RC-triggered ESD power clamp circuit and method for providing ESD protection

An electrostatic discharge protection circuit comprising:

• an RC delay unit connected to a first voltage rail to produce an RC-based signal in response to an electrostatic discharge on said first voltage rail, said RC delay unit including an output to transmit said RC-based signal;
• and
• a plurality of clamping units, each of said clamping units being connected to said output of said RC delay unit to receive said RC-based signal, each of said clamping units comprising:
• a clamping transistor connected between said first voltage rail and a second voltage rail;
• and
• a control circuit connected to said clamping transistor, said control circuit including an enable switch, a disable switch and a latch having first and second terminals, said enable switch being connected to said first voltage rail and said first terminal of said latch, said disable switch being connected to said first voltage rail and said second terminal of said latch, said first terminal of said latch also being connected to said clamping transistor, said enable switch and said disable switch of said control circuit being configured to selectively connect one of said first and second terminals of said latch to said first voltage rail in response to said RC-based signal from said RC delay unit to selectively activate said clamping transistor to discharge said electrostatic discharge on said first voltage rail to said second voltage rail.

A method for providing electrostatic discharge protection comprising:

• producing an RC-based signal in response to an electrostatic discharge on a first voltage rail;
• connecting a control terminal of a clamping transistor to said first voltage rail through a first signal path using said RC-based signal, including activating an enable switch on said first signal path between said control terminal of said clamping transistor and said first voltage rail, such that said clamping transistor is activated to provide a conduction path from said first voltage rail to a second voltage rail through said clamping transistor;
• connecting a first terminal of a latch to said first voltage rail through a second signal path using said RC-based signal, including activating a disable switch on said second signal path between said first terminal of said latch and said first voltage rail, to produce a first signal at said first terminal of said latch;
• and
• producing a second signal at a second terminal of said latch connected to said first signal path and said control terminal of said clamping transistor in response to said first signal at said first terminal of said latch such that said clamping transistor is deactivated to disconnect said conduction path from said first voltage rail to said second voltage rail.