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TMS320F28075: VIH and VILdata on X1/X2 when using external crystal not external oscillator

Julia Li
Expert 4755 points

Part Number: TMS320F28075

Hi Team,

I ask this for our customer.

Now customer have chosen a external crystal and their X1/X2 voltage to ground shown as below:

X1 voltage to ground，max 1.99V，min 0.47

X2 voltage to ground，max 1.99V，min 0.36

According to datasheet there is only VIH/VIL data for external oscillator for X1, there is no data for external crystal and X2. If according to VIH/VIL data for external oscillator this voltage is not fit.

So do we have VIL and VIH data when using external crystal and do we have data for X2? Does customer's X1&X2 voltage to ground is correct? Thanks!

Customer's X1 voltage to ground is shown as below.

Best,

Julia

  • 0
    TI__Guru* 95315 points

    Julia,

              You can refer to www.ti.com/lit/SPRSP61, which has this information on page 90 and a dedicated crystal oscillator section starting page 92. Agree the datasheet is for a different device, but the crystal oscillator used is identical between the two devices.

    Measuring signals at the X1/X2 pins are a bit tricky because the capacitance of the oscilloscope probe itself can distort the signal being measured. These signals are best measured with an active FET probe like shown here. Measuring with ordinary probes are not recommended.

    Are you able to share the part number of the crystal and also the crystal circuit?