Electronic fuse circuit and reset circuit

Abstract

The electronic fuse circuit disclosed herein is coupled to a load device at an output node and includes a fuse switch, a charge pump circuit, a current-to-voltage conversion circuit, and a reset circuit. The fuse switch receives an input voltage to generate an output voltage at the output node and generates an output current to the output node. The charge pump circuit is coupled to a first node and controls the fuse switch to control the output voltage based on the node voltage at the first node. The current-to-voltage conversion circuit is coupled to the fuse switch and a second node and converts the output current to generate a current-dependent voltage at the second node. The reset circuit is coupled to the first and second nodes and, in response to an output current exceeding a current threshold, controls the node voltage after a reaction time matched to the current threshold to trigger the charge pump circuit to turn off the fuse switch.

Claims

1. An electronic fuse circuit coupled to a load device at an output node, comprising: a fuse switch for receiving an input voltage to generate an output voltage at the output node and for generating an output current to the output node; a charge pump circuit coupled to the fuse switch and a first node, and for controlling the fuse switch based on a node voltage at the first node to control the output voltage; a current-to-voltage circuit coupled to the fuse switch and a second node, and for converting the output current to generate a current-dependent voltage at the second node; and a first reset circuit coupled to the first node and the second node, for determining whether the output current exceeds a first current threshold based on the current-dependent voltage, and for responding to the output current exceeding the first current threshold by controlling the node voltage after a first reaction time matching the first current threshold to trigger the charge pump circuit to turn off the fuse switch.

2. The electronic fuse circuit as claimed in claim 1, wherein the first reset circuit comprises: an overcurrent response circuit coupled to the second node and configured to generate a first indication signal based on the current-dependent voltage and a first reference voltage, wherein the first reference voltage corresponds to the first current threshold, and the first indication signal switches to a voltage level when the output current exceeds the first current threshold. A reaction time generating circuit, coupled to the overcurrent response circuit and a third node, is used to selectively adjust a charging voltage at the third node according to the first indication signal to generate a second indication signal based on the charging voltage. When the first indication signal switches to the enable voltage level, the voltage level of the charging voltage is adjusted to a second reference voltage according to the first reaction time, so that the second indication signal switches to the enable voltage level. A disable circuit, coupled to the reaction time generating circuit and the first node, is used to switch the node voltage to a disable voltage level according to the second indication signal of the enable voltage level, so that the charge pump circuit turns off the fuse switch.

3. The electronic fuse circuit as claimed in claim 2, wherein the overcurrent response circuit comprises: a comparator, wherein a positive input terminal of the comparator is coupled to the second node and is used to receive the current-dependent voltage, a negative input terminal of the comparator is used to receive the first reference voltage, and an output terminal of the comparator is coupled to the reaction time generation circuit and is used to output the first indication signal.

4. The electronic fuse circuit as claimed in claim 2, wherein the reaction time generating circuit comprises: a current source for providing a charging current, wherein the current level of the charging current is fixed or proportional to the current level of the output current; a switching circuit coupled to the overcurrent response circuit, the current source, and the third node, and configured to be turned on or off under the control of the first indication signal to selectively allow the charging current to pass through; a capacitor coupled to the third node and a ground voltage, and configured to generate the charging voltage at the third node; and a comparator, wherein a positive input terminal of the comparator is coupled to the third node for receiving the charging voltage, a negative input terminal of the comparator is used to receive the second reference voltage, and an output terminal of the comparator is coupled to the disable circuit for outputting the second indication signal.

5. The electronic fuse circuit as claimed in claim 2, wherein the disable circuit comprises: a level sustaining circuit coupled to the reaction time generating circuit and used to generate a switching control signal that sustains the enable voltage level for a preset period based on the second indication signal of the enable voltage level; and a switching circuit coupled to the level sustaining circuit, the first node, and a ground voltage and used to turn on based on the switching control signal of the enable voltage level to switch the node voltage to the disable voltage level.

6. The electronic fuse circuit as claimed in claim 1, further comprising: a second reset circuit coupled to the first node and the second node, configured to determine whether the output current exceeds a second current threshold based on the current-dependent voltage, and configured to, in response to the output current exceeding the second current threshold, trigger the charge pump circuit to turn off the fuse switch after a second reaction time matching the second current threshold, wherein the first current threshold and the first reaction time correspond to a first point of a first current-to-time curve, and the second current threshold and the second reaction time correspond to a second point of the first current-to-time curve.

7. The electronic fuse circuit as claimed in claim 6, wherein when the second current threshold is greater than the first current threshold, the second response time is shorter than the first response time, and when the second current threshold is less than the first current threshold, the second response time is longer than the first response time.

8. The electronic fuse circuit as claimed in claim 1, further comprising: a control circuit coupled to the first node and the second node, configured to determine whether the output current exceeds a third current threshold based on the current-dependent voltage, and configured to, in response to the output current exceeding the third current threshold, trigger the charge pump circuit to turn off the fuse switch after a third reaction time matching the third current threshold, wherein the third current threshold and the third reaction time correspond to a first point of a second current-time curve.

9. The electronic fuse circuit as claimed in claim 8, wherein when the first current threshold and the third current threshold are the same, the third response time is shorter than the first response time, and when the first response time and the third response time are the same, the first current threshold is greater than the third current threshold.

10. A reset circuit for responding to an output current of a fuse switch exceeding a current threshold, triggering a charge pump circuit to turn off the fuse switch after a reaction time matched to the current threshold, and comprising: an overcurrent response circuit coupled to a current-to-voltage circuit at a first node, and for generating a first indication signal based on a first reference voltage and a current-dependent voltage at the first node, wherein the first reference voltage corresponds to the current threshold, and the first indication signal switches to a voltage level when the output current exceeds the current threshold; A reaction time generation circuit, coupled to the overcurrent response circuit and a second node, is used to selectively adjust a charging voltage at the second node according to the first indication signal to generate a second indication signal based on the charging voltage. When the first indication signal switches to the enable voltage level, the voltage level of the charging voltage is adjusted to a second reference voltage according to the reaction time, so that the second indication signal switches to the enable voltage level. A disable circuit, coupled to the reaction time generation circuit and coupled to the charge pump circuit at a third node, is used to switch a node voltage at the third node to a disable voltage level according to the second indication signal of the enable voltage level, so that the charge pump circuit turns off the fuse switch.

Images