I have a question about the amount of current sink by the input pin (pin 16) on LTC1564 low pass filter. I measured 25 mA current on the input pin. I would like to know if that is normal. Thanks in advance!
Hi Cindy,May I know what your input voltage is? Where does it came from? Do you measure the 25mA continuously during operation? This might be a power-up latch-up. This usually happens in dual-supply operation when one supply comes up first than the other supply.Regards,Goz
I am so sorry, the chip I used to breadboard was a bad one. Today I change a new chip, now the input current is normal. I measure 22 mA on the power pin, I think this matches what is says on the datasheet (25 mA when input is 0V). This chip warms up in a few minutes. The temperature on this chip increases around 20 degree F after running a few minutes in room temp. I would like to ask is this the normal phenomenon for LTC1564?
Hi Cindy,Did you mean 20 degrees C? This is normal for most of the parts. The silicon within the package heats up when powered on. Just make sure that you do not violate the maximum ratings for your device to run properly.You can compute the junction temperature with the formula below:
substituting the values from the datasheet at no load and room temp condition,
Isy = 25mAVsy = +5VTj = 25C + (10V)(25mA)(130C/W)Tj = 57.5CLet me know if this helped.Regards,Goz
Thanks for your help. That helped a lot.