LM5060-Q1: Minimizing the thermal effects in the output current set-point.

Nivaldo Bissoli

Part Number: LM5060-Q1
Other Parts Discussed in Thread: LM5060, INA301

Hi,

I'm analysing the potential use of the LM5060-Q1 in a truck application.

A 24V power converter output shall be disconnected from the load when its output reaches 20A continuously.

The customer's specs allows an overcurrent up to 22A during 100ms maximum, but classify the 20A set-point as Significant Characteristic (SC).

Unfortunely the LM5060-Q1 Pspice Model does take in account the thermal effects.

Considering that the ambient temperature will affect the MOSFET Rds and the LM5060-Q1 internal parameters (ISENSE, IOUT-EN etc),

could be possible to minimize the effect of these changes sum-up in the 20A set-point using resistors and thermistors associations

for RSENSE and ROUT for the automotive temperature range (-40ºC to +85ºC) and determine the current set-point's tolerances?

Please, could you give me a circuit and calculations as an example?

Thank you in advance for your support.

over 5 years ago

0 Rakesh over 5 years ago

TI__Guru** 105361 points

Hi NB,

Welcome to E2E.

Can you let me know how overcurrent accuracy helps in your system and do you have any target accuracy value ?

Best Regards,

Rakesh

0 Nivaldo Bissoli over 5 years ago in reply to Rakesh

Prodigy 40 points

Hi, Rakesh

Thank you for your fast response.

We can start with initial accuracy of + - 5% for the current setpoint and see later if it possible to reduce it.

Best regards,

0 Rakesh over 5 years ago in reply to Nivaldo Bissoli

TI__Guru** 105361 points

Hi NB,

Can you let me know why accuracy is important and how it helps to your system ?

BR, Rakesh

0 Rakesh over 5 years ago in reply to Rakesh

TI__Guru** 105361 points

Hi NB,

Any updates ?

BR, Rakesh

0 Nivaldo Bissoli over 5 years ago in reply to Rakesh

Prodigy 40 points

Hi, Rakesh,

Sorry the delay to replay, but I'm very busy on the last days.

The customer request of a SC - Significant Characteristic implies that it must be controlled on the production line and assured during the product life time.

Using the LM5060 Hot Swap Design Tool for my application and defining the overcurrent threshold in 20A, the spreadsheet gives me the nominal and maximum values as 36.6A and 64.5A

That is unfeasible for my application, so I need to reduce these tolerances to 5%.

Best regards.

0 Rakesh over 5 years ago in reply to Nivaldo Bissoli

TI__Guru** 105361 points

Hi NB,

I recommend to use external current shunt resistor with INA device (similar to INA301) to accurately detect the over current event. Most of the hot-swap devices offer accuracy in the range of +/-10%. Coming to LM5060-Q1, it should be treated as high-side over voltage protection device. Meeting 5% accuracy is not possible with LM5060-Q1.

So, Use LM5060-Q1 in series with external current shunt resistor + INA device

BR, Rakesh

0 Nivaldo Bissoli over 5 years ago in reply to Rakesh

Prodigy 40 points

Hi, Rakesh

Thank you for your recommendations.

I'm going to simulate the circuit and evaluate the solution.

Thank you for your support.

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LM5060-Q1: Minimizing the thermal effects in the output current set-point.