Unique Safety IC From Philips Semiconductors Protects LiIon Battery Packs Against Fault Conditions and Misuse

Business Wire, Oct 13, 1997

SUNNYVALE, Calif.--(BUSINESS WIRE)--Oct. 13, 1997--At Power '97, Philips Semiconductors is launching a new safety IC that protects LiIon battery packs against misuse.

The SAA1502A Safety IC, designed to be built into the battery pack, provides effective current limiting during both charging and discharging of the LiIon cell. In addition, it automatically disconnects the battery pack if the cell approaches either an over-charge or deep discharge state -- conditions that inevitably impair the cell's recharge cycle life and at worst can lead to a severe safety hazard.

In a market where small size/weight and long standby/talk times are key selling features of mobile phones, manufacturers are turning to LiIon (Lithium Ion) batteries as a solution to these two conflicting requirements. However, although LiIon batteries allow the design of lightweight single-cell battery packs, their critical charging requirements pose significant safety and reliability problems. If short-circuited, these batteries present a severe fire and explosion hazard. If incorrectly charged or discharged, their energy storage capacity can be seriously impaired.

Unlike most other safety ICs on the market, the SAA1502A can start up correctly from a zero-voltage condition. As a result, it does not require LiIon cells to be pre-charged before they are assembled into the battery pack. This not only simplifies battery pack assembly, it also significantly reduces manufacturing costs and eliminates the hazard of working with partly charged batteries.

Fabricated as a multi-chip module, the SAA1502A incorporates a BCD PowerLogic controller and a TrenchMOS dual power MOSFET chip. Because this construction places the controller and power MOSFETs in close thermal proximity, the over-temperature protection in the controller also protects the MOSFETs against thermal runaway. In addition, the SAA1502A's over-current protection in both charging and discharging modes mean that both MOSFETs remain constantly within their safe operating area. These features combine to make the SAA1502A considerably more reliable than competing solutions that use disely low power consumption of the BCD PowerLogi The SAA1502A is packaged in a 16-lead small-outline surface-mount package. Samples are available now, wmore.

About Philips Semiconductors

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