ATA6870-DK11

ATA6870-DK11 Datasheet

User Guide for Atmel ATA6870 and Atmel ATmega32HVB Evaluation Kit Hardware DK11 ATA6870-DK11

Part	Datasheet
ATA6870-DK11	ATA6870-DK11 (pdf)

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APPLICATION NOTE User Guide for Atmel ATA6870 and Atmel ATmega32HVB Evaluation Kit Hardware DK11 ATA6870-DK11 ● Evaluation of the ATA6870 ● Monitoring 12 battery cells ● Monitoring ● Overvoltage every cell ● Undervoltage every cell ● Overheating ● Overcurrent ● Open clamp detection ● 12-bit battery cell measurement ● 12-bit temperature measurement ● Controlling FET charge/discharge ● Status LEDs for easy evaluation ● Charge active balancing Figure Atmel ATA6870-DK11 9302C-AUTO-04/15 Introduction The ATA6870-DK11 is a demonstration board for the Atmel ATA6870 and offers an easy way to start evaluation of battery applications in combination with the Atmel ATmega32HVB. The included software demonstrates implementation of a 12-cell battery management system, including the function of active balancing through inductors. The supplied code serves as an example of how to use the Atmel ATMega32HVB and Atmel ATA6870 together. Safety Precautions When Using Li-Ion Batteries Please observe the safety guidelines supplied with the batteries. If improperly used or defective, Li-ion and polymer batteries and packs may explode and cause a fire. Demonstration Board The Atmel ATA6870-DK11 is designed to enable easy evaluation of the control software for an MCU controlling multiple Atmel ATA6870 devices. The supplied sample code demonstrates a simple permanent running measurement of voltages and temperatures. Figure Board Concept Cell 12 Cell 11 ATA6870 Cell 02 Cell 01 ATA6870 Charge/ Discharge Control Unit Monitoring V,T Coulomb counting ATmega32HVB A very important characteristic of the ATA6870-DK11 is the ability to realize active balancing. Compared with the passive method, the active method is significantly more efficient with virtually lossless energy transfer between battery cells. There are usually two types of active capacitors and with inductors. The capacitors are used for balancing currents lower than 50mA, while the inductors are for currents up to 1A or even more. On the ATA6870-DK11 the inductors with the value of 470uH are applied. Table 3-1 describes the achievable peak and average balancing currents with different inductors. ATA6870-DK11 [APPLICATION NOTE] Table f kHz 3 Balancing Currents Possible Using Different Inductors Inductor Type Inductance µH Resistor of Inductor Peak Balancing Current mA Toroidal 1240 Toroidal 2280 1620 1500 Average Balancing Current mA 470 280 890 610 430 The structure is shown in Figure It is easy to see that on the demo board the active balancing can only happen between the two neighboring cells and the balancing current flows from the higher cell to the lower cell, with the corresponding Mosfet switched on. However, if it is the lowest cell of a battery stack that needs to be discharged, a transformer concept applies and the energy is transferred from the lowest cell to the top cell in the battery stack. For more information about the active balancing, please see application note “Active Cell Balancing Methods for Li-Ion Battery Management ICs using the ATA6870.” Figure Inductive Charge Balancing between Two Stacked ATA6870s M12 PMOS Cell 12

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APPLICATION NOTE

User Guide for Atmel ATA6870 and Atmel ATmega32HVB Evaluation Kit Hardware DK11 ATA6870-DK11
● Evaluation of the ATA6870 ● Monitoring 12 battery cells
● Monitoring ● Overvoltage every cell ● Undervoltage every cell ● Overheating ● Overcurrent
● Open clamp detection ● 12-bit battery cell measurement ● 12-bit temperature measurement ● Controlling FET charge/discharge ● Status LEDs for easy evaluation ● Charge active balancing Figure Atmel ATA6870-DK11
9302C-AUTO-04/15

Introduction

The ATA6870-DK11 is a demonstration board for the Atmel ATA6870 and offers an easy way to start evaluation of battery applications in combination with the Atmel ATmega32HVB. The included software demonstrates implementation of a 12-cell battery management system, including the function of active balancing through inductors. The supplied code serves as an example of how to use the Atmel ATMega32HVB and Atmel ATA6870 together.

Safety Precautions When Using Li-Ion Batteries

Please observe the safety guidelines supplied with the batteries. If improperly used or defective, Li-ion and polymer batteries and packs may explode and cause a fire.

Demonstration Board

The Atmel ATA6870-DK11 is designed to enable easy evaluation of the control software for an MCU controlling multiple Atmel ATA6870 devices. The supplied sample code demonstrates a simple permanent running measurement of voltages and temperatures.

Figure Board Concept

Cell 12 Cell 11

ATA6870

Cell 02 Cell 01

ATA6870

Charge/ Discharge Control Unit

Monitoring V,T Coulomb counting

ATmega32HVB

A very important characteristic of the ATA6870-DK11 is the ability to realize active balancing. Compared with the passive method, the active method is significantly more efficient with virtually lossless energy transfer between battery cells. There are usually two types of active capacitors and with inductors. The capacitors are used for balancing currents lower than 50mA, while the inductors are for currents up to 1A or even more. On the ATA6870-DK11 the inductors with the value of 470uH are applied. Table 3-1 describes the achievable peak and average balancing currents with different inductors.

ATA6870-DK11 [APPLICATION NOTE]

Table
f kHz 3

Balancing Currents Possible Using Different Inductors

Inductor

Type

Inductance µH

Resistor of Inductor

Peak Balancing Current mA

Toroidal
1240

Toroidal
2280
1620
1500

Average Balancing Current mA 470 280 890 610 430

The structure is shown in Figure It is easy to see that on the demo board the active balancing can only happen between the two neighboring cells and the balancing current flows from the higher cell to the lower cell, with the corresponding Mosfet switched on. However, if it is the lowest cell of a battery stack that needs to be discharged, a transformer concept applies and the energy is transferred from the lowest cell to the top cell in the battery stack. For more information about the active balancing, please see application note “Active Cell Balancing Methods for Li-Ion Battery Management ICs using the ATA6870.”

Figure Inductive Charge Balancing between Two Stacked ATA6870s

M12 PMOS

Cell 12

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Datasheet ID: ATA6870-DK11 519229