TPS7A4201: TPS7A4201 Dropout request

Frank Cai

Intellectual 1455 points

Part Number: TPS7A4201

Tool/software:

Hi Team,

Could you help to check if TPS7A4201 can fulfill the following requirement?

Vin=16V-20V, Vout>15.4V, Iout=35mA
Vout_drop<300mV under T=80°C

If not, could you help to suggest another part which can fulfill the above conditions? Thanks.

BR.

Frank

6 months ago

0 McKyla Beuttler 6 months ago

TI__Expert 6799 points

Hey Frank,

Thanks for your questions. Can you help clarify the need for the dropout voltage? this device can handle the operating conditions above of 16V to 15.4V.

Thanks,

McKyla

0 Frank Cai 6 months ago in reply to McKyla Beuttler

TI__Intellectual 1455 points

Hi McKyla,

Can you help to check if this is a typo on the datasheet? Vin(17V) is greater than Vout(18V). Thanks.

BR.

Frank

0 McKyla Beuttler 6 months ago in reply to Frank Cai

TI__Expert 6799 points

Hey Frank,

This is specification is not a mistake here. This was taken in dropout to get an accurate dropout voltage.

Thanks,

McKyla

0 Frank Cai 6 months ago in reply to McKyla Beuttler

TI__Intellectual 1455 points

Hi McKyla,

Could you help to explain the test principle of Vin<Vout on measuring dropout? Or can you share some documents to help understanding? Thanks.

BR.

Frank

0 McKyla Beuttler 6 months ago in reply to Frank Cai

TI__Expert 6799 points

Hey Frank,

Yes, of course, my apologies for not further explaining. For low dropout regulators (LDO) in order to take this measurement, the LDO will need to be in dropout to conduct this testing. LDOs will regulate voltage and must have some drop in voltage to be regulating, however in order to figure out what that minimum voltage our engineers will need to have the device in dropout meaning Vin<Vout to take this measurement. Here is a good video to explain dropout of an LDO a little more https://www.youtube.com/watch?v=iw4z07oJGq0.

Thank you,

McKyla

0 Frank Cai 6 months ago in reply to McKyla Beuttler

TI__Intellectual 1455 points

Hi McKyla,

I checked the video about measuring the VDO and it shows as following. If Vin=17V, Vout=18V are the condition to measure VDO, that should be totally different from the video. Can you double check it is not a typo?

BR.

Frank

0 Frank Cai 6 months ago in reply to McKyla Beuttler

TI__Intellectual 1455 points

Hi McKyla,

Adding one more question, if the operating condition is Vin=15.6V, the OCP will be 128mA, right? If so, at the load current 50mA<Iload<128mA, is there any potential risk for the device?

BR.

Frank

0 McKyla Beuttler 6 months ago in reply to Frank Cai

TI__Expert 6799 points

Hey Frank,

Can you please clarify this question? What OCP are you referring to? The screenshot that you have taken shows what the current limit of the device is set to. Since this is a 50mA device currently limit will start typically at 128mA.

Hopefully this helps explain a bit.

Thanks,

McKyla

0 McKyla Beuttler 6 months ago in reply to Frank Cai

TI__Expert 6799 points

Hey Frank,

This is not a typo, this is how this test is taken. The video explains what dropout voltage is, not how to test dropout. This is how dropout is measured. Please let me know if you would like to set up a call for further explanation.

Thanks,

McKyla

0 Frank Cai 5 months ago in reply to McKyla Beuttler

TI__Intellectual 1455 points

Hi McKyla,

One more question regarding the the current limit and output current.

1. If the load is sudden pull current >50mA, does the device shutdown or clamps on 50mA? Do you have a waveform which can indicate the behavior of Iout>50mA?

2. Does current limit threshold can be set? I saw for different input voltage the current limit is also different. If it cannot set, what is the current limit for Vin=18V?

Thanks.

BR.

Frank

0 McKyla Beuttler 5 months ago in reply to Frank Cai

TI__Expert 6799 points

Hey Frank,

Thank you for your question! Figure 10. shows the current limit behavior and the input voltage at 18V. The does not clamp at 50mA, but it does have an internal current limit threshold that is shows in the datasheet specs above "current limit" that you have screenshotted above. The below this is showing the typical current limit characteristics below.

Hopefully this helps!

McKyla

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TPS7A4201: TPS7A4201 Dropout request