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BIDIRECTIONAL CURRENT-SENSE AMPS INCLUDE MIDPOINT REFERENCE
SUNNYVALE, CA-May 27, 2002-Maxim Integrated Products introduces the MAX4069-MAX4072 low-cost, bidirectional, high-side current-sense amplifiers that include a precision reference to set the zero-current midpoint. The MAX4070, for example, has an internal 2.5V reference. The charging current has a 2.5V to VCC output voltage, with a 2.5V to ground discharge current. Measuring OUT with respect to REF continuously monitors the transition from charge to discharge and gives an accurate bidirectional output in a single-supply system. These parts are ideal for monitoring battery status in notebooks, cell phones, and other portable equipment.
The MAX4069-MAX4072 feature up to 24V input common-mode voltage range, low 100µA supply current, and a total output error of less than 1.5%. The wide 1.35V to 24V input common-mode range is independent of the supply voltage, ensuring that the current-sense feedback remains accurate even when connected to a battery pack in deep discharge.
To achieve maximum flexibility, an external current-sense resistor is used along with a gain-selectable pin to choose either 50V/V or 100V/V, allowing low, full-scale sense voltages of only 50mV or 75mV. The single output pin monitors both charge and discharge and avoids the need for a separate polarity output.
The MAX4069 has an adjustable reference voltage, the MAX4070 reference is 2.5V, the MAX4071 reference is 1.5V, and the MAX4072 has a pin for an external reference. All devices are specified for operation over the automotive temperature range (-40°C to +125°C). The MAX4069 comes in a 10-pin µMAX, while the MAX4070/MAX4071/MAX4072 are available in 8-pin µMAX or the 37% smaller, 8-pin QFN packages. Prices start at $0.95 (1000-up, FOB USA).
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