19-3450; Rev 1; 5/05
KIT
ATION
EVALU
BLE
AVAILA
Complete Backup-Management ICs
for Lithium and NiMH Batteries
General Description
Features
♦
Automatically Manage All Backup Switchover
Functions
♦
Charge Both NiMH and Rechargeable Lithium
Backup Batteries
♦
On-Chip Battery Boost Converter for 1-Cell NiMH
♦
Two Backup Output Voltages
♦
Programmable Charge Current
♦
Programmable Charge Voltage Limit
♦
Low 17µA Operating Current in Backup Mode
♦
Eliminate Many Discrete Components
♦
Tiny 3mm x 3mm Thin QFN Package
MAX8568A/MAX8568B
The MAX8568A/MAX8568B backup-battery-management
ICs are complete charging and backup switchover con-
trol solutions for PDAs, Smart Phones, and other smart
portable devices. They charge both NiMH and
rechargeable lithium battery types and feature pro-
grammable charge current and termination voltage.
Separate optimized charge algorithms for both lithium
and NiMH cells are included on-chip.
The MAX8568A/MAX8568B also manage backup
switchover from a primary power source. An accurate on-
chip voltage detector monitors the main supply and
backs up two system supplies (typically I/O and memory)
when main power falls. On-chip drivers switch external
MOSFETs to disconnect the main supply from the system
loads so the backup source is not drained.
Low-voltage backup cells can be stepped up by an on-
chip synchronous-rectified, low-quiescent-current boost
converter. Additionally, a low-quiescent-current LDO gen-
erates a second backup voltage. The MAX8568A LDO is
preset to 2.5V while the MAX8568B LDO is preset to 1.8V.
Both devices are supplied in 16-pin 3mm x 3mm thin
QFN packages rated for -40°C to +85°C operation.
Ordering Information
PART
TEMP RANGE
PIN-
PACKAGE
16 Thin QFN
3mm x 3mm
(T1633-4)
16 Thin QFN
3mm x 3mm
(T1633-4)
TOP
MARK
ACK
MAX8568AETE
-40°C to +85°C
Applications
PDAs and PDA Phones
Smart Phones
DSCs and DVCs
Palmtops and Wireless Handhelds
Internet Appliances and Web-Books
MAIN BATTERY
2.8V TO 5.5V
IN
BACKUP
BATTERY
BK
MAX8568BETE
-40°C to +85°C
ACL
Typical Operating Circuit
REF
Pin Configuration
INOK
NI/LI
BKV
TOP VIEW
CHGI
MAX8568A
MAX8568B
TERMV
12
11
10
9
I/O OUT
3.3V, 50mA
LX
BKSU
IN
I/O IN
STRTV
GND
STRTV
TERMV
REF
13
14
15
16
1
IN
2
BK
3
PGND
4
LX
8
7
OD2
OD1
LDO
BKSU
MEM OUT
1.8V OR 2.5V, 10mA
MEM IN
PGND
GND
MAX8568A
MAX8568B
6
5
BKV
OD1
LDO
INOK
CHGI
NI
OD2
NI/LI
LI
THIN QFN
________________________________________________________________
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.
Complete Backup-Management ICs
for Lithium and NiMH Batteries
MAX8568A/MAX8568B
ABSOLUTE MAXIMUM RATINGS
IN, BK, BKSU, OD1, OD2 to GND.........................-0.3V to +6.0V
BKV, LDO, NI/LI to GND.........................-0.3V to (V
BKSU
+ 0.3V)
REF, CHGI, INOK, TERMV, STRTV to GND...-0.3V to (V
IN
+ 0.3V)
PGND to GND ......................................................-0.3V to + 0.3V
LX Current ......................................................................0.9A
RMS
Continuous Power Dissipation (T
A
= +70°C)
16-Pin 3mm x 3mm Thin QFN
(derate 15.6mW/°C above +70°C) .............................1250mW
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
(Circuit of Figure 7, V
IN
= V
INOK
= 3.6V, V
BK
= 1.4V, V
NI/LI
= V
BKSU
= 3.3V, V
BKV
= GND = PGND = 0V, V
STRTV
= V
TERMV
= 1.2V,
R5 = 250kΩ,
T
A
= 0°C to +85°C,
unless otherwise noted. Typical values are at T
A
= +25°C.) (Note 1)
PARAMETER
IN Voltage Range
IN Operating Current
CHGI Current Limit
CHGI Bias Voltage
CHGI Resistor Range
BK Charge Voltage Limit
V
BK
= 1.3V
V
IN
= 5.5V, V
NI/LI
= 0V
V
IN
= 3.8V, V
NI/LI
= 0V, V
TERMV
= 1V
V
IN
= V
NI/LI
= 3.6V
BK Reverse Leakage Current to IN
NiMH Mode BK High Threshold Voltage,
V
BK(NIHI)
NiMH Mode BK Low Threshold Voltage,
V
BK(NILO)
TERMV Input Current
STRTV Input Current
REF Output Voltage
REF Load Regulation
REF Line Regulation
INOK Threshold Voltage
INOK Input Current
NI/LI Logic-Level High
NI/LI Logic-Level Low
V
IN
= 0V
V
TERMV
= 1.2V
V
STRTV
= 1.2V
V
TERMV
= 1.1V
V
STRTV
= 1.1V
I
REF
= 1µA
I
REF
= 1µA to 50µA
V
IN
= 3V to 5.5V, I
REF
= 1µA
V
INOK
falling
V
INOK
rising
V
INOK
= 2V
V
BKSU
= 3.3V
V
BKSU
= 3.3V
T
A
= +25°C
T
A
= +85°C
1.8
0.4
2.38
2.40
T
A
= +25°C
T
A
= +85°C
T
A
= +25°C
T
A
= +85°C
1.23
T
A
= +25°C
T
A
= +85°C
1.37
1.17
50
4.116
3.42
1.746
4.2
3.5
1.8
0.01
0.1
1.4
1.2
0.001
0.01
0.001
0.01
1.25
2.5
1
2.43
2.47
0.005
0.05
1.27
10
7
2.48
2.54
0.1
0.05
1.43
1.23
0.05
Charger off, V
INOK
= 1.5V
T
A
= +25°C
T
A
= +85°C
8
CONDITIONS
MIN
2.8
3
3
50
10
600
1800
4.284
3.58
1.854
0.5
µA
V
V
µA
µA
V
mV
mV
V
µA
V
V
V
90
12
mA
mV
kΩ
TYP
MAX
5.5
5
µA
UNITS
V
Charger on, not including charge current
R
CHGI
= 169kΩ, V
BK
= 1.3V
2
_______________________________________________________________________________________
Complete Backup-Management ICs
for Lithium and NiMH Batteries
ELECTRICAL CHARACTERISTICS (continued)
(Circuit of Figure 7, V
IN
= V
INOK
= 3.6V, V
BK
= 1.4V, V
NI/LI
= V
BKSU
= 3.3V, V
BKV
= GND = PGND = 0V, V
STRTV
= V
TERMV
= 1.2V,
R5 = 250kΩ,
T
A
= 0°C to +85°C,
unless otherwise noted. Typical values are at T
A
= +25°C.) (Note 1)
PARAMETER
NI/LI Input Current
OD_ On-Resistance
OD_ Leakage Current
BACKUP STEP-UP
(Note 2)
BK Input Undervoltage Lockout
BK Input Voltage
Quiescent Current into BKSU
Quiescent Current into BK
Shutdown Current into BK
BKV Feedback Voltage
BKV Feedback Bias Current
BKSU Output-Voltage Accuracy
BKSU Output Voltage Range
n-Channel Switch On-Resistance
p-Channel Switch On-Resistance
LX Leakage Current
LX Current Limit (ILIM)
n-Channel Switch Maximum On-Time
p-Channel Zero-Channel Crossing Current
LOW-DROPOUT REGULATOR
BKSU Input Voltage Range
LDO Output-Voltage Accuracy
LDO Line Regulation
LDO Load Regulation
V
BKSU
= 3.3V
MAX8568A
MAX8568B
2.7
2.375
1.71
2.5
1.8
1
2.5
5.0
2.625
1.89
V
V
mV
mV
I
LX
= 200mA
I
LX
= 200mA
T
A
= +25°C
T
A
= +85°C
400
3.5
5
V
BKV
= 1V
V
BKV
= 0V
V
BKV
= V
BKSU
T
A
= +25°C
T
A
= +85°C
3.17
2.4
2.5
0.4
0.7
0.05
0.1
500
5
20
600
6.5
35
I
LDO
= 0mA, not switching
I
BKSU
= I
LDO
= 0mA, not switching
V
IN
= V
INOK
= V
BKSU
= 0V
T
A
= +25°C
T
A
= +85°C
1.162
17
2.4
0.001
0.1
1.21
5
10
3.3
2.5
3.43
2.6
5
1
2
1
1.258
50
V
NI/LI
= 0V, falling trip point
V
NI/LI
= V
BKSU
= 3.3V, falling trip point
1.05
2.45
1.12
1.21
5.5
25
4
0.5
V
V
µA
µA
µA
V
nA
V
V
Ω
Ω
µA
mA
µs
mA
CONDITIONS
V
BKSU
= V
NI/LI
= 3.3V
V
BKSU
= 3.6V
V
OD_
= 5.5V
T
A
= +25°C
T
A
= +85°C
T
A
= +25°C
T
A
= +85°C
MIN
TYP
0.05
0.1
11
0.01
0.1
30
1
MAX
1
UNITS
µA
Ω
µA
MAX8568A/MAX8568B
2.7V < V
BKSU
< 5V, I
LDO
= 1mA
1µA < I
LDO
< 10mA
_______________________________________________________________________________________
3
Complete Backup-Management ICs
for Lithium and NiMH Batteries
MAX8568A/MAX8568B
ELECTRICAL CHARACTERISTICS
(Circuit of Figure 7, V
IN
= V
INOK
= 3.6V, V
BK
= 1.4V, V
NI/LI
= V
BKSU
= 3.3V, V
BKV
= GND = PGND = 0V, V
STRTV
= V
TERMV
= 1.2V,
R5 = 250kΩ,
T
A
= -40°C to +85°C,
unless otherwise noted. Typical values are at T
A
= +25°C.) (Note 3)
PARAMETER
IN Voltage Range
IN Operating Current
CHGI Current Limit
CHGI Resistor Range
BK Charge Voltage Limit
NiMH Mode BK High Threshold Voltage,
V
BK(NIHI)
NiMH Mode BK Low Threshold Voltage,
V
BK(NILO)
REF Output Voltage
REF Load Regulation
REF Line Regulation
INOK Threshold Voltage
NI/LI Logic-Level High
NI/LI Logic-Level Low
OD_ On-Resistance
BACKUP STEP-UP
(Note 2)
BK Input Undervoltage Lockout
BK Input Voltage
Quiescent Current into BKSU
Quiescent Current into BK
BKV Feedback Voltage
BKSU Output-Voltage Accuracy
BKSU Output Voltage Range
n-Channel Switch On-Resistance
p-Channel Switch On-Resistance
I
LX
= 200mA
I
LX
= 200mA
V
BKV
= 0V
V
BKV
= V
BKSU
I
LDO
= 0mA, not switching
I
BKSU
= I
LDO
= 0mA, not switching
1.162
3.17
2.4
2.5
V
NI/LI
= V
BKSU
= 3.3V, falling trip point
1.05
1.21
5.5
25
4
1.258
3.43
2.6
5.0
1
2
V
V
µA
µA
V
V
V
Ω
Ω
Charger on, not including charge current
R
CHGI
= 169kΩ, V
BK
= 1.3V
V
BK
= 1.3V
V
IN
= 5.5V, V
NI/LI
= 0V
V
IN
= 3.8V, V
NI/LI
= 0V, V
TERMV
= 1V
V
IN
= V
NI/LI
= 3.6V
V
TERMV
= 1.2V
V
STRTV
= 1.2V
I
REF
= 1µA
I
REF
= 1µA to 50µA
V
IN
= 3V to 5.5V, I
REF
= 1µA
V
INOK
falling
V
INOK
rising
V
BKSU
= 3.3V
V
BKSU
= 3.3V
V
BKSU
= 3.6V
2.38
2.40
1.8
0.4
30
8
50
4.116
3.420
1.746
1.37
1.17
1.225
CONDITIONS
MIN
2.8
MAX
5.5
90
12
1800
4.310
3.605
1.854
1.43
1.23
1.275
10
7
2.48
2.54
V
V
V
mV
mV
V
V
V
Ω
V
UNITS
V
µA
mA
kΩ
4
_______________________________________________________________________________________
Complete Backup-Management ICs
for Lithium and NiMH Batteries
ELECTRICAL CHARACTERISTICS (continued)
(Circuit of Figure 7, V
IN
= V
INOK
= 3.6V, V
BK
= 1.4V, V
NI/LI
= V
BKSU
= 3.3V, V
BKV
= GND = PGND = 0V, V
STRTV
= V
TERMV
= 1.2V,
R5 = 250kΩ,
T
A
= -40°C to +85°C,
unless otherwise noted. Typical values are at T
A
= +25°C.) (Note 3)
PARAMETER
LX Current Limit (ILIM)
n-Channel Switch Maximum On-Time
p-Channel Zero-Channel Crossing Current
LOW-DROPOUT REGULATOR
BKSU Input Voltage Range
LDO Output-Voltage Accuracy
V
BKSU
= 3.3V
MAX8568A
MAX8568B
2.7
2.375
1.71
5.0
2.625
1.89
V
V
CONDITIONS
MIN
400
3.5
5
MAX
600
6.5
35
UNITS
mA
µs
mA
MAX8568A/MAX8568B
Note 1:
All units are 100% production tested at T
A
= +25°C. Limits over the operating range are guaranteed by design.
Note 2:
All backup step-up converter specifications are with V
IN
= V
INOK
= 0V, unless otherwise noted.
Note 3:
Specifications to -40°C are guaranteed by design and not production tested.
Typical Operating Characteristics
(Circuit of Figure 7, V
IN
= 3.6V, V
BK
= 1.4V, V
NI/LI
= V
BKSU
= 3.3V, T
A
= +25°C, unless otherwise noted.)
NiMH CHARGE CURRENT
vs. BACKUP BATTERY VOLTAGE
MAX8568 toc01
LITHIUM CHARGE CURRENT
vs. BACKUP BATTERY VOLTAGE
MAX8568 toc02
Li-ION TERMINATION VOLTAGE
vs. TEMPERATURE
4.179
TERMINATION VOLTAGE (V)
4.178
4.177
4.176
4.175
4.174
4.173
4.172
MAX8568 toc03
12
10
CHARGE CURRENT (mA)
8
6
4
2
V
IN
= 3.9V
0
0
0.4
0.8
1.2
1.6
14
LITHIUM CHARGE CURRENT (mA)
12
10
8
6
4
2
0
V
IN
= 3.9V
V
BK(LIMAX)
= 3.4V
V
IN
= 5V, V
BK(LIMAX)
= 4.2V
4.180
FALLING
RISING
4.171
4.170
0
0.6
1.2
1.8
2.4
3.0
3.6
4.2
-40
-15
10
35
60
85
BACKUP BATTERY VOLTAGE (V)
TEMPERATURE (°C)
2.0
BACKUP BATTERY VOLTAGE (V)
_______________________________________________________________________________________
5
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