S1K50000 Epson Electronics America, Inc., S1K50000 Datasheet - Page 85

• Manufacturer Part Number: S1K50000
• Description: Design Guide S1k50000 Series
• Manufacturer: Epson Electronics America, Inc.

Chapter 6: Creating Test Patterns
6.6 Regarding the AC Test
6.6.1 Restrictions on Measurement Events
6.6.2 Restrictions on AC Test Measurement Points
6.6.3 Restrictions on Delays in the Measured Path
6.6.4 Other Restrictions
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In an AC test, the length of time from when an input pin changes state until that change of
state propagates to the output pin is measured. The measurement paths that have been
selected by customers are used for the AC test.
This test is normally performed using the method known as “binary search.” Therefore, the
change points for the measured pin (any output pin that changes state) within a measurement
event must be limited to one. (Measurement cannot be made of pins that are outputting an RZ
waveform, nor can measurement be made when a hazard is output in the measurement
event.) In addition, changes in state of the measured signal must occur in order of High
Low or Low
Other precautions include that events must be selected so as not to cause multiple output pins
to change state simultaneously in a measurement event, or signal contention to occur
between bidirectional pins and the LSI tester. This is due to the fact that a simultaneous
change in state or signal contention causes the LSI power supply to swing, affecting the
measured pin’s output waveform and making accurate measurements impossible.
The measurement points in an AC test must be limited to up to four.
With the AC test measurement paths, the greater the delay in the measured path, the higher
the accuracy of measurement. Make sure the delay time in the measured path is set to 30 ns
or more, and is equal to or less than the strobe point under maximum test simulation
conditions.
(1) Do not specify a path from the oscillator circuit.
(2) Make sure the specified path does not pass through the internal tri-state circuit (internal
(3) Do not specify a path that passes through any other bidirectional cell between the
(4) If there are two or more working voltage ranges, make sure the measured voltages in the
bus).
measured path’s input buffer and the output buffer.
AC test are both within one of such voltage ranges.
High (Z-related changes cannot be measured).
EPSON
STANDARD CELL S1K50000 SERIES
DESIGN GUIDE