ISL6297 Intersil Corporation, ISL6297 Datasheet - Page 11

• Manufacturer Part Number: ISL6297
• Description: Li-ion/Li Polymer Battery Charger
• Manufacturer: Intersil Corporation

Internal Oscillator
The internal oscillator establishes a timing reference. The
oscillation period is programmable with an external timing
capacitor, C
oscillator charges the timing capacitor to 1.5V and then
discharges it to 0.5V in one period, both with 10μA current.
The period T
A 15nF capacitor results in a 3ms oscillation period. The
accuracy of the period is mainly dependent on the accuracy
of the capacitance and the internal current source.
Total Charge Time and C
The time allowed for the battery to charge before an end of
charge indication is limited to the duration of the TIMEOUT
counter. The TIMEOUT period can be calculated by:
where C
Application circuit. A 1nF capacitor leads to 14 minutes of
TIMEOUT. For example, a 15nF capacitor sets the
TIMEOUT to be 3.5 hours. The EOC indication goes active
when the TIMEOUT counter expires, even if the battery has
not reached full charge. At this point, if the voltage is above
4.05V, the recharge mechanism will continue to charge the
T
TIMEOUT
OSC
TIME
TIME
=
OSC
is the timing capacitor shown in the Typical
0.2
Impedance
=
, as shown in Typical Applications. The
is:
×
14
V
10
V2P9
I
GRN
RED
CHG
SEN
V
DT
×
EN
6
IN
C
----------------- -
×
1nF
TIME
C
TIME
11
TIME
(
minutes
Selection
(
sec
POR Threshold
onds
)
15 cycles to 1/8 TIMEOUT
500ms
)
2.8V min.
FIGURE 6. OPERATION WAVEFORMS
Charge Cycle
TIMEOUT
(EQ. 6)
(EQ. 7)
I
MIN
ISL6297
cell until the current drops below I
counter expires before the battery reaches 4.05V, then the
end of charge indication goes active, but the charger turns
off. The charger cannot leave this condition without toggling
the enable pin or cycling the power.
The trickle mode charge has a time limit of 1/8 TIMEOUT. If
the battery voltage does not reach V
period, a TIMEOUT fault is issued and the charger turns off
with a flashing Yellow LED indicator. The charger stays in
trickle mode for at least 15 cycles of the internal oscillator
and, at most, 1/8 of TIMEOUT.
Once the ISL6297 detects that the battery reaches the EOC
condition, it resets the TIMEOUT counter. At the end of this
TIMEOUT period, the charger turns off and does not start
again until the battery reaches a recharge condition.
Recharge Threshold
Once the charger reaches an end of charge condition and
the charger turns off, if the battery voltage drops below the
recharge threshold given in the Electrical Specification table,
the charger starts a re-charge cycle. This is identical to an
inital charge cycle, except the indicator remains green.
LED Indications
The LED indicators show a number of conditions. On initial
power on reset, the LEDs sequence through red, green and
yellow. Once the charge begins, the ISL6297 pulls the RED
pin low to drive a red indicator. Once the charge properly
Recharge
15 cycles
Charge Cycle
I
MIN
MIN
MIN
. If the TIMEOUT
within that time
March 20, 2007
FN9215.1