19-2295; Rev 0; 1/02
Linear Charger for Single-Cell Li+ Battery
General Description
The MAX1898, with an external PNP or PMOS transistor,
forms a complete charger for 1-cell lithium-ion (Li+) bat-
teries. The MAX1898 provides accurate constant-cur-
rent/constant-voltage charging. Battery regulation voltage
accuracy is ±0.75% for optimum battery performance
and cycle life. Charging current is user set, but is sensed
internally so no external current-sense resistor is needed.
The MAX1898 also provides outputs to monitor charge
status, presence-of-input power source, and charge cur-
rent. Additional features include shutdown, optional
charge-cycle restart without input-power cycling, selec-
table charge termination safety timer, and low-current
preconditioning for deeply discharged cells.
The MAX1898 offers the maximum integration and func-
tionality in the smallest, most basic application circuit
possible. Very few external components are required.
The MAX1898 offers two versions to safely charge all
Li+ battery chemistries. The battery regulation voltage
is 4.2V for the MAX1898EUB42 and 4.1V for the
MAX1898EUB41. Both are available in a 10-pin ultra-
thin µMAX package.
o
Simple, Safe Linear Charger
o
Uses Low-Cost PNP or PMOS Pass Element
o
4.5V to 12V Input Range
o
Internal Current-Sense Resistor
o
±0.75% Voltage Accuracy
o
Programmable Charging Current
o
Automatic Input Power-Source Detection
o
LED Charge Status Indicator
o
Programmable Safety Timer
o
Current-Sense Monitor Output
o
Optional/Adjustable Auto-Restart
o
Small µMAX Package
Features
MAX1898
Ordering Information
PART
MAX1898EUB42
MAX1898EUB41
TEMP RANGE
-40°C to +85°C
-40°C to +85°C
PIN-PACKAGE
10 µMAX
10 µMAX
Applications
Single-Cell Li+ Powered Portables
Self-Charging Battery Packs
PDAs
Cell Phones
Cradle Chargers
Typical Operating Circuit
INPUT
4.5V TO 12V
IN
LED
CS
OUTPUT
Li+
BATTERY
Pin Configuration
CHG
MAX1898
DRV
ON
EN/OK
OFF
BATT
ISET
TOP VIEW
IN
1
CHG
EN/OK
ISET
CT
2
3
4
5
10
CS
CT
9
DRV
GND
BATT
RSTRT
MAX1898
8
7
6
CT SETS
CHARGE
TIME
RSTRT
GND
SETS CHARGE
CURRENT
µMAX
________________________________________________________________
Maxim Integrated Products
1
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
Linear Charger for Single-Cell Li+ Battery
MAX1898
ABSOLUTE MAXIMUM RATINGS
IN, DRV, CS,
CHG
to GND .....................................-0.3V to +14V
BATT, EN, ISET, RSTRT, CT to GND ........................-0.3V to +6V
DRV to IN................................................................-14V to +0.3V
IN to CS Current ....................................................................±2A
DRV Continuous Current ..................................................±10mA
Continuous Power Dissipation (T
A
= +70°C)
10-Pin µMAX (derate 5.6mW/°C above +70°C) ..........444mW
Operating Temperature Range ...........................-40°C to +85°C
Junction Temperature ......................................................+150°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (soldering, 10s) ....................………..+300°C
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
ELECTRICAL CHARACTERISTICS
(V
IN
= 8V, V
BATT
= 4V, EN/OK = open, RSET = 2.8kΩ, RSTRT = GND,
T
A
= 0°C to +85°C,
unless otherwise noted. Typical values are
at T
A
= +25°C.)
PARAMETER
Supply Voltage Range
Input OK Trip Point, IN Rising
(V
IN
- V
BATT
)
Input OK Trip Point, IN Falling
(V
IN
- V
BATT
)
V
IN
Input OK Trip Point, IN Rising
V
IN
Input OK Trip Point, IN Falling
EN/OK Sink Current (When Input
Power Not OK)
EN/OK Source Current (When
Input Power OK)
EN/OK Logic Input High
EN/OK Logic Input Low
V
IN
= 3.9V, V
BATT
= 4V,
V
EN/OK
= 0.8V
V
EN/OK
= 2V
4.5V
≤
V
IN
≤
12V
4.5V
≤
V
IN
≤
12V
Done, RSTRT = GND, V
BATT
= 4.1V for
MAX1898EUB42 and 4.0V for MAX1898EUB41
BATT Input Current
Done, RSTRT = open, V
BATT
= 4.1V for
MAX1898EUB42 and 4.0V for MAX1898EUB41
EN/OK = GND
V
IN
= 4V
IN, CS Input Current
VOLTAGE LOOP
Voltage-Loop Set Point
Voltage-Loop Gain
V
BATT
Prequal Voltage Threshold
DRV Sink Current
DRV Output Resistance
MAX1898EUB42
MAX1898EUB41
∆V
DRV
/∆V
BATT
Timers running
MAX1898EUB42
MAX1898EUB41
2.394
2.337
4
470
4.168
4.069
4.2
4.1
51
2.520
2.460
2.646
2.583
4.232
4.131
V
dB
V
mA
Ω
V
IN
= V
BATT
= 4V (I
IN
+ I
CS
)
V
IN
= 12V, (I
IN
+ I
CS
), done, RSTRT = open
40
4
4
3
2
2
CONDITIONS
MIN
4.5
45
30
4.0
3.9
100
5
2
0.6
100
10
10
10
10
5
µA
mA
µA
10
20
70
55
4.25
4.15
TYP
MAX
12
100
85
4.5
4.4
UNITS
V
mV
mV
V
V
µA
µA
V
V
V
DRV
= V
IN
- 1V, V
BATT
= 3.5V
2
_______________________________________________________________________________________
Linear Charger for Single-Cell Li+ Battery
ELECTRICAL CHARACTERISTICS (continued)
(V
IN
= 8V, V
BATT
= 4V, EN/OK = open, RSET = 2.8kΩ, RSTRT = GND,
T
A
= 0°C to +85°C,
unless otherwise noted. Typical values are
at T
A
= +25°C.)
PARAMETER
Maximum Voltage (V
IN
- V
DRV
)
V
BATT
Restart Threshold (As a
Percentage of Voltage-Loop Set
Point)
RSTRT Internal Resistance
CURRENT LOOP
Internal Current-Sense Resistance
RMS Charge Current
Current-Sense Amplifier Gain, I
SET
to I
IN
Fast Charge
Current-Sense Amplifier Gain, I
SET
to I
IN
Prequal
Current-Loop Regulation Set Point
Current-Loop Gain
CHG
Trip Threshold (As a
Percentage of Full Load Current)
TIMER FUNCTION
Timer Source/Sink Current
Timer Accuracy
CHG
Output Low Current
CHG
Output High Leakage
CHG
Blink Rate
V
CT
= 0.9V
C
CT
= 100nF for 2 hours, 54 minutes nominal
V
CHG
= 1V
V
CHG
= 12V
Fault state (50% duty cycle), CT = 100nF
1
1.5
-10
4
5
5
+10
6
1
2
µA
%
mA
µA
Hz
I
CS
= 500mA, V
SET
= 1.4V
I
CS
= 50mA, V
ISET
= 0.14V,
V
BATT
= 2V
RSET = 2.8kΩ, V
BATT
= 3.5V, closed-loop
performance
∆V
DRV
/∆V
ISET
I
LOAD
falling, RSET = 2.8kΩ
I
LOAD
rising, RSET = 2.8kΩ
15
17
0.95
0.73
450
1
1
500
26
20
22
25
27
IN to CS pin-to-pin resistance
50
105
200
1.4
1.05
1.30
550
mΩ
A
mA/A
mA/A
mA
dB
%
V
BATT
= 3.5V
RSTRT = GND
CONDITIONS
MIN
3.5
92
95.25
100
TYP
MAX
7
98
UNITS
V
%
kΩ
MAX1898
ELECTRICAL CHARACTERISTICS
(V
IN
= 8V, V
BATT
= 4V, EN/OK = open, RSET = 2.8kΩ, RSTRT = GND,
T
A
= -40°C to +85°C,
unless otherwise noted.)
PARAMETER
Supply Voltage Range
Input OK Trip Point, IN Rising
(V
IN
- V
BATT
)
Input OK Trip Point, IN Falling
(V
IN
- V
BATT
)
V
IN
Input OK Trip Point, IN Rising
V
IN
Input OK Trip Point, IN Falling
EN/OK Sink Current (When Input
Power Not OK)
EN/OK Source Current (When Input
Power OK)
EN/OK Logic Input High
EN/OK Logic Input Low
V
IN
= 3.9V, V
BATT
= 4V, V
EN/OK
= 0.8V
V
EN/OK
= 2V
4.5V
≤
V
IN
≤12V
4.5V
≤
V
IN
≤12V
CONDITIONS
MIN
4.5
45
30
4.0
3.9
100
5
2
0.6
20
MAX
12
100
85
4.5
4.4
UNITS
V
mV
mV
V
V
µA
µA
V
V
_______________________________________________________________________________________
3
Linear Charger for Single-Cell Li+ Battery
MAX1898
ELECTRICAL CHARACTERISTICS (continued)
(V
IN
= 8V, V
BATT
= 4V, EN/OK = open, RSET = 2.8kΩ, RSTRT = GND,
T
A
= -40°C to +85°C,
unless otherwise noted.)
PARAMETER
CONDITIONS
Done, RSTRT = GND, V
BATT
= 4.1V for
MAX1898EUB42 and 4.0V for MAX1898EUB41
BATT Input Current
Done, RSTRT = open, V
BATT
= 4.1V for
MAX1898EUB42 and 4.0V for MAX1898EUB41
EN/OK = GND
V
IN
= 4V
IN, CS Input Current
VOLTAGE LOOP
Voltage-Loop Set Point
V
BATT
Prequal Voltage Threshold
DRV Sink Current
Maximum Voltage (V
IN
- V
DRV
)
V
BATT
Restart Threshold (As a
Percentage of Voltage-Loop Set
Point)
CURRENT LOOP
Internal Current-Sense Resistance
RMS Charge Current
Current-Sense Amplifier Gain, I
SET
to I
IN
Fast Charge
Current-Sense Amplifier Gain, I
SET
to I
IN
Prequal
Current-Loop Regulation Set Point
CHG
Trip Threshold (As a
Percentage of Full Load Current)
Timer Accuracy
CHG
Output Low Current
CHG
Output High Leakage
CHG
Blink Rate
I
CS
= 500mA, V
SET
= 1.4V
I
CS
= 50mA, V
ISET
= 0.14V,
V
BATT
= 2V
RSET = 2.8kΩ, V
BATT
= 3.5V, closed-loop
performance
I
LOAD
falling, RSET = 2.8kΩ
I
LOAD
rising, RSET = 2.8kΩ
C
CT
= 100nF for 2 hours, 54 minutes nominal
V
CHG
= 1V
V
CHG
= 12V
Fault state (50% duty cycle), CT = 100nF
1
0.93
0.6
440
15
17
-13
3.5
IN to CS pin-to-pin resistance
50
200
1.4
1.07
1.50
560
25
27
+13
7
1
2
mΩ
A
mA/A
mA/A
mA
%
%
mA
µA
Hz
MAX1898EUB42
MAX1898EUB41
Timers running
MAX1898EUB42
MAX1898EUB41
4.137
4.038
2.394
2.337
3.5
3
92
7
98
4.263
4.162
2.646
2.583
V
V
mA
V
%
V
IN
= V
BATT
= 4V (I
IN
+ I
CS
)
V
IN
= 12V, (I
IN
+ I
CS
), done, RSTRT = open
MIN
MAX
100
10
10
10
10
5
µA
mA
µA
UNITS
V
DRV
= V
IN
- 1V, V
BATT
= 3.5V
V
BATT
= 3.5V
RSTRT = GND
Note 1:
Specifications to -40°C are guaranteed by design and not production tested.
4
_______________________________________________________________________________________
Linear Charger for Single-Cell Li+ Battery
Typical Operating Characteristics
(V
IN
= 5V, V
BATT
= 4V, EN/OK = open, RSET = 2.8kΩ, RSTRT = GND, T
A
= +25°C, unless otherwise noted.)
MAX1898
NORMALIZED TIMER PERIOD
vs. TEMPERATURE
MAX1898 toc01
NORMALIZED BATT REGULATION
VOLTAGE vs. TEMPERATURE
MAX1898 toc02
PRECHARGE CURRENT
vs. INPUT VOLTAGE
ISET = 2.8kΩ
CHARGING CURRENT SET
FOR 500mA
55
MAX1898 toc03
1.02
1.00
TIMER PERIOD
0.98
0.96
0.94
0.92
0.90
NORMALIZED TO +25°C
1.002
1.001
1.000
0.999
0.998
0.997
0.996
NORMALIZED TO +25°C
60
BATT REGULATION VOLTAGE
PRECHARGE CURRENT (mA)
50
45
40
-40
-15
10
35
60
85
5
6
7
8
9
10
11
12
TEMPERATURE (°C)
V
IN
(V)
-40
-15
10
35
60
85
TEMPERATURE (°C)
NORMALIZED BATTERY CURRENT
vs. BATTERY VOLTAGE
MAX1898 toc04
VOLTAGE-LOOP GAIN
60
MAX1898 toc05
1.2
NORMALIZED BATTERY CURRENT
1.0
0.8
0.6
0.4
0.2
0
3.9
4.0
4.1
4.2
200
40
PHASE
GAIN (dB)
20
GAIN
150
PHASE (deg.)
100
0
50
-20
0
-40
4.3
0.01
0.1
1
10
100
BATTERY VOLTAGE (V)
FREQUENCY (kHz)
-50
1000
_______________________________________________________________________________________
5
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