19-4841; Rev 8/09
DS2726EVKIT+
10-Cell Li-Ion Battery Protector
Evaluation Kit
www.maxim-ic.com
CONNECTING THE DS2726 EVALUATION KIT BOARD
Figure 1. CONNECTION DIAGRAM FOR DS2726EVKIT+
PACK+
BATT+
V10
V9
+
V8
VCC
CHARGER/
LOAD
V7
DS2726
EV Board
-
V6
SLP
V5
10 Cell
Battery Pack
V4
V3
V2
V1
VSS
BATT-
V0
V10 to V0 are voltage sense lines for the individual cells. For a 10-cell battery pack connect V10 to the positive
terminal of the pack. V9 will be connected to the positive terminal of the next cell and so on down to the last cell. V0
connects to the negative terminal of the battery pack. These connections are for voltage sense and cell balancing
only. The maximum amount of current they will sink is 200mA during cell balancing. The load current does not flow
through these connections. For a connection diagram of a battery pack with less than 10 cells, see Figure 1.
The BATT+ connection should be connected to the positive terminal of the battery pack. The path from PACK+ to
BATT+ is your charge and discharge current path. High currents will flow through this path therefore a heavy gauge
wire should be used.
BATT- should be connected to the negative terminal of the battery pack. VSS is the return current path for the load.
1 of 5
DS2726EVKIT+
Figure 2. CELL CONNECTION DIAGRAM FOR LESS THAN 10 CELLS
9 Cell
8 Cell
7 Cell
6 Cell
5 Cell
V10 = odd
V10 = even
V10 = odd
V10 = even
V10 = odd
V10
V10
V10
V10
V10
V9
V9
V9
V9
V9
V8
V8
V8
V8
V8
V7
V7
V7
V7
V7
V6
V6
V6
V6
V6
V5
V5
V5
V5
V5
V4
V4
V4
V4
V4
V3
V3
V3
V3
V3
V2
V2
V2
V2
V2
V1
V1
V1
V1
V1
V0
V0
V0
V0
V0
CHARGER CONNECTION
The positive terminal of the charge supply should be connected to the PAC+ terminal of the EV board. The
negative terminal of the charge supply should be connected to the negative terminal of your battery pack. This is a
high current path therefore a heavy gauge wire should be used. Also, SLEEP will need to be pulled to VCC when
the charger is connected. The DS2726 does not regulate charge current. Current should be regulated by the
charge supply.
NOTE: The DC FET does not turn on below 2.8V per cell. When charging below 2.8V per cell the charge source
should charge at a lower rate to prevent damaging the DC FET. Once the per-cell voltage exceeds 2.8V, the DC
FET will enable and high current charge (fast charge) can begin.
CONFIGURATION
Overvoltage Threshold
The overvoltage threshold is set at the OVS1 and OVS2 pins through resistors R17, R18, R32, and R33. R17 and
R18 will pull OVS1 and OVS2 to VCC. R32 and R33 will pull OVS1 and OVS2 to VSS. VIM is achieved by floating
the pin.
Table 1
OVS0
OVS1
4.10
VIL
VIL
4.15
VIM
VIL
Nominal VOV Threshold (V)
4.20 4.25 4.30 4.35 4.40
VIH
VIL
VIM
VIH
VIL
VIL
VIM
VIM
VIM
VIH
4.45
VIM
VIH
4.50
VIH
VIH
Cell Balancing Voltage Threshold
The Cell Balancing Voltage Threshold is set at the CBS0 and CBS1 pins through resistors R15, R16, R30, and
R31. R15 and R16 will pull CBS0 and CBS1 to VCC. R30 and R31 will pull CBS0 and CBS1 to VSS. VIM is
achieved by floating the pin.
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DS2726EVKIT+
Table 2
CBS0
CBS1
0.00
VIL
VIL
Cell Balancing Threshold Offset from VOV (V)
0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40
VIM
VIH
VIL
VIM
VIH
VIL
VIM
VIH
VIL
VIL
VIM
VIM
VIM
VIH
VIH
VIH
Cell balancing voltage:
VOV - VCBTO = VCB
Example:
OVS0, OVS1, CBS0, and CBS1 = VIH
4.5V - 0.4V = 4.1V
Cell balancing will begin when a cell’s voltage is greater than 4.1V and will terminate when all cells’ voltages are
greater than 4.1V.
Number of Cells
The number of cells in the battery pack is set at the SEL0 and SEL1 pins through resistors R12, R13, R27, and
R28. R12 and R13 will pull SEL0 and SEL1 to VCC. R27 and R28 will pull CBS0 and CBS1 to VSS. VIM is achieved
by floating the pin. See Figure 2 for proper connections to stacks with fewer than 10 cells.
Table 3
SEL0
SEL1
5
VIL
VIL
6
VIM
VIL
Number of Series Connected Cells
7
8
9
10
10
10
VIH
VIL
VIM
VIH
VIL
VIM
VIL
VIM VIM VIM
VIH
VIH
10
VIH
VIH
Discharge Overcurrent
The RDOC pin is a 1μA current sink. The R34 resistor sets the discharge overcurrent voltage threshold.
R34 x 1μA = VDOC
The voltage seen at RDOC is sent to a comparator with the voltage seen at SNS. When VRDOC > VSNS the DC FET
will turn off. The voltage drop from Bat+ to the SNS pin is determined by the RDS_ON resistance of the DC FET. See
the FET section below for a description of RDS_ON and a link to the datasheet of the FET used the on EV board.
Short Circuit Overcurrent
The RSC pin is a 1μA current sink. The R35 resistor sets the short circuit voltage threshold.
R35 x 1μA = VSC
The voltage seen at RSC is sent to a comparator with the voltage seen at SNS. When VRSC > VSNS the DC FET will
turn off. The voltage drop from Bat+ to the SNS pin is determined by the RDS_ON resistance of the DC FET. See the
FET section for a description of RDS_ON and a reference to the data sheet of the FET used the on EV board.
Discharge Overcurrent Delay
The short circuit delay time is set using the capacitor C14 connected to the CDOCD pin. The short circuit delay
time is defined by the equation:
tDOCD = CDOCD x 32M
Short Circuit Overcurrent Delay
The short circuit delay time is set using the capacitor C15 connected to the CSCD pin. The short circuit delay time
is defined by the equation:
tSCD = CSCD x 500k
FET
The FETs used on the DS2726 EV board are Vishay SUM110P06-07L. Refer to the data sheet for details.
The RDS_ON rating of this FET is typ 5.5m at VGS = -10V. The EV kit board has two FETs in parallel, therefore, the
equivalent resistance is around 2.75m. Multiply RDS_ON times the desired DOC to get VDOC. Multiply RDS_ON times
the desired SC current to get VSC.
3 of 5
1
1
1uF
(short trace)
C12
1uF
C37
1K
R11
6.2V
D1
150
V4
SMAJ16CA-13-F
V1
SMAJ60A-13-F
10K
R19
C35
1uF
R34
120K
104
R27 R28 R29 R30 R31 R32 R33
1K
C13
C14 C15
102 102
8
7
6
5
4
3
C16
NP 2
1
GND
R35
200K
150
R21
NP
C17
CSCD
SLP
CDOCD
SEL1
SEL0
VCC
RDOC
RSC
D2
NP
NP
1uF
GND
C18 C19
C36
R22 R23
150 150
SMAJ16CA-13-F
30
V2
SUM110P06-07L
Q1
Q3
SUM110P06-07L
NP NP NP
C20 C21 C22
U1
DS2726
GND
R26
15
V1
V2
V3
V4
V5
V6
V7
V8
C11
10uF
C1
1uF
GND
C3
GND
1uF
C2
GND
1uF
C8
GND
1uF
C7
GND
1uF
C6
GND
1uF
C5 GND
1uF
C4
GND
1uF
1uF
GND
C10
1uF
C9
C23
C0
1uF
NP
GND GND
C24
NP
C31
NP
C30
NP
C29
NP
C28
NP
C27
NP
C26
NP
C25
NP
C33
NP
C32
NP
NP= Not Populated
17
18
19
20
21
22
23
24
GND
SMAJ16CA-13-F
V3
SUM110P06-07L
Q2
Q4
SUM110P06-07L
R24 R25
150 150
28
GND
R12 R13 R14 R15 R16 R17 R18
1K 1K
1K 1K 1K 1K
Not Populated
C34
0.1uF
(close to pins)
Not Populated
R20
Not Populated
J1
VSS
J2
SLEEP
1
Not Populated
J3
VCC
Not Populated
1
Not Populated
27
J4
PACK+
Not Populated
32
PKP
CBCFG
9
31
CC
CBS0
10
NC
CBS1
11
29
SNS
OVS0
12
DC
OVS1
13
VIN
NC
14
25
V9
V0
26
V10
GND
15
4 of 5
16
V5
SMAJ60A-13-F
GND
1
L0
L1
L2
L3
L4
L5
L6
L7
L8
L9
L10
J5
BATT+
2uH
2uH
2uH
2uH
2uH
2uH
2uH
2uH
2uH
2uH
2uH
R0
R1
R2
R3
R4
R5
R6
R7
R8
R9
7.5
7.5
7.5
7.5
7.5
7.5
7.5
7.5
7.5
7.5
R10 7.5
1
1
1
1
1
1
1
1
1
1
1
V0
V1
V2
V3
V4
V5
V6
V7
V8
V9
V10
DS2726EVKIT+
DS2726EVKIT+
REVISION HISTORY
REVISION
DATE
8/09
DESCRIPTION
Changed the ordering part number from DS2726K to DS2726EVKIT+.
PAGES
CHANGED
All
5 of 5
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