Power supply device including fault detection circuit
A power supply device includes a power supply circuit that permits an output voltage to be supplied to a succeeding-stage circuit, an external terminal configured to be connectable to the succeeding-stage circuit and to a pull-up resistor to which a supply voltage is applied, a transistor having a first terminal connected to the external terminal, a controller that turns the transistor from on to off when, during start-up of the output voltage, the output voltage enters a normal range and a fault detection circuit that can detect at least one of an open fault, in which the external terminal remains open, and a short fault, in which the external terminal is short-circuited to an application terminal for the supply voltage.
1 . A power supply device comprising:
a power supply circuit configured to permit an output voltage to be supplied to a succeeding-stage circuit;
an external terminal connected to the succeeding-stage circuit and to a pull-up resistor to which a supply voltage is applied;
a transistor having a first terminal connected to the external terminal;
a controller configured to turn the transistor from on to off when, during start-up of the output voltage, the output voltage enters a normal range; and
a fault detection circuit configured to detect at least one of an open fault, in which the external terminal remains open, and a short fault, in which the external terminal is short-circuited to an application terminal for the supply voltage.
2 . The power supply device according to claim 1 , wherein
the fault detection circuit is further configured to instruct the power supply circuit to stop outputting the output voltage based on detecting the open fault or the short fault.
3 . The power supply device according to claim 2 , wherein
the fault detection circuit is configured to start up the output voltage again subsequent to stopping output of the output voltage, and
the fault detection circuit is configured to stop the output of the output voltage based on a predetermined number of times that stopping output of the output voltage has been repeated.
4 . The power supply device according to claim 1 , wherein
the fault detection circuit is configured to continue the output of the output voltage and indicate a fault to the succeeding-stage circuit based on detecting the open fault or the short fault.
5 . The power supply device according to claim 1 , wherein
the controller is configured to turn the transistor from on to off based on the output voltage remaining within the normal range for a predetermined period after the output voltage reaches a predetermined lower limit voltage, and
at a lapse of the predetermined period after the output voltage reaches the lower limit voltage, the fault detection circuit is configured to detect the open fault based on a voltage at the external terminal.
6 . The power supply device according to claim 5 , further comprising:
an additional resistor connected between the external terminal and an application terminal that provides a ground potential.
7 . The power supply device according to claim 1 , wherein
the fault detection circuit is configured to detect the short fault by detecting that a voltage at the external terminal has reached a predetermined threshold voltage at a time at which the voltage at the external terminal should normally be at low level.
8 . The power supply device according to claim 1 , wherein
the application terminal for the supply voltage is connected to an application terminal for the output voltage.
9 . The power supply device according to claim 1 , wherein
the fault detection circuit includes:
a monitoring circuit configured to output a monitoring signal with a logic level corresponding to the voltage at the external terminal; and
a control logic circuit configured to detect a fault based on the monitoring signal.
10 . The power supply device according to claim 9 , wherein
the monitoring circuit includes an inverter connected to the external terminal to receive the voltage at the external terminal.
11 . The power supply device according to claim 9 , wherein
the monitoring circuit includes a comparator arranged to receive the voltage at the external terminal and a reference voltage.
12 . The power supply device according to claim 1 , wherein
the external terminal is connected to a reset terminal of an MCU as the succeeding-stage circuit.
13 . The power supply device according to claim 1 , wherein the power supply device is a component of an electronic device of a vehicle.
14 . A power feeding system comprising:
the power supply device according to claim 1 ; and
the succeeding-stage circuit.