Texas Instruments Corporation

Motorola Corporation

Freescale Semiconductor,inc.

Nxp Usa, Inc.

Cynthia Ann Torres

James W Miller

Troy L Cooper

Timothy Alan Rost

Kyle Clifton Schulmeyer

Lloyd P Matthews

Senthil Kumar Sundaramoorthy

Victor James Nuss

Electrostatic discharge (ESD) protection circuitry in an integrated circuit is provided. The protection circuitry includes a trigger circuit coupled between a first power supply bus and a second power supply bus. A delay circuit is coupled to receive an output signal from the trigger circuit. The delay circuit includes a first inverter coupled to the input of the delay circuit and a feedback transistor having a control terminal coupled to the output of the delay circuit, a first current electrode coupled to the first power supply bus, and a second current electrode coupled to the output of the first inverter. A clamp driver circuit is coupled to the output of the delay circuit.

ESD protection circuit having clamp control loop

ESD protection apparatus disclosed herein include an ESD trigger circuit to sense the occurrence of an ESD event and an ESD discharge device to provide a low impedance path to ground through which to discharge energy associated with the ESD pulse. Some embodiments also include a VDD turn-on clamp to prevent the ESD discharge device from switching to a conductive state during a VDD power-on event. Some embodiments further include a VDD glitch clamp to prevent a switching pulse triggered by a transient disruption in the VDD supply from propagating to the ESD discharge device and causing the ESD discharge device to conduct in the absence of an ESD event.

Electrostatic discharge protection apparatus

An electrostatic discharge (ESD)-triggered protection apparatus includes a first circuit and a second circuit. The first circuit includes an ESD trigger circuit to sense an ESD pulse and to generate a switching pulse responsive to the ESD pulse; a first ESD discharge device communicatively coupled to the ESD trigger circuit and responsive to the switching pulse to transfer a current generated by the ESD pulse to the ground rail; a control circuit that generates a control signal in response to the switching pulse. The second circuit includes at least one trigger cell buffer that is configured to receive the control signal and to control a second ESD discharge device such that the current generated by the ESD pulse is transferred to the ground rail.

A circuit implements a method to adjust input/output (I/O) characteristics of an I/O pad circuit () depending upon which value of an I/O supply voltage is used within a range of supply voltages. An I/O supply voltage being supplied to the pad circuit is detected by detecting () its value relative to a known reference (). Portions of the I/O pad circuit are selectively enabled in response to the detected I/O supply voltage. By selecting the ratio of P-channel and N-channel transistors, physical characteristics of the circuit are controlled. Examples of the controlled physical characteristics include slew rate, signal rise and fall times, and duty cycle control which is controlled by forcing all rising and falling edges to have a midpoint at the same point in time. Therefore a same I/O pad circuit may be optimally used in numerous applications regardless of the supply voltage value.

Method and circuit for maintaining I/O pad characteristics across different I/O supply voltages

A circuit (100) ensures electrostatic discharge (ESD) protection during an ESD event. The ESD circuit (100) has a current shunting device (135), a RC trigger circuit (125) and a RC delay circuit (130). The shunting device (135) is connected between two IC power supply rails, and provides the primary current path for a positive ESD event referenced from one power supply rail (V.sub.DD 105) to the other (V.sub.ss 110). The trigger circuit (125) initially activates the shunting device into a low resistance conductive state in response to an ESD event. The RC delay circuit (130) serves to maintain the shunting device in the conductive state, initially produced by the trigger circuit (125), for the remaining duration of the ESD event. A large capacitor required to achieve the delay time in this RC circuit may be eliminated by utilizing the gate-to-body capacitance in the existing shunting device (135).

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Austin, TX, United States of America

Cynthia Ann Torres