JPS54116652A - Logical circuit provided with output protective circuit - Google Patents
Logical circuit provided with output protective circuitInfo
- Publication number
- JPS54116652A JPS54116652A JP2408978A JP2408978A JPS54116652A JP S54116652 A JPS54116652 A JP S54116652A JP 2408978 A JP2408978 A JP 2408978A JP 2408978 A JP2408978 A JP 2408978A JP S54116652 A JPS54116652 A JP S54116652A
- Authority
- JP
- Japan
- Prior art keywords
- output
- condition
- under
- circuit
- interruption
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Classifications
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03K—PULSE TECHNIQUE
- H03K19/00—Logic circuits, i.e. having at least two inputs acting on one output; Inverting circuits
- H03K19/003—Modifications for increasing the reliability for protection
- H03K19/00307—Modifications for increasing the reliability for protection in bipolar transistor circuits
Landscapes
- Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Computer Hardware Design (AREA)
- Computing Systems (AREA)
- General Engineering & Computer Science (AREA)
- Mathematical Physics (AREA)
- Protection Of Static Devices (AREA)
- Logic Circuits (AREA)
- Electronic Switches (AREA)
Abstract
PURPOSE:To normally maintain the action of a TTL circuit, by preventing the thermal failure of output transistors by interruption driving the output transistors under conduction surface conditions by means of a protective circuit only when the collector potential becomes not less than a fixed level. CONSTITUTION:A protective circuit is shaped by transistors (Tr) 14, 15, dioses 18, 19 and resistances 16, 17. When an output Tr7 is under a conduction condition, the collector potential of a current driving Tr6 is low, base current does not flow through the Tr 14 and the Tr 14 is under an interruption condition. When not less than a fixed level abnormal voltage is applied to an output electrode 3 under this condition, current flows through a base of the Tr 15 through the resistance 17 and the diode 19 and the Tr 15 is brought to the conduction condition. The base current of the output Tr7 flows through the Tr 15, and the output Tr7 is brought to the interruption condition. The action of a logical circuit is not prevented because the Tr 14 is conducted when the output Tr7 is under the interruption condition and the interruption condition of the Tr 15 is maintained. Thus, the thermal failure of the output Tr7 can be prevented, and the action of the TTL system logical circuit can normally be kept.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2408978A JPS54116652A (en) | 1978-03-02 | 1978-03-02 | Logical circuit provided with output protective circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2408978A JPS54116652A (en) | 1978-03-02 | 1978-03-02 | Logical circuit provided with output protective circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPS54116652A true JPS54116652A (en) | 1979-09-11 |
Family
ID=12128653
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2408978A Pending JPS54116652A (en) | 1978-03-02 | 1978-03-02 | Logical circuit provided with output protective circuit |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS54116652A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS57125045U (en) * | 1981-01-28 | 1982-08-04 | ||
| JPS58123211A (en) * | 1982-01-19 | 1983-07-22 | Fuji Electric Co Ltd | Base circuit of transistor |
| EP0173148A2 (en) * | 1984-08-29 | 1986-03-05 | Fujitsu Limited | A logic circuit |
-
1978
- 1978-03-02 JP JP2408978A patent/JPS54116652A/en active Pending
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS57125045U (en) * | 1981-01-28 | 1982-08-04 | ||
| JPS58123211A (en) * | 1982-01-19 | 1983-07-22 | Fuji Electric Co Ltd | Base circuit of transistor |
| EP0173148A2 (en) * | 1984-08-29 | 1986-03-05 | Fujitsu Limited | A logic circuit |
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