The DS2770 battery monitor and charge controller performs several functions needed for thorough battery maintenance. When used in conjunction with the host system's processor, a battery-pack resident DS2770 may be utilized for applications that include charging, remaining capacity estimation, safety monitoring, and nonvolatile (NV) parametric storage.
The DS2770 provides a unique ID, a digital temperature sensor, an analog-to-digital (A/D) converter that measures battery voltage and current, an integrated current accumulator that keeps a running total of all current entering and leaving the battery, an elapsed time meter, NV memory for storage of important parameters, and an integrated charge controller supporting rechargeable lithium (including lithium-ion and lithium-ion polymer) and nickel metal hydride (NiMH) batteries. Current measurement can be accomplished through the use of an integrated 25mΩ sense resistor or through an external sense resistor. The resolution of the current, voltage, and temperature measurements is sufficient for process monitoring applications such as battery-charge control and safety. The charge-control technique is user-selectable to support either pulse charge for rechargeable lithium or dT/dt termination for NiMH. Additionally, programmable charge timers and low-battery recovery are provided for safety and convenience.
Information is sent to/from the DS2770 over a 1-Wire® interface so that only one wire (and ground) needs to be connected from a processor to a DS2770. This means that DS2770-equipped battery packs need only four output connectors: battery power, charge source, ground, and the 1-Wire interface. Each device has a factory-programmed 64-bit net address that allows it to be individually addressed by the host system.
Two types of memory are provided on the DS2770 for battery information storage: lockable EEPROM and SRAM. EEPROM memory saves important battery data in true NV memory that is unaffected by severe battery depletion, accidental shorts, or ESD events and becomes ROM when locked to provide additional security for unchanging battery data. SRAM provides inexpensive storage for temporary data.
Key Features
Applications/Uses
Integrated charge controller supporting both rechargeable lithium and NiMH battery technologies
Available in two configurations:
Internal 25mΩ current-sense resistor
External user-selectable sense resistor
Current measurement:
15-bit bidirectional measurement
Internal sense resistor configuration:
62.5µA LSB and ±2A dynamic range
External sense resistor configuration:
1.56µV LSB and ±51.2mV dynamic range
Current accumulation
Internal sense resistor: 0.25mAh LSB
External sense resistor: 6.25µVh LSB
Voltage measurement with 4.88mV resolution
Temperature measurement using integrated sensor with 0.125°C resolution
40 bytes of lockable EEPROM
16 bytes of general-purpose SRAM
42 day timer
Dallas 1-Wire interface with 64-bit ID providing nonambiguous device identity
Download
E-Mail