ICS1712M GALAXY [Galaxy Power, Inc.], ICS1712M Datasheet - Page 18

• Manufacturer Part Number: ICS1712M
• Description: Charge Controller for Nickel-Cadmium and Nickel-Metal Hydride Batteries
• Manufacturer: GALAXY [Galaxy Power, Inc.]

ICS1712
Applications Information
To ensure proper operation of the ICS1712, external components
must be properly selected. The external current source used must
meet several important criteria to ensure optimal performance of
the charging system. The charging current should be constant when
using voltage slope termination. The current may vary when using
temperature slope termination
.
VIN Divider Resistors
Figure 14 shows a typical application using the ICS1712. R1 and
R2 must be carefully selected to ensure that battery detection and
voltage termination methods operate properly. R1 and R2 are
selected to scale the battery voltage down to the voltage of one cell.
The following table shows some typical values. Additional
information is available in the Voltage Input section.
If using voltage slope termination, the current source should
prevent ripple voltage from appearing on the battery. The effects of
ripple on the battery voltage may interfere with proper operation
when using the voltage slope method.
Cells
1
2
3
4
5
6
7
8
Short
2.0k
2.0k
3.0k
9.1k
12k
10k
12k
R1
Open
2.0k
1.0k
1.0k
3.0k
2.0k
2.0k
1.3k
R2
18
PC Board Design Considerations
It is very important that care be taken to minimize noise coupling
and ground bounce. In addition, wires and connectors can add
significant resistance and inductance to the charge and discharge
circuits.
When designing the printed circuit board, make sure ground and
power traces are wide and bypass capacitors are used right at the
controller. Use separate grounds for the signal, charge and
discharge circuits. Separate ground planes on the component side
of the PC board are recommended. Be sure to connect these
grounds together at the negative lead of the battery only. For the
discharge circuit, keep the physical separation between power and
return (ground) to a minimum to minimize field radiation effects.
This precaution is also applicable to the constant current source,
particularly if it is a switch mode type. Keep the ICS1712 and the
constant current source control circuits outside the power and
return loop described above. These precautions will prevent high
circulating currents and coupled noise from disturbing normal
operation.
Selecting the Appropriate Termination Method
In general, the voltage slope termination method works best for
equipment where the battery is fast charged with the equipment off
or the battery is removed from the equipment for fast charge. The
temperature slope and maximum temperature termination methods
are for equipment that must remain operative while the battery is
fast charged.