TPS61178: Ilimit operate

Mark Huang3

Part Number: TPS61178

design spec,

Vin 9V

Vout 12V

Iout 3.2A

I set Ilimit pin as 5A

when i load near 5A, the output voltage be down near 9V, and over 5A, the out is not shutdown, keep current and voltage

I set loader 30A, IC be damage, it look no protect!!!

i would know how the ilimit operate?

0 Jasper Li over 5 years ago

Hi Mark,

did you use the external PMOS to achieve short circuit protection in the schematic?

if not, the device can't support short circuit protection.

refer to the wiki for the basic principle of a boost converter https://en.wikipedia.org/wiki/Boost_converter. there is always path between VIN and VOUT without using the PMOS.

if you had use the PMOS, please share your schematic and layout.

0 Mark Huang3 over 5 years ago in reply to Jasper Li

Hi Jasper,

I use the demo board TPS61178 Evaluation Board to test, so exactly with P-MOS

I only change the FB resistor to set Voutput 12V and ILimit around 5A(by datasheet formula).

0 Jasper Li over 5 years ago in reply to Mark Huang3

Hi Mark,

this application note detail the short circuit protection http://www.ti.com/lit/an/slva889/slva889.pdf

how did you apply the 30A load to the EVM? Is it a Chroma e-load? I want to duplicate the issue in our lab.

0 Mark Huang3 over 5 years ago in reply to Jasper Li

Hi Jasper,

I think I get something wrong, my power supply only 12A, so if I load 30A by e-load, the power supply will do OCP, and may hurt the TPS611781.

I change new IC and retest, It is not happened again.

0 Jasper Li over 5 years ago in reply to Mark Huang3

Hi Mark,

thanks for the update. I would close the post.

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