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TLC5927: Use as an IO expander

Shuji Ishiwata
Mastermind 7805 points
Part Number: TLC5927

Hi All,

I have a question about TLC5927.

(1) Do CLK and SDI have a tolerant function?

(2) Which of the rising and falling edges of CLK is the timing when the SDO data is reflected?

(3) If a short circuit is detected, is the OUT pin disabled? Do you want to continue outputting?

(4) Use TLC5927 like an IO expander. Connect the logic IC to OUTx.
In this case, set Iout = 7mA and pull up the OUT terminal by 10k at 5V.
Is there any concern that the current consumption will increase when the OUT output decreases?
Do you think this usage is possible?

Best Regards,
Ishiwata

  • 0
    TI__Genius 12915 points

    Hi Shuji,

    Sorry for late reply that I am on business trip in last week.

    1. What you mean about the tolerant function? 

    2. The timing requirements for input signal could be referred to Table 7.7 and Figure 4.

    3. No the shorted output would not auto disable.

    4. If the output is pulled up to 5V through 10k resistor, the output cannot be stable at 7V, since there needs around 0.3V saturation voltage for internal current sink to generate precise current. The pull-up resistance can be (5V-0.3V)/7mA = 670ohm.

    The second thing I concern is that, the logic is reversed comparing with TLC5927 input signal. When output channel enables (set to 1), output voltage is driven to low level (0). And also the low level is not GND, but VLED - IOUT * Rpullup.

    Also the device cannot be used as input expander, but only output expander.