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TRS3253E: TRS3253E about the |tPHL – tPLH| and the ten dis test questions

Mickey Zhang
Genius 12080 points
Part Number: TRS3253E

Hi team,

The customer is using TRS3253E. He would like to test two parameters. One is |tPHL – tPLH| that is in the 6.9 Switching Characteristics—Driver 

of the datasheet.  Another is ten and tdis that is in the 6.10 Switching Characteristics—Receiver of the datasheet.

VCC is 3.3V and C1~C4 is 0.1uF in his circuit.

(1). Test  |tPHL – tPLH|:

The customer's test is as below:

The input is  DIN pins. The output DOUT pins. Is this correct? 

Then the test result is that  |tPHL – tPLH| is 4ns.

If the customer's test is uncorrect, how to test this parameter?

For the  |tPHL – tPLH| testing, I notice the Figure 4. Driver Pulse Skew of the datasheet. It is the  |tPHL – tPLH| testing.

I would like to verify which pin the input is and which pin the output is when the customer tests the |tPHL – tPLH|.

（2）Test  ten and tdis:

The customer's test is as below:

The input is FORCEOFF pin. The output is ROUT pin. Then the customer control the high level or the low level for the FORCEOFF pin through  the software,

test the level changes of the ROUT pin. Is this correct?

Then the test result is ten=85ns；tdis=1650ns. 

I notice the Figure 6. Receiver Enable and Disable Times. For Figure 6, I think the input is RIN pin and the output is ROUT pin, then FORCEOFF is connected

to GND and FORCEON is connected to GND or 3V. Is my understanding correct? I also would like to verify which pin the input is and which pin the

output is  when the customer tests the ten and the tdis.

Best Wishes,
Mickey Zhang
Asia Customer Support Center
Texas Instruments

 

  • 0
    TI__Guru 62920 points
    Hi Mickey,

    The inputs/outputs for the driver skew measurement are correctly defined. Are they also making sure that all timing measurements are based off the reference voltages shown in Figure 4? A value of 4 ns is believable for this spec, since ideally it would be as low as possible.

    The procedure for measuring receiver enable/disable times is also correct. The test circuit in the datasheet (Figure 6) shows a signal generator connected to /FORCEOFF in order to vary the voltage while the RIN and FORCEON inputs are tied to either 3 V or 0 V. Note that this measurement involves an output transitioning into and out of a high-impedance state. That means that the transition times will heavily depend on the external resistance and capacitance placed on the net. (These are shown via RL and CL in Figure 6).

    Max