single event latch up and how it can be prevented
TRANSCRIPT
Single-Event latch up and how it can be prevented
By: Zulkifli Abdul Aziz Satellite hardware design
Email: [email protected] Website: www.cubesatpro.com
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Problem StatementAll electronics equipment/component such as an onboard computer (OBC) in the spacecraft will at some point encountered a single event latch-up (SEL) effects caused by heavy ions or protons from cosmic rays or solar flares during it operation. The effect can be very minimal and the effect could potentially get harsh until it can introduce high current on the electronic board (You can find more details about SEL online). These frequent activities on the high current will cause the performance of the OBC to degrade and slowly leave permanent damage to the OBC. But how we deal with it?
What is LATCH-UPMore specifically it is the inadvertent creation of a low-impedance path between the power supply rails of a MOSFET circuit, triggering a parasitic structure which disrupts proper functioning of the part and possibly even leading to its destruction due to over-current. A power cycle is required to correct this situation.
The parasitic structure is usually equivalent to a thyristor (or SCR), a PNPN structure which acts as a PNP and an NPN transistor stacked next to each other.
During a latch-up when one of the transistors is conducting, the other one begins conducting too. They both keep each other in saturation for as long as the structure is forward-biased and some current flows through it - which usually means until a power-down. The SCR parasitic structure is formed as a part of the totem-pole PMOS and NMOS transistor pair on the output drivers of the gates.
Possible thing that could happen to your spacecraft electronic board
High current (Intermittent or Permanent)
Satellite electronic board current has to reset manually
Satellite electronic board not capable to restore the current to the nominal state automatically
Long term effect on the high current can cause permanent damage to the satellite electronic board
How to deal with SELThe Latch up Protection circuit was designed to provide current limiting to the device, detect the increase in current during the SEL event above a preset threshold, force a shutdown when the threshold is exceeded, hold the device in the shutdown mode for a preset time interval, and return the device's supply voltage to its original operating level.
Requirement for Protection Circuit
To eliminate the issue with high current by limit the current flow to the OBC.
To enhance the capability, a protector that can prevent excessive voltage and current flow to the OBC will be designed.
A protector is capable automatically restore the nominal level after detecting the high current.
To design in such that the protector that can protect itself from the excessive latch-up
Comparison spacecraft electronic board design with and without protection circuit
Without Protection With Protection
Thermal Protection ✘ ✔
under voltage protection ✘ ✔
Over-voltage protection ✘ ✔
Over-current protection ✘ ✔
Voltage & Current telemetry ✔ ✔
Manual reset ✔ ✔
Auto reset ✘ ✔
Micro-switch as a protection circuit?
There are various type of switches that is available in the market nowadays that you can simply use as a protection circuit.
Some of the components that you can use as follows;
Analog Devices- For example ADM1191, ADG4613 Texas Instruments - for example TPS201x family Linear Technology - for example LTCR4361
Important FACT!Before the selection of specific components can be made, the skills and knowledge of the selection process are very important. This ensures that the selected components can be used in harsh environment (space). Criteria for what is needed to ensure proper component selection will be discussed later. follow and like our page to find out more. For the time being. Stay tuned!
Reference
Useful link to find out more
SEU and Latchup Tolerant Advanced CMOS Technology
Latch-up, ESD, and Other Phenomena
Radiation Owners Manual
Latch-Up
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By: Zulkifli Abdul Aziz Satellite hardware design
Email: [email protected] Website: www.cubesatpro.com
Click here for my page