ICS1722
Pin Descriptions
The
ICS1722
requires some external components to control the
clock rate and provide an indicator display. The controller must be
interfaced to an external power source that will provide the current
required to charge a battery pack and, if desired, a circuit that will
sink discharge current.
The maintenance mode (MMN) indicator is on when the
ICS1722
is either in the topping charge, maintenance charge, direct
maintenance mode, or the condition mode. The maintenance mode
indicator flashes at a one second rate when the
ICS1702
is
controlling the discharge portion of the discharge-to-charge or the
discharge-only mode.
The polling detect (PFN) indicator is on when the
ICS1722
polls
for a battery. The controller applies periodic charge pulses to detect
the presence of a battery. The indicator is a warning that these
charge pulses are appearing at the charging system terminals at
regular intervals. When a battery is detected, the indicator is turned
off.
Output Logic Signals: CHG, DCHG Pins
The CHG and DCHG pins are active high, TTL compatible
outputs. In addition to being TTL compatible, the CMOS outputs
are capable of sourcing current which adds flexibility when
interfacing to other circuitry. A logic high on the CHG pin
indicates that the charging current supply should be activated. If
applicable, a logic high on the DCHG pin indicates that the
discharge circuit should be activated.
Care must be taken to control wiring resistance and inductance.
The load resistor must be capable of handling this short duration
high-amplitude pulse. If the auxiliary discharge-to-charge mode is
selected, the power dissipation of the load resistor must be properly
selected to accept the extended length of the discharge pulse.
Charge Rate Selection: SEL0, SEL1 Pins
The SEL0 and SEL1 inputs must be programmed by the user to
inform the
ICS1722
of the desired charge rate. When left
unconnected (open), these tri-level pins will float to about 2.3V.
When a low level is required, the pin must be grounded. When a
high level is required, the pin must be tied to V
DD
. The voltage
ranges for low (L), open (Z) and high (H) are listed in Table 6,
DC
Characteristics.
To program the SEL0 and SEL1 inputs, refer to
the
Charge Rate List
in Table 3.
The
ICS1722
does not control the current flowing into the battery
in any way other than turning it on and off. The required current
for the selected charge rate must be provided by the user’s power
source. The external charging circuitry should provide current at
the selected charge rate. For example, to charge a 1.2 ampere hour
battery in 30 minutes (2C), approximately 2.4 amperes of current is
required.
Indicators: CMN, MMN, PFN Pins
The controller has three outputs for driving external indicators.
These pins are active low. The three indicator outputs have open
drains and are designed to be used with LEDs. Each output can
sink over 20mA which requires the use of an external current
limiting resistor. The three indicator signals denote fast charge
stage, topping and maintenance stages, and the polling detect mode
as shown in Table 2.
The charge mode (CMN) indicator is activated continuously during
the soft start and fast charge stages. When the controller enters the
topping charge stage, the output goes high and the indicator turns
off.
Table 2: Indicator Description List
PFN
On
MMN
On
On
Flash
Flash
On
Flash
Flash
CMN
Description
Polling mode or battery fault
Maintenance or topping charge, direct maintenance or condition mode
Fast charge
Discharge portion of the discharge-to-charge or discharge-only mode
See Applications Information
See Applications Information
Fast Charge (See Applications Information)
9
GALAXY [ GALAXY POWER, INC. ]
