Charging circuit for deeply discharged cells
AssigneeNational Semiconductor Corporation
InventorsGregory J. Smith, Yinming Chen
Life of this patent
Estimating the term…
Abstract
The invention is directed towards a charging circuit for charging a cell that may be deeply discharged. A primary charging circuit charges the cell when the cell is not deeply discharged. A deeply discharged charging circuit charges the cell when the cell is deeply discharged. Determining when the cell is deeply discharged includes determining when the voltage of the cell is above, below, or equal to a predetermined threshold. According to one embodiment of the invention, the predetermined threshold is 2V. When the cell voltage is below a predetermined threshold voltage, which according to one embodiment is 0.5V, a low-voltage charging path is used to charge the cell.
Claims22
An apparatus for charging a cell that may be deeply discharged, comprising:
- a pass circuit that includes a first pass circuit input that is coupled to a power signal, a second pass circuit input that is coupled to a first node, and a first pass circuit output that is arranged to provide a charging signal in response an input received at the second input;
- a primary charging circuit that includes a first primary charging circuit input that is coupled to the first pass circuit output, a first primary charging output that is coupled to the first node, a second primary charging circuit output that is coupled to the cell, wherein the primary charging circuit is configured to regulate the pass circuit to charge the cell when the primary charging circuit is enabled;
- and
- a deeply discharged charging circuit that includes a first deeply discharged charging circuit input that is coupled to the first pass circuit output of the pass circuit, a first deeply discharged charging circuit output that is coupled to the first node, a second deeply discharged charging circuit output that is coupled to the cell, wherein the first deeply discharged charging circuit output is configured to regulate the pass circuit to charge the cell when the primary charging circuit is disabled.
A method of charging a cell that may be deeply discharged, comprising:
- determining when the cell is in a deeply discharged state and when the cell is in a non-deeply discharged state;
- activating a primary charging circuit on a battery charging IC when the cell is in the non-deeply discharged state;
- and
- activating a deeply discharged charging circuit on the battery charging IC when the cell is in the deeply-discharged state.
An apparatus for charging a cell that may be deeply discharged comprising;
- a means for determining a state of the cell, wherein the state of the cell relates to when the cell is in a deeply discharged state and when the cell is in a non-deeply discharged state;
- a means for generating a DISABLE signal that relates to the state of the cell;
- a means for enabling and disabling a primary charging circuit integrated onto a battery charging IC in response to the state of the cell;
- and
- a means for enabling and disabling a deeply discharged charging circuit integrated onto a battery charging IC in response to the state of the cell.
Dependencies are inferred from the claim text.