Battery manager saves space and power
28 May 2008
A single chip battery flyback battery charge and discharge manager is for high-reliability applications.
Linear Technology announces today the LTC4110 back-up system manager which has four operating modes: battery backup, battery charge, ‘no-loss’ battery calibration and shutdown. The single IC saves board space, which is significant as medical systems continue to decrease in size and increase in portability.
It provides a supply voltage to a system load from a main supply or battery and can also charge a battery to provide an uninterruptible power source. The IC can supply voltages above or below the input supply rail for the battery configuration to be optimised, independent of input supply.
The device’s PowerPath provides power to the system load and can charge the battery if required on a preferential or simultaneous basis. If the main supply fails, the battery can be used a power source through the low loss switches. The low loss battery calibration mode discharges the battery through a high-efficiency flyback converter into the system load, a feature claimed to eliminate wasted heat and energy. To preserve capacity, the shutdown mode disconnects the battery from the load. The end product can be shipped with a fully-charged battery with minimal drainage, claims the company.
Li-Ion, polymer, nickel and lead acid chemistries are supported and the device is compatible with super-capacitors. Multiple LTC4110s can be combined to form a redundant battery back-up system or increase the number of battery packs needed for longer back-up runtimes. Both standard and smart battery packs are supported.
An optional SMBus/I²C interface can be used to allow the host access to internal status and control the three GPIO pins. It also supports battery capacity and gas gauge calibration. The GPIO pins can be configures as status outputs on power-up.
Programmable charge/calibration current is up to 3A with +/- three per cent accuracy. Back up battery supply ranges from 2.7V to 19V with input supply of 4.5V to 19V. The device has over- and under-battery voltage protection, adjustable battery float voltage with precision charge of +/-0.5 per cent and optimal temperature-qualified charging with a thermistor input. During the no-heat calibration state, which maintains charge, the energy from the battery is sourced to the load rather than being dissipated as heat.
The device is supplied in a low profile, 0.75mm, 38pin 5mm x 7mm QFN package and guaranteed for -40°C to 85°C.
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