CDH2D09 View Datasheet(PDF) - Maxim Integrated
Part Name
Description
MFG CO.
'CDH2D09' PDF : 44 Pages View PDF
PMIC with Integrated Charger and
Smart Power Selector for Handheld Devices
Table 3. Charge Status Outputs
CST1
CST2
CHARGING
STATE
0
0
Yes
Prequalification or
fast charge
0
1
1
0
No
Thermistor suspend
No
Timer fault
1
1
No input power or
No
top-off or
done
Note: CST1 and CST2 are active-low, open-drain outputs. “0”
indicates that the output device is pulling low. “1” indicates
that the output is high impedance.
Charge Timer (CT)
As shown in Figure 7, a fault timer prevents the battery
from charging indefinitely. In prequalification and fast-
charge modes, the timer is controlled by the capaci-
tance at CT (CCT). The MAX8671X supports values of
CCT from 0.01µF to 1µF. Calculate the prequalification
and fast-charge times as follows (Table 4, Figure 8):
tPQ
=
33min ×
CCT
0.15μF
tFC
=
660min
×
CCT
0.15μF
When the charger exits fast-charge mode, a fixed 15s
top-off mode is entered:
tTO = 15s
While in the constant-current fast-charge mode (Figure
6), if the MAX8671X reduces the battery charge current
due to its internal die temperature or large system
loads, it slows down the charge timer. This feature elim-
inates nuisance charge timer faults. When the battery
charge current is between 100% and 50% of its pro-
grammed fast-charge level, the fast-charge timer runs
at full speed. When the battery charge current is
between 50% and 20% of the programmed fast-charge
level, the fast-charge timer is slowed by 2x. Similarly,
when the battery charge current is below 20% of the
programmed fast-charge level, the fast-charge timer is
paused. The fast-charge timer is not slowed or paused
when the charger is in the constant voltage portion of
its fast-charge mode (Figure 6) where charge current
reduces normally.
Table 4. Charge Times vs. CCT
CCT (nF)
68
100
150
220
470
tPQ (min)
15.0
22.0
33.0
48.4
103.4
tFC (min)
100% to 50%
299
440
660
968
2068
tFC (min)
50% to 20%
598
880
1320
1936
4136
CHARGE, PREQUALIFICATION,
AND TOP-OFF CURRENT
vs. CHARGE SETTING RESISTOR
1000
ICHGMAX
100
IPQ
ITO
10
1
0
5
10
15
RCISET (kΩ)
Figure 8. Programming Charge Current
Connect CT to AGND to disable the prequalification
and fast-charge timers. With the internal timers of the
MAX8671X disabled, an external device, such as a µP,
can control the charge time through the CEN input.
Setting the Charger Currents (CISET)
As shown in Table 5 and Figure 9, a resistor from
CISET to ground (RCISET) sets the maximum fast-
charge current (ICHGMAX), the charge current in pre-
qualification mode (IPQ), and the top-off threshold (ITO).
The MAX8671X supports values of ICHGMAX from
200mA to 1000mA. Select the RCISET as follows:
RCISET
=
2000
×
1.5V
ICHGMAX
______________________________________________________________________________________ 31
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