TL16C752D-Q1: TL16C752D-Q1 Failing to read the Data from Microcontroller @ high temperature +85 (During -ve Ramp towards +85 C to Ambient) as per DO-160G, Section 5 (Temp. Variation)

Hey Elangovan,

Just to clarify when you are saying the device does not receive data from the microcontroller, are you saying the microcontroller cannot send data because there is an interrupt flagged? Or are you saying there are no interrupts/errors but when you send data into the FIFO of the device, it does not store the byte you send?

When this error occurs, are you able to check IIR[5:0]? What does it read?

Also what voltages do you see on the CTS/RTS pins?

Are you able to monitor Vcc and see any changes when the device works until the device stops working?

Thanks,

-Bobby

Bobby,

Thank you for the Quick Response. I feel that, i confused little on my query. I straight to the issue now.
Vcc Measured @ 70 C is 4.99 volts. At temperature 70C (After Ramp and Dwell time), When i powered my EUT and Input, The UART Fails in Loop Back test in PBIT. The problem is, UART didnt read back the data during loopback test. We are facing this issue in 2 PCB's at same working Condition. Please let you guide us if you are experienced and expecting same kind of issue. Will share you required data if.

Thanks,

Dear Bobby Nguyen,

Thank you for the comments. My Query is not about the device not performing internal loopback function, It is about when device temperature reaches above +60 degrees , internal loopback function of the

device do not works. it get resolved if the device temperature falls below 60C.

Is this a known issue with this device..?  

Can you comment on this issue..?

Thank you in advance for your support

 

Hey Elangovan,

So you are saying the loopback testing works fine and you have it working in normal conditions (room temperature) however the problem occurs when you raise the temperature above the 60C point. Basically nothing changes in your test except temperature where failure occurs at high temperatures.

During this failure, does the INTA/B pin change? (MCR[3] needs to be set to 1 and IER bits should be enabled for bits 0,1,2,and 3.)
Reading the IIR should give us an idea of what could be happening here.

You could also try connecting the TX RX pins directly into each other rather than using the internal settings and seeing if this set up works.

My thought as to why this could be working at lower temperatures and start malfunctioning at higher temperatures is the oscillating crystal is largely temperature dependent.
-When you increase the temperature, are you able to look at the clock and see what frequency it is at?

"Is this a known issue with this device..? "
-I haven't seen this problem before. I've checked some internal resources to see if this part has been reported for an issue but I didn't find anything.

"Can you comment on this issue..?"
-I can reach out to one of the engineers who used to support this product and see if he has seen something like this before. If he gets back to me on this, I'll let you know.

-Bobby

Dear Bobby,

Thank you for the inputs. We performed the External loop back test and found the below observations.

Please find the waveform captured at ‘CSA’ (Pin 10) and ‘TXA’ (pin 7) in the chip part number TL16C752DPFBRQ1 (Considered channel 1) during Pass and Failure cases for your reference.

 The waveform captured at pin ‘CSA’, Channel 1 selection is identical in both pass and failure cases.

The waveform captured at pin ‘TXA’ is not identical in both pass and fail cases. Please refer the attached waveform, where you can find the difference signal change over before start bit transfer. (Red marking in the image)

Request you to review and comment immediately.

Thanks,

ElangoTL16C752D_Waveforms.zip

Hey Elango,

"Request you to review and comment immediately."

May I ask what you are expecting when you hold the CSA pins high?

The CSA/B pins are meant to disable and enable communication between the CPU(D0-D7) and the TL16C752D during programming. I am assuming you are expecting TXA to remain high when you hold CSA high but if you are sending data into RXA, then holding CSA high does not disable communication and will just spit the data back out on TXA when you are doing the external loopback testing.

You would want to hold CSA/B high when you don't want to read/write to internal registers of the TL16C752D. If you are trying to disable and enable communication then using DSRA and CTSA should be your approach.

-Bobby

EDIT: If you are still running into issues here, providing information about the internal registers and probing the oscillator inputs (before and after temperature increase) could be useful to us.

Registers of interest include: LSR, IIR, MSR, LCR, MCR, and IER

Dear Bobby,

We are enabling the loopback test (Verified both Internal/External for both channels) for both channels, there is an issue observed only at channel 1 during device initialization and first byte transmission irrespective of Temperature (Occurs at some cases).

Example, we Transfer A9 11 12 on both channels for loopback test, Channel 1 reads C4 11 12  at Terminal. I have attached the waveform captured at pin 'TXA' for failure case.

For RS232 Data Transmission,  In Idle Mode, the bus will stay in HIGH and HIGH - LOW for Start bit and then transfer the Data bits. But in Failure case, The Bus Stay in LOW in idle mode, then Goes HIGH and become LOW for Start Bit. This is where A9 is printed s C4.

CSA keeps HIGH in idle Mode and Interrupt keeps LOW.

Can you help us why it is happening only in Channel 1.

Thanks,

Hey Elango,

Your device may be entering the break condition and pulling TXA low.

What is the LCR bit 6 value set to? What is IER [3:0] set to? When INT is low, are you able to read the LSR?

Try turning the break condition off by setting LCR bit 6 to "0."

Thanks,
-Bobby

Dear Bobby,

We have Evaluated this case earlier and understood there is no issue with LCR/IER Registers.

Can you please support an Quick webx setup to discuss the same and close it. We suppose to resolve it immediately, we are about deliver the prototype.

Email Id : Elangovan.m@lnttechservices.com

Looking your valuable support to resolve this issue.

thanks in advance!!