19-4340; Rev 1; 9/09
IT
TION K
VALUA
E
BLE
AVAILA
28V Linear Li+ Battery Chargers with Battery
Detection and Overvoltage Protected Output
General Description
The MAX8845Z/MAX8845Y/MAX8845X/MAX8845W are
intelligent, stand-alone constant-current, constant-volt-
age (CCCV), thermally regulated linear chargers
designed for charging a single-cell lithium-ion (Li+) bat-
tery. The MAX8845Z/MAX8845Y/MAX8845X/MAX8845W
integrate a current-sense circuit, MOSFET pass element,
thermal-regulation circuitry, and eliminate the external
reverse-blocking Schottky diode to create the simplest
and smallest charging solutions for handheld equipment.
The ICs control the charging sequence from the pre-
qualification state through constant current fast-charge,
top-off charge, and full-charge indication. Proprietary
thermal-regulation circuitry limits the die temperature
during fast-charging or when the ICs are exposed to
high ambient temperatures, allowing maximum charg-
ing current without damaging the ICs.
The MAX8845Z/MAX8845Y/MAX8845X/MAX8845W
achieve high flexibility by providing adjustable fast-
charge currents (SETI) and an adjustable top-off cur-
rent threshold (MIN) through external resistors. The
MAX8845Z/MAX8845Y/MAX8845X/MAX8845W feature
a booting assistant circuit that distinguishes input
sources and battery connection and provides an
enable signal (ABO—MAX8845Z and
ABO—
MAX8845Y/MAX8845X/MAX8845W) for system booting.
The MAX8845Z/MAX8845Y/MAX8845X/MAX8845W also
integrate an overvoltage-protected output (SAFEOUT) for
low voltage-rated USB or charger inputs in system, and a
battery-pack detection circuit (DETBAT) that disables the
charger when the battery pack is absent. Other features
include an active-low control input (EN), an active-low
input power source detection output (POK), and a fully
charged top-off threshold detection output (CHG).
The MAX8845Z/MAX8845Y/MAX8845X/MAX8845W
accept an input supply range from 4.25V (4.4V for
MAX8845W only) to 28V, but disable charging if the
supply voltage exceeds +7.5V (+8.0V for MAX8845X
only) to protect against unqualified or faulty AC
adapters. The ICs operate over the extended tempera-
ture range (-40°C to +85°C) and are available in a com-
pact 12-pin, thermally enhanced thin QFN, 3mm x 3mm
package (0.8mm max height).
Features
o
CCCV, Thermally Regulated Linear 1-Cell Li+
Battery Charger
o
No External MOSFET, Reverse Blocking Diode, or
Current-Sense Resistor
o
Programmable Fast-Charge Currents (1A
RMS
max)
o
Programmable Top-Off Current Threshold (MIN)
o
Input Overvoltage Protected 4.7V Output
(MAX8845Z/MAX8845Y/MAX8845W) or 4.85V
(MAX8845X) (SAFEOUT)
o
Proprietary Die Temperature Regulation Control
(+115°C)
o
4.25V (4.4V for MAX8845W only) to 28V Input
Voltage Range with Input Overvoltage Protection
Above +7.5V (+8.0V for MAX8845X only)
o
Low-Dropout Voltage (300mV at 500mA)
o
Input Power-Source Detection Output (POK),
Charge Status Output (CHG), Charge-Enable Input
(EN)
o
Output for Autobooting (ABO—MAX8845Z,
ABO—MAX8845Y/MAX8845X/MAX8845W)
o
Tiny, 3mm x 3mm 12-Pin Thin QFN Package,
0.8mm Height (max)
MAX8845Z/MAX8845Y/MAX8845X/MAX8845W
Ordering Information
PART
MAX8845ZETC+
MAX8845YETC+
MAX8845XETC+
MAX8845WETC+
PIN-PACKAGE
12 Thin QFN-EP*
12 Thin QFN-EP*
12 Thin QFN-EP*
12 Thin QFN-EP*
TOP
MARK
ABL
ABM
ABQ
ABR
ABO
ACTIVE
STATE
Active high
Active low
Active low
Active low
Applications
Cellular and Cordless Phones
Smart Phones and PDAs
Digital Still Cameras
MP3 Players
USB Appliances
Charging Cradles and Docks
Bluetooth
®
Equipment
Note:
All devices are specified over the -40°C to +85°C oper-
ating temperature range.
+Denotes
a lead(Pb)-free/RoHS-compliant package.
*EP
= Exposed pad.
Typical Operating Circuit and Pin Configurations appear at
end of data sheet.
Bluetooth is a registered trademark of Bluetooth SIG.
1
________________________________________________________________
Maxim Integrated Products
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.
28V Linear Li+ Battery Chargers with Battery
Detection and Overvoltage Protected Output
MAX8845Z/MAX8845Y/MAX8845X/MAX8845W
ABSOLUTE MAXIMUM RATINGS
IN to GND ...............................................................-0.3V to +30V
ABI, BATT,
EN, POK,
ABO,
ABO, CHG,
DETBAT, SETI, MIN,
SAFEOUT to GND ................................................-0.3V to +6V
IN to BATT Continuous Current .........................................1A
RMS
Continuous Power Dissipation (T
A
= +70°C)
12-Thin QFN (derate 14.7mW/°C above +70°C)
(multilayer PCB) ......................................................1176.5mW
BATT Short-Circuit Duration .......................................Continuous
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
= 5V, V
BATT
= 4V, R
POK
= 1MΩ to BATT,
EN
= unconnected, R
SETI
= 2.8kΩ to GND, V
DETBAT
= 0, C
BATT
= 2.2µF, T
A
= -40°C to
+85°C, unless otherwise noted. Typical values are at T
A
= +25°C.) (Note 1)
PARAMETER
Input Supply Voltage Range
Input Supply Operating Voltage Range
Overvoltage Lockout Trip Threshold
MAX8845W only
V
IN
rising, 100mV hysteresis (typ)
MAX8845X only
Constant current charging
I
IN
- I
BATT
, I
BATT
= 0
Constant current charging
I
IN
- I
BATT,
I
BATT
= 500mA
IC disabled, V
EN
= 5V
V
IN
= 4V,
V
BATT
= 4.2V (4.35V for
MAX8845W only)
BATT,
CHG, POK
Minimum BATT Bypass Capacitance
V
BATT
Prequalification Threshold Voltage
V
BATT
rising, 100mV hysteresis (typ)
I
BATT
= 0
Battery Regulation Voltage
MAX8845W only
Regulator Dropout Voltage (V
IN
- V
BATT
)
BATT Input Current
Current-Sense Amplifier Gain (I
BATT
to I
SETI
)
V
BATT
= 4.1V, I
BATT
= 425mA
V
IN
= 0 to 4V,
V
BATT
= 4.2V (4.35V for MAX8845W only)
IC disabled
I
BATT
= 500mA
V
BATT
= 3.5V,
R
SETI
= 2.8kΩ
V
BATT
= 3.5V,
R
SETI
= 14kΩ
CHG
Top-Off Threshold
T
A
= 0°C to +85°C
T
A
= -40°C to +85°C
T
A
= 0°C to +85°C
460
425
85
T
A
= -40°C to +85°C
2.3
4.175
4.158
4.324
4.306
2.2
2.5
4.200
4.200
4.350
4.350
260
5
3
1016
500
500
100
106
540
575
115
mA
mA
µA/A
10
2.7
4.225
4.242
4.376
4.394
mV
µA
V
µF
V
T
A
= +25°C
T
A
= +85°C
CONDITIONS
MIN
0
4.25
4.40
7.0
7.5
7.5
8.0
0.22
1
0.20
0.02
0.03
0.50
mA
TYP
MAX
28
7.00
7.00
8.0
8.5
0.50
UNITS
V
V
V
Input Current
Fast-Charge Current
I
BATT
falling, battery is charged
R
MIN
= 1.75kΩ
2
_______________________________________________________________________________________
28V Linear Li+ Battery Chargers with Battery
Detection and Overvoltage Protected Output
ELECTRICAL CHARACTERISTICS (continued)
(V
IN
= 5V, V
BATT
= 4V, R
POK
= 1MΩ to BATT,
EN
= unconnected, R
SETI
= 2.8kΩ to GND, V
DETBAT
= 0, C
BATT
= 2.2µF, T
A
= -40°C to
+85°C, unless otherwise noted. Typical values are at T
A
= +25°C.) (Note 1)
PARAMETER
CHG
Hysteresis
CHG
Detection Delay
Prequalification Charge Current
CHG, POK
Output Low Threshold
CHG, POK
Output High Leakage Current
POK Threshold
DETBAT, SAFEOUT
DETBAT Logic-Input Low Threshold
DETBAT Logic-Input High Threshold
DETBAT Pullup Resistor
Minimum SAFEOUT Bypass Capacitance
I
SAFEOUT
= 30mA, V
IN
= 5V, T
A
= 0°C to
+85°C (MAX8845Z/MAX8845Y/MAX8845W)
I
SAFEOUT
= 20mA, V
IN
= 5V, T
A
= 0°C to
+85°C (MAX8845X)
4.5
4.75
DETBAT to V
L
= 3V
1.3
470
1
4.7
4.85
100
100
4.25V (4.4V for MAX8845W only)
≤
V
IN
≤
7V
4.25V (4.4V for MAX8845W only)
≤
V
IN
≤
7V
V
BATT
= 4V, V
IN
= 0
V
BATT
= 4V, V
IN
= 0
Open drain, I
ABO(SINK)
= 1mA
Open drain, 100kΩ pullup to BATT
I
ABO(SINK)
= 1mA
I
ABO(SOURCE)
= 1mA
V
BATT
-
0.4V
115
V
BATT
-
0.4V
0.4
1.3
0.4
1.3
0.4
200
400
0.4
4.9
V
5.0
mA
kΩ
V
V
V
V
V
V
V
V
CONDITIONS
I
BATT
rising after top-off is detected,
R
MIN
= 1.75kΩ
I
BATT
falls below top-off threshold
Percentage of the fast-
charge current, V
BATT
= 2.2V
T
A
= 0°C to +85°C
4.0
5
MIN
TYP
38
6.2
10
10.7
15
0.4
1
0.01
40
30
0.4
MAX
UNITS
mA
ms
%
V
µA
mV
MAX8845Z/MAX8845Y/MAX8845X/MAX8845W
I
POK
= 5mA , I
CHG
= 5mA
V
POK
= 5.5V,
V
CHG
= 5.5V
V
IN
- V
BATT
T
A
= +25°C
T
A
= +85°C
V
IN
rising
V
IN
falling
V
kΩ
µF
SAFEOUT Regulated Output
SAFEOUT Current Limit
EN,
ABI, ABO,
ABO
EN,
ABI Internal Pulldown Resistor
EN
Logic-Input Low Threshold
EN
Logic-Input High Threshold
ABI Logic-Input Low Threshold
ABI Logic-Input High Threshold
ABO
Output Low Threshold (MAX8845Y/
MAX8845X/MAX8845W)
ABO
Output High Threshold (MAX8845Y/
MAX8845X/MAX8845W)
ABO Output Low Threshold
(MAX8845Z)
ABO Output High Threshold (MAX8845Z)
THERMAL
Die Temperature Regulation Threshold
°C
Note 1:
Specifications are 100% production tested at T
A
= +25°C. Limits over the operating temperature range are guaranteed by
design and characterization.
_______________________________________________________________________________________
3
28V Linear Li+ Battery Chargers with Battery
Detection and Overvoltage Protected Output
MAX8845Z/MAX8845Y/MAX8845X/MAX8845W
Typical Operating Characteristics
(V
IN
= 5V, V
BATT
= 4V, R
POK
= R
CHG
= 200kΩ to 5V,
EN
= unconnected, R
SETI
= 2.8kΩ to GND, R
MIN
= 1.74kΩ to GND, R
DETBAT
=
4.7kΩ to GND, C
BATT
= 2.2µF, T
A
= +25°C, unless otherwise noted.)
SUPPLY CURRENT
vs. INPUT VOLTAGE
MAX8845Z/Y/X/W toc01
DISABLED MODE SUPPLY CURRENT
vs. INPUT VOLTAGE
V
EN
= 5V
0.5
SUPPLY CURRENT (µA)
0.4
0.3
0.2
0.1
0
MAX8845Z/Y/X/W toc02
CHARGE CURRENT
vs. BATTERY VOLTAGE
900
800
CHARGE CURRENT (mA)
700
600
500
400
300
200
100
0
MAX8845Z/Y/X/W toc03
1.0
0.9
0.8
SUPPLY CURRENT (mA)
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
0
4
8
12
16
V
EN
= 0,
I
BATT
= 0
V
IN
RISING
0.6
1000
20
24
28
0
5
10
15
20
25
30
0
0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5
BATTERY VOLTAGE (V)
INPUT VOLTAGE (V)
INPUT VOLTAGE (V)
CHARGE CURRENT
vs. INPUT VOLTAGE
MAX8845Z/Y/X/W toc04
CHARGE CURRENT
vs. INPUT VOLTAGE HEADROOM
MAX8845Z/Y/X/W toc05
SAFEOUT OUTPUT VOLTAGE
vs. INPUT VOLTAGE
4.5
4.0
SAFEOUT VOLTAGE (V)
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0
I
SAFEOUT
= 1mA
MAX8845Z/Y/X/W toc06
600
500
CHARGE CURRENT (mA)
400
300
200
100
0
0
4
8
12
16
20
24
1000
900
800
CHARGE CURRENT (mA)
700
600
500
400
300
200
100
0
V
BATT
= 4V,
V
IN
RISING
5.0
28
0
100
200
300
400
500
600
0
4
8
12
16
20
24
28
INPUT VOLTAGE (V)
V
IN
- V
BATT
(mV)
INPUT VOLTAGE (V)
SAFEOUT OUTPUT VOLTAGE
vs. LOAD CURRENT
4.5
4.0
SAFEOUT VOLTAGE (V)
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0
0
20
40
60
80
100
V
POK
MAX8845Z/Y/X/W toc07
STARTUP INTO PRECHARGE
MAX8845Z/Y/X/W toc08
SHUTDOWN
(FAST-CHARGE TO SHUTDOWN)
MAX8845Z/Y/X/W toc09
5.0
I
BATT
V
IN
V
EN
I
100mA/div
BATT
0
5V/div
0
5V/div
0
5V/div
0
40µs/div
V
POK
40µs/div
V
IN
V
EN
500mA/div
0
5V/div
0
5V/div
0
5V/div
0
LOAD CURRENT (mA)
4
_______________________________________________________________________________________
28V Linear Li+ Battery Chargers with Battery
Detection and Overvoltage Protected Output
Typical Operating Characteristics (continued)
(V
IN
= 5V, V
BATT
= 4V, R
POK
= R
CHG
= 200kΩ to 5V,
EN
= unconnected, R
SETI
= 2.8kΩ to GND, R
MIN
= 1.74kΩ to GND, R
DETBAT
=
4.7kΩ to GND, C
BATT
= 2.2µF, T
A
= +25°C, unless otherwise noted.)
BATTERY REGULATION ACCURACY
vs. AMBIENT TEMPERATURE
MAX8845Z/Y/X/W toc10
MAX8845Z/MAX8845Y/MAX8845X/MAX8845W
FAST-CHARGE CURRENT
vs. R
SETI
MAX8845Z/Y/X/W toc11
TOP-OFF CURRENT THRESHOLD
vs. 1/R
MIN
(kΩ)
TOP-OFF CURRENT THRESHOLD (mA)
550
500
450
400
350
300
250
200
150
100
50
TOP-OFF CURRENT FALLING
TOP-OFF CURRENT RISING
MAX8845Z/Y/X/W toc12
1.0
BATTERY REGULATION ACCURACY (%)
0.8
0.6
0.4
0.2
0
-0.2
-0.4
-0.6
-0.8
-1.0
-40
-15
10
35
60
I
BATT
= 0
1000
600
FAST-CHARGE CURRENT (mA)
100
10
1
85
1
10
100
R
SETI
(kΩ)
1000
10,000
AMBIENT TEMPERATURE (°C)
0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0
0.5 0.7 0.9 1.1 1.3 1.5 1.7 1.9
1/R
MIN
(kΩ)
CHARGE CURRENT
vs. AMBIENT TEMPERATURE
V
BATT
= 4V
MAX8845Z/Y/X/W toc13
AUTOBOOT ENABLED BY ABI SIGNAL
(MAX8845Z)
MAX8845Z/Y/X/W toc14
700
600
CHARGE CURRENT (mA)
500
400
300
V
BATT
= 3.2V
5V/div
V
ABI
0
5V/div
V
IN
0
5V/div
200
100
R
SETI
= 2.8kΩ
0
-40
-20
0
20
40
60
80
100
AMBIENT TEMPERATURE (°C)
V
BATT
0
5V/div
0
4µs/div
V
ABO
AUTOBOOT ENABLED BY INPUT VOLTAGE
(MAX8845Z)
MAX8845Z/Y/X/W toc15
AUTOBOOT ENABLED BY ABI SIGNAL
(MAX8845Y/MAX8845X/MAX8845W)
MAX8845Z/Y/X/W toc16
5V/div
V
ABI
0
5V/div
V
IN
0
5V/div
V
BATT
V
ABO
20µs/div
0
5V/div
0
V
ABO
4µs/div
V
BATT
V
IN
V
ABI
5V/div
0
5V/div
0
5V/div
0
5V/div
0
_______________________________________________________________________________________
5
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