Single floating battery cell voltage level translator circuitry

• US 7,999,554 B2
• Filed: 11/01/2005
• Issued: 08/16/2011
• Est. Priority Date: 03/07/2005
• Status: Expired due to Fees

• Current Assignee: O2 Micro International Limited (O2 Micro Incorporated)
• Original Assignee: O2 Micro International Limited (O2 Micro Incorporated)
• Inventors: Bucur, Constantin, Niculae, Marian
• Primary Examiner(s): Tso; Edward
• Assistant Examiner(s): TORRES RUIZ, JOHALI ALEJANDRA
• Application Number:
  US11/264,768
• Publication Number:
  US 20060197501A1
• Time in Patent Office: 2,114 Days
• Field of Search: 320/112, 320/116, 320/118, 320/119, 320/124, 320/125, 320/162, 324/433, 324/434, 324/435
• US Class Current: 324/434
• CPC Class Codes: G01R 19/16542 for batteries charge condition monitoring in G01R31/36
• CPC Class Codes: H01M 10/4207 for several batteries or cells simultaneously or sequentially
• CPC Class Codes: H01M 10/425 Structural combination with electronic components, e.g. electronic circuits integrated to the outside of the casing printed circuits H05K1/00
• CPC Class Codes: H01M 10/44 Methods for charging or discharging circuits for charging H02J7/00
• CPC Class Codes: H01M 50/202 Casings or frames around the primary casing of a single cell or a single battery
• CPC Class Codes: H01M 50/204 Racks, modules or packs for multiple batteries or multiple cells
• CPC Class Codes: H01M 50/269 Mechanical means for varying the arrangement of batteries or cells for different uses, e.g. for changing the number of batteries or for switching between series and parallel wiring methods or arrangements for servicing or maintenance H01M6/50, H01M10/42
• CPC Class Codes: H02J 7/0031 using battery or load disconnect circuits H02J9/002 takes precedence
• CPC Class Codes: H02J 7/0063 with circuits adapted for supplying loads from the battery
• CPC Class Codes: H02J 7/007182 in response to battery voltage
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

Voltage translator circuitry may include a path including a first resistor, a current controlling device, and a second resistor coupled in series. The voltage translator circuitry may further include an operational amplifier having a positive supply terminal to accept a positive supply voltage and a negative supply terminal to accept a negative supply voltage, neither the positive or negative supply voltage at ground voltage. The first resistor may further be coupled to a positive terminal of the battery cell to be monitored. The operational amplifier may have an input coupled to a negative terminal of the battery cell to be monitored. The voltage translator circuitry may further include an output terminal coupled to a node of the path between the current controlling device and the second resistor. The output terminal may be configured to provide the ground referenced cell voltage for the battery cell.

Claims

1. Voltage translator circuitry for translating a floating cell voltage of at least one of a plurality of battery cells to a ground referenced cell voltage, said voltage translator circuitry comprising:

a single operational amplifier comprising;

a positive supply terminal configured to receive a positive supply voltage,

a negative supply terminal configured to receive a negative supply voltage,

an inverting input coupled to a path wherein said path is configured to be individually coupled to a positive terminal of each battery cell to be monitored, and

a noninverting input configured to be individually coupled to a corresponding negative terminal of each said battery cell to be monitored wherein a voltage, Vcell-, between said non-inverting input and a ground terminal depends on which of the plurality of battery cells is being monitored;

a first circuitry configured to adjust said negative supply voltage in response to Vcell- so that said negative supply voltage is less than Vcell- for each battery cell to be monitored, wherein said first circuitry comprises a first voltage regulating device, a first current source and a first transistor; and

a second circuitry configured to adjust said positive supply voltage in response to Vcell- so that said positive supply voltage is greater than Vcell- for each battery cell to be monitored, wherein said second circuitry comprises a second voltage regulating device, a second current source and a second transistor.

2. The voltage translator circuitry of claim 1, wherein said first voltage regulating device, said first current source and said first transistor are coupled to a third node, said first voltage regulating device is further coupled to said noninverting input, said first current source is further coupled to said ground terminal and said first transistor is further coupled to said ground terminal and said negative supply terminal, and wherein said second voltage regulating device, said second current source and said second transistor are coupled to a fourth node, said second voltage regulating device is further coupled to said negative supply terminal, said second current source is configured to be coupled to a positive terminal of said plurality of battery cells and said second transistor is configured to be coupled to said positive terminal of said plurality of battery cells and is coupled to said positive supply terminal.

3. The voltage translator circuitry of claim 1, wherein said first circuitry and said second circuitry are configured to provide a differential supply voltage to said operational amplifier and said differential supply voltage is less than or equal to 5 volts.

4. The voltage translator circuitry of claim 1, further comprising:

a switch network coupled to said single operational amplifier, said switch network configured to individually couple each of said plurality of battery cells to said single operational amplifier.

5. The voltage translator circuitry of claim 1, further comprising an output terminal, wherein:

said path comprises a first resistor, a current controlling device and a second resistor coupled in series,

said inverting input is coupled to a first node of said path between said first resistor and said current controlling device, and

said output terminal is coupled to a second node of said path between said current controlling device and said second resistor, said output terminal configured to provide said ground referenced cell voltage for each said battery cell when said first resistor is coupled to said positive terminal of said battery cell and said noninverting input is coupled to said negative terminal of said battery cell.

6. A battery pack comprising:

a plurality of battery cells;

a switch network coupled to each of said plurality of battery cells; and

voltage translator circuitry comprising;

a single operational amplifier comprising;

a positive supply terminal configured to receive a positive supply voltage,

a negative supply terminal configured to receive a negative supply voltage,

an inverting input coupled to a path wherein said path is configured to be individually coupled to a positive terminal of each battery cell to be monitored, and

a noninverting input configured to be individually coupled to a corresponding negative terminal of each said battery cell to be monitored wherein a voltage, Vcell-, between said non-inverting input and a ground terminal depends on which of the plurality of battery cells is being monitored;

a first circuitry configured to adjust said negative supply voltage in response to Vcell- so that said negative supply voltage is less than Vcell- for each battery cell to be monitored, wherein said first circuitry comprises a first voltage regulating device, a first current source and a first transistor; and

a second circuitry configured to adjust said positive supply voltage in response to Vcell- so that said positive supply voltage is greater than Vcell- for each battery cell to be monitored, wherein said second circuitry comprises a second voltage regulating device, a second current source and a second transistor.

7. The battery pack of claim 6, wherein said first voltage regulating device, said first current source and said first transistor are coupled to a third node, said first voltage regulating device is further coupled to said noninverting input, said first current source is further coupled to said ground terminal and said first transistor is further coupled to said ground terminal and said negative supply terminal, and wherein said second voltage regulating device, said second current source and said second transistor are coupled to a fourth node, said second voltage regulating device is further coupled to said negative supply terminal, said second current source is coupled to a positive terminal of said plurality of battery cells and said second transistor is coupled to said positive terminal of said plurality of battery cells and said positive supply terminal.

8. The battery pack of claim 6, wherein said first circuitry and said second circuitry are configured to provide a differential supply voltage to said operational amplifier and said differential supply voltage is less than or equal to 5 volts.

9. The battery pack of claim 6, wherein said switch network is coupled to said single operational amplifier, said switch network configured to individually couple each of said plurality of battery cells to said single operational amplifier.

10. The battery pack of claim 6, wherein said voltage translator circuitry further comprises an output terminal, and wherein:

said path comprises a first resistor, a current controlling device and a second resistor coupled in series,

said inverting input is coupled to a first node of said path between said first resistor and said current controlling device, and

said output terminal is coupled to a second node of said path between said current controlling device and said second resistor, said output terminal configured to provide said ground referenced cell voltage for each said battery cell when said first resistor is coupled to said positive terminal of said battery cell and said noninverting input is coupled to said negative terminal of said battery cell.

11. A method of translating a floating cell voltage of at least one of a plurality of battery cells to a ground referenced cell voltage, said method comprising:

for each battery cell to be monitored of the plurality of battery cells;

coupling a path to a positive terminal of said battery cell to be monitored, wherein a single operational amplifier is coupled to said path at an inverting input of said operational amplifier;

coupling a noninverting input of said single operational amplifier to a corresponding negative terminal of said battery cell to be monitored, wherein a voltage, Vcell-, between said noninverting input and a ground terminal depends on which of the plurality of battery cells is being monitored;

adjusting a negative supply voltage in response to Vcell- so that said negative supply voltage is less than Vcell- for said battery cell to be monitored, wherein said adjusting said negative supply voltage is performed by a first circuitry coupled to said noninverting input, said first circuitry comprising a first voltage regulating device, a first current source and a first transistor;

adjusting a positive supply voltage in response to Vcell- so that said positive supply voltage is greater than Vcell- for said battery cell to be monitored, wherein said adjusting said positive supply voltage is performed by a second circuitry coupled to said first circuitry, said second circuitry comprsing a second voltage regulating device, a second current source and a second transistor; and

providing said negative supply voltage to a negative supply terminal of said single operational amplifier and said positive supply voltage to a positive supply terminal of said single operational amplifier.

12. The method of claim 11, wherein said positive supply voltage less said negative supply voltage is a differential supply voltage to said single operational amplifier and said differential supply voltage is less than or equal to 5 volts.

13. The method of claim 11, wherein said coupling said path and said coupling said noninverting input are performed by a switch network.

14. The method of claim 11, further comprising:

controlling a current through said path in response to an output of said single operational amplifier wherein said inverting input is coupled to a first node of said path; and

providing said ground referenced cell voltage at an output terminal coupled to a second node of said path.

15. The method of claim 14, wherein said path comprises a first resistor, said current controlling device and a second resistor coupled in series, said first node is between said first resistor and said current controlling device and said second node is between said current controlling device and said second resistor.