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