MAX1898EUB41+ Maxim Integrated Products, MAX1898EUB41+ Datasheet - Page 6

• 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

The MAX1898 forms a complete charger for 1-cell Li+
batteries. It includes precision voltage control (±0.75%)
to optimize both cell performance and cycle life.
Factory-set 4.2V (MAX1898EUB42) and 4.1V
(MAX1898EUB41) versions charge all common Li+
chemistries. Externally selectable charge current is
sensed internally, eliminating the need for a current-
sense resistor. The charger also supplies outputs that
indicate charge status (CHG), the presence of input
power (EN/OK), and charge-current magnitude (ISET).
Other features include a shutdown control input
(EN/OK), selectable threshold for charge-cycle restart
without cycling input power (RSTRT), and a selectable
charge termination safety timer. See Figure 1.
The MAX1898 initiates fast charge when any of these
conditions are met (see Figure 6):
• An external power source is connected AND the cell
• The cell voltage falls to the restart threshold, 4.0V in
• The IC is reset by driving the EN/OK pin low and
Linear Charger for Single-Cell Li+ Battery
6
voltage is above 2.5V.
the MAX1898EUB42, or 3.9V for the MAX1898EUB41.
then high again.
PIN
_______________________________________________________________________________________
10
1
2
3
4
5
6
7
8
9
EN/OK
RSTRT
NAME
BATT
CHG
GND
ISET
DRV
CS
CT
IN
Sense Input. Detects power source; positive side of internal current-sense resistor.
Open-Drain LED Driver. See Table 1 for CHG output states.
Logic-Level Enable Input and Input Power OK Output. Hold low to disable charger. Float for normal
operation, drive with an open-drain device to utilize both pin functions, or connect through 10kΩ for logic-
controlled ON/OFF. See the EN/OK (EN Input, OK Output) section for details.
ISET serves two functions. It provides an analog output proportional to the actual charge current. Output
current from ISET is 1mA per amp of battery charging current. The charging current is set by connecting a
resistor from ISET to ground. See the Current-Limit Mode section.
Safety Charge Timer Control. Connect timer capacitor to program safety time-out interval; 100nF for
approximately three hours. Connect to GND to disable the timer function.
Automatic-Restart Control Pin. When tied to GND, a new charging cycle starts if the cell drops 200mV below
the battery regulation threshold. The restart threshold may be lowered by connecting a resistor from RSTRT
to ground. See the Reinitiating a Charging Cycle section. Automatic restart is disabled when RSTRT is
unconnected or when CT is grounded (timer disabled).
Battery Sense Input. Positive terminal of single Li+ cell.
Ground
External Transistor Driver. This pin drives the gate/base of an external PMOS/PNP pass transistor.
Current-Sense Input. Negative side of internal current-sense resistor. Connect to source/emitter of
PMOS/PNP pass transistor.
Detailed Description
• The prequalification cycle ends with the cell reaching
Li+ cells can be damaged when fast-charged from a
completely dead state. A fully discharged cell may indi-
cate an abnormal cell condition. As a built-in safety fea-
ture, the MAX1898 prequalifies the cell with 10 percent
of the user-programmed fast-charge current at the start
of a charge cycle. When the cell voltage rises to 2.5V,
the MAX1898 begins fast-charging.
The MAX1898 regulates charging current by linearly
controlling an external PMOS or PNP transistor. The
maximum charging current is programmed by an exter-
nal RSET resistor connected from ISET to GND. Select
the RSET value based on the following formula:
where:
I
The ISET pin may also be used to monitor the actual
charging current at any time. The output current from
FASTCHG
2.5V.
FUNCTION
is in amps and RSET is in ohms.
I
FASTCHG
=
1400
R
SET
Current-Limit Mode
Pin Description
V