Title:
REGULATED POWER SUPPLY CIRCUIT
Document Type and Number:
Japanese Patent JPH03136112
Kind Code:
A
Abstract:
PURPOSE:To improve the accuracy for protecting an overcurrent by detecting a fact that an excessive current flows between an emitter and a collector of a PNP type transistor, and limiting a base current by a control means. CONSTITUTION:The circuit is constituted of a control circuit 2 being a control means for controlling a base current of a PNP type transistor Tr1 and a protect ing circuit 3 provided with various protecting function. The protecting circuit 3 is provided with an overcurrent protecting circuit 8, this overcurrent protecting circuit 8 detects a potential difference across a resistance R1, and when this potential difference reaches an overcurrent detection voltage, the base current of the transistor Tr1 is limited by limiting a current flowing to a buffer ampli fier 7. Accordingly, even if there is a variance in a DC current amplification factor of the transistor, an output current is limited without being influenced thereby. In such a way, the overcurrent protection is executed with high accu racy.
Inventors:
KUMADA KIYOSHI
NAGAO HISAO
IZUMI HIRONOBU
SUZUKI KENJI
NAGAO HISAO
IZUMI HIRONOBU
SUZUKI KENJI
Application Number:
JP27676189A
Publication Date:
June 10, 1991
Filing Date:
October 23, 1989
Export Citation:
Assignee:
SHARP KK
International Classes:
G05F1/56; (IPC1-7): G05F1/56
Domestic Patent References:
| JPS5622605B2 | 1981-05-26 | |||
| JPS6034620B2 | 1985-08-09 |
Attorney, Agent or Firm:
Kenzo Hara