Cell Management Electronics for Lithium-Ion Battery BEU8642-EVAL Balancing for 8-Cell Battery Cell Voltage Monitoring Temperature Monitoring www.aeroflex.com/BEU January 29, 2009 Description The Aeroflex 8642-EVAL is a Lithium-Ion battery cell balancer. It provides voltage balancing among eight series stacked cells within a multi-cell battery to actively drive the voltage of each cell towards the average voltage of all cells using a patented charge-sharing technology. Features ● Cell Balancing of eight series stacked Lithium-Ion cells ● Transfer Ratio: 1 ohm nominal ● Cell Balancing to within ±10 mV ● Temperature Monitoring ● Cell Voltage Monitoring with high cell and low cell detection ● Built In Test (BIT) Discrete Output ● Suitable for a wide range of cell capacities, from less than 1 A-h to greater than 200 A-h ● RS-232 Output for data logging ● LCD Display for cell voltages, temperatures and status Benefits When Lithium-Ion battery cells are charged and discharged, small differences in the internal electrical characteristics of each cell may lead to cell voltage differences. At beginning of life, battery manufacturers take great care to match the cell characteristics very precisely. After many charge cycles, the characteristics diverge, causing cell voltage imbalances. Since the battery can only be charged until the highest cell reaches the maximum allowed voltage, the remaining cells are never fully charged. Similarily, as the battery is discharged, the battery must be disconnected when the lowest cell reaches the minimum allowed voltage, thereby preventing the charge in the remaining cells from being used. By keeping the cells balanced the useful capacity and life of the battery are maximized. The 8642-EVAL provides continous balancing for maximum protection against non-balance of Lithium-Ion cells. Safety The 8642-EVAL incorporates fuses to protect the battery in the event of a balancing circuit failure, as well as fuses to protect the 8642-EVAL if a battery cell fails. The maximum balancing current supplied by the 8642-EVAL is 1A. All cells must be balanced to be within 1V before connecting the 8642-EVAL to the battery. High cell detection can be used to prevent overcharging. Low cell detection can be used to prevent deep discharge. SCD8642-EVAL Rev B JTAG INPUT FOR THRESHOLD SETTINGS VOLTAGE REFERENCES - 2.00V AND 4.00V THERMISTOR 1 CONDITIONING CIRCUIT THERMISTOR 2 CONDITIONING CIRCUIT THERMISTOR 3 CONDITIONING CIRCUIT THERMISTOR 4 CONDITIONING CIRCUIT RS232 OUTPUT +28VDC (16VDC TO 34VDC) INPUT EMI FILTER MUX S/H A/D +12VDC (FLOATING) 3TR -12VDC 3TR +12VDC 3TR +5VDC 3TR +3.3VDC 3TR -5VDC 3TR DC-DC CONVERTER MUX INPUT SELECT MON CLK ON CONTROL OFF CONTROL EIGHT CELLS 9 WIRES HIGH CELL INPUTS #1 THRU #8 CONTROL LOGIC CELL BALANCING CIRCUITS LOW CELL BIT (ALL OK) LED TEMP 1 ERROR TEMP 2 ERROR FLYBACK EDGE SHARE BUS BAL CLK TEMP 3 ERROR PLL CONDITIONING CIRCUIT TEMP 4 ERROR THRESHOLD ADJ. THRESHOLD ADJ. TEMPERATURE SENSORS THRESHOLD DETECTORS DISPLAY MODULE V 1 4 . 0 0 0 Balancer Block Diagram Organization and Application The nominal impedance between each cell and the Share Bus, also known as the transfer ratio, is 1 ohm. This ratio determines the amount of balancing current and is based on the voltage difference between each cell and the Share Bus. For example a cell that is 200mV higher than the Share Bus will deliver 200mA to the Share Bus, whereas a cell that is 100mV less than the Share Bus will receive 100mA charging current from the Share Bus. The Aeroflex BEU8642-EVAL contains eight cell balancing circuits. Each cell balancing circuit is connected in parallel with one of the stacked cells of a multi-cell Lithium-Ion battery. In operation, energy is shared among the cells of the battery by way of the balancing circuits. The point in the circuit of energy exchange is called the Share Bus, which represents the average voltage of all the cells. Those cells having higher voltages deliver energy to the Share Bus while those cells with lower voltages receive energy from the Share Bus. Aeroflex Plainview SCD8642-EVAL Rev B 1/29/09 2 Technical Specifications A. Cell Balancing Number of Cells: Transfer Ratio: Cell Voltage Range: Cell Balancing Current: 8 1 ohm nominal (0.8 ohms to 1.39 ohms) 2.0 volts to 4.5 volts 1.0 amperes maximum B. Cell Voltage Monitoring Discrete Cell Voltage Monitor Outputs: There are two discrete Cell Voltage Monitor Outputs: High Cell (HC) and Low Cell (LC). Each output circuit is an NPN transistor, rated at 100 mA and 40 VDC, suitable for driving an LED. The transistor turns on when the measured cell voltage of any cell is outside the set limits. For example, if the HC limit is set at 4.200 volts, the transistor turns on if any measured cell voltage is greater than 4.200 volts. If the LC limit is set at 3.200 volts, the transistor turns on if any measured cell voltage is lower than 3.200 volts. Hysteresis: Each detection circuit has a hysteresis of 30 mV. For example, the HC limit turns on when any cell voltage exceeds 4.200 volts. It remains on until the voltage drops below 4.170 volts. Voltage Measurement Accuracy: Cell voltage monitoring accuracy is + 10 mV, over the range of 2.000 volts to 4.500 volts. C. Temperature Monitoring Number of sensors: Sensor Type: 4 (Typically located in battery) NTC Thermistor Type: Keystone RL0503-55.36K-122-MS2 100KΩ Thresholds: Each sensor has an Upper Threshold (UT) and a Lower Threshold (LT). For example, the UT may be set at 70°C and the LT may be set at 0°C. Processing: Threshold voltages for Sensors 1 and 2 are set by the Control Logic. Thresholds for Sensors 3 and 4 are set by separate analog circuits. The Sensor 1, 2 circuits and the Sensor 3, 4 circuits are independent, so that a failure in either section does not affect the performance of the other section. Setting of Analog Thresholds: The analog thresholds (Sensors 3 and 4) are set by potentiometers, with resolution of 1°C. Temperature Accuracy: Discrete Temperature Monitor Outputs: Measurement accuracy of the 8642-EVAL unit (independent of the accuracy of the thermistors) is less than + 3°C, over the range of -10°C to +80°C. There are four Temperature Sensor Monitor outputs (one for each sensor). Each output circuit is an NPN transistor, rated at 100 mA and 40 VDC, suitable for driving an LED. The transistor turns on when the measured temperature is outside the set limits. For example, if the limits are set at 0°C and 70°C, the transistor is off when the temperature is between 0°C and 70°C, and turns on when the temperature is less than 0°C or greater than 70°C, within the specified accuracy limits. Aeroflex Plainview SCD8642-EVAL Rev B 1/29/09 3 D. Built In Test (BIT) Discrete Output BIT Functions: BIT Output: The Control Logic autonomously performs a series of internal tests to verify that the circuits are operating correctly. These tests include measuring: 2V reference 4V reference Power Supply Monitor PLL frequency PLL closed loop Open/shorted temperature sensors (all 4) The "All OK" LED is lit and the discrete output is high when no errors are detected by BIT. E. Power Supply F. Input Voltage: The balancing unit meets all functional requirements for input voltages from 16.0 VDC to 34.0 VDC. Brownout Protection: No damage (to either the 8642-EVAL card or the battery) can occur for any input voltage between 0 VDC and 34.0 VDC. On/Off Control Circuit Latching Relay: A latching relay is included on the card. When this relay is latched (turned on), the DC-DC converter output voltages are on, and the balancing card operates. When the latching relay is reset (turned off), the balancing card is inactive. The latching relay is magnetically latched, and maintains its state without power. On Command: The On command must be a pulse with amplitude of 16.0 volts to 34.0 volts and pulse width of 10.0 milliseconds or greater. Off Command: The Off command must be a pulse with amplitude of 16.0 volts to 34.0 volts and pulse width of 10.0 milliseconds or greater. G. Settings in Nonvolatile Memory Nonvolatile Memory: The Control Logic contains a nonvolatile memory which holds settings for certain functions. These settings can be customized at the factory. These settings include the following: 1) Hi Cell limit (1.25mV/bit) 2) Lo Cell limit (1.25 mV/bit) 3) Hi Temp 1 limit (2’s complement degrees C) 4) Lo Temp 1 limit (2’s complement degrees C) 5) Hi Temp 2 limit (2’s complement degrees C) 6) Lo Temp 2 limit (2’s complement degrees C) 7) Hi/Lo Cell hysteresis (1.25mV/bit) 8) In Balance limit (1.25mV/bit) 9) Out of Balance limit (1.25mV/bit) 10) Balancing duty cycle [1/(n+1)] Aeroflex Plainview SCD8642-EVAL Rev B 1/29/09 4 H. Panel LED Indicators. LED Indicators: There are 8 LEDs on the top panel of the 8642-EVAL for quick status of the following parameters: 1) BALANCE ACTIVE: This LED is on when the balancer clock is functioning properly. 2) ALL OK: This LED is on when there are no errors detected by the BIT circuit, which monitors the following parameters: a. 2V internal reference b. 4V internal reference c. Power Supply Monitor d. PLL frequency e. PLL closed loop f. Open or shorted temperature sensors (all 4) 3) TEMPERATURE ERROR 4: This LED is on when the temperature sampled by sensor 4 is not within the range set by sensor 4’s upper and lower thresholds. 4) TEMPERATURE ERROR 3: This LED is on when the temperature sampled by sensor 3 is not within the range set by sensor 3’s upper and lower thresholds. 5) TEMPERATURE ERROR 2: This LED is on when the temperature sampled by sensor 2 is not within the range set by sensor 2’s upper and lower thresholds. 6) TEMPERATURE ERROR 1: This LED is on when the temperature sampled by sensor 1 is not within the range set by sensor 1’s upper and lower thresholds. 7) LOW CELL: This LED will be on when the voltage on any of the 8 cells falls below 3.20 volts. 8) HIGH CELL: This LED will be on when the voltage on any of the 8 cells exceeds 4.20 volts I. Serial Output RS232 Serial Digital Output: Continuously outputs the following values: 2V reference voltage 4V reference voltage Cell 1 voltage Cell 2 voltage Cell 3 voltage Cell 4 voltage Cell 5 voltage Cell 6 voltage Cell 7 voltage Cell 8 voltage Thermistor 1 temperature Thermistor 2 temperature Thermistor 3 temperature Thermistor 4 temperature Power supply monitor voltage These values are outputted in a comma-separated value ASCII format at 115.2K BAUD, 1 stop bit and no parity. Each measurement is updated approximately every 30 seconds. Aeroflex Plainview SCD8642-EVAL Rev B 1/29/09 5 J. LCD Display Continuously outputs the following values: Built-in test status 2V reference voltage 4V reference voltage Cell 1 voltage Cell 2 voltage Cell 3 voltage Cell 4 voltage Cell 5 voltage Cell 6 voltage Cell 7 voltage Cell 8 voltage Thermistor 1 temperature Thermistor 2 temperature Thermistor 3 temperature Thermistor 4 temperature Power supply monitor voltage K. Preconditioning Function: L. A voltage applied between this pin and CELL_RTN, to pre-charge the input capacitors to match each balancer cell’s voltage with its mating battery cell’s voltage, which prevents large in-rush currents when the battery is connected to the balancer. Mechanical Requirements Mechanical Size: Connector Types: The dimensions of the BEU8642-EVAL are in accordance with the box outline. The edge measurements are as follows: Length: 12.00” Width: 9.00” Height: 2.65” Tyco Electronics-Amp – 206151-1 – 206150-1 On unit Mating Connector Aeroflex Plainview SCD8642-EVAL Rev B 1/29/09 6 Pinouts and Description External view of male connector mounted on 8642-EVAL unit Pin # Description Pin # Description Pin # Description Pin # Description 1 CELL 2+ 11 TEMP ERR 1 21 LOW CELL 31 NC 2 CELL 4+ 12 TEMP ERR 2 22 BIT 32 +28V RTN 3 CELL 6+ 13 TEMP ERR 3 23 TS1 RTN 33 +28V RTN 4 CELL 8+ 14 TEMP ERR 4 24 TS2 RTN 34 ON HI 5 CELL 1+ 15 OUTPUT RTN 25 TS3 RTN 35 OFF HI 6 CELL 3+ 16 TS1 26 TS4 RTN 36 OFF LO 7 CELL 5+ 17 TS2 27 PS_MON 37 ON LO 8 CELL 7+ 18 TS3 28 RS232 OUT 9 CELL RTN 19 TS4 29 +28VDC 10 PRE CONDITION 20 HIGH CELL 30 +28VDC NOTE: Cell 1+ connects to the top (+) of the battery stack and CELL RTN connects to the bottom (-) of the battery stack Aeroflex Plainview SCD8642-EVAL Rev B 1/29/09 7 Standard Configuration Power Requirement 83 mA Typ at +28VDC Operating Temperature 0°C to +70°C Storage Temperature -40°C to +85°C Ordering Information MODEL NUMBER BEU8642-EVAL EXPORT CONTROL: EXPORT WARNING: This product is controlled for export under the International Traffic in Arms Regulations (ITAR). A license from the U.S. Department of State is required prior to the export of this product from the United States. Aeroflex’s military and space products are controlled for export under the International Traffic in Arms Regulations (ITAR) and may not be sold or proposed or offered for sale to certain countries. (See ITAR 126.1 for complete information.) PLAINVIEW, NEW YORK Toll Free: 800-THE-1553 Fax: 516-694-6715 INTERNATIONAL Tel: 805-778-9229 Fax: 805-778-1980 NORTHEAST Tel: 603-888-3975 Fax: 603-888-4585 SE AND MID-ATLANTIC Tel: 321-951-4164 Fax: 321-951-4254 WEST COAST Tel: 949-362-2260 Fax: 949-362-2266 CENTRAL Tel: 719-594-8017 Fax: 719-594-8468 www.aeroflex.com [email protected] Aeroflex Microelectronic Solutions reserves the right to change at any time without notice the specifications, design, function, or form of its products described herein. All parameters must be validated for each customer's application by engineering. No liability is assumed as a result of use of this product. No patent licenses are implied. Our passion for performance is defined by three attributes represented by these three icons: solution-minded, performance-driven and customer-focused SCD8642-EVAL Rev B 1/29/09 8