Hi I am working on a design which has  LT6106 current sense amplifier where the VCC is 5V and IN  and IN- is 12V. Device is working now and I want to understand if the internal ESD structure of the IC are specialised enough for this application a

Hi Manoj, 

According the Absolute Maximum ratings of the LT6106, the inputs need to be kept within the supplies. 

The AD8211 is pin compatible and looks like it could work in your configuration. Unlike the LT6106 though, its gain is fixed to 20V/V. What current are you trying to sense? Could you provide more details about your application so I can check to see whether this device suits your purposes?

Thanks, 

Kris

Hi Krisf,

Thanks for the response.

I have 12V which is generated from a source for the DIMM connectors on the boards. I am monitoring this power using a current monitoring device also parallely I have connected the LT6 device for sensing the current. Output is sensed by a Phase controller which in turn controls a voltage regulator which generates required DDR voltages (VDDQ) . I have set the gain of LT6 device as 20 itself.

Hi Shenoy, 

Thanks for the information. I would check the specifications to make the accuracy works for you, but I've confirmed that the AD8211 should work in your application. You'll need to remove Rout on your configuration. 

Thanks, 

Kris 

Hi Krisf,

Meanwhile on one of the board I tried connecting 12V on the VCC pin isolating the 5V rail. Now the VIN+, VIN- and VCC are at 12V. I should be getting in the range of .8V output. While simulating in Spice I got around 0.7V but I am getting around 3.2V on the VOUT pin when I probed on board. Maximum Voltage swing on that pin is 1.4V as per datasheet. So little confused on how it is producing 3.2V after correcting the VCC. Is it because device is already gone bad due to initial conditions? Have you faced something similar ?

Thanks

Shenoy

Hi Shenoy, 

Are you still talking about the LT6106?

If so, and the IN+ and IN- pins were set to voltages outside of the supply, there is a high likelihood that the amplifier was damaged because the absolute maximum ratings were violated. 

If you're able to check the supply current to see if it is still within spec, that would be a good indication of whether the part is really still good or not. 

Thanks, 

Kris

Hi Krisf,

Yes I am talking about LT61606.

I checked the current and its close to 200uA which is a little above the limit. Assuming the device has gone bad. but here my another doubt is since we assume now the device has gone bad It hasn't made any catastrophe to the system or any other power rails ! ( I thought either 5V rail or 12V rail might cause some short issue) . Do you know any reason behind it?

Regards

Shenoy