Current sense amp offers adjustable fault flags

When connected to a current shunt resistor, the amplifier is designed to extract the shunt voltage, amplify it and translate it to ground. This output is available for monitoring and can be connected to either of the on-chip comparators. The LT6109 is targeted at current measurement and load current fault monitoring. It has less than 350µV of offset and the combined threshold error of the comparators and reference is said to be less than 2%. From the input of the amplifier to the output of the comparators, the LT6109 responds to threshold exceeding events within 1.4µsec. External resistors set the amplifier gain and comparator trip points. The gain resistors are the primary determinants of the amplifier's accuracy. Two versions of the LT6109 are available; the LT6109-1 and the LT6109-2. The comparator inputs of the LT6109-1 are connected to the internal reference in opposing polarity, allowing for window comparison such as for overcurrent and undercurrent conditions. The comparator inputs of the LT6109-2 are connected in the same polarity, allowing for two threshold levels, such as 'warning' and 'emergency disconnect'. The open drain outputs are designed to ensure easy interface to other system components and comparator latching is said to enable detection of high speed events. The LT6109 is fully specified for operation from –40 to 125°C and is available in a small 10-lead MSOP. "The LT6109 is not simply an integration of separate devices," said Kris Lokere, design manager for Linear Technology. "Each element offers outstanding performance, and in combination, this part sets a new standard in current monitoring."