SN74LVC1G32: Test condition of the rising time of input signal

Lijia Zhu

Part Number: SN74LVC1G32

Hi, team

For low speed logic devices such as SN74LVC1G32, the data sheet gives a maximum rise time for input signal. Our customer use an oscilloscope with 33G bandwidth to test the rise time, and they get a very bad result. And the input impedance of an oscilloscope is 50 ohms in they test condition.

Is the input impedance of the oscilloscope affecting the rise time of the signal?Since 50 ohms is a relatively large load for a logic device, the correct test method is to use a probe with high input impedance.

Dear team, please answer my questions above and point out the correct test conditions.

Best regards,

Lijia

over 6 years ago

0 Dylan Hubbard over 6 years ago

TI__Mastermind 46045 points

Hi Lijia,

The Scope should be set to a high impedance input for this test. The rise time can be affected by parasitics as well. The more parasitic capacitance you have the slower the rise time will be.

0 Lijia Zhu over 6 years ago in reply to Dylan Hubbard

TI__Expert 5730 points

Good，thanks for your reply!

0 Dylan Hubbard over 6 years ago in reply to Lijia Zhu

TI__Mastermind 46045 points

Hi Lijia,

You're welcome! If you could hit the green verify button to help others with the same question (or something similar) that'd be great!

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SN74LVC1G32: Test condition of the rising time of input signal