General Description

The MAX9928/MAX9929 low-cost, uni-/bidirectional, high-side, current-sense amplifiers are ideal for monitoring battery charge and discharge currents in notebooks, cell phones, and other portable equipment. These devices feature a wide -0.1V to +28V input common-mode voltage range, low 20μA supply current with VOS less than 0.4mV, and a gain accuracy better than 1.0. The input common-mode range is independent of the supply voltage, ensuring that the current-sense information remains accurate even when the measurement rail is shorted to ground.

The MAX9928F features a current output with a transconductance ratio of 5μA/mV. An external resistor converts the output current to a voltage, allowing adjustable gain so that the input sense voltage can be matched to the maximum ADC input swing. The MAX9929F has a voltage output and integrates a 10kΩ output resistor for a fixed voltage gain of 50V/V.

A digital SIGN output indicates direction of current flow, so the user can utilize the full ADC input range for measuring both charging and discharging currents.

Features

? Wide -0.1V to +28V Common-Mode Range, Independent of Supply Voltage

? 2.5V to 5.5V Operating Supply Voltage

? 20μA Quiescent Supply Current

? 0.4mV (max) Input Offset Voltage

? Gain Accuracy Better than 1 (max)

? SIGN Output Indicates Current Polarity

? Transconductance and Gain Versions Available

?? 5μA/mV (MAX9928F)

?? 50V/V (MAX9929F)

? Pin Compatible with the MAX4372 in UCSP

? Available in Ultra-Small, 3x2 UCSP (1mm x 1.5mm) and 8-Pin μMAX Packages

Applications

? Monitoring Charge/Discharge Currents in Portable/Battery-Powered Systems

? Notebook Computers

? General-System/Board-Level Current Monitoring

? Smart-Battery Packs/Chargers

? Precision Current Sources

? Smart Cell Phones

? Super Capacitor Charge/Discharge

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