Date: 22/01/2009

Current sense amplifier for precision monitoring of USB ports of battery operated electronics

Designed for battery-operated devices, current sense amplifier MAX9610 from Maxim Integrated Products uses a precision input stage to achieve an extended, 1.6V to 5.5V input common-mode range (battery voltage). This input range is suits very well for monitoring the current of a single-cell, lithium-ion (Li+) battery, which at full-charge is 4.2V, typically 3.6V in normal use, and less than 2.9V when ready to be recharged. Additionally, the MAX9610 provides an ultra-low, 1µA supply current to extend battery life, and a low 500µV (max) VOS and ±0.5% (max) gain error for maximum precision. Available in tiny µDFN and SC70 packages, this high-accuracy device is ideal for monitoring USB ports and single-cell, Li+ batteries in cell phones, PDAs, and other portable electronics.

The MAX9610 is a voltage-output device and is offered in three gain options: 25V/V, 50V/V, and 100V/V. An external sense resistor can be used to set the maximum sense voltage at full-scale battery load current. For example, at 2A, a sense resistor of 25m? will give a VSENSE of 50mV, and a gain of 50V/V will provide an output voltage of 2.5V, which is suitable for matching the input range of a typical ADC.

Fully specified over the -40°C to +85°C extended temperature range, the MAX9610 is available in ultra-small, 1mm x 1.5mm x 0.8mm, 6-pin µDFN and 5-pin SC70 packages. Prices start at $0.64 (1000-up, FOB USA)