发明名称 |
Off-chip driver circuit |
摘要 |
An off-chip driver circuit having circuitry for providing protection against high voltages when the off-chip driver circuit is disabled is described. The circuitry for providing protection against high voltages utilizes a minimum number of transistors and therefore minimizes the chip area utilized by the off-chip driver circuit. An off-chip driver circuit has an input terminal and an output terminal. A pull-up transistor has a controllable path connected between a first power supply voltage and the output terminal of the off-chip driver circuit, and a control terminal connected to the input terminal via a pass gate connected to isolate the input terminal from high voltages applied to the output terminal. A control transistor has a controllable path connected between the control terminal of the pull-up transistor and the output terminal, and a control terminal connected to a control potential. An auxiliary pass transistor has a control terminal and a controllable path connected between a reference terminal and the control terminal of the pull-up transistor. An auxiliary control transistor has a control terminal connected to receive the control potential, and a controllable path connected between the output terminal and the control terminal of the auxiliary pass transistor. Auxiliary circuitry holds the control terminal of the auxiliary pass transistor in a state determined by the auxiliary control transistor. The auxiliary circuitry may include an auxiliary pull-down transistor having a controllable path connected between the control terminal of the auxiliary pass transistor and a reference potential, and a control terminal connected to a voltage selected to maintain the auxiliary pull-down transistor on.
|
申请公布号 |
US5729157(A) |
申请公布日期 |
1998.03.17 |
申请号 |
US19950506879 |
申请日期 |
1995.07.25 |
申请人 |
SGS-THOMSON MICROELECTRONICS LIMITED |
发明人 |
MONK, TREVOR;DICKE, CURTIS |
分类号 |
H03K19/003;H03K19/0175;H03K19/094;H03K19/0948;(IPC1-7):H03K19/017 |
主分类号 |
H03K19/003 |
代理机构 |
|
代理人 |
|
主权项 |
|
地址 |
|