ICS1702EB Galaxy Power, Inc., ICS1702EB Datasheet - Page 4

• Manufacturer Part Number: ICS1702EB
• Description: Ics1702 Evaluation Board.
• Manufacturer: Galaxy Power, Inc.

ICS1702 Evaluation Board
If either direct maintenance or the condition mode is selected, the
MAINT LED will turn on. The LED will remain on until a reset is
issued either by interrupting the power, removing the batteries or
depressing the reset switch SW1.
If the discharge-only mode is selected, the MAINT LED will flash
at a one second rate until the battery has been discharged. When
the battery is discharged, the controller will shut down and the
MAINT LED will turn off.
If the discharge-to-charge mode is selected, the MAINT LED will
flash at a one second rate until the battery has been discharged.
When the battery is discharged, the appropriate charge indicator
will turn on. See the data sheet for more detailed information on
this auxiliary mode of operation.
Polling for a Battery
Upon power-up or after a reset is issued, any excess charge from
filter capacitors at the +BAT and +CUR terminals is removed with
a series of discharge pulses. After the discharge pulse series is
complete, the voltage at VIN must be greater than 0.5V when a
battery is present. If the voltage at the pin is less than 0.5V, the
ICS1702 assumes no battery is attached, and the polling detect
mode is initiated.
The ICS1702 then applies a 100ms charge pulse. During the pulse,
the ICS1702 monitors the VIN pin to determine if the divided
down terminal voltage is above OPREF. If the battery is present,
the voltage will be clamped below the reference on OPREF when
the current pulse is applied. If a battery is not present, the voltage
at VIN will rise above the reference at OPREF. The POLL LED
lights immediately.
Charge pulses will repeat at one second intervals until the battery is
reinstalled. The POLL LED is active as long as the
ICS1702 is in the polling detect mode. Once a battery is installed,
the ICS1702 will turn off the POLL LED and enter the soft start
stage. The ICS1702 will automatically re-enter the polling detect
mode if the battery is removed during the fast charge, topping
charge, or maintenance charge stages. Any open circuit in the
current path to the battery will initiate the polling detect mode.
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When in the topping charge or maintenance charge stages, a charge
pulse may not occur for several seconds. During the period between
charge pulses, the voltage at VIN should be greater than 0.5V if a
battery is attached. If the voltage at VIN is less than 0.5V, the
ICS1702 assumes the battery has been removed, and the polling
detect mode is initiated.
Out-of-Temperature Range
The TEMP LED activates if the battery is either too hot or too cold to
fast charge. If a thermistor is used, the ICS1702 employs internal
voltage references to determine if a battery is hot or cold. Note:
Remove R9 and replace with a jumper when using a thermistor. A
10k
typically used. See the ICS1702 data sheet for additional
information.
If a thermal switch is used, choose a switch that opens at 45 C or
lower. If a thermal protection device is not used, the TS terminal
must be grounded.
GPI strongly recommends the use of a thermal safety device in the
battery pack. One source of thermal switches is Portage Electric
Products, Inc., in North Canton, Ohio; [phone]. A source of
thermistors is Semetic USA (Ishizuka Electronics Corp.), Babylon,
NY; [phone].
Design Considerations
When designing external current source circuitry for use with the
ICS1702, there are several important considerations to make before
starting the design and the PC board layout.
For fast charge rates (1C through 4C), consideration has to be given
to the use of a pulse-width modulated switch mode current source in
order to reduce size and power dissipation.
Switch mode current sources can provide the ability to charge battery
packs that require voltages higher than the primary supply. For
instance, to charge a 24 volt battery from a 12 volt vehicle battery, a
switch mode boost converter could be used.
In general, linear chargers are less complex and more cost effective,
but less efficient than switch mode chargers. For lower charge rates
(C/1.5 through C/4), consideration should be given to using a linear
charger unless the size and ability to dissipate heat are not available.
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.
@ 25 C thermistor with an external pull-up resistor is