Tiny current-sense amplifier sets benchmarks for accuracy, power consumption

Sunnyvale, Calif. — Maxim Integrated Products has introduced the MAX9938, touted as the industry's smallest high-side, current-sense amplifier. Packaged in a 1 x 1 x 0.6-mm, 4-bump chip-scale package (UCSP), this device is 9x smaller than competitive SOT23 devices. The device integrates precision resistors to minimize total solution size, eliminating the need for two to three external gain-setting resistors. Maxim says the MAX9938 is 12% smaller than a single resistor.

Maxim's proprietary BiCMOS process technology enables the MAX9938 to achieve the industry's lowest quiescent-current consumption and highest accuracy. According to Maxim, competitive devices typically offer an input-offset voltage (Vos) of ±2 mV to ±5 mV and gain error of 2% to 5%, for a total error of 3% to 5%. In contrast, the MAX9938 features an ultra-low, ±0.5 mV (max) Vos and 0.5% (max) gain error, for a total error of less than 1% (max).

In addition, the MAX9938's low Vos allows the use of a lower full-scale Vsense voltage and, therefore, smaller Rsense resistor. This 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, Maxim said.

Designed for power-sensitive applications, the MAX9938 consumes an industry-low 1 microamp of quiescent current (IQ) and is designed to operate from a 1.6-V to 28-V input-voltage range. Applications include smartphones, digital cameras, PDAs, MP3 players, notebook computers, and other battery-operated devices.

The MAX9938 is offered in three voltage-gain versions (25V/V, 50V/V, and 100V/V). It is available in 4-bump UCSP and 5-pin SOT23 packages. All versions are fully specified for operation over the -40° to +85° extended temperature range.

Pricing: Starts at $0.64 (1000-up, FOB USA).
Product information: MAX9938

Maxim Integrated Products , 1-800-998-8800,

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