S1K50000 Datasheet, PDF (28/130 Pages) Epson Company – Standard-Cell Development Flow

Chapter 2: Precautions on Circuit Design
(5) Configuration of test patterns generated by ATPG
The test patterns generated by ATPG have the two modes specified below, and these two
modes must be switched over using a scan enable input pin (SCANEN). Because the
SCANEN pin is connected for circuit scanning, make sure your circuits have this pin
prepared as a dedicated input pin.
• Scan shift mode
In this mode, data is input and output to and from the circuit’s internal storage device (flip-
flop) configured as a shift register.
• Scan test mode
In this mode, the data applied to the storage device in scan shift mode is operated
internally through the entry of a clock.
(6) Input/output pins for ATPG
The pins needed for ATPG are described below. Of these, the provision of two pins,
SCANEN and ATPGEN, is sufficient for ATPG to be run efficiently. This may result in a
reduced delivery period and an increased fault detection rate, however.
• Scan enable input pin (SCANEN)
This pin is used to switch between scan-shift and scan-test modes. It also is used to
reset or set the flip-flop, and to fix the bidirectional input/output select signal during scan
shift. Because this pin is always necessary for scanning, be sure to prepare it as a
dedicated input pin.
• ATPG test input pin (ATPGEN)
This pin makes the circuit suitable for ATPG, and is used to fix the circuit’s internal
asynchronous parts or for switchover to make clock lines controllable that cannot be
controlled from the outside. This pin is unnecessary if the ATPG rules were taken into
consideration in the design of the original circuit. Prepare this pin as a dedicated input
pin.
• Scan data input pin
This input pin is used to set data in the shift register generated by scanning. Two or more
of these pins may exist, depending on the number of scan flip-flops, and this pin may be
shared with other pins. However, it cannot be shared with the control pins that reset/set
the clock, nor can it be shared with other pins employed for scanning. If it is shared with
bidirectional pins, make sure the pin is always in input state through the use of the
ATPGEN pin, for example.
• Scan data output pin
This pin is used to read data from the shift register generated by scanning. Two or more
of these pins may exist, depending on the number of scan flip-flops, and this pin may be
shared with other pins. However, if it is shared with bidirectional pins, make sure the pin
is always in output state through the use of the ATPGEN pin, for example.
STANDARD CELL S1K50000 SERIES
EPSON
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DESIGN GUIDE