Product category: Analogue and Mixed Signal ICs
News Release from: Maxim Integrated Products | Subject: DS2756
Edited by the Electronicstalk Editorial Team on 05 June 2006
Fuel gauge gets the measure of Li-ion
batteries
A high-precision battery fuel gauge integrates precise current, voltage and temperature measurements along with nonvolatile data storage into one IC.
Dallas Semiconductor has released the DS2756, a high-precision battery fuel gauge that integrates precise current, voltage, and temperature measurements along with nonvolatile data storage into one IC The DS2756 contains three power states, including active, sleep, and a unique "suspend" mode
This article was originally published on Electronicstalk on 27 Aug 2002 at 8.00am (UK)
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Suspend mode allows the DS2756 to optimise its own current drain while other devices in the host enter low-power inactive states.
Suspend mode thus extends the battery and operational life of the host product.
Using suspend mode, the DS2756 remains in an ultra-low-power state while the host product is in a low-power operative state, such as standby.
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The DS2756 periodically cycles between suspend mode and active mode to measure current at a reduced supply as low as 10uA.
Cycling between these power states lets the DS2756 detect if the pack is being discharged or charged above programmable low-current suspend thresholds.
If the DS2756 detects either of these conditions, it sends a microcontroller or other pack circuitry a wake-up alert to begin normal active operation.
The DS2756 measures current, average current, and accumulated current.
Using a 20mW sense resistor, current accumulation is performed over a range of +/-3.2A.
An external filtering capacitor allows peak currents of higher values to be integrated in the current-accumulation (fuel-gauging) measurement.
Accumulated current is reported with an accuracy of +/-2% of reading, +/-3.9uV over a range of +/-64mV.
Standby currents are measured with an accuracy of +/-195uA.
Voltage is measured over a 0 to 4.75V range with a resolution of 4.88mV.
Temperature is measured over the entire operating range with a resolution of 0.125C.
If either the accumulated current or the temperature measurement exceeds user-programmed limits, the DS2756 sends an interrupt to the host processor to indicate that the event has occurred.
A unique "snapshot" mode allows both current and voltage measurements to be synchronised, so the DS2756 can obtain an instantaneous power measurement for a specific single event.
All measured data is stored in on-chip EEPROM or SRAM, and can reported to the host through the D2756's 1-Wire communication interface.
Typical applications for the DS2756 include handheld wireless products such as multimedia players, mobile phones, PDAs, and digital cameras.
The device is available in a tiny 8-pin TSSOP package, small enough to easily fit on the side of a Li-ion prismatic cell and thus, ideal for battery packs.
Prices start at $1.90 (1000-up, FOB USA).
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