19-2099; Rev 0; 7/01
VAILABLE
TION KIT A
EVALUA
Simple Current-Limited Switch-Mode
Li+ Charger Controller
General Description
The low-cost MAX1873R/S/T provides all functions
needed to simply and efficiently charge 2-, 3-, or 4-
series lithium-ion cells at up to 4A or more. It provides a
regulated charging current and voltage with less than
±0.75% total voltage error at the battery terminals. An
external P-channel MOSFET operates in a step-down
DC-DC configuration to efficiently charge batteries in
low-cost designs.
The MAX1873R/S/T regulates the battery voltage and
charging current using two control loops that work
together to transition smoothly between voltage and
current regulation. An additional control loop limits cur-
rent drawn from the input source so that AC adapter
size and cost can be minimized. An analog voltage out-
put proportional to charging current is also supplied so
that an ADC or microcontroller can monitor charging
current.
The MAX1873 may also be used as an efficient current-
limited source to charge NiCd or NiMH batteries in mul-
tichemistry charger designs. The MAX1873R/S/T is
available in a space-saving 16-pin QSOP package. Use
the evaluation kit (MAX1873EVKIT) to help reduce
design time.
o
Low-Cost and Simple Circuit
o
Charges 2-, 3-, or 4-Series Lithium-Ion Cells
o
AC Adapter Input-Current-Limit Loop
o
Also Charges Ni-Based Batteries
o
Analog Output Monitors Charge Current
o
±0.75% Battery-Regulation Voltage
o
5µA Shutdown Battery Current
o
Input Voltage Up to 28V
o
200mV Dropout Voltage/100% Duty Cycle
o
Adjustable Charging Current
o
300kHz PWM Oscillator Reduces Noise
o
Space-Saving 16-Pin QSOP
o
MAX1873 Evaluation Kit Available to Speed
Designs
Features
MAX1873
Ordering Information
PART
MAX1873REEE
MAX1873SEEE
MAX1873TEEE
TEMP. RANGE
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
PIN-PACKAGE
16 QSOP
16 QSOP
16 QSOP
Applications
Notebook Computers
Portable Internet Tablets
2-, 3-, or 4-cell Li+ Battery Pack Chargers
6-, 9-, or 10-cell Ni Battery Pack Chargers
Hand-Held Instruments
Portable Desktop Assistants (PDAs)
Desktop Cradle Chargers
Typical Operating Circuit
VIN 9V TO
28V
(9V MIN
FOR 2-
CELLS)
VH VL
CSSP
SYSTEM
LOAD
Selector Guide
PART
MAX1873REEE
MAX1873SEEE
MAX1873TEEE
SERIES CELLS TO CHARGE
2-Cell Li+ or 5- or 6-cell Ni Battery
3-Cell Li+ or 7- or 9-cell Ni Battery
4-Cell Li+ 10-cell Ni Battery Packs
4V OUT PER
200mV ON R
CS
DCIN
MAX1873
CSSN
IOUT
ICHG/EN
REF
CSB
BATT
CCI
VADJ
EXT
Pin Configuration appears at end of data sheet.
CCS
GND
CCV
2- TO 4-CELL
Li+
________________________________________________________________
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.
Simple Current-Limited Switch-Mode
Li+ Charger Controller
MAX1873
ABSOLUTE MAXIMUM RATINGS
CSSP, CSSN, DCIN to GND ...................................-0.3V to +30V
VL, ICHG/EN to GND................................................-0.3V to +6V
VH, EXT to DCIN.......................................................-6V to +0.3V
VH, EXT to GND ......................................(V
DCIN
+ 0.3V) to -0.3V
EXT to VH .................................................................+6V to -0.3V
DCIN to VL..............................................................+30V to -0.3V
VADJ, REF, CCI, CCV, CCS,
IOUT to GND.............................................-0.3V to (VL + 0.3V)
BATT, CSB to GND.................................................-0.3V to +20V
CSSP to CSSN.......................................................-0.3V to +0.6V
CSB to BATT..........................................................-0.3V to +0.6V
VL Source Current ............................................................+50mA
VH Sink Current ................................................................+40mA
Continuous Power Dissipation (T
A
= +70°C)
16-Pin QSOP (derate 8.3mW/°C above +70°C..........+667mW
Operating Temperature Range
MAX1873_EEE ................................................-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
(Circuit of Figure 1, V
DCIN
= V
CSSP
= V
CSSN
= 18V, V
ICHG/EN
= V
REF
, V
VADJ
= V
REF
/2. MAX1873R: V
BATT
= V
CSB
= 8.4V;
MAX1873S: V
BATT
= V
CSB
= 12.6V; MAX1873T: V
BATT
= V
CSB
= 16.8V;
T
A
= 0°C to +85°C.
Typical values are at T
A
= +25°C, unless
otherwise noted.)
PARAMETER
INPUT SUPPLY AND REFERENCE
DCIN Input Voltage Range
DCIN Quiescent Supply Current
DCIN to BATT Undervoltage Threshold
DCIN to BATT Undervoltage Threshold
VL Output Voltage
VL Output Load Regulation
REF Output Voltage
REF Line Regulation
REF Load Regulation
SWITCHING REGULATOR
PWM Oscillator Frequency
EXT Driver Source On-Resistance
EXT Driver Sink On-Resistance
VH Output Voltage
CSSN/CSSP Input Current
CSSN/CSSP Off-State Leakage
BATT, CSB Input Current
BATT, CSB Input Current
DCIN - VH, 6V < V
DCIN
<28V, I
VH
= 0 to 20mA
V
CSSN
/V
CSSP
= 28V, V
DCIN
= 28V
V
DCIN
= V
SSN
/V
CSSP
= 18V, V
BATT
= V
CSB
= 18V
ICHG/EN = 0 (charger disabled)
ICHG/EN = REF (charger enabled)
DCIN
≤
BATT (input power removed)
4.75
70
1.5
0.2
250
1.5
270
300
4
2.5
330
7
4.5
5.75
200
5
1
500
5
kHz
Ω
Ω
V
µA
µA
µA
µA
6.0V < V
DCIN
< 28V
DCIN
≤
BATT
CSSP = DCIN, input falling
CSSP = DCIN, input rising
6.0V < V
DCIN
< 28V
I
VL
= 0 to 3mA
I
REF
= 21µA (200kΩ load)
6.0V < V
DCIN
< 28V
I
REF
= 0 to 1mA
4.179
0.05
0.22
5.15
5.40
15
4.20
2
22
6
6
4
0.1
28
7
10
0.175
0.38
5.65
50
4.221
6
65
13
V
mA
µA
V
V
V
mV
V
mV
ppm/V
mV
CONDITIONS
MIN
TYP
MAX
UNITS
2
_______________________________________________________________________________________
Simple Current-Limited Switch-Mode
Li+ Charger Controller
ELECTRICAL CHARACTERISTICS (continued)
(Circuit of Figure 1, V
DCIN
= V
CSSP
= V
CSSN
= 18V, V
ICHG/EN
= V
REF
, V
VADJ
= V
REF
/2. MAX1873R: V
BATT
= V
CSB
= 8.4V;
MAX1873S: V
BATT
= V
CSB
= 12.6V; MAX1873T: V
BATT
= V
CSB
= 16.8V;
T
A
= 0°C to +85°C.
Typical values are at T
A
= +25°C, unless
otherwise noted.)
PARAMETER
BATT Overvoltage Cutoff Threshold
CONDITIONS
2-cell version MAX1873R
3-cell version MAX1873S
4-cell version MAX1873T (Note 1)
MAX1873R
(2 Li+ cells)
V
VADJ
= 0
V
VADJ
= V
REF
/2
V
VADJ
= V
REF
(Note 1)
Battery Regulation Voltage
MAX1873S
(3 Li+ cells)
V
VADJ
= 0
V
VADJ
= V
REF
/2
V
VADJ
= V
REF
(Note 1)
MAX1873T
(4 Li+ cells)
V
VADJ
= 0
V
VADJ
= V
REF
/2
V
VADJ
= V
REF
(Note 1)
MAX1873R
BATT Undervoltage Threshold
CURRENT SENSE
CSB to BATT Battery Current-Sense
Voltage
CSB to BATT Current-Sense Voltage
when V
BATT
< 2.5V per Cell
CSSP to CSSN Current-Sense Voltage
CONTROL INPUTS/OUTPUTS
ICHG/EN Input Threshold
ICHG/EN Input Voltage Range For
Charge Current Adjustment
VADJ Input Current
ICHG/EN Input Current
VADJ Input Voltage Range
Full scale
25% scale
Trickle charge
No charge
current
V
CSB
- V
BATT
= 200mV,
0 < I
OUT
< 500µA
V
CSB
- V
BATT
= 50mV,
0 < I
OUT
< 500µA
V
CSB
- V
BATT
= 10mV
V
CSB
- V
BATT
= 0,
I
IOUT
= sinking 20µA
Includes 50mV of hysteresis
500
700
V
VADJ
= V
REF
/2
V
ICHG/EN
= V
REF
-100
-100
0
3.6
0.9
75
40
4.0
1.0
200
70
600
700
V
REF
100
100
V
REF
4.4
V
1.1
325
90
mV
mV
mV
nA
nA
V
6V < V
CSSP
< 28V
V
ICHG/EN
= V
REF
V
ICHG/EN
= V
REF
/4
190
40
5
90
200
50
10
100
210
60
15
110
mV
mV
mV
For I
CHG
/20 trickle
charge
MAX1873S
MAX1873T
MIN
10.45
15.675
17.575
7.898
8.337
8.775
11.847
12.505
13.163
15.796
16.674
17.551
4.8
7.2
9.6
TYP
11
16.5
18.5
7.958
8.4
8.842
11.937
12.6
13.263
15.916
16.8
17.684
5.0
7.5
10
MAX
11.55
17.325
19.425
8.018
8.463
8.909
12.027
12.695
13.363
16.036
16.926
17.817
5.2
7.8
10.4
V
V
V
UNITS
MAX1873
IOUT Voltage
_______________________________________________________________________________________
3
Simple Current-Limited Switch-Mode
Li+ Charger Controller
MAX1873
ELECTRICAL CHARACTERISTICS
(Circuit of Figure 1, V
DCIN
= V
CSSP
= V
CSSN
= 18V, V
ICHG/EN
= V
REF
, V
VADJ
= V
REF
/2. MAX1873R: V
BATT
= V
CSB
= 8.4V;
MAX1873S: V
BATT
= V
CSB
= 12.6V; MAX1873T: V
BATT
= V
CSB
= 16.8V;
T
A
= -40°C to +85°C.
Typical values are at T
A
= +25°C,
unless otherwise noted.)
PARAMETER
INPUT SUPPLY AND REFERENCE
DCIN Input Voltage Range
DCIN Quiescent Supply Current
DCIN to BATT Undervoltage Threshold
DCIN to BATT Undervoltage Threshold
VL Output Voltage
VL Output Load Regulation
REF Output Voltage
REF Line Regulation
REF Load Regulation
SWITCHING REGULATOR
PWM Oscillator Frequency
EXT Driver Source On-Resistance
EXT Driver Sink On-Resistance
VH Output Voltage
CSSN/CSSP Input Current
CSSN/CSSP Off-State Leakage
BATT, CSB Input Current
BATT, CSB Input Current
BATT Overvoltage Cutoff Threshold
DCIN - VH, 6V < V
DCIN
<28V, I
VH
= 0 to 20mA
V
CSSN
/V
CSSP
= 28V, V
DCIN
= 28V
V
DCIN
= V
SSN
/V
CSSP
= 18V V
BATT
= V
CSB
= 18V
ICHG/EN = 0 (charger disabled)
ICHG/EN = REF (charger enabled)
DCIN
≤
BATT (input power removed)
2-cell version MAX1873R
3-cell version MAX1873S
4-cell version MAX1873T (Note 1)
MAX1873R
(2 Li+ cells)
V
VADJ
= 0
V
VADJ
= V
REF
/2
V
VADJ
= V
REF
(Note 1)
Battery Regulation Voltage
MAX1873S
(3 Li+ cells)
V
VADJ
= 0
V
VADJ
= V
REF
/2
V
VADJ
= V
REF
(Note 1)
MAX1873T
(4 Li+ cells)
V
VADJ
= 0
V
VADJ
= V
REF
/2
V
VADJ
= V
REF
(Note 1)
10.45
15.675
17.575
7.898
8.337
8.775
11.847
12.505
13.163
15.796
16.674
17.551
4.75
270
330
7
4.5
5.75
200
5
1
500
5
11.55
17.325
19.425
8.018
8.463
8.909
12.027
12.695
13.363
16.036
16.926
17.817
V
V
kHz
Ω
Ω
V
µA
µA
µA
µA
6.0V < V
DCIN
< 28V
DCIN
≤
BATT
CSSP = DCIN, input falling
CSSP = DCIN, input rising
6.0V < V
DCIN
< 28V
I
VL
= 0 to 3mA
I
REF
= 21µA (200kΩ load)
6.0V < V
DCIN
< 28V
I
REF
= 0 to 1mA
4.179
0.05
0.22
5.15
6
28
7
10
0.2
0.38
5.65
50
4.221
6
65
13
V
mA
µA
V
V
V
mV
V
mV
ppm/V
mV
CONDITIONS
MIN
MAX
UNITS
4
_______________________________________________________________________________________
Simple Current-Limited Switch-Mode
Li+ Charger Controller
ELECTRICAL CHARACTERISTICS (continued)
(Circuit of Figure 1, V
DCIN
= V
CSSP
= V
CSSN
= 18V, V
ICHG/EN
= V
REF
, V
VADJ
= V
REF
/2. MAX1873R: V
BATT
= V
CSB
= 8.4V;
MAX1873S: V
BATT
= V
CSB
= 12.6V; MAX1873T: V
BATT
= V
CSB
= 16.8V;
T
A
= -40°C to +85°C.
Typical values are at T
A
= +25°C,
unless otherwise noted.)
PARAMETER
BATT Undervoltage Threshold
CURRENT SENSE
CSB to BATT Battery Current-Sense
Voltage
CSB to BATT Current-Sense Voltage
when V
BATT
< 2.5V per Cell
CSSP to CSSN Current-Sense Voltage
CONTROL INPUTS/OUTPUTS
ICHG/EN Input Threshold
ICHG/EN Input Voltage Range for
Charge Current Adjustment
VADJ Input Current
ICHG/EN Input Current
VADJ Input Voltage Range
Full scale
25% scale
Trickle charge
No charge
current
V
CSB
- V
BATT
= 200mV,
0 < I
OUT
< 500µA
V
CSB
- V
BATT
= 50mV,
0 < I
OUT
< 500µA
V
CSB
- V
BATT
= 10mV
V
CSB
- V
BATT
= 0,
I
IOUT
= sinking 20µA
V
VADJ
= V
REF
/2
V
ICHG/EN
= V
REF
Includes 50mV of hysteresis
500
700
-100
-100
0
3.6
0.9
75
40
700
V
REF
100
100
V
REF
4.4
V
1.1
325
90
mV
mV
mV
nA
nA
V
6V < V
CSSP
< 28V
V
ICHG/EN
= V
REF
V
ICHG/EN
= V
REF
/4
190
40
5
90
210
60
15
110
mV
mV
mV
mV
CONDITIONS
MAX1873R
For I
CHG
/20 trickle
charge
MAX1873S
MAX1873T
MIN
4.8
7.2
9.6
MAX
5.2
7.8
10.4
V
UNITS
MAX1873
IOUT Voltage
Note 1:
While it may appear possible to set the Battery Regulation Voltage higher than the Battery Overvoltage Cutoff Threshold, this
cannot happen because both parameters are derived from the same reference and track each other.
Note 2:
Specifications to -40°C are guaranteed by design, not production tested.
_______________________________________________________________________________________
5
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