ICS1722 datasheet(16/24 Pages) GALAXY

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ICS1722

Charging System Status by Indicator

The Indicator Description List in Table 2 contains displays that are

caused by charging system abnormalities. When the CMN

indicator is flashing with no other indicator active, there is voltage

present at the battery terminals with the current source off and no

battery. Check the current source and ensure that it produces no

more than the equivalent of 350mV/cell when turned off with no

battery. If the VIN divider resistors were not properly selected, an

open circuit voltage that is actually less than the equivalent of

350mV/cell with the charger off and no battery will not divide

down this open circuit voltage properly and produce the CMN

flash indication. Check the VIN divider and ensure that it properly

normalizes the battery voltage to the electrochemical potential of

about 1.2V cell. If the CMN flash indication occurs with the

battery installed, then the constant current source is producing

more than the equivalent of 350mV/cell when off and there is an

open connection between the charger terminals and the battery.

Check wires, connections, battery terminals, and the battery itself

for an open circuit condition.

If the MMN and CMN indicators are alternately flashing, the likely

cause is no battery with the ICS1722 programmed in the

discharge-to-charge auxiliary mode. If the battery is present, check

wires, connectors, battery terminals, and the battery itself for an

open circuit condition.

If the MMN indicator is active at the initiation of fast charge, check

the external pull-down resistor from OPREF to ground. A voltage

at OPREF that exceeds 2.3V will prevent the start of fast charge.

The voltage slope termination method used by the ICS1722

requires a nearly constant current flow into the battery during fast

charge. Charging the battery in equipment that draws a known

constant current while the battery is charging should have this

current draw added to the fast charge current. Using the ICS1722

for charging the batteries in equipment that randomly or

periodically requires moderate current from the battery during fast

charge needs evaluation. Equipment that randomly or periodically

requires high current from the battery during fast charge may cause

a voltage inflection that results in termination before full charge. A

voltage inflection can occur due to the charge current decreasing or

fluctuating as the load changes rather than by the battery reaching

full charge. The voltage slope method will terminate charge based

on voltage inflections that are characteristic of a fully charged

battery. The

ICS1702 and ICS1712 charge controllers have temperature

termination methods for equipment that randomly or periodically

draws significant current from the battery during fast charge.

Charging sources that produce decreasing current as fast charge

progresses may also cause a voltage inflection that may result in

termination before full charge. For example, if the charge current is

supplied through a resistor or if the charging source is a constant

current type that has insufficient input voltage, the current will

decrease and may cause a termination before full charge. Other

current source abnormalities that may cause a voltage inflection

that is characteristic of a fully charged battery are inadequate ripple

and noise attenuation capability or charge current decreasing due to

thermal drift. Charging sources that have any of the above

characteristics need evaluation to access their suitability for the

application if the use of the voltage slope termination is desired.

The controller soft start stage, built-in noise filtering, and fast

charge timer operate optimally when the constant current source

charges the battery at the rate selected. If the actual charge current

is significantly less than the rate selected, the conditioning effect of

the soft start stage and the controller noise immunity are lessened.

Also, the fast charge timer may cause termination based on time

duration rather than by the battery reaching full charge due to

inadequate charge current.

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