TIOL1123: output abnormal when in Hi-Z status

user6514048

Prodigy 20 points

Part Number: TIOL1123
Other Parts Discussed in Thread: TIOL1113

Tool/software:

Hi，

We use TIOL1123 as output, output mode is NPN,

circuit is shown as below:

When EN is high, CQ is normal, 0V. When EN is low, CQ is about 4V at the beginning and then turn into 0V after about 40ms.

Purple is EN, Yellow is CQ.

SO why output is abnormal when TIOL1123 become Hi-Z status?

11 months ago

0 Jonathan Nerger 11 months ago

TI__Mastermind 32970 points

Can you please share the status of the TX pin during this as well?

Is there any load on CQ besides the SMBJ33CA diode and a scope probe?

Regards,

Jonathan

0 user6514048 11 months ago in reply to Jonathan Nerger

Prodigy 20 points

TX pin is fixed as high. And no other load. If I add a 100K resistor as load, CQ is about 2V at the beginning and still turn into 0V after about 40ms.

+1 Jonathan Nerger 11 months ago in reply to user6514048

TI__Mastermind 32970 points

The TIOL112x devices contain internal circuitry that enables fast and safe demagnetization when configured as either P-Switch or N-Switch mode and an inductive load is connected to CQ. Because the device has no way to know what type of load is connected and whether it is inductive, the device uses the state of the TX and EN pins to determine what clamp may be needed if an inductive load is connected and engages this clamp circuit for approximately 40ms if an inductive load is present.

The transition of EN from High to Low starts engages this clamping circuit and the internal clamping voltage of approximately 4V is what you are seeing. These circuits are mentioned in the Driving Inductive Loads section of the datasheet.

Regards,

Jonathan

0 user6514048 11 months ago in reply to Jonathan Nerger

Prodigy 20 points

Got it. Thanks for your reply。

0 user6514048 11 months ago in reply to Jonathan Nerger

Prodigy 20 points

L+ voltage is 24V, you can see from below picture:

CH1 is CQ, CH2 is L+, CH3 is EN, CH4 is TX, noload.

You can see L+ is fiexed as 24V, TX is fixed as 3.3V

And for PNP mode, you can see as below

CQ still have a 40ms long voltage.

But you said you can't replicate the waveforms, so what's my problem?

0 Jonathan Nerger 11 months ago in reply to user6514048

TI__Mastermind 32970 points

If you notice, that post was deleted from this thread and I had mistakenly misread the part number as TIOL1113 which does not have the same inductive demagnetization clamp circuit as the TIOL1123. After I posted this, I realized you were referring to the TIOL1123, so I deleted that post and posted a new post which explains the waveforms you are seeing.

Regards,

Jonathan

0 user6514048 11 months ago in reply to Jonathan Nerger

Prodigy 20 points

Thanks a lot! It seams that TIOL1113 is more suitable for our product.

0 Jonathan Nerger 11 months ago in reply to user6514048

TI__Mastermind 32970 points

I don't know the details or requirements for your product, but if you have any additional questions you are welcome to ask.

Regards,

Jonathan

Interface

Interface forum

TIOL1123: output abnormal when in Hi-Z status