Other Parts Discussed in Thread: TLV61046
Good morning....
I need some help solving an issue. I am using the above subject which then drives an LDO that then ultimately supplies power to a two wire current sensor. The sensor is fed through a two block amp design (1st stage is resistor of 6.34 ohms and diff amp with gain of x200, second stage is a gain of 10). The ultimate voltage on the sensor is 15.8V and the load is light 3.5mA. Unfortunately light load puts the boost into burst mode. This burst mode frequency (~38kHz) propagates through the linear onto the sensor. FFT and time domain both support this theory. The burst switching freq is about 25dB above the noise floor. I need the design to be wide bandwidth (25kHz). I do have a differential filter on the front end of the diff amp but this doesn't help remove the noise. If I remove the switcher and drive the LDO from a linear bench supply the interfering signal goes away. Is there someone I can send dwgs to offline for recommendations on what I can do to remove this? My PCB is single sided with ground pours on both sides and vias all over connecting the two....I place power supplies on lower side of the top side and amplifier design on upper side of the top side AND put a large cutout between the sections trying to keep the switching noise contained.
Thanks
Steve
