19-3243; Rev 1; 9/05
KIT
ATION
EVALU
E
BL
AVAILA
Step-Up/Step-Down
Li+ Battery Charger
Features
♦
♦
♦
♦
♦
♦
♦
♦
♦
♦
♦
Step-Up/Step-Down Control Scheme
±0.5%
Charge-Voltage Accuracy
±9%
Charge-Current Accuracy
±8%
Input Current-Limit Accuracy
Programmable Maximum Battery Charge Current
Analog Inputs Control Charge Current, Charge
Voltage, and Input Current Limit
Analog Output Indicates Adapter Current
Input Voltage from 8V to 28V
Battery Voltage from 0 to 17.6V
Charges Li+ or NiCd/NiMH Batteries
Tiny 32-Pin Thin QFN (5mm x 5mm) Package
General Description
The MAX1870A step-up/step-down multichemistry bat-
tery charger charges with battery voltages above and
below the adapter voltage. This highly integrated
charger requires a minimum number of external compo-
nents. The MAX1870A uses a proprietary step-up/step-
down control scheme that provides efficient charging.
Analog inputs control charge current and voltage, and
can be programmed by the host or hardwired.
The MAX1870A accurately charges two to four lithium-
ion (Li+) series cells at greater than 4A. A programma-
ble input current limit is included, which avoids
overloading the AC adapter when supplying the load
and the battery charger simultaneously. This reduces
the maximum adapter current, which reduces cost. The
MAX1870A provides analog outputs to monitor the cur-
rent drawn from the AC adapter and charge current. A
digital output indicates the presence of an AC adapter.
When the adapter is removed, the MAX1870A con-
sumes less than 1µA from the battery.
The MAX1870A is available in a 32-pin thin QFN (5mm
x 5mm) package and is specified over the -40°C to
+85°C extended temperature range. The MAX1870A
evaluation kit (MAX1870AEVKIT) is available to help
reduce design time.
MAX1870A
Ordering Information
PART
MAX1870AETJ
TEMP RANGE
-40°C to +85°C
PIN-PACKAGE
32 Thin QFN
32 Thin QFN
MAX1870AETJ+
-40°C to +85°C
+Denotes
lead-free package.
Typical Operating Circuit
FROM WALL ADAPTER
SYSTEM
LOAD
Applications
Notebook and Subnotebook Computers
Handheld Terminals
CSSS
DCIN
VHP
CSSP
CSSN
VHN
REF
CLS
MAX1870A
DHI
P
CELLS
N
ASNS
IINP
DBST
CSIP
CSIN
REFIN
SHDN
ICTL
VCTL
LDO
PGND
DLOV
GND
BATT
BLKP
Pin Configuration appears at end of data sheet.
________________________________________________________________
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.
Step-Up/Step-Down
Li+ Battery Charger
MAX1870A
ABSOLUTE MAXIMUM RATINGS
DCIN, CSSP, CSSS, CSSN,
VHP, VHN, DHI to GND ......................................-0.3V to +30V
VHP, DHI to VHN .....................................................-0.3V to +6V
BATT, CSIP, CSIN, BLKP to GND ..........................-0.3V to +20V
CSIP to CSIN, CSSP to CSSN,
CSSP to CSSS, PGND to GND ..........................-0.3V to +0.3V
CCI, CCS, CCV, REF, IINP to GND ..........-0.3V to (V
LDO
+ 0.3V)
DBST to GND..........................................-0.3V to (V
DLOV
+ 0.3V)
DLOV, VCTL, ICTL, REFIN, CELLS,
CLS, LDO, ASNS,
SHDN
to GND .........................-0.3V to +6V
LDO Current........................................................................50mA
Continuous Power Dissipation (T
A
= +70°C)
32-Pin Thin QFN 5mm x 5mm
(derate 21mW/°C above +70°C) ......................................1.7W
Operating Temperature Range
MAX1870AETJ .................................................-40°C to +85°C
Storage Temperature Range .............................-60°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 2, V
DCIN
= V
CSSP
= V
CSSN
= V
CSSS
= V
VHP
= 18V, V
BATT
= V
CSIP
= V
CSIN
= V
BLKP
= 12V, V
REFIN
= 3.0V, V
ICTL
=
0.75 x V
REFIN
, VCTL = LDO, CELLS = FLOAT, GND = PGND = 0, V
DLOV
= 5.4V,
T
A
= 0°C to +85°C,
unless otherwise noted. Typical
values are at T
A
= +25°C.)
PARAMETER
CHARGE-VOLTAGE REGULATION
VCTL Range
V
VCTL
= V
LDO
(2 cells)
V
VCTL
= V
LDO
(3 cells)
V
VCTL
= V
LDO
(4 cells)
Battery Regulation Voltage
Accuracy
V
VCTL
= V
REFIN
(2 cells)
V
VCTL
= V
REFIN
(3 cells)
V
VCTL
= V
REFIN
(4 cells)
V
VCTL
= V
REFIN
/ 20 (2 cells)
V
VCTL
= V
REFIN
/ 20 (3 cells)
V
VCTL
= V
REFIN
/ 20 (4 cells)
VCTL Default Threshold
VCTL Input Bias Current
VCTL rising
0 < V
VCTL
< V
REFIN
DCIN = 0, V
REFIN
= V
VCTL
= 3.6V
VCTL = DCIN = 0, V
REFIN
= 3.6V
CHARGE-CURRENT REGULATION
ICTL Range
V
ICTL
= V
REFIN
Quick-Charge-Current Accuracy
Trickle-Charge-Current Accuracy
BATT/CSIP/CSIN Input Voltage
Range
DCIN = 0
CSIP Input Current
ICTL = 0
ICTL = REFIN
V
ICTL
= V
REFIN
x 0.8
V
ICTL
= V
REFIN
x 0.583
V
ICTL
= V
REFIN
x 0.0625
0
67
54
39
3.0
0
0.1
0.1
350
73
59
43
4.5
3.6
79
64
47
6.0
19
2
2
600
µA
mV
V
mV
V
0
-0.5
-0.5
-0.5
-0.8
-0.8
-0.8
-1.2
-1.2
-1.2
4.0
-1
-1
-1
4.1
3.6
+0.5
+0.5
+0.5
+0.8
+0.8
+0.8
+1.2
+1.2
+1.2
4.2
+1
+1
+1
µA
V
%
V
CONDITIONS
MIN
TYP
MAX
UNITS
2
_______________________________________________________________________________________
Step-Up/Step-Down
Li+ Battery Charger
ELECTRICAL CHARACTERISTICS (continued)
(Circuit of Figure 2, V
DCIN
= V
CSSP
= V
CSSN
= V
CSSS
= V
VHP
= 18V, V
BATT
= V
CSIP
= V
CSIN
= V
BLKP
= 12V, V
REFIN
= 3.0V, V
ICTL
=
0.75 x V
REFIN
, VCTL = LDO, CELLS = FLOAT, GND = PGND = 0, V
DLOV
= 5.4V,
T
A
= 0°C to +85°C,
unless otherwise noted. Typical
values are at T
A
= +25°C.)
PARAMETER
DCIN = 0
CSIN Input Current
ICTL Power-Down-Mode
Threshold Voltage
ICTL Input Bias Current
INPUT-CURRENT REGULATION
Charger-Input Current-Limit
Accuracy (V
CSSP
- V
CSSN
)
System-Input Current-Limit
Accuracy (V
CSSP
- V
CSSS
)
CSSP/CSSS/CSSN Input Voltage
Range
CSSP Input Current
CSSS/CSSN Input Current
CLS Input Range
CLS Input Bias Current
IINP Transconductance
IINP Output Current
IINP Output Voltage
CLS = REF
V
CSSP
- V
CSSS
= 102mV, CSSN = CSSP
V
CSSP
- V
CSSN
= 200mV, V
IINP
= 0V
V
CSSP
- V
CSSS
= 200mV, V
IINP
= 0V
V
CSSP
- V
CSSN
= 200mV, IINP float
V
CSSP
- V
CSSS
= 200mV, IINP float
V
CSSP
= V
CSSN
= V
CSSS
= V
DCIN
= 6V
V
CSSP
= V
CSSN
= V
CSSS
= V
DCIN
= 8V, 28V
V
CSSP
= V
CSSN
= V
CSSS
= V
DCIN
= 6V
V
CSSP
= V
CSSN
= V
CSSS
= V
DCIN
= 8V, 28V
-1
-1
V
REF
/ 2
-1
2.5
350
350
3.5
3.5
8
DCIN falling
DCIN rising
8.0V < V
DCIN
< 28V
0
DCIN = 0
VBATT = 2V to 19V
No load
0 < I
LDO
< 10mA
V
DCIN
= 8V, LDO rising
4.00
5.3
0.1
300
5.4
70
5.0
4
6.2
6.3
3.5
7.85
6
19
1
500
5.5
150
5.25
28
2.8
CSSS = CSSP
CSSN = CSSP
CLS = REF
CLS = REF x 0.845
CLS = REF
CLS = REF x 0.845
97
81
97
81
8
-1
700
105
88
105
88
113
95
113
95
28
+1
1200
+1
+1
V
REF
+1
3.1
mV
mV
V
µA
µA
V
µA
µA/mV
µA
V
0 < V
ICTL
< V
REFIN
ICTL = DCIN = 0, V
REFIN
= 3.6V
ICTL = 0
ICTL = REFIN
REFIN /
100
-1
-1
CONDITIONS
MIN
TYP
0.1
0.1
0.1
REFIN /
55
MAX
2
2
2
REFIN /
32
+1
+1
V
µA
µA
UNITS
MAX1870A
SUPPLY AND LINEAR REGULATOR
DCIN Input Voltage Range
DCIN Undervoltage Lockout
DCIN Quiescent Current
BATT Input Voltage Range
BATT Input Bias Current
LDO Output Voltage
LDO Load Regulation
LDO Undervoltage Lockout
V
V
mA
V
µA
V
mV
V
_______________________________________________________________________________________
3
Step-Up/Step-Down
Li+ Battery Charger
MAX1870A
ELECTRICAL CHARACTERISTICS (continued)
(Circuit of Figure 2, V
DCIN
= V
CSSP
= V
CSSN
= V
CSSS
= V
VHP
= 18V, V
BATT
= V
CSIP
= V
CSIN
= V
BLKP
= 12V, V
REFIN
= 3.0V, V
ICTL
=
0.75 x V
REFIN
, VCTL = LDO, CELLS = FLOAT, GND = PGND = 0, V
DLOV
= 5.4V,
T
A
= 0°C to +85°C,
unless otherwise noted. Typical
values are at T
A
= +25°C.)
PARAMETER
REFERENCE
REF Output Voltage
REF Load Regulation
REF Undervoltage-Lockout Trip
Point
REFIN Input Range
REFIN UVLO Rising
REFIN UVLO Hysteresis
REFIN Input Bias Current
SWITCHING REGULATOR
Cycle-by-Cycle Step-Up Maximum
Current-Limit Sense Voltage
Cycle-by-Cycle Step-Down
Maximum Current-Limit Sense
Voltage
Step-Down On-Time
Minimum Step-Down Off-Time
Step-Up Off-Time
Minimum Step-Up On-Time
MOSFET DRIVERS
VHP - VHN Output Voltage
VHN Load Regulation
DHI On-Resistance High
DHI On-Resistance Low
VHP Input Bias Current
BLKP Input Bias Current
DLOV Supply Current
DBST On-Resistance High
DBST On-Resistance Low
ERROR AMPLIFIERS
GMV Amplifier Loop
Transconductance
GMI Amplifier Loop
Transconductance
VCTL = REFIN, V
BATT
= 16.8V
ICTL = REFIN, V
CSIP
- V
CSIN
= 72mV
0.05
1.8
0.1
2.4
0.20
3.0
µA/mV
µA/mV
8V < V
VHP
< 28V, no load
0 < I
VHN
< 10mA
I
SOURCE
= 10mA
I
SINK
= 10mA
DCIN = 0
V
DCIN
= 18V
ICTL = 0
V
ICTL
= V
REFIN
= 3.3V
DBST low
I
SOURCE
= 10mA
I
SINK
= 10mA
4.5
5
70
2
1
0.1
1.3
0.1
100
5
2
1
5.5
150
5
3
1
2
2
400
10
5
3
V
mV
Ω
Ω
µA
mA
µA
µA
Ω
Ω
V
DCIN
= 12V, V
BATT
= 16.8V
135
150
165
mV
V
DCIN
= 18V
DCIN = 0, V
REFIN
= 3.6V
-1
I
REF
= 0µA
0 < I
REF
< 500µA
V
REF
falling
2.5
1.9
50
50
100
+1
4.076
4.096
5
3.1
4.116
10
3.9
3.6
2.2
V
mV
V
V
V
mV
µA
CONDITIONS
MIN
TYP
MAX
UNITS
V
DCIN
= 19V, V
BATT
= 16.8V
V
DCIN
= 18V, V
BATT
= 16.8V
V
DCIN
= 18V, V
BATT
= 16.8V
V
DCIN
= 12V, V
BATT
= 16.8V
V
DCIN
= 12V, V
BATT
= 16.8V
135
2.2
0.15
1.6
0.15
150
2.4
0.4
1.8
0.3
165
2.6
0.50
2.0
0.40
mV
µs
µs
µs
µs
4
_______________________________________________________________________________________
Step-Up/Step-Down
Li+ Battery Charger
ELECTRICAL CHARACTERISTICS (continued)
(Circuit of Figure 2, V
DCIN
= V
CSSP
= V
CSSN
= V
CSSS
= V
VHP
= 18V, V
BATT
= V
CSIP
= V
CSIN
= V
BLKP
= 12V, V
REFIN
= 3.0V, V
ICTL
=
0.75 x V
REFIN
, VCTL = LDO, CELLS = FLOAT, GND = PGND = 0, V
DLOV
= 5.4V,
T
A
= 0°C to +85°C,
unless otherwise noted. Typical
values are at T
A
= +25°C.)
PARAMETER
GMS Amplifier Loop
Transconductance
CCV Output Current
CCI Output Current
CONDITIONS
V
CLS
= REF, V
CSSP
- V
CSSN
= 102mV, V
CSSP
= V
CSSS
V
CLS
= REF, V
CSSP
- V
CSSS
= 102mV, V
CSSP
= V
CSSN
VCTL = REFIN, V
BATT
= 15.8V
VCTL = REFIN, V
BATT
= 17.8V
ICTL = REFIN, V
CSIP
- V
CSIN
= 0mV
ICTL = REFIN, V
CSIP
- V
CSIN
= 150mV
CLS = REF, V
CSSP
= V
CSSN
, V
CSSP
= V
CSSS
CCS Output Current
CLS = REF, V
CSSP
- V
CSSN
= 200mV,
V
CSSP
- V
CSSS
= 200mV
1.1V < V
CCV
< 3.5V, 1.1V < V
CCS
< 3.5V,
1.1V < V
CCI
< 3.5V
V
IINP
= GND, I
SINK
= 1mA
V
IINP
= 4V, I
SOURCE
= 1mA
V
IINP
rising
Hysteresis
V
SHDN
= 0 to V
REFIN
DCIN = 0, V
REFIN
= 5V, V
SHDN
= 0 to V
REFIN
SHDN
falling, V
REFIN
= 2.8V to 3.6V
-1
-1
22
23.5
1
0.75
40
REFIN -
0.75V
CELLS = 0 to REFIN
-2
+2
50
60
LDO -
0.5
1.1
1.15
50
+1
+1
25
1.2
100
300
100
-100
500
µA
150
-150
MIN
1.2
1.2
50
-50
TYP
1.7
1.7
MAX
2.2
2.2
UNITS
µA/mV
µA
µA
MAX1870A
CCI/CCS/CCV Clamp Voltage
LOGIC LEVELS
ASNS Output-Voltage Low
ASNS Output-Voltage High
ASNS Current Detect
SHDN
Input Bias Current
SHDN
Threshold
SHDN
Hysteresis
CELLS Input Low Voltage
CELLS Float Voltage
CELLS Input High Voltage
CELLS Input Bias Current
mV
0.4
V
V
V
mV
µA
% of
REFIN
% of
REFIN
V
% of
REFIN
V
µA
_______________________________________________________________________________________
5
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