Methods and apparatus for managing the charging and discharging

Details Methods and apparatus for managing the charging and discharging Methods and apparatus for managing the charging and discharging

1998-03-20

1999-09-07

Tso, Edward H.

Electricity: battery or capacitor charging or discharging

Battery or cell discharging

With charging

320136, H01M 1044, H01M 1046

Patent

active

059492180

ABSTRACT:
An apparatus and corresponding method are provided for regulating the voltage potential of a lithium ion battery based upon an operating range having an upper threshold (e.g., on the order of 4.2 v) and a lower threshold (e.g., on the order of 2.5 v) and for providing a reduction in dissipated power when the lithium ion battery is charging and when a load is drawing upon the lithium ion battery. The apparatus includes a p-minus substrate and a first p-channel enhancement Field Effect Transistor (FET) integrally formed on the p-minus substrate. The first p-channel enhancement FET is configured to limit charging of the lithium ion battery when the voltage potential of the lithium ion battery is greater than the upper threshold. A second p-channel enhancement FET is integrally formed on the p-minus substrate and connected in parallel with the first p-channel enhancement FET and configured to limit discharging of the lithium ion battery when the voltage potential of the lithium ion battery is less than the lower threshold. A third p-channel enhancement FET is integrally formed on the p-minus substrate and connected in parallel with the first p-channel enhancement FET and the second p-channel enhancement FET. The third p-channel enhancement FET encompasses a substantially larger area of the p-minus substrate as compared to each of the first p-channel enhancement FET and the second p-channel enhancement FET such that a substantially reduced resistive path is presented by the third p-channel enhancement FET relative to the resistive paths associated with the first and second p-channel enhancement FETs. The reduced resistive path provides reduced dissipated power while the lithium ion battery is charging and when the load is drawing upon the battery in the operating range.

REFERENCES:
patent: 5397974 (1995-03-01), Tamai et al.
patent: 5477124 (1995-12-01), Tamai
patent: 5637413 (1997-06-01), Fernandez et al.
patent: 5747969 (1998-05-01), Tamai
Memo entitled "One-Cell Li-Ion Battery Pack Management" from Motorola Semiconductor Products Sector, Semiconductor Components Group, author and date unknown.
Ricoh, "Li-Ion Battery Protector RN5VM1xxC/D Series", May 1997.

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