MAX1898EUB41+ Maxim Integrated Products, MAX1898EUB41+ Datasheet - Page 9

• Manufacturer Part Number: MAX1898EUB41+
• Description: IC CHARGER LI+ SNGL 10-UMAX
• Manufacturer: Maxim Integrated Products

Specifications of MAX1898EUB41+

• Function: Charge Management
• Battery Type: Lithium-Ion (Li-Ion)
• Voltage - Supply: 4.5 V ~ 12 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 10-MSOP, Micro10™, 10-uMAX, 10-uSOP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

power is present at IN. If there is no (or insufficient)
voltage at IN, EN/OK will remain low and the charger
will remain off.
The MAX1898 uses advanced CMOS circuitry to com-
pletely monitor battery state, while drawing minimal current
from the cell itself. When the input voltage is less than the
battery, battery drain is typically 3µA. When input power is
present and charging is complete (the charge timer
expires), battery drain is then typically 40µA. This current
may be reduced to 4µA by disabling the restart feature.
The MAX1898 basic application circuit is shown in
Figure 4.
Figure 4. Basic Application Circuit
An LED can be added as a charge-state indicator. A
10µF bypass capacitor must be added to the BATT pin.
A Schottky diode should be added between the exter-
nal transistor drain/collector and BATT, to avoid battery
discharge in the event of an input source short circuit.
Figure 5 shows a charger circuit using an external PNP
pass transistor.
The maximum charge time can be set with an external
capacitor connected from CT to GND. Select the timing
capacitor using:
OK OUTPUT OR
5V TO 12V
INDICATOR
ENABLE INPUT
INPUT POWER
CHARGE
LED
Selecting Maximum Charge Time
Applications Information
Linear Charger for Single-Cell Li+ Battery
1
2
6
3
IN
CHG
EN/OK
RSTRT
_______________________________________________________________________________________
MAX1898
100nF
GND
8
BATT
ISET
DRV
CT
CS
Battery Drain Current
10
9
7
5
4
R
CHARGE
CURRENT
C
SETS CHARGE TIME
TO 3hr
SET
CT
10µF
OUTPUT VOLTAGE
PROPORTIONAL
TO CHARGE CURRENT
, 100nF CAPACITOR
SETS
Li+ CELL
where:
t
The maximum charge timer is intended as a safety timer.
It is normally not intended to be part of the charge-con-
trol loop. When charging a Li+ cell at a 1C rate, normal
charge time is approximately 1.5 hours, but this may
have wide variations that depend on temperature and
cell type. In most cases, 3 hours is recommended for the
maximum charge time limit when fast-charging at 1C so
that normal-charging is never interrupted by the charge
timer. Consult the battery manufacturer for details on rec-
ommended timer settings.
The charge safety timer may also be completely dis-
abled by connecting CT to ground. Note: If the charge
timer is disabled, both the restart function and prequali-
fication fault indication are also disabled. Only the indi-
cation (blinking LED) is disabled, the prequalification
function itself is not modified.
The MAX1898 features automatic restart that resumes
charging when the cell voltage drops to a predetermined
level. In most timed chargers, once charging times out,
subsequent loading of the battery can discharge the bat-
tery and charging will not resume unless the charger is
restarted by an outside signal. By automatically resuming
charging when the battery voltage drops, the MAX1898
ensures that the cell does not remain partially charged
Figure 5. Application Circuit with PNP Pass Transistor
CHG
OK OUTPUT OR
5V TO 12V
INDICATOR
ENABLE INPUT
INPUT POWER
= nominal charge time limit in hours.
CHARGE
LED
C
CT
1
2
6
3
Controlling Automatic Restart
[ ]
nF
IN
CHG
EN/OK
RSTRT
=
MAX1898
34 33
220nF
GND
8
.
×
t
BATT
ISET
DRV
CHG
CT
CS
10
9
7
5
4
[
hours
R
CHARGE
CURRENT
C
SETS CHARGE TIME
TO 3hr
SET
CT
OUTPUT VOLTAGE
PROPORTIONAL
TO CHARGE CURRENT
10µF
, 100nF CAPACITOR
SETS
]
Li+ CELL
9