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# I desperately need help with how to look at the specifications of the IC chip.

Associate II

Hello.
I want to control multiple solenoids using multiple FET switches and isolate all these solenoids from the circuit in case of trouble using large FET switches.

But I got into trouble looking at the specs. I don't know how long the IC can withstand the current.
For example, if you look at the data sheet of VN9004AJTR, the current limitation (type.) is 108A, and the Iout says Internally limited.
The Ron also says On-state resistance / Iout = 15 A, TJ = 25°C / 4.2 mΩ.
I use a battery voltage of 12-14V. Which number is correct?
108?15?
Is 108A the limit current value that the IC can withstand in the event of a short circuit problem, and is 15A the maximum current value that can be output under normal conditions?

Or is the Reverse DC output current value a value that can withstand? I have a load that flows about 8-9A when all the loads are activated.

5 REPLIES 5
Chief II

Hi,

>Is 108A the limit current value that the IC can withstand in the event of a short circuit problem

This (90..108A) is the current, that it limits to , in case of overload/short.

15A is a typical use case, as some info for the datasheet.

So it can be used up to about 20A , depends mostly on the inductance of the load.

At lower inductance even more current possible.

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ST Employee

The 108A mentioned is the typical value of the current at which the current limitation becomes active at the latest. At the latest because there are other protective functions (e.g. overtemperature shutdown) that may become active beforehand.

The current of 15A mentioned in the tables is only a test condition under which the respective parameter was measured.

Of course, high currents result in corresponding power loss, but you can still load the high-side driver up to the current limit, provided you take sufficient cooling measures.

Regards
/Peter

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Associate II

Hello.
I'm glad to see you again. Thank you for your reply.
If so, is it indicated on the data sheet about how much is available at normal temperatures??
Do you have them in numbers or graphs?
Even if I go to the data sheet of VNQ7E100AJTR, the numbers are not written like the answer above.

ST Employee

Your posted excerpt seems to be from an old data sheet, in the current revision the figure has the number 39. Irrespective of this, this picture shows the turn-off current via a connected inductor, which does not have much to do with your question.

There are no diagrams in the data sheet for the maximum current, as it depends on several parameters. To avoid overloading, the current is therefore limited internally - with less cooling, you inevitably have more heating and therefore tend to have an earlier limit.

However, there are practical limits for the current: the CS pin supplies a maximum of 2mA, which corresponds to an output current of 38.1A with the typical factor of 19050. You can therefore no longer measure larger currents with the current sense.

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Associate II

Hello, thank you for your response.
You mean it has nothing to do with the picture above.
How do I know that I can use up to about 38A based on VN9004AJ? Do I need to calculate it? Or can I find it as a picture?
I need to compare this model as well as other models to determine the appropriate level of IC.
I can also use 7 1.2A loads as 7 ICs or 2 or 4 channel ICs each and I need about 9A of 1 channel ICs to cover this in its entirety.
But I haven't found the value, so it's not too overflowing and I'm not finding the right IC. Of course, proper cooling is necessary, but I can't add a separate cooling system. I'm not sure if I'll need a cooling system because the load runs for a short moment, not for a long time.

I'd really appreciate it if you could help me again this time. PETER.

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This is what I looked for additionally when I got home.
For example, if it is VN7008AJ, the current limitation is 96A. But ILIMH and ILIML are about 98A and 33A at about 13V, which is the test condition. Is it related to this? Of course, I don't use all of this. As I said before, I use 10A or less for the entire circuit momentarily. I want to know how to find the right model for the current value.
And if we go back to the data sheet of VN9004AJ, it's current limitation 108A. And ILIMH says about 16V to 120A under test conditions. Also, VN9004AJ has no ILIML value.
This different data sheet for each product makes it even more difficult for me..
It doesn't matter if it doesn't match exactly, so I'd be very grateful if you could tell me how to find a figure that can withstand the right current value and select a model.

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I was able to find the 19050 and 2mA that PETET said in that part. Is that right?
By the way, the test was based on 5V, but can I get the same result even though it's based on 12V? I just multiplied the two and got 38.1.. I honestly don't know what it is. I'm sorry.