TL16C752C: No interrupt occur even if the CDA#, CDB# pin state changed?

Hello,

We have been adopt many TI's UART in our products.
We want to confirm about interrupt by Data Carrier Detect (DCD, CD) pin in these UART.

The PC16552D datasheet(lower left of page 11) has the following description regarding the behavior of the DCD pin.

- Note: Whenever the DCD bit of the MODEM Status Register changes state, an interrupt is generated if the MODEM Status Interrupt is enabled.

From this note, we assume that interrupt occurs every DCD signal change time ,when MODEM Status Interrupt is enabled.


And TL16C752C datasheet(RIA#, RIB# pin description on page 4) has the following description.

- A low-to-high transition on these input pins generates a modem status interrupt, if enabled.


Hoever, TL16C752C datasheet did not have a similar description for CDA#, CDB# pins.
For these reasons, an interrupt occurs when the state of the RIA#, RIB# pin changes.
But we assume that no interrupt occurs even if the CDA#, CDB# pin state changes.
We confirmed with our product that adopted TL16C752, but no interrupt occurred even if the CDA#, CDB# pin state changed.

We have some questions about TL16C752C.

Q1. No interrupt occur even if the CDA#, CDB# pin state changed?
    Could you confirm our understanding is correct?

Q2. If your answer of Q1 is "No", would you tell us how should we do?
    (Shoud we set some additional setting to TL16C752C?)

Q3. If your answer of Q1 is "Yes", do you know the device that can generate an interrupt by changing pin state of CDA#, CDB# by pin compatible with TL16C752C?


Thank you for your time and consideration.

Best Regards,
Toshiyuki Maekawa, Advanet Inc.