TPS62175: TPS62175 Power up issue with 250mA Load.

Kunal barot

Part Number: TPS62175

Hi I am using TPS62175 buck Regulator.

My input is 15V and Output is 3.3V , Sch is same as shown on page 1 of datasheet (http://www.ti.com/lit/ds/symlink/tps62175.pdf

Inductor is 10uH with 1A rating.

Test 1 :- Output Short ,

Method:- 50mA load was connected, Turn on the unit , 3.3V buit here then i shorted the output for 30-40Sec and remove the short , after removal of short condition 3.3V recover.

Test 2:- Power Up ( Issue observed)

Method:- 250mA load was connected, turn on the unit, but 3.3V never built up. tried multiple times. Then i reduced the load to 200mA then power up this time 3.3V built up and i can changed the load to 500mA , no problem. Question is why with 250mA load output 3.3V never build up during power on.

DC electronic load used for Testing.

over 5 years ago

0 Kunal barot over 5 years ago

Intellectual 605 points

Correction:- Sch is same as shown on page 1 of datasheet (www.ti.com/.../tps62175.pdf ) , excpet feedback resistor 324K and 100K used and sleep pin is connected to VOS pin.

0 Chris Glaser over 5 years ago in reply to Kunal barot

TI__Guru*** 142860 points

Hi Kunal,

You are likely reaching the reduced current limit at startup, explained in section 8.4.1 of the D/S and shown in Figure 41. As well, your electronic load is probably drawing more than 250 mA. Electronic loads generally do a poor job at holding the proper current during startup situations.

0 Kunal barot over 5 years ago in reply to Chris Glaser

Intellectual 605 points

Hi Chris

figure 41 in datasheet , i think with 500 mA load start up (3.3V out and 6.6ohm load) , but in my case i set the load only 250mA only. and i hook current probe and observe start up current is less than 300mA. Slev rate i set on DC load is 25000A/sec.

also try to simulate this using web bench , but web bench have some problem to show this IC. see attached.

0 Chris Glaser over 5 years ago in reply to Kunal barot

TI__Guru*** 142860 points

Hi Kunal,

The D/S figure is just an example. Can you post your waveform?

I've let Webench know about your issue with the schematic above. What browser are you working in?

0 Kunal barot over 5 years ago in reply to Chris Glaser

Intellectual 605 points

google chrome

0 Kunal barot over 5 years ago in reply to Chris Glaser

Intellectual 605 points

HI Chris

I checked with 250mA load with Resistor load of 13.2 ohms, that time 3.3V build perfect , even i tried with 300mA start up, no problem with resistor load.

only problem comes with DC load,

Thanks

0 Chris Glaser over 5 years ago in reply to Kunal barot

TI__Guru*** 142860 points

Hi Kunal,

Can you post some waveforms of a good and bad startup? Did you already read through section 8.4.1 in the D/S?

0 Kiran Kumar10 over 5 years ago in reply to Chris Glaser

TI__Intellectual 1625 points

Hi Kunal,

The issue of IC not being present on production is resolved. You will be able to see the latest changes on ti.com in our next release.

Thanks,
Kiran Kumar

Power management

Power management forum

TPS62175: TPS62175 Power up issue with 250mA Load.