ISL9208EVAL2Z Intersil, ISL9208EVAL2Z Datasheet - Page 6

• Manufacturer Part Number: ISL9208EVAL2Z
• Description: EVAL BOARD 2 FOR ISL9208
• Manufacturer: Intersil

Specifications of ISL9208EVAL2Z

• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

charge current, the threshold is about 60mA, for discharge
the threshold is about 800mA. These thresholds can be
changed by replacing a resistor, but making the thresholds
much lower may cause problems due to the LM358 input
offset. To change the discharge current detection threshold,
change the value of R
threshold. To change the charge current detection threshold,
change the value of R
threshold.
Future code revisions will have support for this hardware,
but if custom code is desired, then the charge indicator
connects to the microcontroller pin PTB4 and the discharge
indicator connects to pin PTB5. See Figure 8.
1.8M
1k
CURRENT DIRECTION DETECT CIRCUITS
FIGURE 8. ISL9208EVAL2Z CURRENT DETECTION
FIGURE 7. USING OP AMP AND FETS TO DETECT
RGO
1M
R46
DISCHARGE DETECT
CONNECTIONS
CHARGE AND DISCHARGE CURRENT
0.005
1k
BSS84DW
1M
R40
46
40
. A lower value lowers the current
. A lower value lowers the current
0.05
LM358
6
-
+
-
+
GND
RGO
2 OF 2
1 OF 2
CHARGE DETECT
1k
CHARGE
DISCHARGE
DISCHARGE
INDICATOR
Application Note 1444
FMMT619
INDICATOR
1M
CHARGE
Pack Voltage Monitoring
The ISL9208EVAL2Z has a circuit that is activated by the
microcontroller to monitor the pack voltage directly. The input
to the microcontroller is the pack voltage divided by 16 (see
Figure 9).
The purpose of this circuit is to get a more accurate reading
of the pack voltage. Without this circuit, the pack voltage is
determined by adding the individual cell voltages. However,
this results in adding the measurement errors of each cell,
so the accuracy of the pack voltage is not very useful. With
an accurate reading of the pack voltage, the microcontroller
can use the value to determine if there is any low level
discharge current or can use the value to compare to the
summation of the cell voltages to detect any gross cell
measurement errors.
The software revision 1.5 does not support the pack voltage
monitor hardware, but if support is desired, then the
microcontroller needs to turn on the PTB6 output to enable
the circuit, then do an analog read of the ADP4 input.
FIGURE 10. ISL9208EVAL2Z PACK VOLTAGE MONITORING
FIGURE 9. DIRECT MONITOR OF THE PACK VOLTAGE
PACK VOLTAGE ENABLE
100k
368k
CONNECTIONS
PACK+
GND
GND
PACK VOLTAGE MONITORING CIRCUIT
1.21M
80.6k
50k
PACKV
PACK VOLTAGE µC INPUT
16
TO µC
OUTPUT
TO µC
A/D INPUT
December 15, 2008
AN1444.0