LP3996: Alternate part to LP3996 with the same pinout

Sir, I need (POR) power on the reset option also.

Hi Murthy,

Unfortunately we don't have any other devices with the same pinout that also have POR feature. 

Regarding the damaged parts the most common sources of damage are Abs Max violations and ESD which exceeds the ratings of the part. Eliminating those should eliminate the failures since each device is tested before shipping from TI. 

Hi Sir,
Can you suggest TVS Diode or Protection circuit for this IC
LP3996SD/X-3333/NOPB at input & output?
I have tested without load, after multiple turns on's it got damaged.

Hi Murthy, 

What does the voltage look like during these tests? We do not specify what components a customer should use, but generally if you select protection components that keep the voltage within the abs max values there shouldn't be any issues. 

Depending on the type of voltage excursion you are seeing will dictate what sort of protection topology you need.  

Dear Sir,

Sometimes we are getting 3.3V DC and Sometimes 5V DC.
Continuously we are getting low high signals on POR.
Can you please suggest, How to resolve this?

Regards
Murthy

Hi Murthy, 

As mentioned previously you will need to look at scope shots to determine how you are damaging the LDO. Without scope shots you will be guessing and so would I so I can't provide any further guidance without seeing test data. 

Dear Sir,

Please find the attached scope waveforms of input Voltage and 2 channels output voltages.

Please note that
1. I have not noticed any peak voltages at the input.
2. Output is connected to 220E load in both channels.

Please find the attached schematic for your reference.

Please guide me, How to resolve this issue?
Your earliest reply will be highly appreciated.

Regards
Murthy

Hi Murthy,

This shows a DC condition, what about startup, shutdown, and load transients? All those conditions need to be evaluated since those are the cases that most problems in systems cause a spike or exceed abs max or cause reverse current  (Vout>Vin+0.3V). 

When you say the output is connected to a 220E load, what is that? Is that an electronic load or is it a 220 Ohm resistor to GND? 

If it is an electronic load then it is critical to make sure the e-load doesn't pull the output voltage negative, e-load pull a set amount of current regardless of the output voltage. So if the load is on before the LDO turns on or after it turns off that could easily damage the LDO.

Sir, the Pink waveform is measured on POR in the image attached above, May be because of Internal FET is ON.
It is staying continuously low.
But I observed sometimes the internal MOSFET turns OFF, at that time we are getting a proper output voltage of 3.3V DC.

Now I am getting output 5V DC, after feeding the Input Volatge:5 VDC.
Does it work, If I feed 3.3V DC Input?
If I get the same 3.3V DC at the output. But I need POR should work properly.