EFuse for use in high voltage applications
An eFuse for use in high voltage applications is disclosed. In one embodiment, an apparatus includes a solid-state switch having source and drain terminals connected to switch a load current from a high voltage source through a high voltage load. The apparatus also includes a sense circuit that senses a voltage between the switch source and drain terminals and turns off the switch when the voltage exceeds a selected voltage level.
1. An apparatus comprising:
a solid-state switch having source and drain terminals connected to switch a load current from a high voltage source through a high voltage load;
a sense circuit that senses a voltage between the source and drain terminals and turns off the solid-state switch when the voltage exceeds a selected voltage level;
a diode coupled between a voltage sense terminal and the drain terminal; and
a capacitor having a first terminal connected to the voltage sense terminal and a second terminal coupled to the source terminal.
2. The apparatus of claim 1 , wherein the selected voltage level is selected to correspond to a desired load current level based on a characterization of the solid-state switch.
3. The apparatus of claim 1 , wherein the solid-state switch has a gate terminal that is connected to the sense circuit to selectively turn on and off the solid-state switch.
4. The apparatus of claim 1 , wherein the solid-state switch is an enhancement mode N-type MOSFET transistor.
5. The apparatus of claim 1 , wherein the sense circuit comprises:
a comparator having a first input terminal connected to the voltage sense terminal, a second input terminal connected to a reference voltage, and an output terminal that outputs a fault indicator.
6. The apparatus of claim 1 , wherein a voltage at the voltage sense terminal indicates a level of the load current.
7. An apparatus comprising:
a solid-state switch having source and drain terminals connected to switch a load current from a high voltage source through a high voltage load;
a sense circuit that senses a voltage between the source and drain terminals and turns off the solid-state switch when the voltage exceeds a selected voltage level; and
a diode coupled between a voltage sense terminal and the drain terminal, wherein the sense circuit comprises:
a first control switch that selectively connects the voltage sense terminal to the source terminal in response to a control signal.
8. The apparatus of claim 7 , wherein the selected voltage level is selected to correspond to a desired load current level based on a characterization of the solid-state switch.
9. The apparatus of claim 7 , wherein the solid-state switch has a gate terminal that is connected to the sense circuit to selectively turn on and off the solid-state switch.
10. The apparatus of claim 7 , wherein the solid-state switch is an enhancement mode MOSFET transistor.
11. An apparatus comprising:
a solid-state switch having source and drain terminals connected to switch a load current from a high voltage source through a high voltage load;
a sense circuit that senses a voltage between the source and drain terminals and turns off the solid-state switch when the voltage exceeds a selected voltage level; and
a diode coupled between a voltage sense terminal and the drain terminal, wherein the sense circuit comprises:
one of a control switch or diode that selectively connects a reference current to the voltage sense terminal in response to a control signal.
12. The apparatus of claim 11 , wherein the sense circuit further comprises:
a current source that generates the reference current.
13. An apparatus comprising:
a solid-state switch having source and drain terminals connected to switch a load current from a high voltage source through a high voltage load;
a sense circuit that senses a voltage between the source and drain terminals and turns off the solid-state switch when the voltage exceeds a selected voltage level;
a diode coupled between a voltage sense terminal and the drain terminal; and
a voltage reference connected in series with the diode, wherein a voltage drop across the voltage reference is set by at least one external thermistor.
14. A method, comprising:
closing a switch that switches a load current from a high voltage source through a high voltage load;
sensing, at a node, a voltage produced by the load current;
opening the switch when the voltage exceeds a selected voltage level;
coupling a programmable voltage reference and a diode in series between the node and a voltage sense terminal; and
adding temperature compensation to the programmable voltage reference to compensate for temperature sensitivity of the diode.
15. The method of claim 14 , further comprising:
selecting the selected voltage level to correspond to a desired load current level based on a characterization of the switch.
16. The method of claim 14 ,
wherein a voltage at the voltage sense terminal is compared to a reference voltage
and the switch is opened when the voltage at the voltage sense terminal exceeds the reference voltage.
17. The method of claim 16 , further comprising:
outputting a fault signal when the switch is opened.
18. The method of claim 14 , wherein the selected voltage level is selected to correspond to a desired load current level based on a characterization of the switch.
19. The method of claim 14 , wherein the switch has a gate terminal that is connected to selectively turn on and off the switch.
20. The method of claim 14 , wherein the switch is an enhancement mode MOSFET transistor.