MAX11068EVKIT+ Maxim Integrated Products, MAX11068EVKIT+ Datasheet - Page 24

• Manufacturer Part Number: MAX11068EVKIT+
• Description: KIT SMART BATT MEASUREMENT 12CH
• Manufacturer: Maxim Integrated Products

Specifications of MAX11068EVKIT+

• Main Purpose: Power Management, Battery Monitor, Car
• Utilized Ic / Part: MAX11068
• Primary Attributes: Monitors Current, Voltage, Temperature
• Secondary Attributes: 1 ~ 12 Cell- Li-Ion, 1 ~ 12 Cell- NiMH
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Embedded: -

12-Channel, High-Voltage Sensor, Smart
Data-Acquisition Interface
Table
Note 1: t
Note 2:
Based on the calculations, up to two nonadjacent inter-
nal cell-balancing enabled switches are supported for
a discharge current of 250mA per cell. At least a 0.5W
rated R
rent and its worst-case range of 210mA to 308mA.
When using the internal cell-balancing switches, the
measured voltage on the C
by the external R
measurements, disabling the internal cell-balancing
switch is required. These switches are not disabled
automatically during a conversion. After the internal cell-
balancing switch is disabled, allow the input voltage to
settle for a time period (t
external components C
cell-measurement sequence:
If adjacent internal cell-balancing switches are enabled,
the discharge current would be much higher than the
desired value. Figure 14 shows the adjacent enabled bal-
ancing switches and the resulting discharge current (I
From the I
current grows with the number of adjacent active internal
cell-balancing switches. This is because the cell voltages
across the active switches and the R
24
t
SETTLE
Max No. of Switches On
I
DIS
EQ
Nonadjacent cell switches.
1. Cell-Balancing Circuit Parameter Variation
SETTLE
= (V
CELL NAME
Measurements During Cell Balancing
FILTER
I
DIS
at C N+1 (Note 1)
BALANCE
(Note 2)
is required to handle the 250mA nominal cur-
V
R
R
CELL5
CELL
C
Current Variation Due to Enabled
SW
EQ
equation, it is apparent that the discharge
F
is five time constants after the cell-balancing switch is disabled.
t
3dB
SETTLE
EQ
+ V
resistors. For accurate cell-voltage
CELL4
F
= 10 x R
SETTLE
and R
Adjacent Cell Switches
N
)/(2 x R
to C
), which is determined by
EQ
3435
EQ
MIN
308
5.1
4.1
0.6
9
3
3
, before performing a
N+1
x C
EQ
SW
input is reduced
F
+ (2 x R
values are grow-
3061
TYP
250
5.2
4.1
0.8
10
6
2
SW
))
DIS
):
MAX
2755
210
5.3
4.1
1.1
11
9
2
Figure 14. Discharge Current Path for Adjacent Enabled
Balancing Switches
ing proportionally, but R
many adjacent switches are active. Consequently, the
numerator of the discharge current equation grows faster
than the denominator with increasing active switch count
and discharge current increases. Unless this is accounted
for by the host controller, the package power-dissipation
limit could be reached unexpectedly and damage to the
device could occur. To avoid this possibility, it is recom-
mended to use an odd or even switch-enable control
scheme for the internal cell-balancing switches.
Switches
UNITS
V
V
CELL5
CELL4
mA
Hz
ms
FF
I
I
V
ACCURACY (%)
F1
F2
F3
HIGH-SIDE
I
DIS
NA
10
50
16
—
—
—
1
EQ
R
R
R
EQ
EQ
EQ
remains fixed no matter how
C
C
F
F
ACCURACY (%)
C
C
C
5
4
3
LOW-SIDE
-10
-50
-23
NA
—
—
—
-1
R
R
SW
SW