Adaptable electrostatic discharge clamp trigger circuit
An apparatus includes one or more circuits configured to control an Electrostatic Discharge (ESD) clamp device. The one or more circuits include a Resistor-Capacitor (RC) delay portion, a pull-up device, a pull-down device and a discharge pathway. The RC delay portion is configured to control the pull-up device. The pull-up device is connected to a control node of the pull-down device to control the pull-down device. The pull-down device is configured to control the ESD clamp device. The discharge pathway is connected to the control node of the pull-down device to discharge the control node in non-ESD conditions.
1 . An apparatus comprising:
one or more circuits configured to control an Electrostatic Discharge (ESD) clamp device, the one or more circuits including a Resistor-Capacitor (RC) delay portion, a pull-up device, a pull-down device, a capacitor and a discharge pathway, the RC delay portion is configured to control the pull-up device, the pull-up device is connected to a control node of the pull-down device to control the pull-down device, the pull-down device is configured to control the ESD clamp device, the capacitor is connected between the control node of the pull-down device and ground and the discharge pathway is connected in parallel with the capacitor between the control node of the pull-down device and ground, the discharge pathway is formed of one or more depletion-mode devices configured to discharge the control node in non-ESD conditions, each depletion-mode device having a negative threshold voltage.
2 . The apparatus of claim 1 , wherein one or more depletion-mode devices of the discharge pathway includes a depletion-mode Metal Oxide Semiconductor (MOS) device that has a source and a gate that are connected to ground.
3 . The apparatus of claim 1 , wherein the discharge pathway includes a plurality of depletion-mode MOS devices connected in series, each depletion-mode MOS device having a source connected directly to a gate.
4 . The apparatus of claim 1 , wherein the RC delay portion includes a resistor connected in series with a capacitor, the resistor and the capacitor connected to a control node of the pull-up device such that an ESD voltage across the resistor and the capacitor in series causes an increase in voltage of the control node that turns on the pull-up device.
5 . The apparatus of claim 4 , wherein the pull-up device is connected to the control node of the pull-down device such that turning on the pull-up device causes the pull-down device to turn on.
6 . The apparatus of claim 1 , wherein the discharge pathway has an impedance configured to enable the discharge pathway to pull-down voltage of the control node such that voltage of the control node of the pull-down device remains low during non-ESD conditions without significantly affecting voltage of the control node during ESD conditions.
7 . The apparatus of claim 6 , wherein the impedance is configured such that during an ESD event, the pull-up current is unaffected by the discharge pathway, the discharge pathway does not sink the pull-up device current and the voltage of the control node of the pull-down device increases.
8 . The apparatus of claim 1 , wherein the RC delay portion, the pull-up device, the pull-down device and the discharge pathway are in a first stage of an ESD clamp control circuit, the pull-down device is configured to provide an output of the first stage, the ESD clamp control circuit further includes a second stage between the output of the first stage and the ESD clamp device and the second stage includes an inverter portion such that an output of the second stage is an inverse of the output of the first stage.
9 . The apparatus of claim 8 , wherein the second stage further includes one or more depletion-mode MOS devices connected to the output of the inverter portion to discharge the output of the inverter portion in non-ESD conditions.
10 . The apparatus of claim 8 , wherein the second stage further includes a bypass capacitor, a first electrode of the bypass capacitor connected to an input terminal of the ESD clamp control circuit and a second electrode of the bypass capacitor connected to the output of the second stage.
11 . The apparatus of claim 8 , further comprising a second RC delay portion in the second stage, the second RC delay portion including a resistor connected in series with a capacitor, the resistor and the capacitor connected to an input of the inverter portion.
12 . The apparatus of claim 8 , further comprising at least one additional node that is connected to a first input terminal by an additional transistor and is connected to a second input terminal by an additional capacitor, a control gate of the additional transistor is connected to the output of the second stage.
13 . A method implemented in an Electrostatic Discharge (ESD) clamp control circuit that includes a pull-up device having a first terminal connected to a supply voltage and a second terminal connected to a control node of a pull-down device that controls switching of the clamp control circuit, the method comprising:
when the supply voltage is in a non-ESD range and the pull-up device is off, sinking a first current through one or more depletion-mode Metal Oxide Semiconductor (MOS) devices connected to the control node of the pull-down device to ensure that the voltage of the control node of the pull-down device is substantially stable, each depletion-mode MOS device having a negative threshold voltage; and
when the supply voltage is in an ESD range, sinking a second current through the one or more depletion-mode MOS devices such that the second current is less than a current through the pull-up device and the voltage of the control node of the pull-down device increases, the second current is the saturation current of the one or more depletion-mode MOS devices.
14 . The method of claim 13 , further comprising delaying a control signal to the pull-up device through a Resistor Capacitor (RC) delay portion.
15 . The method of claim 14 , further comprising inverting an output of the pull-down device to generate a control signal to control the ESD clamp.
16 . A data storage system comprising:
a plurality of nonvolatile memory cells;
one or more control circuits connected to the plurality of nonvolatile memory cells, the one or more control circuits having a power input terminal;
an Electrostatic Discharge (ESD) clamp device connected to the power input terminal to discharge an ESD voltage on the power input terminal; and
means for controlling the ESD clamp device by discharging a node under non-ESD conditions through a depletion-mode transistor that has a negative threshold voltage and has a gate connected to a source to maintain the node in a first voltage range and by enabling voltage at the node to rise to a second voltage range under ESD conditions.
17 . The data storage system of claim 16 , wherein the plurality of nonvolatile memory cells are located on a memory die and the one or more control circuits, the ESD clamp device and the means for controlling the ESD clamp device are located on a control die.
18 . The data storage system of claim 17 , wherein the power input terminal is configured to receive a power input at a supply voltage that is less than 0.8 volts.
19 . The data storage system of claim 18 , wherein the ESD conditions include a voltage of more than 300 volts at the power input terminal.
20 . The data storage system of claim 16 , wherein the means for controlling the ESD clamp device by discharging the node is in a first stage of an ESD clamp control circuit, the ESD clamp control circuit further includes a second stage between an output of the first stage and the ESD clamp device and the second stage includes an inverter portion such that an output of the second stage is an inverse of the output of the first stage, the data storage system further includes at least one additional node that is connected to a first input terminal by an additional transistor and is connected to a second input terminal by an additional capacitor, a control gate of the additional transistor is connected to the output of the second stage.