How to use SDA signal as interrupt signal?

I got a chip called "HY3118".
It's a 23-bit adc .
This chip supports two model:
one of these two model ask me use SDA as interrupt signal
But i am not sure how to do this kind of interrupt.
Is there any master programmer can share your ideal?
I think data that got from interrupt is much more correct than counting timing.

Can you post a link to a datasheet?

http://ppt.cc/rzBL

It's the link of datasheet.
Thanks a lot for your kindness.

If you wanna use this interrupt scheme you have to implement I2C in software because the SDA line is pulled down by the chip while no clock edge is received. This mode is not usable if the I2C bus is used for more than one device (as a bus) and it's not complying to the I2C standard. You could implement this in software if you connect the SDA line to one of the external interrupt pins (2 or 3 on the UNO) and activate the interrupt routine while waiting for the finished AD conversion.

Datasheet
http://www.hycontek.com/attachments/DataConverters/DS-HY3118_EN.pdf
See Figure 4 on Page 9.

Read Section 8 on page 22. You can use standard I2C master/slave communications. Send a command to start the conversion, send a command to read a register, keep reading that register until the status changes to 'conversion done'.
Or use millis() to keep track of how long the conversion has gone on, when the conversion time has elapsed read the result.

Thanks for both two kind programmers:
To pylon:
Your idea is just what i want,i will try if i can get interrupt signal from SDA by your idea.

To CrossRoads:
I have already finish getting data by using time interval.
But I want to use interrupt do the same work.
Thanks for your help. I will try pylon's idea. I will report to both of you later.

Best Regards