ATA6870-DK10
●
®
●
● Monitoring:
● Overvoltage (every cell)
● Undervoltage (every cell)
● Overheating
● Overcurrent
●
●
●
●
●
●
●
Figure 1.
Atmel ATA6870-DK10
9228C-AUTO-02/15

The Atmel ® ATA6870-DK10 is a demonstration board for the Atmel ATA6870, which offers an easy way to start evaluation of battery applications using the Atmel ATmega32HVB in combination with the Atmel ATA6870. The included software demonstrates implementation of a 12 Cell Battery Management System. The supplied code serves as an example of how to use the Atmel ATMega32HVB and Atmel ATA6870 together. The example is not a complete application intended for use with smart batteries, and it is best to use the devices in a slightly different way in a smart battery application.
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.
The Atmel ATA6870-DK10 was developed to allow easy evaluation of control software for a microcontroller which controls multiple Atmel ATA6870s. The sample code supplied demonstrates a simple permanent running measurement of voltages and temperatures.
Figure 3-1.
Board Concept
Cell 12
Cell 11
ATA6870
Cell 02
Cell 01
ATA6870
Charge/
Discharge
Control Unit
Monitoring (V,T)
Coulomb counting
ATmega32HVB
9228C–AUTO–02/15

Follow these steps to launch the system.
3.1.1
Installing the Hardware
● Connect the load/charger to be powered between pack+ and pack- on J1
● For demonstration purposes it is possible to use a resistor to simulate a load
● Connect the battery cell stack to the screw connectors on the demonstration board
● Led 1 indicates the enabled status of the demonstration board (controlled by microcontroller SW)
● In case of emulating cells such as a voltage divider, apply sufficient voltage (see
Section 3.3 “Powering the Board” on page 5
)
3.1.2
Number of Cells
It is possible to run the board with a reduced number of cells. The minimum voltage for each IC is 6.9V. Cell 1 and cell 6
(MBAT) have to be connected. The missing cells should be connected to the upper cell potential of the module. For further information refer to the Atmel ATA6870 datasheet Section 7.3: Reduced Number of Battery Cells Configuration. For the voltage range see
Section 3.3 “Powering the Board” on page 5
. If fewer than 6 cells are used per IC, the config.h file should
be adjusted (CELLSIC# under General Setting). See Section 4.1 “Supplied Code” on page 7
for further information on how to configure the supplied software correctly.
Figure 3-2.
Evaluation Board with 2 Stacked Atmel ATA6870 and Atmel ATMega32HVB
9228C–AUTO–02/15

3.2.1
On-board Features
The demonstration board includes the following items:
● 2  Atmel ® ATA6870 QFN 7mm  7mm
● Atmel ATMega32HVB
● 12 external N-channel MOSFETs for balancing of battery cells
● Connectors
● ISP connector for programming/debugging the Atmel ATMega32HVB
● Screw connectors for connecting up to 12 battery cells
Table 3-1.
Connector Overview
J7
7
8
5
6
3
4
1
2
9
10
Function
CELL-
PACK-
VFET
GND
OD
OC
RESET
GND
J8
9
10
7
8
5
6
3
4
1
2
Function
VDDHVM
VCC
GND
IRQ
CLK
MISO
MOSI
SCK
CS_N
J1
J2
J3
J4
J9
Connector for charger/device to be powered
ISP connector
Upper battery stack (cells 7-12)
Bottom battery stack (cells 1-6)
Jumper to enable/disable MISO line of Atmel ATA6870
J9 should never be set while the Atmel ATmega32HVB is being programmed or while it is entering debug mode. It can be mounted as soon as AVR Studio prompts for additional SPI lines to be connected in debug mode or after the device has been correctly programmed.
9228C–AUTO–02/15

Figure 3-3.
Connectors
3.3.1
Power Supply
The board supports supply voltages from 13.8V (6.9V per Atmel ATA6870) to 60V. However, to run the board on voltages below 24V the ZDiode D3 needs to be replaced with a jumper to supply the Atmel ® ATmega32HVB with sufficient voltage. If the jumper is mounted, the stack voltage should not exceed 48V! The Atmel ATmega32HVB supports operating voltage from
4V to 24V.
3.3.2
Emulating Cells
Battery cells can be emulated by connecting a voltage divider to the specified clamps.
Section 3.1.1 “Installing the Hardware” on page 3 describes how to connect cells. The voltage limits for this setup are the same as for real batteries.
Section 3.3.1
“Power Supply” on page 5 specifies these limits.
9228C–AUTO–02/15

The supplied code is documented and easy to adjust for verifying the functions of the Atmel ® ATA6870 and start BMS application development work.
After the board has been connected as described above the microcontroller automatically starts a cyclic measurement of voltages, temperature, and current. LED 1 indicates these cyclic measurements. It toggles in default operation. A continuously illuminated LED1 indicates an open clamp. See
Section 4.2 “Open Cell Check” on page 7
for more information about open clamp detection. LED 2 indicates that for some reason the MOSFETS have been disabled. The default software disables the FETs in case of these events:
● Overvoltage (at least 1 cell exceeds the upper default threshold of 4.2V)
● Undervoltage (at least 1 cell exceeds the lower default threshold of 2.5V)
● Overcurrent (the current through the shunt exceeds the default threshold of 80mA)
● Overheating (the temperature exceeds the upper threshold, default value is 60°C)
● Low temperature threshold (the default threshold is -20°C)
LED 3 indicates whether the Atmel ATA6870s are turned on or not. An active LED indicates that the Atmel ATA6870s are enabled.
Table 4-1.
LED Functions
LED
LED 1
LED 2
LED 3
Function
Indicates clamp is open when permanently illuminated
Indicates cyclic measurements when blinking
On indicates disabled MOSFETs for one of the reasons listed above
On indicates active Atmel ATA6870
The Atmel ATmega32HVB has no clock divider to provide an external slower clock than 1/2 CPU clock. Requirement of
Atmel ATA6870 is f
CLK
> 2  f
SPI
. Hence, the clock frequency of 1MHz is mandatory to provide a 500kHz clock for the ADCs of the Atmel ATA6870 and 250kHz for SPI.
9228C–AUTO–02/15

4.1.1
config.h
This section refers to the config.h file provided in the zip archive with this Application Note. Only values in the User Setting paragraph should be changed!
------------- GENERAL SETTING--------------------------------
CELLSIC# Selecting which Cells are used Bits 0-5 -> Cells 1-6
------------- TEMPERATURE SETTING----------------------------
RES_REF#
T_TLS
Value of the mounted reference resistor (default: 3300)
Temperature belonging to the first Value in the lookup
T_TLE table (index 0, default: -20)
Temperature belonging to the last value in the lookup table (default: 80)
Temperature step size used in the lookup table (default: T_TLSZ
1)
T_LOWERTHRESHOLD Lower temperature threshold
T_UPPERTHRESHOLD Upper temperature threshold
------------- COULOMBCOUNTER SETTING-------------------------
SHUNT_RESISTANCE
RCC_CONVERSIONPERIOD
Value of the shunt resistor in mOhm
The cycle times for the Regular Current Check
0x00 - 256ms (default)
0x01 - 512ms
RCC_DIVIDEDSZ
RCC_CHARGETHRESHOLD
RCC_DISCHARGETHRESHOLD
0x02 - 1s
0x11 - 2s
0x01 to enable divided Voltage (Current) stepsize
Threshold for charging current, exceeding the threshold will turn off the Mosfets
Threshold for discharging current, exceeding the threshold will turn off the Mosfets
Other values should not be changed in the default HW setup!
The implemented function checks for open clamps by measuring the cell voltages two times. During the first check a normal measurement is completed and the values stored. During the second check the voltages are measured while the discharge function for all cells is active. If the two measurements for the same cell differ by more than 100mV it is very likely that one or more cells are not properly connected. The implemented method cannot be used to determine which cell is not properly connected. A continuously illuminated LED1 indicates an open clamp.
The standard software loop measures the voltage ADC value and the offset ADC value for every cell and checks for overvoltage and undervoltage once per cycle. Further information about the acquiring of voltages can be found in the Atmel ®
ATA6870 datasheet Section 7.5.1. The formula for calculating the voltage:
Voltage (Cell) = 4V



V – V
---------------------------------
3031 – V offset


9228C–AUTO–02/15

The default software only measures channel 1 of chip 1. The temperature sensors are based on a resistor divider using a standard resistor and an NTC resistor. This resistor divider is connected to the reference of the ADC for temperature measuring. Because the ADC is sharing the same reference value, the output of temperature measurement with ADC is ratio metric. Further information is found in the Atmel ATA6870 datasheet Section 7.5.3: Temperature Channel.
For this application Atmel recommends using Res_Ref1 = 3.3k
 and RES_NTC1 R25 = 10k  , B = 3435. The software supplied for this board uses these values as default. The function uses a lookup table to determine the temperature. This table has to be edited if an NTC other than the recommended one is used. The values in the lookup table range from –20°C
(index 0) to +80°C (index 100). These values can be edited via the config.h file in the User Settings section. More
Information about this file can be found in
Section 4.1 “Supplied Code” on page 7
. The calculation of RES_NTC is carried out based on the formula provided in the Atmel ATA6870 datasheet Section 7.5.3: adc (out) = 2048



1 +
(RES_NTC(1) + RES_REF(1))

15
–
10


When using another NTC, the LookupADC.txt has to be edited to match the NTC used.
Highly precise SOC measurement is possible by combining the features of the Atmel ATmega32HVB and the Atmel
ATA6870. The coulomb counting feature of the Atmel ATmega32HVB enables highly precise measurements of the change in the state of charge. Frequent reading of the current in a shunt is used to update the SOC frequently. The acquired cell voltages and temperatures can be used to determine the SOC without the Atmel ATmega32HVB. The easiest way is to compare the SOC measured by the added/extracted charge with the calculated SOC using the cell voltage, temperature, and the data provided by the manufacturer of the cells. Further information regarding the coulomb counting ADC as well as an implementation suitable for the Atmel ATmega16HVA is found in Application Note AVR352.
The current through the shunt is calculated by measured voltage drop. The limit can be set via the CADRDC/CADRCC register. The step size depends on the settings of the CADCSRC register and the shunt used. For further information about limiting current see the Atmel ATmega32HVB datasheet Section 19.4: Regular Current Detection Operation. The supplied software allows the feature to be tested by adjusting the values in the config.h file. More Information about this file can be found in
Section 4.1 “Supplied Code” on page 7
. Values/part of the code should only be changed if you are aware of possible consequences. The default implementation continuously measures the current and generates an interrupt if the entered thresholds are exceeded. The thresholds are defined in the config.h file. The thresholds are written to the registers in the function CCinit in the Atmel ATA6870_func.c file. Refer to the features of the Atmel ATmega32HVB in the coulomb counter section to learn more about the time the controller waits for the values to be written.
C Code Example
CADRCC = RCC_CADRCC; while(CADCSRA & (1 << CADUB));
CADRDC = RDC_CADRDC; while(CADCSRA & (1 << CADUB));
// Charge Threshold
// Wait values to be written
// Discharge Threshold
// Wait values to be written
9228C–AUTO–02/15

Since the Atmel ® ATmega32HVB is a part of the Atmel AVR ® family which is dedicated to battery management there are several special features such as coulomb counting and the control of the two charge/discharge MOSFETs.
The coulomb counter ADC runs on a different clock than the CPU. This clock is slower and therefore several things have to be kept in mind before using it. Writing several registers in sequence takes a long time depending on the delays between each write cycle. A possible solution is given in the supplied software example:
C Code Example void CCinit(){
CADRCC = RCC_CADRCC; while(CADCSRA & (1 << CADUB));
CADRDC = RDC_CADRDC; while(CADCSRA & (1 << CADUB));
SETBIT(CADCSRB,1<<CADRCIE); while(CADCSRA & (1 << CADUB));
// Charge Threshold
// Discharge Threshold
// Interrupt Enable
// Voltage Scaling
SETBIT(CADCSRC,RCC_DIVIDEDSZ<<CADVSE); while(CADCSRA & (1 << CADUB));
SETBIT(CADCSRA,((1<<CADEN)|(1<<CADSE)|(RCC_CONVERSIONPERIOD<<1)));
// ADC Enable, RCC Mode, Sampling
// Interval while(CADCSRA & (1 << CADUB));
}
The Update Busy (CADUB) bit in CADSRA is cleared and written by hardware.
The two FETs are controlled by an N-channel FET driver. The pins (OC and OD) are designed for outputting a high voltage of approx. 13V. The status of the pins is controlled by software via the FCSR - FET control and status register.
C Code Example void Configure_Fet(unsigned char Fet){ if(Fet&0x01)
SETBIT(FCSR, (1<<DFE)); else
CLEARBIT(FCSR,(1<<DFE)); if(Fet&0x02)
SETBIT(FCSR,(1<<CFE)); else
CLEARBIT(FCSR,(1<<CFE));
}
The example above implements an easy method to enable or disable the two FETs independently of each other. For more information, see the Atmel ATmega32HVB datasheet page 148ff.
9228C–AUTO–02/15

There are several ways to reduce the power consumption of the Atmel ATA6870 and the Atmel ATmega32HVB. Sleep modes are documented in the datasheet of the Atmel ATA6870 Section 7.1.1 and in the Atmel ATmega32HVB datasheet
Section 10. This board allows the Atmel ATA6870 to be enabled/disabled using the Atmel ATmega32HVB software. The pin
PB2 is used to control a transistor for activating/deactivating the Atmel ATA6870. Other options which are not implemented are the use of interrupts and a timer (sleep between cycles).
9228C–AUTO–02/15

Figure 7-1.
Schematic
J1-1
J1-2
J1-3
J1-4
S
R96 R109
56kΩ
D2
56kΩ
MM3Z13VC
G
Q5
IRF5210SPBF
Q2
MMBT2222A
D
D
S
Q4
IRF5210SPBF
G
D1
MM3Z13VC
R93
56kΩ
PACK+
R94
56kΩ
Q1
MMBT2222A
R10
4.7kΩ
R95
4.7kΩ
J3-1 opt. ext.supply
TP1
Q2
NSS60601MZ4
R12 tbd
D3
BZV55C6V8-TP
R18 nc
R11
J4-7
100Ω
ZXMN2F34FH
R19
0Ω
R22
R10
J4-6 nc
100Ω
ZXMN2F34FH
T12
T11
R9
J4-5
100Ω
ZXMN2F34FH
T10
R8
J4-4
100Ω
ZXMN2F34FH
T7
R6
J4-3
100Ω
ZXMN2F34FH
R1
J4-2
100Ω
ZXMN2F34FH
T8
T9
CELL+
R34
J3-7
100Ω
ZXMN2F34FH
T18
R33
J3-6
100Ω
ZXMN2F34FH
T17
R32
J3-5
100Ω
ZXMN2F34FH
T16
R31
J3-4
100Ω
ZXMN2F34FH
T13
R30
J3-3
100Ω
ZXMN2F34FH
R29
J3-2
100Ω
ZXMN2F34FH
T14
T15
J4-1
CELL-
R59
1kΩ
R4
10Ω/0.25W
C10
100nF
R58
1kΩ
C11
100nF
R45
1kΩ
C12
100nF
R46
1kΩ
C13
100nF
R47
1kΩ
C14
100nF
R53
1kΩ
C15
100nF
R54
1kΩ
R39
10Ω/0.25W
R25
1kΩ
C16
100nF
R24
1kΩ
C17
100nF
R3
1kΩ
C18
100nF
R5
1kΩ
C21
100nF
R7
1kΩ
C22
100nF
R15
1kΩ
C23
100nF
R16
1kΩ
R26
10/0.25WΩ
+ C1
10μF
30V
R27
0Ω
C32
100nF
30V
R86
10Ω/0.25W
+ C3
10μF
30V
C19
100nF
30V
9
10
11
12
3
4
1
2
5
6
3
4
7
8
1
2
DISCH5
MBAT5
5
DISCH4
MBAT4
DISCH3
MBAT3
DISCH2
MBAT2
DISCH1
MBAT1
IRQ
CLK
DISCH5
MBAT5
DISCH4
MBAT4
DISCH3
10
11
8
9
6
7
MBAT3
DISCH2
MBAT2
DISCH1
MBAT1
IRQ
12
CLK
IC2
Atmel
ATA6870
IC1
Atmel
ATA6870
R37
150Ω
S
R38
7.5kΩ
G
Q7
SQ2301ES
D
R40
51kΩ
Q6
FMMT620
C38 GND_2
220nF
C6
+ nc (33μF/50V)
GND_2
R41
4.7kΩ
PB2
VDDHVM
PD_N_OUT
POW_ENA
PWTST
BIASRES
TEMPREF
TEMP2
36
35
TEMP1
TEMPVSS
AVSS
AVDD
ATST
28
27
26
25
34
33
32
31
30
29
R55
121kΩ
GND_2
GND_2
GND_2
1
2
3
J5
0Ω
VDDHVM
PD_N_OUT
POW_ENA
PWTST
BIASRES
36
35
34
33
32
TEMPREF
TEMP2
TEMP1
TEMPVSS
AVSS
AVDD
ATST
25
31
30
29
28
27
26
C24
220nF
C7
+ nc (33μF/50V)
R21
121kΩ
1
2
3
J6
0Ω
10x1F
5
6
3
4
7
8
1
2
9
10
J7
CELL-
PACK-
VFET
OD
OC
RESET
RSENSE
VDD_HVM
VCC
IRQ
CLK
MISO
MOSI
SCK
CS_N
9
10
5
6
3
4
7
8
1
2
10x1F
J8
Piggypack Board for other Microcontroller
VFET
C5
100nF
50V
R113
RSENSE
PACK-
J9
R89
R99
R91
R100
100Ω
1kΩ
100Ω
1kΩ
C2
C30
C27
R88
1kΩ
+
2.2μF
100nF
100nF
C8
2.2μF
25V
C34
100nF
R2
1kΩ
IC3
ATMEGA32HVB
100nF
C31
OC
OD
14
36
12
13
6
4
11
5
15
35
3
44
43
42
18
1
2
16
37
17
27
VCC
VCC
VREG
VREF
VFET
BATT
VCLMP10
GND
GND
GND
VREFGND
PI
PPI
NI
NNI
NV
OC
OD
PVT
NC
NC
PA0 (ADC0/SGND/PCINT1)
PA1 (ADC1/SGND/PCINT1)
PA2 (PCINT2/T0)
7
8
9
10
PA3 (PCINT3/T1)
PB0 (PCINT4/ICP00)
PB1 (PCINT5/CKOUT)
PB2 (PCINT6)
PB3 (PCINT7)
PB4 (SS/PCINT8)
PB5 (SCK/PCINT9)
PB6 (MOSI/PCINT10)
PB7 (MISO/PCINT11)
29
PC0 (INT0/EXTPROT)
PC1 (INT1)
PC2 (INT2)
PC3 (INT3/SDA)
PC4 (SCL)
PC5
41
PV1
PV2
PV3
PV4
RESET/DW
19
40
39
38
30
31
32
33
34
24
25
26
28
20
21
22
23
PB2
LED1
LED_0603
LED2
LED3
R14
4.7kΩ
D4
LL4148
C24 nc
RESET
R28
R35
R36
CLK
IRQ
CS_N
1kΩ
1kΩ
1kΩ
MISO
SCK
RESET
SCK
MOSI
MISO
1
3
5
3x2M
J2
2
4
6
VCC
MOSI
9228C–AUTO–02/15

Figure 7-2.
PCB Top
9228C–AUTO–02/15

Figure 7-3.
PCB Bottom
9228C–AUTO–02/15

Please note that the following page numbers referred to in this section refer to the specific revision mentioned, not to this document.
Revision No.
9228C-AUTO-02/15
9228B-AUTO-10/12
History
 Put document in the latest template
 Section 4.4 “Temperature Measurements” on page 8 updated
9228C–AUTO–02/15

X X X X X X
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