Power supply device and electric circuit
View Patent ↗An FET for malfunction check is connected between the gate and source of an FET for power-source output control, which is connected in series in a power output line from a battery used as a power source for a load. A malfunction determination circuit determines whether the FET for power-source output control is operating normally or not, by monitoring output voltage of the FET for malfunction check. Further, the malfunction determination circuit identifies malfunction of the FET for power-source output control due to short-circuiting during actual use.
1. A power supply device used as a power source for a load, comprising:
an FET for power-source output control connected in series in a power output line,
an FET for malfunction check connected between the gate and source of the FET for power-source output control, and
a malfunction determination circuit for determining whether the FET for power-source output control is operating normally or not, by monitoring output voltage of the FET for malfunction check,
wherein the FET for power-source output control is controlled to be in on- or off-state by a charge/discharge control circuit controlling gate voltage of the FET for power-source output control, and
when the output voltage of the FET for malfunction check disappears while the FET for power-source output control is controlled to be in on-state, the malfunction determination circuit determines that this indicates malfunction of the FET for power-source output control due to short-circuiting.
2. The power supply device according to claim 1 , wherein
the FET for power-source output control forms a power output line from a positive electrode of a rechargeable battery, with its source connected to the positive electrode of the rechargeable battery and its drain connected to a load,
the FET for malfunction check is connected between the gate and source of the FET for power-source output control, with its source and gate connected to the source and gate of the FET for power-source output control, respectively, and
the malfunction determination circuit detects drain voltage of the FET for malfunction check.
3. The power supply device according to claim 1 , wherein the malfunction determination circuit determines malfunction of the FET for power-source output control from the drain voltage of the FET for malfunction check.
4. The A power supply device used as a power source for a load, comprising:
an FET for power-source output control connected in series in a power output line,
an FET for malfunction check connected between the gate and source of the FET for power-source output control, and
a malfunction determination circuit for determining whether the FET for power-source output control is operating normally or not, by monitoring output voltage of the FET for malfunction check,
wherein the FET for power-source output control forms a power output line from a positive electrode of a rechargeable battery, with its source connected to the positive electrode of the rechargeable battery and its drain connected to a load,
the FET for malfunction check is connected between the gate and source of the FET for power-source output control, with its source and gate connected to the source and gate of the FET for power-source output control, respectively, and
the malfunction determination circuit detects drain voltage of the FET for malfunction check.
5. The power supply device according to claim 1 or 4 , wherein
the FET for power-source output control and the FET for malfunction check are combined into an FET having a malfunction check function.
6. The power supply device according to claim 4 , wherein the malfunction determination circuit determines malfunction of the FET for power-source output control due to short-circuiting.