Overcurrent Protective Device, Electronic Apparatus, Integrated Circuit, and Signal Transmission Circuit

Patent metadata

Field	Value
Publication number	US-2017063074-A1
Application number	US-201615248193-A
Country	US
Kind code	A1
Filing date	Aug 26, 2016
Priority date	Aug 27, 2015
Publication date	Mar 2, 2017
Grant date	—

Abstract

The present overcurrent protective device comprises an input terminal configured to receive a power supply voltage, an output terminal, a switch, a detector, and a controller. The switch is provided between the input terminal and the output terminal. The detector is configured to output a limitation signal without delay when a current flowing through the switch exceeds a prescribed tolerance value. The controller is configured to receive the limitation signal and control the switch to prevent the current from exceeding the tolerance value. The detector is configured output a turn-off signal to the controller when a first state continues for a delay time determined depending on the current's magnitude. The first state is a state where the current is smaller than the tolerance value and the current exceeds a first threshold value smaller than the tolerance value. The controller turns off the switch in response to the turn-off signal.

First claim

What is claimed is:

1 . An overcurrent protective device comprising:
an input terminal configured to receive a power supply voltage; an output terminal; a switch provided between the input terminal and the output terminal; a detector configured to output a limitation signal without delay when a current flowing through the switch exceeds a prescribed tolerance value; and a controller configured to receive the limitation signal and control the switch to prevent the current from exceeding the tolerance value, the detector being configured to output a turn-off signal to the controller when a first state continues for a delay time determined depending on the current's magnitude, the first state being a state where the current is smaller than the tolerance value and the current exceeds a first threshold value smaller than the tolerance value, the controller turning off the switch in response to the turn-off signal.

2 . The overcurrent protective device according to claim 1 , wherein:
the detector outputs the turn-off signal when the first state continues for a first delay time; and the detector outputs the turn-off signal when a second state continues for a second delay time shorter than the first delay time, the second state being a state where the current is smaller than the tolerance value and the current exceeds a second threshold value larger than the first threshold value and smaller than the tolerance value.

3 . The overcurrent protective device according to claim 1 , wherein, the controller is configured to return the switch to a conducting state when a prescribed period of time elapses from turning off the switch in response to the turn-off signal.

4 . The overcurrent protective device according to claim 1 further comprising an adjustment unit configured to adjust the delay time.

5 . The overcurrent protective device according to claim 4 , wherein the adjustment unit sets the delay time to be shorter as the current increases.

6 . The overcurrent protective device according to claim 4 , wherein the adjustment unit sets the delay time to be shorter as the switch's temperature increases.

7 . The overcurrent protective device according to claim 1 , wherein:
the detector includes a capacitor and a resistor; the delay time increases as the capacitor's capacitance value or the resistor's resistance value increases; and at least one of the capacitor and the resistor is attachable from outside the overcurrent protective device.

8 . An overcurrent protective device comprising:
an input terminal configured to receive a power supply voltage; an output terminal; a switch provided between the input terminal and the output terminal; a detector configured to output a turn-off signal when a specific state continues for a delay time determined depending on the current's magnitude, the specific state being a state in which a current flowing through the switch exceeds a first threshold value; and a controller configured to turn off the switch in response to the turn-off signal.

9 . The overcurrent protective device according to claim 8 , wherein:
the detector outputs the turn-off signal when the specific state continues for a first delay time; and the detector outputs the turn-off signal when a state where the current exceeds a second threshold value larger than the first threshold value continues for a second delay time shorter than the first delay time.

10 . The overcurrent protective device according to claim 8 , wherein the controller is configured to return the switch to a conducting state when a prescribed period of time elapses from turning off the switch in response to the turn-off signal.

11 . The overcurrent protective device according to claim 8 further comprising an adjustment unit configured to adjust the delay time.

12 . The overcurrent protective device according to claim 11 , wherein the adjustment unit sets the delay time to be shorter as the current increases.

13 . The overcurrent protective device according to claim 11 , wherein the adjustment unit sets the delay time to be shorter as the switch's temperature increases.

14 . The overcurrent protective device according to claim 8 , wherein:
the detector includes a capacitor and a resistor; the delay time increases as the capacitor's capacitance value or the resistor's resistance value increases; and at least one of the capacitor and the resistor is attachable from outside the overcurrent protective device.

15 . An electronic apparatus for supplying a power supply voltage to a load, comprising:
a circuit including an input terminal configured to receive the power supply voltage, an output terminal configured to supply the power supply voltage to the load, an internal circuit configured to receive the power supply voltage and thus operate, and a ground terminal connected to the internal circuit; and a resistor provided between the ground terminal and ground.

16 . The electronic apparatus according to claim 15 , wherein:
the circuit further includes a first protection circuit connected to the input terminal and the ground terminal; and the first protection circuit is configured such that when a voltage larger than a prescribed first voltage is applied to the input terminal the first protection circuit passes a current to protect the circuit.

17 . The electronic apparatus according to claim 16 , wherein the first protection circuit includes a Zener diode.

18 . The electronic apparatus according to claim 16 , wherein:
the circuit further includes a second protection circuit connected between the output terminal and the ground terminal; and the second protection circuit is configured such that when a voltage larger than a prescribed second voltage is applied to the output terminal the second protection circuit passes a current to protect the circuit.

19 . The electronic apparatus according to claim 15 further including a switch electrically connected between the input terminal and the output terminal and configured to switch between supply and interruption of electric power from the input terminal to the output terminal, wherein the internal circuit includes:
a detection circuit configured to detect a current flowing through the switch; and
a control circuit configured to control the switch in response to a signal from the detection circuit.

20 . An overcurrent protective device comprising:
an input terminal configured to receive a power supply voltage; an output terminal; a switch provided between the input terminal and the output terminal and configured to switch between supply and interruption of electric power from the input terminal to the output terminal; a control device configured to turn off the switch when a current flowing through the switch exceeds a prescribed threshold value; and a bias circuit configured to supply an intermediate voltage between the power supply voltage and a ground voltage to the control device.

21 . The overcurrent protective device according to claim 20 , wherein the bias circuit includes a clamping circuit configured to clamp the power supply voltage to the intermediate voltage.

22 . The overcurrent protective device according to claim 20 , wherein the bias circuit includes a voltage conversion circuit configured to lower the power supply voltage to the intermediate voltage.

23 . The overcurrent protective device according to claim 20 , wherein the control device includes:
an

Assignees

• Rohm Co Ltd

Inventors

• Yasusaka Makoto
• Shugo Daisaku
• Hirata Shinichi

Classifications

• H01L29/866

  Electricity · mapped topic

• H01L27/0255

  Electricity · mapped topic

• H02H1/0007 Primary

  concerning the detecting means (in general G01R or other subclasses of G01; reed switches H01H71/2445) · CPC title

• H03K17/687

  the devices being field-effect transistors · CPC title

• H02H3/10 Primary

  additionally responsive to some other abnormal electrical conditions · CPC title