Most high current LDO's that I have seen have current limit and thermal shutdown. Note: these protection solutions are present to protect the device so it can survive either a short or an application where the LDO is dissipating too much power

I Hope this answers your question.

Regards,

0 Kuo John over 8 years ago in reply to JCHK

Expert 1075 points

Hi Sir,

Thank you!!

Regards,
John

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