To measure hold time
Hold time is usually defined as the time for which a data input to a clocked
device must remain stable after the active edge of the clock occurs. Violating
the hold-time specification of a device can lead to unstable circuit operation.
You can use the Hold Time measurement in the HP 54620A/C to verify that
your circuit design meets the device specifications.
1
Press
Dual Channel
.
2
Press the
Hold
softkey.
3
Press the
Clock
softkey to highlight the clock channel.
The clock channel is the reference point for the hold time measurement.
That is, the hold time is the time between a transition on the clock channel
and a subsequent transition on the data channel.
4
Select the clock channel by using the Entry knob or Select knob, or
by repeatedly pressing the
Clock
softkey.
5
Select whether the measurement should be referenced to the rising
or falling edge of the clock signal by pressing the
Edge
softkey to
highlight the positive or negative edge symbol.
6
Press the
Data
softkey to highlight the data channel.
The data channel is the channel for which you want to measure hold time.
7
Select the data channel by using the Entry knob or Select knob, or by
repeatedly pressing the
Data
softkey.
You must select the desired channels and clock edge before pressing the
Meas Hold
softkey to start the measurement in the next step.
8
Press
Meas Hold
.
The hold time appears on the message line of the display.
You may repeat the above steps as desired to measure the hold time between
different sets of input channels. The three most recent single- or
dual-channel measurements (of any kind) will be shown on the message line
of the display.
To calculate the hold time, the analyzer measures the time between the first
transition of the correct type (positive- or negative-going) on the data
channel and the previous clock transition. A glitch on the data channel will be
considered a transition for measurement purposes.
Making Analyzer Measurements
To measure hold time
102
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