SCD8635-12 Rev A
BEU8635-12
Cell Management Electronics for Lithium-Ion Battery
Description
The Aeroflex 8635-12 is a Lithium-Ion cell
balancing system. It controls the balancing
of one battery consisting of a series stack
of Lithium-Ion cells to ensure that each cell
is precisely charged to its proper level of
energy and to monitor each cell's
operational voltage.
The cell balancing circuitry uses a set of
bilateral DC-DC converters which tie each
cell of a battery to a common share bus.
Cell charge is distributed among the
multiple cells so that the charge of each
cell is automatically matched to the
average charge of the other cells.
Features
Cell Balancing to within ±5.0mV
Cell Voltage Monitoring Accuracy
±10.0mV (±20.0mV Space Mission Life)
Total Battery Voltage Monitoring
Accuracy ±0.3% of Full Scale
Supports 12 Lithium-Ion battery cells in
series
Battery Drain Current at Balance
15mA maximum
Discrete output lines for critical signaling
with user definable thresholds:
Overvoltage Protection 4.40V typ
Cell Voltage High 4.20V typ
Cell Voltage Low 3.20V typ
MIL-STD-1553B telemetry for data
logging and monitoring
Safety
The safety of Lithium-Ion battery
technology requires that extreme care be
taken in the provisions made for cell
charging and cell monitoring.
Precision measurements of each of the
individual cell voltages in the battery stack
and precise charge balancing to each
individual cell are critical.
The Aeroflex 8635-12 provides the
necessary precision of control and
monitoring to ensure that safety.
Discrete logic outputs are provided for
critical signaling, enabling the user to
initiate load shedding and/or to halt
charging.
Low operating losses enable continuous
operation. Continuous balancing provides
maximum protection against any one cell
becoming overcharged.
Cell Voltage Monitoring and Telemetry
www.aeroflex.com/BEU
March 3, 2008
Balancing for 12-Cell Battery
SCD8635-12 Rev A 3/3/08 Aeroflex Plainview
2
7
12
+
-
+
-
+
-
+
-
+
-
ON
OFF
+30 VDC
Channel B
1553B
LOW
CELL
OVP
HIGH
CELL
Channel A
1553B
+12VDC
+12VDC
-12VDC
+5VDC
(ISOLATED)
SHARE BUS
MON
CLK
BAL
CLK
SELECT
MUX
VIN
CELL BALANCE
BOARD
BATTERY
12 CELLS
CONTROL BOARD
4.000V
REFERENCE
PRECISION
RELAY
XFMR
XFMR
XCVR
A/D
12-B IT
MUX
BALANCING
CIRCUIT
1
BALANCING
CIRCUIT
2
BALANCING
CIRCUIT
3
BALANCING
CIRCUIT
4
BALANCING
CIRCUIT
2
BALANCING
CIRCUIT
12
POWER
SUPPLY
Block Diagram
CONTROLLER
BALANCING
CIRCUIT
CLOCK
DRIVER
DIFF. AMPS
VOLTAGE
BATTERY (3x)
HI AND LO
BATTERY
2 2 2
8635-12 Operating Details
Battery Cell Balancing
Provides 12 individual continuous balancing circuits.
Maximum Cell Balancing Current Limit
Each cell is provided with a 1Amp fuse for overload interrupt
in the event of a shorted cell to protect the remaining cell
balance functionality.
Cell Balancing Accuracy
When connected to a battery, the 8635-12 provides
balancing currents into each of the battery's cells. The
directions and the magnitudes of the individual currents are
proportional to the deviations of the cell voltages from the
average cell voltage. The transfer ratio of voltage to current is
1.0 Ohm nominal and is satisfied for cell voltages of up to
4.2V.
Battery Cell Current Drawn in Off State
In the off state, the differential mode battery cell current
drawn by each cell balancing circuit is less than 50μA.
Battery Cell Voltage Monitoring
Measures cell voltages for up to 12-cells.
4V and 0V References for Calibration
Provides 4V and 0V references for cell voltage telemetry
calibration.
Battery and Cell Protection
Incorporates overvoltage protection (OVP) circuits. These
circuits monitor all of the battery cell voltages and only
register the highest of all cell voltages monitored. When a
cell voltage threshold of 4.40V is reached, the protection
circuit output changes state and latches within 50mS.
Battery Cell Overvoltage Latch Output
The status of the OVP latch is provided by telemetry as
specified in Tables II, III & IV and also as a discrete output.
Recovery from Cell Overvoltage Indication
The OVP latch is reset by a 1553B reset command or by
recycling the input power.
Highest Battery Cell Voltage Telemetry
Provides highest battery cell voltage telemetry as specified in
Tables I & IV.
Lowest Battery Cell Voltage Telemetry
Provides lowest battery cell voltage telemetry as specified in
Tables I & IV.
Test Points
Provides test points for total battery voltage, low cell
indicator and high cell indicator. Access to the total battery
voltage is provided to permit pre-charging before connection
to the battery.
SCD8635-12 Rev A 3/3/08 Aeroflex Plainview
3
MIL-STD-1553B Telemetry & Commands
Analog or bi-level telemetry can be requested from the controller
and reported over the dual redundant 1553B interface with the
RT addresses configurable at the J1 connector.
Analog Telemetry
Each analog telemetry item can be requested individually on
sub-addresses 18, 19 or 22.
First a 1553B receive command with one data word as defined in
Table I, which specifies the telemetry item being requested, must
be issued. After a minimum delay of 1.2ms, the data can be
retrieved by sending a 1553B transmit command for one data
word on the same sub-address on which the request was
initiated.
The 12-bit data reply is left justified in the 16-bit 1553B data word
with the four LSBs set to "0".
Bi-Level Telemetry
Bi-level telemetry can be requested on sub-addresses 18, 19 or
22.
First a 1553B receive command with one data word as defined in
Table II, which specifies the telemetry item being requested, must
be issued. After a minimum delay of 1.2ms, the data can be
retrieved by sending a 1553B transmit command for one data
word on the same sub-address on which the request was
initiated.
Table I – Analog Telemetry
Item Telemetr y Tit le Telemetry Reply
Scale 1st Data Word of
1553B Receive
Command (Hex)
1 4V Reference -0.40V to 4.89V 0800
2 0V Reference -0.40V to 4.89V 0803
3 Total Battery Voltage 1 0V to 122.88V 0805
4 Total Battery Voltage 2 0V to 122.88V 0806
5 Total Battery Voltage 3 0V to 122.88V 0809
6 Share Bus Voltage 0V to 5.12V 080A
7 Cell 1 Voltage 0V to 5.12V 0811
8 Cell 2 Voltage 0V to 5.12V 0812
9 Cell 3 Voltage 0V to 5.12V 0814
10 Cell 4 Voltage 0V to 5.12V 0817
11 Cell 5 Voltage 0V to 5.12V 0818
12 Cell 6 Voltage 0V to 5.12V 081B
13 Cell 7 Voltage 0V to 5.12V 081D
14 Cell 8 Voltage 0V to 5.12V 081E
15 Cell 9 Voltage 0V to 5.12V 0821
16 Cell 10 Voltage 0V to 5.12V 0822
17 Cell 11 Voltage 0V to 5.12V 0824
18 Cell 12 Voltage 0V to 5.12V 0827
19 Lowest Cell Voltage 0V to 5.12V 0871
20 Highest Cell Voltage 0V to 5.12V 0872
Table II – Bi-level Telemetry
Item Telemetry Title Status Reply
Bit
1st Data Word
of 1553B
Receive
Command
(Hex)
1 Overvoltage Latch Status 1 = Set D13 0C80
SCD8635-12 Rev A 3/3/08 Aeroflex Plainview
4
32-Word Telemetry
To reduce data bus bandwidth usage, the 8635-12 supports
a 32-word telemetry request on sub-address 20 as defined
in Table III.
First a 1553B receive command with one data word of
AAAA(Hex) must be issued. After a minimum delay of
1.2ms, the data can be retrieved by sending a 1553B
transmit command for 32 data words on sub-address 20.
Reply word 31 is a modulo-16 message count. This counter
increments by one for each valid telemetry request.
The 12-bit analog data reply is left justified in the 16-bit
1553B data word with the four LSBs set to "0"..
8-Word Telemetry
To reduce data bus bandwidth usage, the 8635-12 supports
an 8-word telemetry request on sub-address 24 as defined
in Table IV.
First a 1553B receive command with one data word of
5555(Hex) must be issued. After a minimum delay of 1.2ms,
the data can be retrieved by sending a 1553B transmit
command for 8 data words on sub-address 24.
Reply word 8 is a modulo-16 message count. This counter
increments by one for each valid telemetry request.
The 12-bit analog data reply is left justified in the 16-bit
1553B data word with the four LSBs set to "0".
Table III – 32-Word Telemetry
Item Telemetry Title Telemetry
Type Reply
Word Reply Bits
1 4V Reference Analog 1 D(15:4)
2 Total Battery Voltage 1 Analog 2 D(15:4)
3 Total Battery Voltage 2 Analog 3 D(15:4)
4 Total Battery Voltage 3 Analog 4 D(15:4)
5 Share Bus Voltage Analog 5 D(15:4)
6 Reserved - 6 -
7 Cell 1 Voltage Analog 7 D(15:4)
8 Cell 2 Voltage Analog 8 D(15:4)
9 Cell 3 Voltage Analog 9 D(15:4)
10 Cell 4 Voltage Analog 10 D(15:4)
11 Cell 5 Voltage Analog 11 D(15:4)
12 Cell 6 Voltage Analog 12 D(15:4)
13 Cell 7 Voltage Analog 13 D(15:4)
14 Cell 8 Voltage Analog 14 D(15:4)
15 Cell 9 Voltage Analog 15 D(15:4)
16 Cell 10 Voltage Analog 16 D(15:4)
17 Cell 11 Voltage Analog 17 D(15:4)
18 Cell 12 Voltage Analog 18 D(15:4)
19 Reserved - 19 -
20 Reserved - 20 -
21 Reser ved - 21 -
22 Reserved - 22 -
23 Reserved - 23 -
24 Reserved - 24 -
25 Reserved - 25 -
26 Reserved - 26 -
27 Reserved - 27 -
28 Reserved - 28 -
29 Reserved - 29 -
30 Reserved - 30 -
31 Message Count Analog 31 D(15:0)
32 Overvoltage Latch Status Bi-level 32 D13
Table IV – 8-Word Telemetry
Item Telemetry Title Telemetry
Type Reply
Word Reply Bits
1 Overvoltage Level Status Bi-Level 1 D13
2Reserved - 2 -
3Reserved - 3 -
4Reserved - 4 -
50V Reference Analog 5 D(15:4)
6 Lowest Cell Voltage Analog 6 D(15:4)
7 Highest Cell Voltage Analog 7 D(15:4)
8 Message Count Analog 8 D(15:0)
SCD8635-12 Rev A 3/3/08 Aeroflex Plainview
5
Additional Commands
Data Load Command
1553B receive commands consist of 2 data words to the
sub-address specified in Table V. Only the first data word is
used.
Telemetry Frame Sync Command
1553B broadcast command on sub-address 17 (any data
word) commands the 8635-12 to refresh its RT address.
Remote Terminal State Command
1553B transmit command on sub-address 21 for one data
word. The reply word will be 4000(Hex), to indicate that the
unit is ready to accept another command or 5000(Hex), to
indicate that the unit is busy and cannot accept another
command.
1553B Data Wrap Around
Sub-address 30 is dedicated to data wrap around as
specified in MIL-STD-1553B.
Supported Mode Codes
The 8635-12 supports the 1553B Mode Codes in Table VI.
1553B Status Flag Bits
The 8635-12 supports the following 1553B status flag bits:
1. Message Error bit
2. Broadcast Message Received bit
All other status bits are set to "0".
Table V – Commands
Item Function Title Sub-Address
1st Data Word
of 1553B
Receive
Command
(Hex)
1Reserved 13 -
2Reserved 14 -
3 Reset OVP Latch 15 0400
Table VI – 1553B Mode Codes
Mode Code Name Mode Code Number
Transmit Status Word 2
Transmitter Shutdown 4
Override Transmitter Shutdown 5
Reset Remote Terminal 8
SCD8635-12 Rev A 3/3/08 Aeroflex Plainview
6
Connector P1
26 Pin Subminiature-D Plug
Cell Sense
Pin
#Function Name Pin
#Function Name
23 CELL_12+ 17 RESERVED
9 CELL_11+ 7 RESERVED
3 CELL_10+ 14 RESERVED
19 CELL_9+ 1 RESERVED
10 CELL_8+ 20 RESERVED
13 CELL_7+ 12 RESERVED
16 CELL_6+ 18 RESERVED
26 CELL_5+ 8 RESERVED
5 CELL_4+ 4 RESERVED
2 CELL_3+ 21 RESERVED
15 CELL_2+ 22 RESERVED
24 CELL_1+ 6 RESERVED
11 CELL_1- 25 RESERVED
Connector J2 for Control Board
Triaxial
1553B Bus A
CHA_DATA_H
CHA_DATA_L
SHIELD
Connector J3 for Control Board
Triaxial
1553B Bus B
CHB_DATA_H
CHB_DATA_L
SHIELD
Connector J1 for Control Board
51 Pin Micro -D Receptacle
Control & Test Points
Pin
#Function Pin
#Function Pin
#Function
1 30V_RTN 18 V_BAT_3 35 V_BAT_2
2NC_ISOLATION 19 NC_ISOLATION 36 NC_ISOLATION
3NC_ISOLATION 20 +30V_POWER 37 NC_ISOLATION
4NC_ISOLATION 21 +30V_POWER 38 NC_ISOLATION
530V_RTN 22 NC_ISOLATION 39 SPARE
6NC_ISOLATION 23 NC_ISOLATION 40 CHASSIS GND
7CHASSIS GND 24 CHASSIS GND 41 RESERVED
8CELL_CHG_12 25 LOW_CELL 42 SPARE
9SPARE 26 RESERVED 43 BEU_ON_CMD_1
10 BEU_OFF_CMD_2 27 BAL_ON_1 44 BEU_ON_CMD_2
11 BEU_OFF_CMD_1 28 BAL_ON_2 45 HIGH_CELL
12 RTA_2 29 RTA_0 46 RTA_4
13 RTA_GND 30 RTA_GND 47 RTA_GND
14 RTA_GND 31 RTA_GND 48 RTA_GND
15 RTA_1 32 RTA_3 49 RTPTY
16 OV_PROT 33 V_BAT_TP 50 V_BAT_RTN1
17 V_BAT_RTN3 34 V_BAT_RTN2 51 V_BAT_1
SCD8635-12 Rev A 3/3/08 Aeroflex Plainview
7
3-D View
Outline
11.50
5.250
0.20
2x 0.25
2x 0.40
2x 1.00
4x
11.002x
P1
J1
J2
J3
2.01
1.50
2.50
3.25
0.76
8
SCD8635-12 Rev A 3/3/08
PLAINVIEW, NEW YORK
Toll Free: 800-THE-1553
Fax: 516-694-6715
SE AND MID-ATLANTIC
Tel: 321-951-4164
Fax: 321-951-4254
INTERNATIONAL
Tel: 805-778-9229
Fax: 805-778-1980
WEST COAST
Tel: 949-362-2260
Fax: 949-362-2266
NORTHEAST
Tel: 603-888-3975
Fax: 603-888-4585
CENTRAL
Tel: 719-594-8017
Fax: 719-594-8468
www.aeroflex.com info-ams@aeroflex.com
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, pe rformance-driven and customer-focuse d
EXPORT CONTROL: EXPOR T 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.)
Standard Configuration
Power Dissipation
7.1 Watts from 30V Supply
0.75 Watts from battery
Operating Base Plate Temperature
BEU8635-12-S -34°C to +71°C
BEU8635-12 0°C to +70°C
Storage Temperature
-34°C to +71°C
Dimensions
11.5'' L x 2.01'' W x 5.25'' H
Weight
3.5 lbs (1.59 kg)
Ordering Information
MODEL NUMBER SCREENING
BEU8635-12-S High Reliablilty Space Grade
BEU8635-12 Commerical Flow