| 摘要 |
A fail-safe system for automotive electronic circuitry (4) blows a main power supply fuse (3) forcibly when the battery (1) voltage exceeds acceptable levels. The fuse (3) is connected between the battery (1) and a voltage regulator (5). The battery (1) voltage is monitored by comparison with a constant reference voltage derived from the regulated voltage. When the battery (1) voltage exceeds the reference voltage, a normally-open shorting circuit (7) is closed. The shorting circuit is connected between the fuse and ground in parallel with the voltage regulator (5) and has effectively zero impedance. Thus, when closed, the shorting circuit (7) draws a large current from the battery (1) causing the fuse (3) blow. The operating status of the fuse (3) may be indicated by a monitor lamp (9) connected in parallel with the voltage regulator (5). The monitor lamp (9) may be either illuminated or turned off when the fuse (3) blows, provided it exhibits the opposite state while the fuse (3) is intact. |
