My customer verify surge for input pin of AD8418.
Is it DC or transient voltage, may not cause permanent damage to the product?
ABSOLUTE MAXIMUM RATINGS for Input Voltage Range −4 V to +85 V survival.
How big is the measured overvoltage on the input pin?
Thank you for quick reply.
My customer want to know survival input voltage of -4V is DC or transient.
If it is transient, then how long the time of survival voltage?
The customer understood meaning of ABSOLUTE MAXIMUM RATINGS.
If the overvoltage excess -4V, then they will use external clamp Di.
The system surge voltage is +/-300V while few ms, but they have not finished measureed INPUT pin voltage in thier board.
The -4V to 85V is a survival rating for DC voltages. Use of the part beyond this voltage will cause permanent damage to the device.
Thank you so much.
It's very helpful information for us and customer.
I hope it is reflect to datasheet update next time.
For transient voltages, we can deduce what transient voltages the devices can survive by checking their ESD ratings. Below are the ratings (highest pass voltages) for each device:
HBM (Human body model) simulates the discharge from a human body to the device and is characterized by fast rise times. UG-311 provides a timing diagram of the ESD discharge for this model, given below:
From this, we can deduce that the AD8418 can handle a 3500V transient of about 150ns duration, while the AD8418A can handle 2000V of the same duration.
The FICDM model simulates charge buildup on the device and discharged from any one of the inputs to ground. The timing diagram for FICDM is provided below:
As you can see, the model is characterized by a much faster peak, about 1.23ns in the figure. Both devices can survive to 1250V.
MM (machine model) simulates the discharge due to different automated machines. The model corresponds to a non-realistic worst-case human body model, but is still tested. The MM simulation is highly correlated to the HB model, however the waveform for MM is more oscillatory than HBM. Unfortunately, I do not have a waveform to provide, but the time duration is around 75ns for MM. Due to its oscillatory nature though, the voltage "looks" to be applied for a longer time, which is why it passes at a lower voltage. However, as the HBM model is more widely accepted as a realistic ESD model, I would tend towards the HBM spec.
I hope this helps.
The information that Kris provided is a good start for initial indications of transient survival, however the durations and voltages only directly predict application survival if they applied with a capacitor and a through a source impedance matching the test conditions for each test. For sure, +/-300V for several ms, directly applied to inputs with a low source impedance, will break the AD8418A. If the +/-300V is applied with a 100pF cap, with a source impedance of 1.5kOhms, then the AD8418A's survival would likely match the HBM ESD results.
Hello Kris & Paul
Thank you so much good infomation.
And I'm so sorry too late may response, bucause I'm business traveling this week.
It is very helpfull for us to customer support and also for our knowledges..
My understanding for AD8418 is more deeper.
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