Learning from VLSI Design Experience by Weng Fook Lee

Author:Weng Fook Lee
Language: eng
Format: epub, pdf
ISBN: 9783030032388
Publisher: Springer International Publishing

The use of level shifters when the scan chain crosses power domain is applicable if the power domains are on during testing. If one of the power domains is off during testing, an isolation cell is required instead of a level shifter.

When a functional signal crosses from a power domain to another, when the transmitting signal power domain switches off, the transmitting signal voltage level floats, and the functionality of the receiving signal will be affected. For such conditions, an isolation cell is required as shown in Fig. 5.18. The isolation cell will tie the floating signal X to logic signal Y which can be a logic 1, logic 0, or previous latched value of signal X, depending on the type of isolation cell used.

Fig. 5.18Diagram showing isolation cell bridging an off power domain to an on power domain

Download

Copyright Disclaimer:
This site does not store any files on its server. We only index and link to content provided by other sites. Please contact the content providers to delete copyright contents if any and email us, we'll remove relevant links or contents immediately.