| US 7,589,499 B2 | ||
| Over voltage transient controller | ||
| Bruce S. Denning, Monterey, Calif. (US); Guoxing Li, Sunnyvale, Calif. (US); and Liusheng Liu, San Jose, Calif. (US) | ||
| Assigned to O2Micro International Limited, Grand Cayman (Cayman Islands) | ||
| Filed on Apr. 27, 2004, as Appl. No. 10/832,620. | ||
| Claims priority of provisional application 60/556254, filed on Mar. 25, 2004. | ||
| Prior Publication US 2005/0212489 A1, Sep. 29, 2005 | ||
| Int. Cl. H02J 7/00 (2006.01); H02J 7/04 (2006.01) | ||
| U.S. Cl. 320—134 [320/140] | 10 Claims |
| 1. An apparatus comprising:
a charge switch;
a discharge switch coupled in series with said charge switch;
an over voltage transient controller comprising:
a comparator to compare a first signal with a second signal representative of a reference voltage level and to provide an
output signal representative of an over voltage transient condition to said charge switch if said first signal is greater
than or equal to said second signal, said charge switch responsive to said output signal to protect a rechargeable battery
from said over voltage transient condition; and
current limiting circuitry configured to control an internal resistance of said discharge switch or said charge switch, to
adjust a sensed current to at least approach a predefined value, wherein said current limiting circuitry comprises:
an analog to digital converter (ADC) configured to receive a signal representative of said sensed current; and
a second DAC configured to control a voltage supplied to said discharge switch or said charge switch based on said sensed
current.
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