EVALUATION KIT AVAILABLE
L
AVAILAB
MAX1908/MAX8724/
MAX8765/MAX8765A
Low-Cost Multichemistry Battery Chargers
E
General Description
The MAX1908/MAX8724/MAX8765/MAX8765A highly
integrated, multichemistry battery-charger control ICs
simplify the construction of accurate and efficient charg-
ers. These devices use analog inputs to control charge
current and voltage, and can be programmed by the host
or hardwired. The MAX1908/MAX8724/MAX8765/
MAX8765A achieve high efficiency using a buck topology
with synchronous rectification.
The MAX1908/MAX8724/MAX8765/MAX8765A feature
input current limiting. This feature reduces battery
charge current when the input current limit is reached
to avoid overloading the AC adapter when supplying
the load and the battery charger simultaneously. The
MAX1908/MAX8724/MAX8765/MAX8765A provide out-
puts to monitor current drawn from the AC adapter (DC
input source), battery-charging current, and the pres-
ence of an AC adapter. The MAX1908’s conditioning
charge feature provides 300mA to safely charge deeply
discharged lithium-ion (Li+) battery packs.
The MAX1908 includes a conditioning charge feature
while the MAX8724/MAX8765/MAX8765A do not.
The MAX1908/MAX8724/MAX8765/MAX8765A charge two
to four series Li+ cells, providing more than 5A, and are
available in a space-saving, 28-pin, thin QFN package (5mm
×
5mm). An evaluation kit is available to speed designs.
Features
o
±0.5% Output Voltage Accuracy Using Internal
Reference (±0.4% for MAX8765A, 2-/3-Cell Only)
o
±4% Accurate Input Current Limiting
o
±5% Accurate Charge Current
o
Analog Inputs Control Charge Current and
Charge Voltage
o
Outputs for Monitoring
Current Drawn from AC Adapter
Charging Current
AC Adapter Presence
o
Up to 17.6V Battery-Voltage Set Point
o
Maximum 28V Input Voltage
o
> 95% Efficiency
o
Shutdown Control Input
o
Charge Any Battery Chemistry
Li+, NiCd, NiMH, Lead Acid, etc.
Ordering Information
PART
MAX1908ETI+
MAX8724ETI+
MAX8765ETI+
MAX8765AETI+
TEMP RANGE
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
PIN-PACKAGE
28 Thin QFN-EP*
28 Thin QFN-EP*
28 Thin QFN-EP*
28 Thin QFN-EP*
Applications
Notebook and Subnotebook Computers
Personal Digital Assistants
Handheld Terminals
Functional Diagrams
Minimum Operating Circuit
AC ADAPTER
INPUT
0.01Ω
TO EXTERNAL
LOAD
+Denotes
a lead(Pb)-free/RoHS-compliant package.
*EP
= Exposed pad.
Pin Configuration
TOP VIEW
CELLS
PGND
VCTL
15
14
13
12
GND
ICTL
CELLS
DCIN
REFIN
VCTL
ICTL
ACIN
ACOK
FROM HOST
µP
SHDN
ICHG
IINP
CCV
CCI
CCS
CSIN
BATT
BST
DLOV
LDO
21
DLOV
LX
DHI
LX
20 19
18
17
16
LDO
22
23
24
25
26
27
28
MAX1908
MAX8724
MAX8765
MAX8765A
BST
DHI
BATT
CSSP
CSSN
CSIN
CSIP
DLO
REFIN
ACOK
ACIN
DLO
10µH
PGND
CSSN
CSSP
CSIP
0.015Ω
MAX1908
MAX8724
MAX8765
MAX8765A
11
10
9
8
ICHG
SHDN
IINP
BATT+
+
1
DCIN
2
LDO
3
CLS
4
REF
5
CCS
6
CCI
7
CCV
REF
Pin Configurations appear
CLS
end of data sheet.
at
GND
Functional Diagrams continued at end of data sheet.
UCSP is a trademark of Maxim Integrated Products, Inc.
THIN QFN
For pricing, delivery, and ordering information, please contact Maxim Direct
at 1-888-629-4642, or visit Maxim’s website at www.maximintegrated.com.
19-2764; Rev 5; 11/09
MAX1908/MAX8724/MAX8765/MAX8765A
Low-Cost Multichemistry Battery Chargers
ABSOLUTE MAXIMUM RATINGS
DCIN, CSSP, CSSN,
ACOK
to GND.......................-0.3V to +30V
BST to GND ............................................................-0.3V to +36V
BST to LX..................................................................-0.3V to +6V
DHI to LX ...................................................-0.3V to (V
BST
+ 0.3V)
LX to GND .................................................................-6V to +30V
BATT, CSIP, CSIN to GND .....................................-0.3V to +20V
CSIP to CSIN or CSSP to CSSN or
PGND to GND ....................................................-0.3V to +0.3V
CCI, CCS, CCV, DLO, ICHG,
IINP, ACIN, REF to GND.......................-0.3V to (V
LDO
+ 0.3V)
DLOV, VCTL, ICTL, REFIN, CELLS, CLS,
LDO,
SHDN
to GND .............................................-0.3V to +6V
DLOV to LDO.........................................................-0.3V to +0.3V
DLO to PGND .........................................-0.3V to (V
DLOV
+ 0.3V)
LDO Short-Circuit Current...................................................50mA
Continuous Power Dissipation (T
A
= +70°C)
28-Pin Thin QFN (5mm
×
5mm)
(derate 20.8mW/°C above +70°C) .........................1666.7mW
Operating Temperature Range ..........................-40°C to +85°C
Junction Temperature ......................................................+150°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
(V
DCIN
= V
CSSP
= V
CSSN
= 18V, V
BATT
= V
CSIP
= V
CSIN
= 12V, V
REFIN
= 3V, V
VCTL
= V
ICTL
= 0.75 x V
REFIN
, CELLS = open, CLS =
REF, V
BST
- V
LX
= 4.5V, ACIN = GND = PGND = 0, C
LDO
= 1µF, LDO = DLOV, C
REF
= 1µF; CCI, CCS, and CCV are compensated
per Figure 1a;
T
A
= 0°C to +85°C,
unless otherwise noted. Typical values are at T
A
= +25°C.)
PARAMETER
Battery-Regulation Voltage
Accuracy
(MAX1908/MAX8724/MAX8765
(2, 3, or 4 Cells) and MAX8765A
(4 Cells Only))
Battery-Regulation Voltage
Accuracy (MAX8765A, 2 or 3
Cells Only)
VCTL Default Threshold
REFIN Range
REFIN Undervoltage Lockout
CHARGE-CURRENT REGULATION
CSIP-to-CSIN Full-Scale Current-
Sense Voltage
V
ICTL
= V
REFIN
V
ICTL
= V
REFIN
V
ICTL
= V
REFIN
x 0.6
Charging-Current Accuracy
V
ICTL
= V
LDO
MAX8765/MAX8765A only; V
ICTL
= V
REFIN
x
0.036
MAX8724 only; V
ICTL
= V
REFIN
x 0.058
Charge-Current Gain Error
(MAX8765/MAX8765A Only)
Charge-Current Offset
(MAX8765/MAX8765A Only)
ICTL Default Threshold
BATT/CSIP/CSIN Input Voltage
Range
V
ICTL
rising
71.25
-5
-5
-6
-45
-33
-2
-2
4.0
0
4.1
75
78.75
+5
+5
+6
+45
+33
+2
+2
4.2
19
%
mV
V
V
%
mV
SYMBOL
V
VCTL
= V
REFIN
V
VCTL
= V
REFIN
/20
V
VCTL
= V
LDO
V
VCTL
= V
REFIN
V
VCTL
= V
REFIN
/20
V
VCTL
= V
LDO
V
VCTL
rising
(Note 1)
V
REFIN
falling
CONDITIONS
MIN
-0.5
-0.5
-0.5
-0.4
-0.4
-0.4
4.0
2.5
1.20
4.1
TYP
MAX
+0.5
+0.5
+0.5
+0.4
+0.4
+0.4
4.2
3.6
1.92
V
V
V
%
UNITS
CHARGE-VOLTAGE REGULATION
%
2
Maxim Integrated
MAX1908/MAX8724/MAX8765/MAX8765A
Low-Cost Multichemistry Battery Chargers
ELECTRICAL CHARACTERISTICS (continued)
(V
DCIN
= V
CSSP
= V
CSSN
= 18V, V
BATT
= V
CSIP
= V
CSIN
= 12V, V
REFIN
= 3V, V
VCTL
= V
ICTL
= 0.75 x V
REFIN
, CELLS = open, CLS =
REF, V
BST
- V
LX
= 4.5V, ACIN = GND = PGND = 0, C
LDO
= 1µF, LDO = DLOV, C
REF
= 1µF; CCI, CCS, and CCV are compensated
per Figure 1a;
T
A
= 0°C to +85°C,
unless otherwise noted. Typical values are at T
A
= +25°C.)
PARAMETER
CSIP/CSIN Input Current
Cycle-by-Cycle Maximum Current
Limit
ICTL Power-Down Mode
Threshold Voltage
(MAX1908/MAX8724 Only)
ICTL, VCTL Input Bias Current
REFIN Input Bias Current
ICHG Transconductance
(MAX1908/MAX8724 Only)
ICHG Transconductance
(MAX8765/MAX8765A Only)
ICHG Transconductance Error
(MAX8765/MAX8765A Only)
ICHG Transconductance Offset
(MAX8765/MAX8765A Only)
V
CSIP
- V
CSIN
= 75mV
ICHG Accuracy
ICHG Output Current
ICHG Output Voltage
INPUT-CURRENT REGULATION
CSSP-to-CSSN Full-Scale
Current-Sense Voltage
V
CLS
= V
REF
Input Current-Limit Accuracy
Input Current-Limit Gain Error
(MAX8765/MAX8765A Only)
Input Current-Limit Offset
(MAX8765/MAX8765A Only)
CSSP, CSSN Input Voltage
Range
CSSP, CSSN Input Current
(MAX1908/MAX8724 Only)
CSSP Input Current
(MAX8765/MAX8765A Only)
V
DCIN
= 0V
V
CSSP
= V
CSSN
= V
DCIN
> 8V
V
CSSP
= V
CSSN
= 28V
V
DCIN
= 0V
V
DCIN
= 28V
V
CLS
= V
REF
/2
V
CLS
= 1.1V (MAX8765/MAX8765A only)
72
-4
-7.5
-10
-2
-2
8
0.1
350
0.1
400
75
78
+4
+7.5
+10
+2
+2
28
1
600
1
650
%
mV
V
µA
µA
%
mV
V
CSIP
- V
CSIN
= 45mV
V
CSIP
- V
CSIN
= 5mV
V
CSIP
- V
CSIN
= 150mV, V
ICHG
= 0V
V
CSIP
- V
CSIN
= 150mV, ICHG = open
G
ICHG
G
ICHG
SYMBOL
Charging
RS2 = 0.015mΩ
6.0
REFIN/
100
-1
-1
-1
-1
2.7
2.85
-5
-5
-6
-5
-40
350
3.5
3
3
CONDITIONS
V
DCIN
= 0V or V
ICTL
= 0V or V
SHDN
= 0V
400
6.8
REFIN/
55
MIN
TYP
MAX
1
650
7.5
REFIN/
33
+1
+1
+1
+1
3.3
3.15
+5
+5
+6
+5
+40
µA
V
%
UNITS
µA
A
V
VCTL
rising
V
VCTL
= V
ICTL
= 0 or 3V
V
DCIN
= 0V, V
VCTL
= V
ICTL
= V
REFIN
= 5V
V
DCIN
= 5V, V
REFIN
= 3V
V
REFIN
= 5V
V
CSIP
- V
CSIN
= 45mV
V
CSIP
- V
CSIN
= 45mV
V
µA
µA
µA/mV
µA/mV
%
µA
Maxim Integrated
3
MAX1908/MAX8724/MAX8765/MAX8765A
Low-Cost Multichemistry Battery Chargers
ELECTRICAL CHARACTERISTICS (continued)
(V
DCIN
= V
CSSP
= V
CSSN
= 18V, V
BATT
= V
CSIP
= V
CSIN
= 12V, V
REFIN
= 3V, V
VCTL
= V
ICTL
= 0.75 x V
REFIN
, CELLS = open, CLS =
REF, V
BST
- V
LX
= 4.5V, ACIN = GND = PGND = 0, C
LDO
= 1µF, LDO = DLOV, C
REF
= 1µF; CCI, CCS, and CCV are compensated
per Figure 1a;
T
A
= 0°C to +85°C,
unless otherwise noted. Typical values are at T
A
= +25°C.)
PARAMETER
CSSN Input Current
(MAX8765/MAX8765A Only)
CLS Input Range
(MAX1908/MAX8724 Only)
CLS Input Range
(MAX8765/MAX8765A Only)
CLS Input Bias Current
IINP Transconductance
(MAX1908/MAX8724 Only)
IINP Accuracy
IINP Transconductance
(MAX8765/MAX8765A Only)
IINP Transconductance Error
(MAX8765/MAX8765A Only)
IINP Transconductance Offset
(MAX8765/MAX8765A Only)
IINP Output Current
IINP Output Voltage
SUPPLY AND LDO REGULATOR
DCIN Input Voltage Range
DCIN Undervoltage-Lockout Trip
Point
DCIN Quiescent Current
BATT Input Current
LDO Output Voltage
LDO Load Regulation
LDO Undervoltage-Lockout Trip
Point
REFERENCE
REF Output Voltage
REF Undervoltage-Lockout Trip
Point
0 < I
REF
< 500µA
V
REF
falling
4.072
4.096
3.1
4.120
3.9
V
V
I
DCIN
I
BATT
V
DCIN
V
DCIN
falling
V
DCIN
rising
8.0V < V
DCIN
< 28V
V
BATT
= 19V, V
DCIN
= 0V
V
BATT
= 2V to 19V, V
DCIN
= 19.3V
8V < V
DCIN
< 28V, no load
0 < I
LDO
< 10mA
V
DCIN
= 8V
3.20
5.25
200
5.4
34
4
8
7
7.4
7.5
3.2
7.85
6
1
500
5.55
100
5.15
28
V
V
mA
µA
V
mV
V
V
CSSP
- V
CSSN
= 150mV, V
IINP
= 0V
V
CSSP
- V
CSSN
= 150mV, V
IINP
= open
G
IINP
G
IINP
V
CLS
= 2V
V
CSSP
- V
CSSN
= 75mV
V
CSSP
- V
CSSN
= 75mV
V
CSSP
- V
CSSN
= 37.5mV
V
CSSP
- V
CCSN
= 75mV
SYMBOL
CONDITIONS
V
CSSP
= V
CSSN
= 28V
V
DCIN
= 0V
V
DCIN
= 28V
1.6
1.1
-1
2.7
-5
-7.5
2.82
-6
-10
350
3.5
3
3
MIN
TYP
0.1
0.1
MAX
1
1
REF
REF
+1
3.3
+5
+7.5
3.18
+6
+10
UNITS
µA
V
V
µA
µA/mV
%
µA/mV
%
µA
µA
V
4
Maxim Integrated
MAX1908/MAX8724/MAX8765/MAX8765A
Low-Cost Multichemistry Battery Chargers
ELECTRICAL CHARACTERISTICS (continued)
(V
DCIN
= V
CSSP
= V
CSSN
= 18V, V
BATT
= V
CSIP
= V
CSIN
= 12V, V
REFIN
= 3V, V
VCTL
= V
ICTL
= 0.75 x V
REFIN
, CELLS = open, CLS =
REF, V
BST
- V
LX
= 4.5V, ACIN = GND = PGND = 0, C
LDO
= 1µF, LDO = DLOV, C
REF
= 1µF; CCI, CCS, and CCV are compensated
per Figure 1a;
T
A
= 0°C to +85°C,
unless otherwise noted. Typical values are at T
A
= +25°C.)
PARAMETER
TRIP POINTS
V
DCIN
falling, referred to V
CSIN
(MAX1908/MAX8724 only)
BATT Power-Fail Threshold
V
CSSP
falling, referred to V
CSIN
(MAX8765/MAX8765A only)
BATT Power-Fail Threshold
Hysteresis
ACIN Threshold
ACIN Threshold Hysteresis
ACIN Input Bias Current
SWITCHING REGULATOR
DHI Off-Time
DHI Minimum Off-Time
DHI Maximum On-Time
DLOV Supply Current
BST Supply Current
BST Input Quiescent Current
LX Input Bias Current
LX Input Quiescent Current
DHI Maximum Duty Cycle
Minimum Discontinuous-Mode
Ripple Current
Battery Undervoltage Charge
Current
Battery Undervoltage Current
Threshold
DHI On-Resistance High
DHI On-Resistance Low
DLO On-Resistance High
DLO On-Resistance Low
V
BATT
= 3V per cell (RS2 = 15mΩ),
MAX1908 only, V
BATT
rising
CELLS = GND, MAX1908 only, V
BATT
rising
CELLS = open, MAX1908 only, V
BATT
rising
CELLS = V
REFIN
, MAX1908 only, V
BATT
rising
V
BST
- V
LX
= 4.5V, I
DHI
= +100mA
V
BST
- V
LX
= 4.5V, I
DHI
= -100mA
V
DLOV
= 4.5V, I
DLO
= +100mA
V
DLOV
= 4.5V, I
DLO
= -100mA
150
6.1
9.15
12.2
DLO low
DHI high
V
DCIN
= 0V, V
BST
= 24.5V,
V
BATT
= V
LX
= 20V
V
DCIN
= 28V, V
BATT
= V
LX
= 20V
V
DCIN
= 0V, V
BATT
= V
LX
= 20V
99
V
BATT
= 16V, V
DCIN
= 19V,
V
CELLS
= V
REFIN
V
BATT
= 16V, V
DCIN
= 17V,
V
CELLS
= V
REFIN
0.36
0.24
2.5
0.4
0.28
5
5
6
0.3
150
0.3
99.9
0.5
300
6.2
9.3
12.4
4
1
4
1
450
6.3
9.45
12.6
7
3.5
7
3.5
Ω
Ω
Ω
Ω
V
0.44
0.33
7.5
10
15
1
500
1
µs
µs
ms
µA
µA
µA
µA
µA
%
A
mA
ACIN rising (MAX8765/MAX8765A only)
ACIN rising (MAX1908/MAX8724 only)
0.5% of REF
V
ACIN
= 2.048V
-1
2.028
2.007
50
100
200
2.048
2.048
20
+1
2.068
2.089
150
mV
V
mV
µA
50
100
150
mV
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
Maxim Integrated
5
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