ESD Shunt Circuit with Dual RC Blocks for Latch-Up Prevention
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Solution Overview
Problem
Existing ESD protection circuits can cause reliability issues during normal operation due to power-up conditions and high-frequency noise, leading to latch-up and potential damage to integrated circuits, as they either fail to efficiently handle current spikes or provide inadequate ESD protection.
Innovation Solution
A dual RC circuit approach is implemented, where a first RC block with a shorter time constant renders the shunt structure non-conductive during power-up or noise events, and a second RC block with a longer time constant keeps the shunt structure conductive during ESD events, utilizing ESD feedback and control logic to manage the shunt transistor's conductivity effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the shunt structure remains conductive during power-up, then ESD protection is maintained, but latch-up conditions occur causing circuit damage
Solution Approach 1:
The first RC block with shorter time constant preemptively disables the shunt structure during the power-up phase before ESD events can occur. This preliminary action prevents the harmful latch-up condition from developing, while the second RC block ensures the shunt structure becomes conductive again for ESD protection once power-up is complete.
Solution Approach 2:
The shunt structure's conductivity is dynamically controlled based on operational phase. During power-up, it is rendered non-conductive to prevent latch-up damage. During ESD events, it becomes conductive to provide protection. This dynamic control eliminates the harmful effect while maintaining the protective function.
2Object-affected harmful factors
If the shunt structure is rendered non-conductive during power-up, then latch-up is prevented, but ESD protection is compromised
Solution Approach 1:
The circuit is segmented into two RC blocks with different time constants that work in sequence: the first RC block temporarily disables the shunt during power-up to prevent latch-up, while the second RC block subsequently enables it for ESD protection. This segmentation allows both objectives to be achieved at different time intervals.
Solution Approach 2:
The first RC block performs a preliminary action of disabling the shunt structure during power-up to prevent latch-up. After this preliminary phase completes, the second RC block takes over to enable the shunt structure for ESD protection, ensuring both latch-up prevention and ESD protection are achieved through sequential actions.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution eliminates latch-up conditions and reduces the risk of chip damage from power rail to ground shortages during power-up, while providing efficient ESD protection by ensuring proper current handling and energy discharge during ESD events.
Implementation Method 1
Integrated circuit pins are susceptible to receiving electrostatic discharge (ESD) pulses during the assembling process
Data Source
AI summary
A method and integrated circuit renders a shunt structure non-conductive during a power up event or noise event for and in addition, during an electrostatic discharge event, keeps the shunt structure conductive for a period of time to discharge electrostatic energy through the shunt structure. In one example, a shunt structure, such as a transistor, is interposed between a power node and a ground node. Circuitry is operative during a power up event or noise event, to render the shunt structure non-conductive for a period of time during the power up event or during the noise event (when power is applied). Second circuit is operative, during an electrostatic discharge event, to keep the shunt structure conductive for a period of time to discharge electrostatic energy through the shunt structure. In one example, a plurality of resistor/capacitors (RC) circuits are utilized wherein the RC circuits have different time constants. In addition, an ESD feedback circuit is employed in conjunction with control logic to suitably control the ESD control logic during an ESD event. Circuitry is also used during a power up event to render the shunt structure non-conductive.