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TWO CONTACT BATTERY SCHEME THAT ALLOWS CAPACITY AND THERMISTOR IDENTIFICATION

IP.com Disclosure Number: IPCOM000006999D
Original Publication Date: 1993-Oct-01
Included in the Prior Art Database: 2002-Feb-15
Document File: 1 page(s) / 72K

Publishing Venue

Motorola

Related People

Joseph Patino: AUTHOR [+2]

Abstract

This invention eliminates two of the four bat- tery contacts presently necessary on the battery to determine the battery's capacity and thermistor val- ues. The proposal uses the capability of the charg- er's pp to read an A/D voltage to calculate a corresponding resistance. In the existing scheme, two independent A/Ds are used to determine the capacity resistor (Rc) and the thermistor (Rt) value. Since the pull up resistor value is a known constant, the JJP can calculate the resistance presented to the A/D for either Rc or Rt. The invention eliminates both of the above A/Ds and corresponding battery contacts. This is accomplished through the use of 4 switches: Ql, Q2, 43, and Q4. Refer to Block Dia- gram Proposed. In normal charging operation, the charge current would be enabled, and the switches would be conhgured in the following manner (Ql-06 Q2-tristate, Q3-tristate, and Q4-On) such that B- would be grounded and B+ would pass the charger current to the battery for charging. The diode D2 in the battery isolates the Rt and Z from the charger current.

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MOTOROLA INC. Technical Developments Volume 20 October 1993

TWO CONTACT BATTERY SCHEME THAT A,LLOWS CAPACITY AND THERMISTOR IDENTIFICATION

by Joseph Patiiio and Henry Anthony Bogut

  This invention eliminates two of the four bat- tery contacts presently necessary on the battery to determine the battery's capacity and thermistor val- ues. The proposal uses the capability of the charg- er's pp to read an A/D voltage to calculate a corresponding resistance. In the existing scheme, two independent A/Ds are used to determine the capacity resistor (Rc) and the thermistor (Rt) value. Since the pull up resistor value is a known constant, the JJP can calculate the resistance presented to the A/D for either Rc or Rt. The invention eliminates both of the above A/Ds and corresponding battery contacts. This is accomplished through the use of 4 switches: Ql, Q2, 43, and Q4. Refer to Block Dia- gram Proposed. In normal charging operation, the charge current would be enabled, and the switches would be conhgured in the following manner (Ql-06 Q2-tristate, Q3-tristate, and Q4-On) such that B- would be grounded and B+ would pass the charger current to the battery for charging. The diode D2 in the battery isolates the Rt and Z from the charger current.

  When the Rt value is needed to be determined the charge current would be disabled and the switches would be configured in the following manner (Ql-On, QZ-tristate, Q3-On, and Q4-Ofl) such that B+ would be grounded and B- would yield...