Electrostatic discharge trigger circuit using voltage detection circuit to detect occurrence of electrostatic discharge event and associated method
An electrostatic discharge (ESD) trigger circuit includes a voltage detection circuit and a trigger circuit. The voltage detection circuit is used to detect occurrence of an ESD event on an ESD-protected supply voltage according to the ESD-protected supply voltage and an additional supply voltage, and assert an enable signal in response to the ESD event being detected on the ESD-protected supply voltage, wherein the additional supply voltage is independent of the ESD-protected supply voltage. The trigger circuit is used to control activation of ESD protection for the ESD-protected supply voltage according to the enable signal.
1. An electrostatic discharge (ESD) trigger circuit comprising:
a voltage detection circuit, arranged to detect occurrence of an ESD event on an ESD-protected supply voltage according to the ESD-protected supply voltage and an additional supply voltage, and assert an enable signal in response to the ESD event being detected on the ESD-protected supply voltage, wherein the additional supply voltage is independent of the ESD-protected supply voltage; and
a trigger circuit, arranged to control activation of ESD protection for the ESD-protected supply voltage according to the enable signal;
wherein the voltage detection circuit comprises:
a reference voltage generator circuit, arranged to generate a reference voltage according to the additional supply voltage; and
a voltage comparator circuit, arranged to set the enable signal by comparing an input voltage and the reference voltage, wherein the input voltage is derived from the ESD-protected supply voltage.
2. The ESD trigger circuit of claim 1 , further comprising:
a frequency detection circuit, arranged to detect occurrence of another ESD event on the ESD-protected supply voltage according to a time-domain change of the ESD-protected supply voltage, and assert the enable signal in response to said another ESD event being detected on the ESD-protected supply voltage;
wherein the enable signal is jointly controlled by the voltage detection circuit and the frequency detection circuit.
3. The ESD trigger circuit of claim 1 , wherein the input voltage is directly set by the ESD-protected supply voltage.
4. The ESD trigger circuit of claim 1 , wherein the voltage detection circuit further comprises:
a voltage divider circuit, arranged to generate a divided voltage according to the ESD-protected supply voltage, and output the divided voltage as the input voltage.
5. The ESD trigger circuit of claim 4 , wherein the voltage divider circuit is further arranged to receive the enable signal via a feedback path between the voltage comparator circuit and the voltage divider circuit, and adjust a divider ratio of the divided voltage to the ESD-protected supply voltage in response to the enable signal being asserted.
6. An electrostatic discharge (ESD) triggering method comprising:
detecting occurrence of an ESD event on an ESD-protected supply voltage according to the ESD-protected supply voltage and an additional supply voltage, wherein the additional supply voltage is independent of the ESD-protected supply voltage;
asserting an enable signal in response to the ESD event being detected on the ESD-protected supply voltage; and
controlling activation of ESD protection for the ESD-protected supply voltage according to the enable signal;
wherein detecting the occurrence of the ESD event on the ESD-protected supply voltage according to the ESD-protected supply voltage and the additional supply voltage comprises:
generating a reference voltage according to the additional supply voltage; and
setting the enable signal by comparing an input voltage and the reference voltage, wherein the input voltage is derived from the ESD-protected supply voltage.
7. The ESD triggering method of claim 6 , further comprising:
detecting occurrence of another ESD event on the ESD-protected supply voltage according to a time-domain change of the ESD-protected supply voltage;
wherein the enable signal is jointly controlled by detecting the occurrence of said another ESD event on the ESD-protected supply voltage according to the time-domain change of the ESD-protected supply voltage and detecting the occurrence of the ESD event on the ESD-protected supply voltage according to the ESD-protected supply voltage and the additional supply voltage.
8. The ESD triggering method of claim 7 , wherein detecting the occurrence of the ESD event on the ESD-protected supply voltage according to the ESD-protected supply voltage and the additional supply voltage further comprises:
directly setting the input voltage by the ESD-protected supply voltage.
9. The ESD triggering method of claim 7 , wherein detecting the occurrence of the ESD event on the ESD-protected supply voltage according to the ESD-protected supply voltage and the additional supply voltage further comprises:
generating a divided voltage according to the ESD-protected supply voltage; and
outputting the divided voltage as the input voltage.
10. The ESD triggering method of claim 9 , wherein generating the divided voltage according to the ESD-protected supply voltage comprises:
adjusting a divider ratio of the divided voltage to the ESD-protected supply voltage in response to the enable signal being asserted.