发明名称 |
STATE-DEPENDENT DISCHARGE PATH CIRCUIT |
摘要 |
Attorney Docket No. NS1937 STATE-DEPENDENT DISCHARGE PATH CIRCUIT A circuit for use in connection with tristate output buffers in order to provide concurrently for fast discharge of the output pulldown transistor base and at the same time for building in protection against reverse breakdown in the pulldown transistor. The innovation consists of providing two discharge paths to ground for the base of the output pullup transistor. A low-capaci-tance path is activated only while the output buffer is in its active mode. In the preferred embodiment of the invention, this low discharge path consists of two MOS transistors in series (Q23 and Q26), one of which is controlled by the enable signal input E of the buffer circuit and the other by the data signalinput VIN of the buffer circuit. The other path to ground is available whenever the data signal input VIN is low regardless of whether the buffer is in its active or inactive mode. This other path provides discharge protection for the base of the pullup transistor for the buffer in its inactive mode, and has incorporated into it reverse breakdown protection in the form of voltage drop devices such as forward-biased diodes.
|
申请公布号 |
CA2084544(A1) |
申请公布日期 |
1993.06.07 |
申请号 |
CA19922084544 |
申请日期 |
1992.12.04 |
申请人 |
NATIONAL SEMICONDUCTOR CORPORATION |
发明人 |
OHANNES, JAMES R.;CLUKEY, STEPHEN W.;HAACKE, ERNEST D.;YARBROUGH, ROY L. |
分类号 |
H03K19/0175;H03K19/003;H03K19/08;H03K19/082;H03K19/088;H03K19/0944;(IPC1-7):H03K19/017 |
主分类号 |
H03K19/0175 |
代理机构 |
|
代理人 |
|
主权项 |
|
地址 |
|