SE9018 Datasheet, PDF (7/9 Pages) Seaward Electronics Inc. – 1A Standalone Linear Li-lon Battery Charger

SE9018
1A Standalone Linear Li-lon Battery Charger
R_PROG (k)
I_BAT (mA)
28
40
18.6
60
9.3
120
4.6
240
3.73
300
2.8
400
1.86
600
1.55
720
1.4
800
1.24
900
1.12
1000
Charge termination
A charge cycle is terminated when the charge
current falls to 1/10th the programmed value after
the final float voltage is reached. This condition is
detected by using an internal filtered comparator to
monitor the PROG pin. When the PROG pin
voltage falls below 100mV for longer than tTEMP
(typically 1.8mS), Charging is terminated. The
charge current is latched off and the SE9018
enters standby mode, where the input supply
current drops to 55μA (Note:C/10 termination is
disabled in trickle charging and thermal limiting
modes).
When charging, transient loads on the BAT pin
can cause the PROG pin to fall below 100mV for
short periods of time before the DC charge current
has dropped to 1/10th the programmed value. The
state all loads on the BAT pin must be supplied by
the battery.
The SE9018 constantly monitors the BAT pin
voltage in standby mode. If this voltage drops below
the 4.02V recharge threshold (VRECHRG ), another
charge cycle begins and current is once again
supplied to the battery. To manually restart a
charge cycle when in standby mode, the input
voltage must be removed and reapplied or the
charger must be shut down and restarted using the
PROG pin. Figure 1 shows the state diagram of a
typical charge cycle.
Charge status indicator
SE9018 has two open-drain status indicator
output CHRG and STDBY . CHRG is pull-down
when the SE9018 in a charge cycle. In other status
CHRG in high impedance. CHRG and STDBY are
all in high impedance when the battery out of the
normal temperature.
Represent in failure state, when TEMP pin in
typical connecting, or the charger with no battery:
red LED and green LED all don’t light. The battery
temperature sense function is disabled by
connecting TEMP pin to GND. If battery is not
connected to charger, CHRG pin outputs a PWM
level to indicate no battery. If BAT pin connects a
10μF capacitor, the frequency of CHRG flicker
about 1-4S, If not use status indicator should set
status indicator output connected to GND.
1.8mS filter time (tTEMP) on the termination
comparator ensures that transient loads of this
nature do not result in premature charge cycle
termination. Once the average charge current
drops below 1/10th the programmed value, the
SE9018 terminated the charge cycle and ceases to
provide any current through the BAT pin. In this
Rev1.0
Preliminary and all contents are subject to change without prior notice
© Seaward Electronics Inc., 2013. • www.seawardinc.com.cn • Page 7