发明名称 |
POWER SOURCE THRESHOLD ACTIVATION CIRCUIT |
摘要 |
<p>An improved tristate enable circuit is described for activating a tristate enable gate to maintain the high impedance third state of a common bus tristate output device during "power down" and "power up" transitions of the common power supply Vcc. The enable gate circuit element tends to turn off at a voltage level Vcc2 generally greater than the voltage level Vcc3 at which the tristate output device circuit elements turn off. As a result the high impedance state may be lost during "power down". A threshold activation circuit is coupled to the enable gate for activating the enable gate when the threshold activation circuit senses a higher common power supply voltage level Vcc1. The threshold activation circuit operatively activates the enable gate over a voltage range from Vcc1 to a lesser common power supply voltage level Vcc4. Component values are selected for relating the voltage levels so that Vcc1>Vcc2 and Vcc3>Vcc4. As a result the turn off of circuit elements is sequenced by the threshold activation circuit.</p> |
申请公布号 |
JPS5949620(A) |
申请公布日期 |
1984.03.22 |
申请号 |
JP19830140627 |
申请日期 |
1983.08.02 |
申请人 |
FAIRCHILD CAMERA & INSTRUMENT CORP |
发明人 |
UIRIAMU AARU HOOKU;HAYAGURIBA BUI RAO |
分类号 |
G06F1/28;G06F1/26;H03K17/22;H03K19/082 |
主分类号 |
G06F1/28 |
代理机构 |
|
代理人 |
|
主权项 |
|
地址 |
|