Claims
- 1. A battery charging system, comprising:
- (a) a charging current output terminal having a voltage;
- (b) a variable-voltage generator with an output node;
- (c) a variable resistor; and
- (d) a controller electrically coupled to said variable-voltage generator, to said variable resistor, and to said charging current output terminal, said controller comprising at least one memory for storing (V.sub.1, R.sub.1, BP.sub.1), (V.sub.2, R.sub.2, BP.sub.2), . . . (V.sub.N, R.sub.N, BP.sub.N) where V.sub.j is an output voltage, R.sub.j is a resistance, and BP.sub.j is a breakpoint voltage, wherein j is an index between 1 and n;
- (e) wherein said controller can compare said voltage at said charging current output terminal to said BP.sub.j s and when said voltage at said charging current output terminal lies between BP.sub.j-1 and BP.sub.j, said controller can drive said variable-voltage generator to provide said output voltage of V.sub.j at said output node and can drive said variable resistor to provide said resistance of R.sub.j between said output node and said charging current output terminal.
- 2. The battery charging system of claim 1, further comprising:
- (a) a timer, wherein said timer can periodically drive said controller to compare the voltage at said Charging current output terminal to said BP.sub.j s.
- 3. The battery charging system of claim 2, wherein:
- (a) when driven by said timer said controller successively reads said codes for (V.sub.j, R.sub.j, BP.sub.j) and compares said voltage at said charging current output terminal to BP.sub.j for j equal to n, n-1, . . . , 1 until said voltage at said charging current output terminal is greater than BP.sub.j and then said controller drives said variable voltage generator to provide a voltage of V.sub.j and drives said variable resistor to provide a resistance of R.sub.j.
- 4. The battery charging system of claim 2, wherein:
- (a) said controller comprises a comparator with one input electrically coupled to said charging current output terminal and with another input electrically coupled to a digital-to-analog converter, said controller providing said BP.sub.j s to said digital-to-analog converter.
- 5. The battery charging system of claim 4, further comprising:
- (a) a disconnected-battery detector electrically coupled to said controller, said disconnected-battery detector comprising a second comparator with a first input electrically coupled to said charging current output terminal and a second input electrically coupled to said output node, said second comparator having an offset so that equal voltages at said first and second inputs yield a second comparator output indication of a higher voltage at said first input than at said second input.
- 6. The battery charging system of claim 1, wherein:
- (a) said variable-voltage generator comprises an operational amplifier and a first voltage divider resistor and a second voltage divider resistor, with a first input of said operational amplifier electrically coupled to a reference voltage, said first voltage divider resistor electrically coupled between a second input of said operational amplifier and a ground node, and said second voltage divider resistor electrically coupled between said second input and said output node, said operational amplifier having an output and a gain;
- (b) said first voltage divider resistor is comprised of a fixed resistor in series with a first trim resistor; and
- (c) said second voltage divider resistor is comprised of a second variable resistor in series with a second trim resistor, wherein V.sub.j applied to said variable resistor sets said gain of said operational amplifier to provide V.sub.j at said output node.
- 7. The battery charging system of claim 6, wherein:
- (a) said first trim resistor having a first resistance and said second trim resistor having a second resistance, further wherein said first resistance and said second resistance combine to form a sum of resistance;
- (b) said memory stores a trim T, said trim T applied to said first trim resistor and said second trim resistor to adjust the first resistance of said first voltage divider resistor and said second resistance of said second voltage divider resistor while keeping said sum of resistances remaining constant.
- 8. The battery charging system of claim 6, wherein:
- (a) the output of said operational amplifier drives a gate of a field effect transistor electrically coupled between a power supply and said output node.
- 9. The battery charging system of claim 8, wherein:
- (a) said variable resistor is comprised of at least one component grouping with each of said at least one component grouping comprising
- (1) at least one resistor electrically coupled between said charging current output terminal and a first node and
- (2) at least one field effect transistor electrically coupled between said power supply and said first node, each of said at least one field effect transistor having a corresponding gate;
- (b) wherein R.sub.j applied to said variable resistor couples one or more of said at least one component groupings to said variable-voltage generator with said output of said operational amplifier electrically coupled to said corresponding gate of said at least one field effect transistor of said at least one field effect transistor and with the output node electrically coupled to said first node.
- 10. The battery charging system of claim 9, wherein:
- (a) said variable resistor includes an adder and a decoder;
- (b) said memory stores code for a component grouping trim S, wherein said adder adds said code for a component grouping trim S to said code for R.sub.j to yield a selection sum for said component grouping, and said decoder decodes said selection sum to couple said one or more of said component groupings to said variable-voltage generator.
- 11. A programmable battery charging system, comprising:
- (a) a charging current output terminal;
- (b) a voltage generator, said voltage generator with an output node at voltage V selectable from a set of voltages V.sub.1, V.sub.2, . . . V.sub.N ;
- (c) a resistor electrically coupled between said output node and said charging current output terminal, said resistor with a resistance, R, selectable from a set of resistances R.sub.1, R.sub.2, . . . R.sub.M ;
- (d) a comparator with one input electrically coupled to said charging current output terminal and one input coupled to a breakpoint generator, said breakpoint generator with an output breakpoint voltage BP selectable from a set of breakpoint voltages BP.sub.1, BP.sub.2, . . . BP.sub.K ;
- (e) a controller comprising a memory, said memory programmable to store a plurality of triples (V.sub.j, R.sub.j, BP.sub.j) where V.sub.j is selected from V.sub.1, V.sub.2, . . . V.sub.N, R.sub.j is selected from R.sub.1, R.sub.2, . . . R.sub.M, and BP.sub.j is selected from BP.sub.1, BP.sub.2, . . . BP.sub.K ;
- (f) said controller is electrically coupled to said voltage generator, to said resistor, to said comparator, and to said breakpoint generator, wherein said controller can
- (1) determine BP.sub.j, said BP.sub.j is the smallest BP.sub.j stored in said memory and which is greater than the voltage at said charging current output terminal, by providing stored BP.sub.j s to said breakpoint generator and sensing the output of said comparator, and wherein said controller can
- (2) adjust said output breakpoint voltage and said resistance by providing V.sub.j and R.sub.j to said voltage generator and said resistor, respectively.
- 12. The programmable battery charging system of claim 11, wherein:
- (a) said memory is an erasable programmable read only memory; and
- (b) said plurality of triples (V.sub.j, R.sub.j, BP.sub.j) are stored in said erasable programmable read only memory in coded form.
- 13. The programmable battery charging system of claim 11, wherein:
- (a) said memory can be programmed by access at said output terminal, said output terminal also provides for one-wire communication.
- 14. The programmable battery charging system of claim 11, wherein:
- (a) said voltage generator is comprised of an operational amplifier and first and second voltage divider resistors, with a first input of said operational amplifier electrically coupled to a reference voltage, said first voltage divider resistor electrically coupled between a second input of said operational amplifier and a ground node, and said second voltage divider resistor electrically coupled between said second input and said output node;
- (b) said first voltage divider resistor is comprised of a fixed resistor in series with a first trim resistor;
- (c) said second voltage divider resistor is comprised of a variable resistor in series with a second trim resistor, wherein V.sub.j applied to said variable resistor sets a gain of said operational amplifier to provide V.sub.j at said output node; and
- (d) said memory programmable to store a trim T, said trim T applied to said first and second trim resistors adjusts resistances of said first and second trim resistors with the sum of the resistances remaining constant.
- 15. The programmable battery charging system of claim 14, wherein:
- (a) said second voltage divider resistor is comprised of at least one component grouping with each of said at least one component grouping comprising
- (1) at least one feedback resistor electrically coupled between said charging current output terminal and a first node and
- (2) at least one field effect transistor electrically coupled between a power supply and said first node, each at least one field effect transistor having a corresponding gate;
- (b) wherein R.sub.j configures said second voltage divider resistor by coupling one or more of said at least one component groupings to said voltage generator with the output of said operational amplifier electrically coupled to said corresponding gate of said at least one field effect transistor and with said output node electrically coupled to said first node.
- 16. The programmable battery charging system of claim 15, wherein:
- (a) said feedback resistor is comprised of an adder and a decoder;
- (b) said memory programmable to store code for a component grouping trim S, wherein said adder adds said code for a component grouping trim S to R.sub.j to yield a component grouping selection sum, and said decoder decodes said component grouping selection sum to couple said one or more of said at least one component grouping to said voltage generator.
- 17. A method of battery charging, comprising the steps of:
- (a) providing a plurality of (V.sub.j, R.sub.j, BP.sub.j) where V.sub.j is a charging voltage for j, R.sub.j is a series resistance for j, and BP.sub.j is a breakpoint voltage for j, wherein j is an index number in a series of said index numbers, so that j+1 is the next index number in said series of said index numbers;
- (b) sensing a voltage on a battery;
- (c) applying said voltage V.sub.j in series with said series resistance R.sub.j to said battery when said voltage on said battery lies between BP.sub.j and BP.sub.j+1.
- 18. The method of battery charging of Claim 17, further comprising the step of (d) repeating steps (b)-(c) with (V.sub.j, R.sub.j, BP.sub.j) until said voltage on said battery is above BP.sub.j+1.
- 19. The method of battery charging of claim 17, wherein said battery is NiCd.
- 20. The battery charging system of Claim 1, wherein said system charges a NiCad battery.
Government Interests
All of the material in this patent application is subject to copyright protection under the copyright laws of the United States and of other countries. As of the first effective filing date of the present application, this material is protected as unpublished material.
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However, permission to copy this material is hereby granted to the extent that the owner of the copyright and maskwork fights has no objection to the facsimile reproduction by anyone of the patent document or patent disclosure, as it appears in the United States Patent and Trademark Office patent file or records, but otherwise reserves all copyright and maskwork fights whatsoever.
US Referenced Citations (4)
Foreign Referenced Citations (2)
Number |
Date |
Country |
1588279 |
Jun 1970 |
DEX |
3509149 |
May 1986 |
DEX |