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TL16C550D issue

Other Parts Discussed in Thread: TL16C550C, TL16C550D

Hi Sir,

We have used TL16C550C many years. Now, we want to replace TL16C550C to TL16C550D.

We have a problem. When we tx " FB,FC,FD,FE,FF" code, the RX always receive "00" code.

If the TL16C550D "A01 & RD1"  between GND connect cap "40p" . The " FB,FC,FD,FE,FF" code is received correctly.

We used The PCB many years. so we can not modify our PCB layout.

Would you please tell us how to solve this problem & Let me know what's different between TL16C550C & TL16C550D. Thanks a lot.

  

  • Hello Grace,

    The Rev D is a speed upgrade from the Rev C device. The Rev D also supports 2.5V Vcc. TIming wise the only differences are (at Vcc = 5V):

    Parameter        550C              550D
                                (Min)               (Min)

    tw1, tw2              25 ns              18 ns
    tw3, tw4              50 ns              30 ns

    All other timing parameters are the same.

    In the case where the 550D fails, can you provide an oscilloscope capture of the TX and RX lines? From your example it appears that the START bit is not being detected by the receiver. Placing a 40pF cap between /RD1 and GND would slow the high-to-low transition on the read line but the 550C and 550D have the same td10 (delay time from /RD low to data valid) so ths should not impact reading the receiver FIFO.

    Best Regards,

    Joe

     

  • Hi joe,

    Thanks a lot for your reply.

    If the TL16C550D "A01 & RD1"  between GND connect cap "40p  ---> not A01 is A02

    I used oscilloscope to measure TX & RX. the data is right. so I'll measure "d0~d7" data bus output to MCU.