LM5116: Over temperature protection about.

Onur Keskin

Part Number: LM5116
Other Parts Discussed in Thread: LM5122

Hi,

I am using the LM5116 for buck converter. I need to protect the circuit from temperature. The IC has protection but it doesn't matter to my application.

* I will use NTC. Using the NPN transistor with serial diode, i will keep the UVLO between 0.4-1.2V. The system will then enter standby mode. I'm thinking of working with VCC on IC. My question is; Can I use this circuit smoothly with VCC?

Do you have any other suggestions for this (with NTC)?

* I'm thinking of using this protection circuit for LM5122(for boost). There is an overvoltage protection circuit for the LM5122. I want to apply both. (OTP and OVP)

Is it correct to manipulate UVLO.

over 6 years ago

0 Marshall_Beck over 6 years ago

TI__Mastermind 35210 points

Hi,

do you have concerns with the accuracy of the thermal shutdown of the device?

Are you requiring that the LDO/VCC of the device to provide the current for the external circuitry?

The minimum current that the LM5116 can source from the LDO is 15mA.

0 Onur Keskin over 6 years ago in reply to Marshall_Beck

Intellectual 390 points

Hi Marshall,

I don't expect high accuracy from NTC. NTC will be located close to the FETs.

I cannot use external LDO with input or output voltage. The most reliable method seems to be use vcc.

I'm adding the schematic I intend to use for your review.

0 Marshall_Beck over 6 years ago in reply to Onur Keskin

TI__Mastermind 35210 points

Going back to your original question:

"Is it correct to manipulate UVLO."

The UVLO pin is an input and can be controlled as described in section 5 of the LM5116 datasheet.

Often we don't recommend to power external circuitry from device LDO.

You will need to ensure that the current limit of the LDO is not violated (15mA) by validating your circuit performance.

0 Onur Keskin over 6 years ago in reply to Marshall_Beck

Intellectual 390 points

I think my circuit has very low current consumption.

I will use standby mode for ovp and otp. Finally, Is it right to wait long in standby mode?

0 Marshall_Beck over 6 years ago in reply to Onur Keskin

TI__Mastermind 35210 points

I dont see any timing requirement for how long you can be in standby mode. You can pop in or out of it with some (startup) delay associated to internal logic to when the device starts switching again.

Power management

Power management forum

LM5116: Over temperature protection about.