Current-Sense Amplifier

Maxim Integrated Products introduces the MAX9938, a high-side, current-sense amplifier. It integrates precision resistors to minimize total solution size, eliminating the need for external gain-setting resistors.

 The MAX9938 features a ±0.5mV (max) VOS and 0.5% (max) gain error, for a total error of less than 1% (max). Additionally, the MAX9938's low VOS allows the use of a lower full-scale VSENSE voltage and, therefore, smaller RSENSE resistor. The device thus minimizes voltage-drop loss in the line and power dissipation in the sense resistor, which otherwise could create a hot spot behind the LCD display of a notebook computer.

Summary of MAX9938 key features

    1µA (max) supply current
    ±0.5mV (max) input-offset voltage
    Less than 0.5% (max) gain error
    Less than 1% (max) total error
    1mm x 1mm x 0.6mm, 4-bump UCSP or 5-pin SOT23 package

The MAX9938 is offered in three voltage-gain versions (25V/V, 50V/V, and 100V/V). All versions are fully specified for operation over the -40°C to +85°C extended temperature range. Prices start at $0.64 (1000-up, FOB USA).