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AD8515 - Low voltage limits, Negative values

Question asked by FernandoGuerraBR on Oct 2, 2013
Latest reply on Oct 2, 2013 by harryh

Hi,

 

One of our customers is using the AD8515AKSZ-REEL7 as shown in figure:


 

In this circuit, the AD8515 is supplied with 3.3V (V+ = 3.3V and V- = 0V).

The datasheet of the component informs the input voltage range for different supply voltages and in this case it would be 0 to 3.3V. One of the tests performed by us is the verification of the amplitude of the integrated circuits signals. During this test, it was observed that the signal on pins 3 and 4 (+IN and –IN) were below the low limit specification (0V).

 


 

As is possible to see, during 120ns the signal is lower than 0V and reaches a peak of ‑94mV.

The same situation is possible to observe on pin 4 (-IN) referenced to pin 2 (0V), as shown below.

 

During 120ns the signal is lower than 0V and reaches a peak of ‑54mV.

The signals were measured using a Tektronix Oscilloscope (5054 – 500MHz - 5GS/s) and a Tektronix voltage probe (TPP0502 - 500MHz - 2x). The probe was connected very close to the measured point aiming to minimize the influence of measurement system. The probe capacitance is lower than 4pF.

What are the real low voltage limits for AD8515? Is there some risk of failure of this component in this application duo to these negative values on pins 3 and 4?

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