Tr/Tf Measurement

Introduction

Rise time(Tr) and fall time(Tf) of a pulse are important characteristics of IC.
This document explains how to measure and judge Tr/Tf using CloudTesting™ Service.

Case

In this document, define Tr as “Required time to rise an output voltage from 10% to 90% of its specification” and explain how to measure it. Tf can be measured as well by applying this methodology.

Measurement Procedure

1. Measure a required time to rise an output voltage to 10% of specified output voltage

Required IP
Timing Parameter Search

Measurement
Measure a required time to rise an output voltage to 10% of specified output voltage and put its value to a variable by following steps.

  • Measure a required time to rise an output voltage to 10% of specified output voltage using Timing Parameter Search
  • Put measured value into a variable(call this variable as ‘A’ hereinafter) using Post Interpose(cf.1) function

cf.1 Use ”Store Pin Measure Value” built-in interpose algorithm to put measured value into variable

2. Measure a required time to rise an output voltage to 90% of specified output voltage

Required IP
Timing Parameter Search

Measurement
Similarly to step 1, measure a required time to rise an output voltage to 90% of specified output voltage and put its value to a variable by following steps.

  • Measure a required time to rise an output voltage to 90% of specified output voltage using Timing Parameter Search
  • Put measured value into a variable(call this variable as ‘B’ hereinafter) using Post Interpose(cf.1) function

cf.1 Use ”Store Pin Measure Value” built-in interpose algorithm to put measured value into variable

3. Judge difference of variable A and B

Required IP
Value Judgement IP

Measurement
Calculate Tr from measured values in step 1 and 2, then judge whether it is in the specified range of Tr by following steps.

  • Calculate a difference between variable B and A, then put its result into variable(call this variable as ‘C’ hereinafter) using Pre Interpose(cf.2) function
  • Judge variable C using Value Judgement IP

cf.2 Use ”Set Variable” built-in interpose algorithm

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Updated at
January 01, 2017