19-4279; Rev 0; 3/09
EVALUATION KIT
AVAILABLE
28V Dual Input Linear Li+ Battery Chargers with
Battery Detection and Overvoltage-Protected Output
General Description
The MAX8844Z/MAX8844Y intelligent, stand-alone con-
stant-current, constant-voltage (CCCV), thermally regu-
lated dual input linear chargers are designed for
charging a single-cell lithium-ion (Li+) battery. The
MAX8844Z/MAX8844Y 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 IC controls 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 IC is exposed to high
ambient temperatures, allowing maximum charging
current without damaging the IC.
The MAX8844Z/MAX8844Y achieve high flexibility by pro-
viding adjustable fast-charge currents (SETI) and an
adjustable top-off current threshold (MIN) through external
resistors. The IC features a booting assistant circuit that
distinguishes input sources and battery connection and
provides an enable signal (ABO,
ABO)
for system booting.
The ICs also integrate two input overvoltage-protected
LDO outputs (SAFEOUT, SAFEUSB) for low-voltage-
rated USB or charger inputs in system, and a battery
pack detection circuit (DETBAT) that disables the charg-
er 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 MAX8844Z/MAX8844Y automatically select between
either the USB or IN source. If both sources are present
at the same time, highest priority is given to the IN source.
The IN source is selected to ensure the shortest charging
time for the system since it is able to deliver the highest
current.
The MAX8844Z/MAX8844Y accept an input supply range
from 4.25V to 28V (IN and USB), but disable charging if
the input voltage exceeds +7.5V to protect against
unqualified or faulty AC adapters. The ICs operate over
the extended temperature range (-40°C to +85°C) and are
available in a compact 14-pin, thermally enhanced, lead-
free TDFN 3mm x 3mm package (0.8mm max height).
Features
♦
CCCV, Thermally Regulated Linear One-Cell Li+
Battery Charger
♦
No External MOSFET, Reverse Blocking Diode, or
Current-Sense Resistor
♦
Programmable Fast-Charge Currents (1A
RMS
max)
♦
Programmable Top-Off Current Threshold
♦
Input Overvoltage Protected 4.7V Output
(SAFEOUT) from IN
♦
Input Overvoltage Protected 4.7V Output
(SAFEUSB) from USB
♦
Proprietary Die Temperature Regulation Control
(+115°C)
♦
4.25V to 28V Input Voltage Range with Input
Overvoltage Protection Above +7.5V
♦
Low-Dropout Voltage (300mV at 500mA)
♦
Input Power-Source Detection Output (POK),
Charge Status Output (CHG), Charge-Enable Input
(EN)
♦
Output for Autobooting (ABO, MAX8844Z)
♦
Output for Autobooting (ABO, MAX8844Y)
♦
Tiny 3mm x 3mm, 14-Pin TDFN Package, 0.8mm
Height (max)
MAX8844Z/MAX8844Y
Ordering Information
PART
MAX8844ZETD+
MAX8844YETD+
PIN-
PACKAGE
14 TDFN-EP*
14 TDFN-EP*
TOP MARK
AEK
AEN
ABO
ACTIVE
STATE
Active high
Active low
+Denotes
a lead(Pb)-free/RoHS-compliant package.
*EP
= Exposed pad.
Applications
Cellular and Cordless
Phones
Smart Phones and PDAs
Digital Still Cameras
MP3 Players
Bluetooth is a registered trademark of Bluetooth SIG.
Note:
All devices are specified over the -40°C to +85°C oper-
ating temperature range.
USB Appliances
Charging Cradles and
Docks
Bluetooth® Equipment
Typical Operating Circuit and Pin Configuration appear at
end of data sheet.
________________________________________________________________
Maxim Integrated Products
1
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 Dual Input Linear Li+ Battery Chargers with
Battery Detection and Overvoltage-Protected Output
MAX8844Z/MAX8844Y
ABSOLUTE MAXIMUM RATINGS
IN, USB to GND......................................................-0.3V to +30V
ABI, BATT,
EN, POK,
ABO,
ABO, CHG,
DETBAT, SETI,
MIN, SAFEOUT,
SAFEUSB to GND.................................................-0.3V to +6V
IN to BATT Continuous Current .........................................1A
RMS
Continuous Power Dissipation (T
A
= +70°C)
14 TDFN (derate 24.4mW/°C above 70°C)
(multilayer PCB) ....................................................1951.2mW
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 or V
USB
= 5V, V
BATT
= 4V, R
POK
= 1MΩ to BATT,
EN
= unconnected, R
SETI
= 2.8kΩ to GND, V
DETBAT
= 0V, 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
IN, USB
Input Supply Voltage Range
Input Supply Operating Voltage
Range
Overvoltage Lockout Trip
Threshold
V
IN
rising, 100mV hysteresis (typ)
Constant current charging
I
IN
- I
BATT
, I
BATT
= 0A
Input Current
Constant current charging
I
IN
- I
BATT,
I
BATT
= 500mA
IC disabled, V
EN
= 5V
V
IN
= 4V,
V
BATT
= 4.2V
BATT,
CHG, POK
Minimum BATT Bypass
Capacitance
V
BATT
Prequalification Threshold
Voltage
Battery Regulation Voltage
Regulator Dropout Voltage (V
IN
-
V
BATT
)
BATT Input Current
(Note 2)
Current-Sense Amplifier Gain
(I
BATT
to I
SETI
)
V
BATT
rising, 100mV hysteresis (typ)
I
BATT
= 0A
V
BATT
= 4.1V, I
BATT
= 425mA
V
IN
= 0 to 4V,
V
BATT
= 4.2V
IC disabled
I
BATT
= 500mA
T
A
= 0°C to +85°C
T
A
= -40°C to +85°C
T
A
= 0°C to +85°C
T
A
= -40°C to +85°C
2.3
4.175
4.158
2.2
2.5
4.200
4.200
260
5
3
1120
1120
µA/A
10
2.7
4.225
4.242
µF
V
V
mV
T
A
= +25°C
T
A
= +85°C
0
4.25
7.0
7.5
0.25
1
0.23
0.02
0.03
0.50
28
7.00
8.0
0.50
V
V
V
CONDITIONS
MIN
TYP
MAX
UNITS
mA
µA
2
_______________________________________________________________________________________
28V Dual Input Linear Li+ Battery Chargers with
Battery Detection and Overvoltage-Protected Output
MAX8844Z/MAX8844Y
ELECTRICAL CHARACTERISTICS (continued)
(V
IN
= 5V or V
USB
= 5V, V
BATT
= 4V, R
POK
= 1MΩ to BATT,
EN
= unconnected, R
SETI
= 2.8kΩ to GND, V
DETBAT
= 0V, C
BATT
=
2.2µF, T
A
= -40°C to +85°C, unless otherwise noted. Typical values are at T
A
= +25°C.) (Note 1)
ABI Logic Input Low Threshold
ABI Logic Input High Threshold
ABO Output Low Threshold
ABO Output High Threshold
ABO
Output Low Threshold
ABO
Output High Threshold
THERMAL
Die Temperature Regulation
Threshold
115
°C
V
BATT
= 4V, V
IN
= 0V
V
BATT
= 4V, V
IN
= 0V
I
ABO(SINK)
= 1mA
I
ABO(SOURCE)
= 1mA
Open drain, I
ABO(SINK)
= 1mA
Open drain, 100kΩ pullup on BATT
V
BATT
-
0.4V
V
BATT
-
0.4V
0.4
1.3
0.4
0.4
V
V
V
V
Note 1:
Specifications are 100% production tested at T
A
= +25°C. Limits over the operating temperature range are guaranteed by
design and characterization.
Note 2:
The IN input supply and USB input supply are interchangeable (V
IN
= V
USB
). See the
DC and USB Power Supplies
section
for further details.
Note 3:
See the
Top-Off Current Threshold Setting
section for further details.
Typical Operating Characteristics
(V
IN
= 5V or V
USB
= 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
MAX8844 toc01
DISABLED MODE SUPPLY CURRENT
vs. INPUT VOLTAGE
V
EN
= 5V
0.5
SUPPLY CURRENT (mA)
0.4
0.3
0.2
0.1
0
MAX8844 toc02
CHARGE CURRENT
vs. BATTERY VOLTAGE
700
CHARGE CURRENT (mA)
600
500
400
300
200
100
0
V
IN
= 0V,
V
USB
= 5V
V
IN
= 5V,
V
USB
= 0V
MAX8844 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
20
24
V
EN
= 0V,
I
BATT
= 0A,
V
IN
RISING
0.6
800
28
0
4
8
12
16
20
24
28
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)
4
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