MAX8568AETE-T [MAXIM]
Battery Charge Controller, BICMOS, 3 X 3 MM, 0.80 MM HEIGHT, MO-220WEED-2, TQFN-16;
| 型号： | MAX8568AETE-T |
| 厂家： | 
MAXIM INTEGRATED PRODUCTS |
| 描述： | Battery Charge Controller, BICMOS, 3 X 3 MM, 0.80 MM HEIGHT, MO-220WEED-2, TQFN-16 电池 信息通信管理 |
| 文件： | 总17页 (文件大小：743K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
19-3450; Rev 1; 5/05
Complete Backup-Management ICs
for Lithium and NiMH Batteries
General Description
Features
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.
♦ 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
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.
♦ 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
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
PIN-
PACKAGE
TOP
MARK
PART
TEMP RANGE
16 Thin QFN
3mm x 3mm
(T1633-4)
MAX8568AETE -40°C to +85°C
ACK
ACL
Applications
16 Thin QFN
MAX8568BETE -40°C to +85°C 3mm x 3mm
PDAs and PDA Phones
Smart Phones
(T1633-4)
DSCs and DVCs
Palmtops and Wireless Handhelds
Internet Appliances and Web-Books
Typical Operating Circuit
MAIN BATTERY
2.8V TO 5.5V
REF
IN
Pin Configuration
BACKUP
BATTERY
BK
MAX8568A
MAX8568B
TOP VIEW
TERMV
12
11
10
9
I/O OUT
LX
STRTV
3.3V, 50mA
BKSU
GND
STRTV
TERMV
REF
OD2
OD1
LDO
BKSU
13
14
15
16
8
7
6
5
IN
I/O IN
PGND
GND
MAX8568A
MAX8568B
BKV
OD1
LDO
INOK
CHGI
MEM OUT
1.8V OR 2.5V, 10mA
MEM IN
1
2
3
4
NI
LI
OD2
NI/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
ABSOLUTE MAXIMUM RATINGS
IN, BK, BKSU, OD1, OD2 to GND.........................-0.3V to +6.0V
Continuous Power Dissipation (T = +70°C)
A
BKV, LDO, NI/LI to GND.........................-0.3V to (V
REF, CHGI, INOK, TERMV, STRTV to GND...-0.3V to (V + 0.3V)
PGND to GND ......................................................-0.3V to + 0.3V
LX Current ......................................................................0.9A
+ 0.3V)
16-Pin 3mm x 3mm Thin QFN
BKSU
(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
IN
RMS
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 = V
= 3.6V, V = 1.4V, V
= V
= 3.3V, V
= GND = PGND = 0V, V
= V = 1.2V,
TERMV
IN
INOK
BK
NI/LI
BKSU
BKV
STRTV
R5 = 250kΩ, T = 0°C to +85°C, unless otherwise noted. Typical values are at T = +25°C.) (Note 1)
A
A
PARAMETER
CONDITIONS
MIN
TYP
MAX
5.5
5
UNITS
IN Voltage Range
2.8
V
T
T
= +25°C
= +85°C
3
3
A
A
Charger off, V
= 1.5V
INOK
IN Operating Current
µA
Charger on, not including charge current
= 169kΩ, V = 1.3V
50
10
600
90
12
CHGI Current Limit
CHGI Bias Voltage
CHGI Resistor Range
R
8
mA
mV
kΩ
CHGI
BK
V
V
V
V
= 1.3V
50
1800
4.284
3.58
BK
IN
IN
IN
= 5.5V, V
= 3.8V, V
= 0V
4.116
3.42
4.2
3.5
NI/LI
BK Charge Voltage Limit
= 0V, V
= 1V
V
NI/LI
TERMV
= V
= 3.6V
1.746
1.8
1.854
0.5
NI/LI
T
= +25°C
0.01
0.1
A
A
BK Reverse Leakage Current to IN
V
V
V
V
V
= 0V
µA
V
IN
T
= +85°C
NiMH Mode BK High Threshold Voltage,
= 1.2V
1.37
1.17
1.4
1.2
1.43
TERMV
STRTV
TERMV
STRTV
V
BK(NIHI)
NiMH Mode BK Low Threshold Voltage,
= 1.2V
= 1.1V
= 1.1V
1.23
0.05
V
V
BK(NILO)
T
T
T
T
= +25°C
= +85°C
= +25°C
= +85°C
0.001
0.01
0.001
0.01
1.25
2.5
A
A
A
A
TERMV Input Current
STRTV Input Current
µA
µA
0.05
REF Output Voltage
REF Load Regulation
REF Line Regulation
I
= 1µA
1.23
1.27
10
V
REF
REF
I
= 1µA to 50µA
mV
mV
V
V
V
= 3V to 5.5V, I
= 1µA
1
7
IN
REF
falling
rising
2.38
2.40
2.43
2.47
0.005
0.05
2.48
2.54
0.1
INOK
INOK
INOK Threshold Voltage
INOK Input Current
V
T
T
= +25°C
= +85°C
A
A
V
= 2V
µA
INOK
NI/LI Logic-Level High
NI/LI Logic-Level Low
V
V
= 3.3V
= 3.3V
1.8
V
V
BKSU
BKSU
0.4
2
_______________________________________________________________________________________
Complete Backup-Management ICs
for Lithium and NiMH Batteries
ELECTRICAL CHARACTERISTICS (continued)
(Circuit of Figure 7, V = V
= 3.6V, V = 1.4V, V
= V
= 3.3V, V
= GND = PGND = 0V, V
= V = 1.2V,
TERMV
IN
INOK
BK
NI/LI
BKSU
BKV
STRTV
R5 = 250kΩ, T = 0°C to +85°C, unless otherwise noted. Typical values are at T = +25°C.) (Note 1)
A
A
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
µA
T
T
= +25°C
= +85°C
0.05
0.1
1
A
A
NI/LI Input Current
V
V
V
= V
= 3.3V
NI/LI
BKSU
BKSU
OD_ On-Resistance
= 3.6V
= 5.5V
11
30
1
Ω
T
T
= +25°C
= +85°C
0.01
0.1
A
OD_ Leakage Current
µA
OD_
A
BACKUP STEP-UP (Note 2)
BK Input Undervoltage Lockout
V
V
= 0V, falling trip point
2.45
1.12
NI/LI
NI/LI
V
= V
= 3.3V, falling trip point
1.05
1.21
5.5
25
BKSU
BK Input Voltage
V
Quiescent Current into BKSU
Quiescent Current into BK
I
I
= 0mA, not switching
17
2.4
0.001
0.1
1.21
5
µA
µA
LDO
= I
= 0mA, not switching
4
BKSU
LDO
T
T
= +25°C
= +85°C
0.5
A
A
Shutdown Current into BK
BKV Feedback Voltage
V
= V
= V = 0V
BKSU
µA
V
IN
INOK
1.162
1.258
50
T
T
= +25°C
= +85°C
A
A
BKV Feedback Bias Current
V
= 1V
nA
BKV
10
V
V
= 0V
3.17
2.4
3.3
2.5
3.43
2.6
5
BKV
BKV
BKSU Output-Voltage Accuracy
V
= V
BKSU
BKSU Output Voltage Range
n-Channel Switch On-Resistance
p-Channel Switch On-Resistance
2.5
V
Ω
Ω
I
I
= 200mA
= 200mA
= +25°C
= +85°C
0.4
0.7
0.05
0.1
500
5
1
LX
LX
2
T
T
1
A
A
LX Leakage Current
µA
LX Current Limit (ILIM)
400
3.5
5
600
6.5
35
mA
µs
n-Channel Switch Maximum On-Time
p-Channel Zero-Channel Crossing Current
LOW-DROPOUT REGULATOR
BKSU Input Voltage Range
20
mA
2.7
2.375
1.71
5.0
2.625
1.89
V
V
MAX8568A
MAX8568B
2.5
1.8
1
LDO Output-Voltage Accuracy
V
= 3.3V
BKSU
LDO Line Regulation
LDO Load Regulation
2.7V < V
< 5V, I
= 1mA
mV
mV
BKSU
LDO
1µA < I
< 10mA
2.5
LDO
_______________________________________________________________________________________
3
Complete Backup-Management ICs
for Lithium and NiMH Batteries
ELECTRICAL CHARACTERISTICS
(Circuit of Figure 7, V = V
= 3.6V, V = 1.4V, V
= V
= 3.3V, V
= GND = PGND = 0V, V
= V = 1.2V,
TERMV
IN
INOK
BK
NI/LI
BKSU
BKV
STRTV
R5 = 250kΩ, T = -40°C to +85°C, unless otherwise noted. Typical values are at T = +25°C.) (Note 3)
A
A
PARAMETER
CONDITIONS
MIN
MAX
5.5
UNITS
V
IN Voltage Range
2.8
IN Operating Current
CHGI Current Limit
CHGI Resistor Range
Charger on, not including charge current
= 169kΩ, V = 1.3V
90
µA
R
8
12
mA
kΩ
CHGI
BK
V
V
V
V
= 1.3V
50
1800
4.310
3.605
1.854
BK
IN
IN
IN
= 5.5V, V
= 3.8V, V
= 0V
4.116
3.420
1.746
NI/LI
BK Charge Voltage Limit
V
= 0V, V
= 1V
NI/LI
TERMV
= V
= 3.6V
NI/LI
NiMH Mode BK High Threshold Voltage,
V
V
= 1.2V
= 1.2V
1.37
1.43
1.23
V
V
TERMV
STRTV
V
BK(NIHI)
NiMH Mode BK Low Threshold Voltage,
1.17
V
BK(NILO)
REF Output Voltage
REF Load Regulation
REF Line Regulation
I
= 1µA
1.225
1.275
10
V
REF
REF
I
= 1µA to 50µA
mV
mV
V
V
V
V
V
V
= 3V to 5.5V, I
= 1µA
7
IN
REF
falling
rising
2.38
2.40
1.8
2.48
2.54
INOK
INOK
BKSU
BKSU
BKSU
INOK Threshold Voltage
V
NI/LI Logic-Level High
NI/LI Logic-Level Low
= 3.3V
= 3.3V
= 3.6V
V
V
0.4
30
OD_ On-Resistance
Ω
BACKUP STEP-UP (Note 2)
BK Input Undervoltage Lockout
BK Input Voltage
V
= V
= 3.3V, falling trip point
BKSU
1.05
1.21
5.5
25
V
V
NI/LI
Quiescent Current into BKSU
Quiescent Current into BK
BKV Feedback Voltage
I
I
= 0mA, not switching
µA
µA
V
LDO
= I
= 0mA, not switching
4
BKSU
LDO
1.162
3.17
2.4
1.258
3.43
2.6
5.0
1
V
V
= 0V
BKV
BKV
BKSU Output-Voltage Accuracy
V
= V
BKSU
BKSU Output Voltage Range
n-Channel Switch On-Resistance
p-Channel Switch On-Resistance
2.5
V
Ω
Ω
I
I
= 200mA
= 200mA
LX
LX
2
4
_______________________________________________________________________________________
Complete Backup-Management ICs
for Lithium and NiMH Batteries
ELECTRICAL CHARACTERISTICS (continued)
(Circuit of Figure 7, V = V
= 3.6V, V = 1.4V, V
= V
= 3.3V, V
= GND = PGND = 0V, V
= V = 1.2V,
TERMV
IN
INOK
BK
NI/LI
BKSU
BKV
STRTV
R5 = 250kΩ, T = -40°C to +85°C, unless otherwise noted. Typical values are at T = +25°C.) (Note 3)
A
A
PARAMETER
CONDITIONS
MIN
400
3.5
5
MAX
600
6.5
UNITS
mA
LX Current Limit (ILIM)
n-Channel Switch Maximum On-Time
p-Channel Zero-Channel Crossing Current
LOW-DROPOUT REGULATOR
BKSU Input Voltage Range
µs
35
mA
2.7
2.375
1.71
5.0
2.625
1.89
V
V
MAX8568A
MAX8568B
LDO Output-Voltage Accuracy
V
= 3.3V
BKSU
Note 1: All units are 100% production tested at T = +25°C. Limits over the operating range are guaranteed by design.
A
Note 2: All backup step-up converter specifications are with V = V
= 0V, unless otherwise noted.
IN
INOK
Note 3: Specifications to -40°C are guaranteed by design and not production tested.
Typical Operating Characteristics
(Circuit of Figure 7, V = 3.6V, V = 1.4V, V
= V
= 3.3V, T = +25°C, unless otherwise noted.)
IN
BK
NI/LI
BKSU A
NiMH CHARGE CURRENT
vs. BACKUP BATTERY VOLTAGE
LITHIUM CHARGE CURRENT
vs. BACKUP BATTERY VOLTAGE
Li-ION TERMINATION VOLTAGE
vs. TEMPERATURE
12
10
8
14
4.180
4.179
4.178
4.177
4.176
4.175
4.174
4.173
4.172
4.171
4.170
V
IN
= 5V, V
= 4.2V
BK(LIMAX)
12
10
8
V = 3.9V
IN
V
BK(LIMAX)
6
FALLING
RISING
= 3.4V
6
4
4
2
2
V
= 3.9V
0.4
IN
0
0
0
0.8
1.2
1.6
2.0
0
0.6 1.2 1.8 2.4 3.0 3.6 4.2
BACKUP BATTERY VOLTAGE (V)
-40
-15
10
35
60
85
BACKUP BATTERY VOLTAGE (V)
TEMPERATURE (°C)
_______________________________________________________________________________________
5
Complete Backup-Management ICs
for Lithium and NiMH Batteries
Typical Operating Characteristics (continued)
(Circuit of Figure 7, V = 3.6V, V = 1.4V, V
= V
= 3.3V, T = +25°C, unless otherwise noted.)
IN
BK
NI/LI
BKSU A
CHARGE PROFILE FOR LiVeO5
CHARGE PROFILE FOR NiMH
CHARGE CURRENT vs. TEMPERATURE
MAX8568 toc06
MAX8568 toc05
3.6
3.4
3.2
3.0
2.8
2.6
2.4
2.2
2.0
8
7
6
5
4
3
2
1
0
1.42
6
5
4
3
2
1
0
11.0
10.8
10.6
10.4
10.2
10.0
9.8
V
= 3.4V
VARTA V20HR
BK(LIMAX)
R5 = 432kΩ
V
BK
= 3.6V, V = 4.2V, R5 = 127kΩ
IN
1.40
1.38
1.36
1.34
1.32
1.30
BK VOLTAGE
BK VOLTAGE
V
V
V
= 1.2V
= 1.4V
BK(NILO)
BK(NIHI)
= 1.8V
BK(NIMAX)
R5 = 953kΩ
CHARGE CURRENT
9.6
V
BK
= 3.6V, V = 4V, R5 = 127kΩ
IN
9.4
CHARGE CURRENT
V
= 1.4V, V = 4V, R5 = 169kΩ
IN
BK
9.2
PANASONIC VL2330
9.0
0
2
4
6
8
10
0
2
4
6
8
10
-40
-15
10
35
60
85
CHARGE TIME (HOURS)
CHARGE TIME (HOURS)
TEMPERATURE (°C)
3.3V STEP-UP EFFICIENCY
vs. LOAD CURRENT
2.5V STEP-UP EFFICIENCY
vs. LOAD CURRENT
BKSU OUTPUT VOLTAGE
vs. LOAD CURRENT
100
90
80
70
60
50
40
30
20
10
0
100
90
80
70
60
50
40
30
20
10
0
3.34
3.32
3.30
3.28
3.26
3.24
3.22
3.20
T
A
= -40°C
T
= +25°C
A
T
= +85°C
A
V
= 2.9V
BK
V
BK
= 2.9V
V
= 1.4V
BK
V
= 1.4V
BK
L1 = MURATA LQH32CN100K
0.01 0.1
L1 = MURATA LQH32CN100K
0.01 0.1
1
10
100
1
10
100
0
10
20
30
40
50
60
LOAD CURRENT (mA)
LOAD CURRENT (mA)
LOAD CURRENT (mA)
BK SUPPLY CURRENT
vs. INPUT VOLTAGE
LIGHT-LOAD SWITCHING WAVEFORMS
HEAVY-LOAD SWITCHING WAVEFORMS
MAX8568 toc11
MAX8568 toc12
70
60
50
40
30
20
10
0
V
BKSU
20mV/div
AC-COUPLED
BOOST AND LDO ACTIVE
20mV/div
AC-COUPLED
V
BKSU
2V/div
0
2V/div
0
V
LX
V
LX
200mA/div
0
200mA/div
0
I
LX
I
LX
V
BKSU
= 3.3V
C3 = 22µF
LOAD = 1mA
C3 = 22µF
LOAD = 50mA
50µs/div
1
2
3
4
5
5µs/div
INPUT VOLTAGE (V)
6
_______________________________________________________________________________________
Complete Backup-Management ICs
for Lithium and NiMH Batteries
Typical Operating Characteristics (continued)
(Circuit of Figure 7, V = 3.6V, V = 1.4V, V
= V
= 3.3V, T = +25°C, unless otherwise noted.)
IN
BK
NI/LI
BKSU A
BKSU LOAD TRANSIENT
V
BKSU
vs. LDO LOAD CURRENT
MAIN-TO-BK TRANSITION WAVEFORMS
MAX8568 toc14
MAX8658 toc13
3.32
3.31
3.30
3.29
3.28
3.27
3.26
3V
2V
V
INOK
I
BKSU
10mA/div
0
I
= 20mA
BKSU
2V/div
0
V
LX
MAX8568 PROVIDES 3.3V
MAX1586 PROVIDES 3.3V
I
= 40mA
BKSU
20mV/div
AC-COUPLED
V
BKSU
50mV/div
AC-COUPLED
V
BKSU
C3 = 22µF
C3 = 22µF
LOAD = 10mA
SWITCHOVER POINT
200µs/div
200µs/div
0.1
1
10
100
LDO LOAD CURRENT (mA)
LDO OUTPUT VOLTAGE
vs. BK INPUT VOLTAGE
BKSU RESPONSE TO
LDO LOAD TRANSIENT
LDO LOAD TRANSIENT
MAX8568 toc17
MAX8568 toc18
2.0
1.8
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0
I
10mA/div
0
LDO
10mA/div
0
I
LDO
20mV/div
AC-COUPLED
V
BKSU
20mV/div
AC-COUPLED
V
LDO
I
BKSU = 0mA
C3 = 22µF
0
1
2
3
4
5
200µs/div
400µs/div
BK INPUT VOLTAGE (V)
V
INOK
RISING
V
INOK
FALLING
MAX8568 TOC20
MAX8568 toc19
1V/div
2V
V
INOK
V
INOK
2V/div
0V
5V/div
0
V
LX
5V/div
0
V
LX
V
1V/div
0
1V/div
0
OD2
V
OD2
2V/div
0
2V/div
0
V
OD1
V
OD1
4ms/div
200µs/idv
_______________________________________________________________________________________
7
Complete Backup-Management ICs
for Lithium and NiMH Batteries
Pin Description
PIN
NAME
FUNCTION
Main Battery Input. Connect to a 2.8V to 5.5V battery or other power source. Bypass with a 4.7µF
ceramic capacitor to GND.
1
IN
Backup Battery Input. Connect to an NiMH or rechargeable lithium backup battery. Connect a ceramic
bypass capacitor from BK to GND. See the Step-Up Capacitor Selection section for more details.
2
BK
Power Ground. Connect PGND to the ground side of the BK input capacitor and BKSU output
capacitor. Use this connection as the star point for all grounds. See the PC Board Layout and Routing
section for specific instructions regarding PGND.
3
4
5
PGND
LX
Inductor Connection for Low-I Step-Up DC-DC Converter
Q
Step-Up Converter Output. Bypass with a 10µF to 22µF ceramic capacitor to PGND. The BKSU output
voltage is set to either 3.3V or 2.5V without resistors, or to an adjustable voltage with an external
resistor-divider. See the Setting the Step-Up Converter Voltage section.
BKSU
2.5V (MAX8568A) or 1.8V (MAX8568B), 10mA LDO Output for Memory Supply. LDO is powered from
BKSU. Bypass with a 4.7µF ceramic capacitor to GND.
6
LDO
7
8
OD1
OD2
11Ω Open-Drain Output. OD1 drives the gate of an external pMOS switch.
11Ω Open-Drain Output. OD2 drives the gate of an external pMOS switch.
Selects NiMH or Rechargeable Lithium Backup Battery. Connect NI/LI to BKSU if an NiMH backup
battery is used. Connect NI/LI to GND if a rechargeable lithium backup battery is used.
9
NI/LI
Sets the BKSU Output Voltage. Connect to GND for 3.3V output at BKSU. Connect to BKSU for 2.5V
output. Connect to the midpoint of a resistor-divider connected from BKSU to GND for adjustable
output. See the Setting the Step-Up Converter Voltage section.
10
BKV
Main Battery Monitor. When V
step-up converter and LDO turn on, and OD1 and OD2 go high impedance.
falls below 2.43V, charging stops and backup mode starts. The
INOK
11
12
INOK
CHGI
Sets Backup Battery Charge Current. Connect a resistor from CHGI to GND to set the charge current.
See the Setting the Charge Current section for details.
13
14
GND
Ground. Connect to the exposed paddle. Star all grounds at the BKSU output capacitor ground.
STRTV
Sets Fast-Charge Start Voltage for NiMH. See the Using an NiMH Backup Battery section.
Sets Fast-Charge Stop Voltage for NiMH, as Well as the Battery Regulation Voltage for Both
Rechargeable Lithium and Maximum Voltage for NiMH. See the Using a Lithium Backup Battery
section and the Using an NiMH Backup Battery section.
15
TERMV
16
EP
REF
—
Reference Output. Bypass with a 0.22µF ceramic capacitor to GND.
Exposed Paddle. Connect to the analog ground plane. EP also functions as a heatsink. Solder to the
circuit-board analog ground plane.
8
_______________________________________________________________________________________
Complete Backup-Management ICs
for Lithium and NiMH Batteries
that the I/O supply be activated at least one time before
Detailed Description
the backup battery can be stepped up. This allows the
end product to draw no backup battery current while “on
the shelf” waiting for its first activation. The step-up DC-
DC converter is enabled, and reaches regulation, 50µs
(typ) after INOK falls below 2.43V (typ).
The MAX8568A/MAX8568B are compact ICs for manag-
ing backup battery charging and utilization in PDAs and
other smart handheld devices. The MAX8568A/
MAX8568B are comprised of three major blocks: 1) A
multichemistry charger for small lithium-ion, lithium-man-
The step-up converter includes a built-in synchronous
rectifier that reduces cost by eliminating the need for
an external diode and improves overall efficiency. The
converter also features a clamp circuit that reduces
EMI due to inductor ringing. The output voltage is set to
3.3V or 2.5V by connecting BKV to either GND or
BKSU, respectively. For adjustable output, connect
BKV to a resistor-divider from BKSU to GND.
ganese, LiVeO , and NiMH batteries; 2) a small very-
5
low-current step-up DC-DC converter that generates a
boosted backup supply when the backup battery output
is less than required; and 3) an LDO that supplies a
second backup voltage to an additional system block
(typically low-voltage RAM).
Multichemistry Charger
The backup battery charger charges most types of
rechargeable lithium and NiMH cells. Charging current
can be set up to 25mA by a resistor connected from
CHGI to GND. The charger operates a current-limited
voltage source for rechargeable lithium batteries, and
switches between fast and trickle charging for NiMH
batteries.
LDO
For designs that require two different backup voltages,
the MAX8568 includes a small LDO that is powered from
BKSU. This LDO can supply up to 10mA and uses only
5µA of operating current. The LDO output is preset to
2.5V in the MAX8568A and 1.8V in the MAX8568B. The
LDO is activated after V
falls below 2.43V (typ).
INOK
NiMH Charging Scheme
The NiMH charger operates at two different charge cur-
rents based upon the voltages at TERMV and STRTV.
Switchover Behavior
See Figure 1 for switchover timing. If the backup bat-
tery is connected to the system before main power, the
MAX8568 remains off and draws very little current, typi-
cally less than 0.5µA. This allows the end product to
draw no backup battery current while “on the shelf”
waiting for its first activation. When main power is con-
nected, the MAX8568 powers on, assuming the main
battery is greater than 2.8V. The MAX8568 begins to
charge the backup battery if needed (see the
Multichemistry Charger section). The OD1 and OD2
outputs pull to GND and turn on the external p-channel
MOSFETs. This allows the voltage on I/O IN and MEM
IN (Figure 7) to pass through to the I/O OUT and MEM
OUT outputs. These I/O and MEM voltages are typically
provided by a MAX1586/MAX1587 power-supply IC.
V
sets the BK voltage below which fast charging
STRTV
(set by CHGI) occurs. V
sets the upper BK trip
TERMV
point where fast charging stops and trickle charging
begins, and also sets a maximum voltage limit for the
NiMH battery. If V
is 1.2V, then fast charge stops
TERMV
at 1.2 / 0.86 = 1.4V, and the maximum voltage limit is
1.2 / 0.67 = 1.791V.
An NiMH battery fast charges until it hits 1.4V set by
V
. The charger then switches to trickle charge at
TERMV
a current that is 10% of fast charge (set by CHGI). If the
voltage drops (due to loading or self-discharge) to 1.2V
(with V
= 1.2V), fast charge resumes. If the volt-
STRTV
age then increases back to 1.4V (with V
= 1.2V),
TERMV
trickle charge resumes. If the cell voltage reaches 1.8V,
the charge current falls to zero.
INOK monitors the main battery voltage and activates
the backup boost converter and LDO when the voltage
on V
falls below 2.43V. The backup converter
INOK
Lithium Charging Scheme
starts 50µs after V
falls. OD1 and OD2 go high
INOK
When charging rechargeable lithium-type batteries,
impedance and turn off the external p-channel
MOSFETs. These MOSFETs disconnect the I/O IN and
MEM IN inputs from the load. This ensures that the I/O
and MEM main supplies do not draw current from the
backup source (MAX8568). The charger also turns off
when INOK is less than 2.43V.
V
sets the charging voltage while V
is unused.
TERMV
STRTV
Charge current is set by a resistor from CHGI to GND.
There is no trickle charge for lithium mode. This charging
scheme is essentially a current-limited voltage source.
Step-Up DC-DC Converter
If an NiMH battery or lower-voltage rechargeable lithium
battery is used for backup, it may be necessary to boost
the battery voltage to 2.5V, 3.3V, or some other voltage to
power RAM, RTC, or other devices. The step-up DC-DC
converter is powered by the backup battery but requires
If the MAX8568 is being evaluated as a stand-alone
device, note that the backup-battery boost converter will
not operate unless I/O IN has been activated at least one
time. The typical power removal sequence for testing is 1)
main battery goes low, then 2) MEM IN and I/O IN go low.
_______________________________________________________________________________________
9
Complete Backup-Management ICs
for Lithium and NiMH Batteries
1.12V
BK
CHARGER
50µs
IN
2.43V
INOK
I/O IN
I/O OUT
STEP-UP DC-DC CONVERTER
OD1
MEM IN
MEM OUT
LDO
OD2
Figure 1. Timing Diagram
where V is the nominal voltage of the charged back-
BK
Applications Information
up battery. This is the fast-charge current for both
NiMH and lithium batteries. For NiMH batteries, the
trickle charge is 10% of the fast-charge current.
Setting the Charge Current
Charge current is set by a resistor connected from
CHGI to GND (R5 in Figure 7). The acceptable resistor
Using a Rechargeable Lithium
Backup Battery
The MAX8568 can charge a lithium-type backup bat-
tery from the main battery connected at IN. Connect
NI/LI to GND for lithium backup battery charging.
STRTV is unused and should be connected to GND in
lithium charge mode.
range is from 50kΩ to 1800kΩ. R
is calculated by
CHGI
the following.
1.1641
41.2 × V −V
+679.4
(
)
IN
BK
R
kΩ =
(
)
CHGI
I
mA
CHG
10 ______________________________________________________________________________________
Complete Backup-Management ICs
for Lithium and NiMH Batteries
The lithium charger acts like a current-limited voltage
source. The battery regulation voltage for lithium mode,
, is:
ues to rise when trickle charged, all charging ceases at
V
. V
, V
, and V are
BK(NIMAX)
BK(NIMAX)
BK(NILO)
BK(NIHI)
V
set as follows:
BK voltage where fast charge begins:
= V
BK(LIMAX)
V
= 3.5 x V
TERMV
BK(LIMAX)
If V
= 1.2V, then the final charge voltage is 4.2V.
V
BK(NILO)
TERMV
STRTV
Connect TERMV to a resistor-divider from REF to GND.
BK voltage where trickle charge begins:
= 1.163 x V
Adjust V
with resistors R11 and R12 (Figure 2).
TERMV
V
BK(NIHI)
TERMV
Select R12 to be in the 100kΩ to 1MΩ range. Calculate
R11 as follows:
BK voltage where all charging stops:
= 1.493 x V
V
BK(NIMAX)
TERMV
3.5 × V
REF
Resistor-dividers (see Figure 3) set V
and V
TERMV
STRTV
R11 = R12
− 1
V
by dividing down REF. To minimize operating current,
resistors between 100kΩ and 1MΩ should be used for
R14 and R16 in Figure 3. The formulas for the upper
BK(LIMAX)
where V
=1.25V.
REF
divider-resistors in terms of V
BK(NIMAX)
, V
, and
BK(NIHI)
BK(NILO)
Using an NiMH Backup Battery
The MAX8568 can charge NiMH backup batteries from
the main battery connected at IN. Connect NI/LI to
V
are:
V
REF
BKSU for NiMH backup battery charging. V
sets
TERMV
R13 = R14
− 1
V
the maximum cell voltage and also the trip point for the
BK(NILO)
fast-charge-to-trickle-charge transition. V
trickle-to-fast-charge transition threshold.
sets the
STRTV
1.163 × V
REF
R15 = R16
− 1
In NiMH charge mode (NI/LI connected to BKSU), the
charger ramps the battery between two thresholds
V
BK(NIHI)
measured at the battery connection BK, V
and
BK(NILO)
Once V
age is:
is selected, the maximum battery volt-
BK(NIHI)
V
. When the battery falls to V
, trickle
BK(NIHI)
BK(NILO)
charging stops and fast charging starts. When the bat-
V
= 1.283 x V
BK(NIMAX)
BK(NIHI)
tery rises to V
, fast charging stops and trickle
BK(NIHI)
charging begins. If, for any reason, the battery contin-
16
REF
16
REF
R13
R15
R11
15
14
TERMV
STRTV
15
TERMV
R16
R12
14
STRTV
R14
Figure 2. Resistor-Divider for Setting the Maximum Battery
Voltage, V , for Rechargeable Lithium-Type Backup
BK(LIMAX)
Batteries
Figure 3. 2-Resistor-Dividers for Setting V
and V
BK(NIHI)
BK(NILO)
______________________________________________________________________________________ 11
Complete Backup-Management ICs
for Lithium and NiMH Batteries
Note that both V
and V
can be set with a
BK(NILO)
BK(NIHI)
2-resistor voltage-divider as shown in the typical applica-
tion circuit (see Figure 7) if the factory-set ratio between
the two thresholds is acceptable. In that case:
16
15
14
REF
TERMV
STRTV
R17
R18
V
REF
R6 = R8
− 1
V
BK(NILO)
V
= 1.163 x V
BK(NILO)
BK(NIHI)
V
= 1.283 x V
BK(NIHI)
BK(NIMAX)
One 3-resistor-divider can be used to set both
and V independently. Figure 4 shows
R19
V
BK(NILO)
BK(NIHI)
the connections of R17, R18, and R19. Select R19 in
the 100kΩ to 1MΩ range. The equations for the two
upper divider-resistors are:
Figure 4. 3-Resistor Divider Used to Set V
and V
BK(NIHI)
BK(NILO)
V
REF
R18 = R19
− 1
V
BK(NILO)
Step-Up Capacitor Selection
Choose output capacitors to supply output peak cur-
rents with acceptable voltage ripple. Low equivalent-
series-resistance (ESR) capacitors are recommended.
Ceramic capacitors have the lowest ESR, but low-ESR
tantalum or polymer capacitors offer a good balance
between cost and performance.
1.163 × V
REF
R17 = (R18 + R19) ×
− 1
V
BK(NIHI)
Setting the Switchover Voltage
sets the IN voltage at which backup mode starts.
V
INOK
Output voltage ripple has two components: variations in
the charge stored in the output capacitor with each LX
pulse and the voltage drop across the capacitor’s ESR
caused by the current into and out of the capacitor. The
equations for calculating output ripple are:
INOK connects to a resistor-divider between IN and
GND. The MAX8568 requires V greater than 2.8V for
IN
proper operation when not backing up, so the backup
threshold, V
2.8V. Once V
, must be set for no less than
drops below 2.43V (typ), V may be
IN(BACKUP)
INOK
IN
V
= V
+ V
x R
less than 2.8V. The resistor-divider for INOK is shown in
Figure 7 (R9 and R10). Select resistor R10 to be in the
100kΩ to 1MΩ range. Calculate R9 as follows:
RIPPLE
RIPPLE(C)
RIPPLE(ESR)
ESR(CBKSU)
V
= I
RIPPLE(ESR)
PEAK
L
1
2
2
V
=
I
V
RIPPLE(C)
PEAK
IN(BACKUP)
V
− V
C
R9 = R10
− 1
(
)
BKSU
BK BKSU
V
INOK
where I
is the peak inductor current (see the
PEAK
where V
= 2.43V, and V
must be set
IN(BACKUP)
INOK
Inductor Selection section). For ceramic capacitors, the
greater than 2.8V.
output voltage ripple is typically dominated by
V
.
RIPPLE(C)
Step-Up Converter
The step up DC-DC converter is most likely used with
NiMH backup batteries, but can also be used with
rechargeable lithium backup batteries. If the backup
battery voltage is greater than the set output voltage at
BKSU, the output voltage follows the backup battery
voltage. The voltage difference between the backup
battery and BKSU never exceeds a diode forward-volt-
age drop. If I/O OUT (Figure 7) is less than BK during
charge mode, no current flows from BK to I/O OUT.
Input capacitors connected to IN and BK should be
X5R or X7R ceramic capacitors. C should be 4.7µF or
IN
greater. C should be 10µF or greater when using the
BK
step-up converter. If the step-up converter is not used,
then C can be reduced to 1µF.
BK
Capacitance and ESR variation with temperature should
be considered for best performance in applications with
wide operating temperature ranges.
12 ______________________________________________________________________________________
Complete Backup-Management ICs
for Lithium and NiMH Batteries
Inductor Selection
The control scheme of the MAX8568 permits flexibility in
choosing an inductor. A 10µH inductor performs well in
most applications. Smaller inductance values typically
offer smaller physical size for a given series resistance,
allowing the smallest overall circuit dimensions. Circuits
using larger inductance may provide higher efficiency
and exhibit less ripple, but also may reduce the maxi-
mum output current. This occurs when the inductance is
LDO Capacitor Selection
Capacitors are required at the LDO output of the
MAX8568 for stable operation over the full load and tem-
perature range. A 4.7µF or greater X5R or X7R ceramic
capacitor is recommended. To reduce noise and
improve load-transient response, larger output capaci-
tors up to 10µF can be used. Surface-mount ceramic
capacitors have very low ESR and are commonly avail-
able in values up to 10µF. Note that some ceramic
dielectrics, such as Z5U and Y5V, exhibit large capaci-
tance and ESR variation with temperature and require
larger than the recommended values to maintain stability
and good load-transient response over temperature.
sufficiently large to prevent the LX current limit (I
)
LIM
from being reached before the maximum on-time
(t ) expires.
ON(MAX)
For maximum output current, choose the inductor value
so that the controller reaches the current limit before
the maximum on-time is reached:
External MOSFET Drivers—OD1, OD2
OD1 and OD2 are open-drain outputs and are
designed to be connected to the gates of external p-
channel MOSFETs (see Figure 7). These MOSFETs
connect the main system power supplies (I/O IN and
MEM IN) to the system loads (I/O OUT and MEM OUT)
during normal operation. During backup, they discon-
nect the power supplies from the system loads to pre-
vent the power supplies from drawing backup current
away from the system. For this reason, the MOSFETs
are connected “backwards” from what might be
expected. The source of the MOSFETs are connected
to the system load side (I/O OUT and MEM OUT). The
MOSFETs’ purpose is to block current flow from the
backup supply (BKSU) to the main supplies (I/O IN and
MEM IN). They do not block current flow from I/O IN to
I/O OUT and from MEM IN to MEM OUT. Even when off,
the MOSFET body diodes allow current to pass in that
direction.
V
× t
BK
ON(MAX)
L <
I
LIM
where t
is typically 5µs, and the current limit (I
)
ON(MAX)
LIM
is typically 500mA (see the Electrical Characteristics
table).
For larger inductor values, determine the peak inductor
current (I
) by:
PEAK
V
× t
BK
ON(MAX)
L
I
=
PEAK
Setting the Output Voltage
The output voltage is set to 2.5V or 3.3V, or is
adjustable. Connect BKV to GND for 3.3V, and BKV to
BKSU for 2.5V. The adjustable output voltage is set
from 2.5V to 5V using external resistors R1 and R2
(Figure 7). Since FB leakage is 50nA (max), select
feedback resistor R2 in the 100kΩ to 1MΩ range.
Calculate R1 as follows:
OD1 is intended to drive the MOSFET switch for I/O IN
and I/O OUT, while OD2 is intended to drive the MOSFET
switch for MEM IN and MEM OUT. See the Typical
Operating Characteristics and Figure 1 for typical opera-
tion of OD1 and OD2.
V
V
BKSU
R1 = R2
− 1
External MOSFET Selection
The external MOSFET should be chosen based upon
BKV
R
and gate capacitance. When V
> 2.43V
INOK
DS(ON)
where V
= 1.21V.
BKV
(main battery > 2.8V), the current required for normal
operation of I/O and MEM goes through these external
LDO
The LDO output voltage is preset to 2.5V for the
MAX8568A and 1.8V for the MAX8568B. The LDO can
supply up to 10mA. The LDO output voltage is not
adjustable.
MOSFETs. Choose an R
MOSFET voltage drop. When V
that minimizes the
DS(ON)
< 2.43V, the
INOK
MOSFET turns off, and MEM and I/O are powered by
the MAX8568. The gate capacitance of the external
MOSFET must discharge through the external gate-to-
source resistor. This discharge time determines how
quickly the main supply is disconnected and isolated.
______________________________________________________________________________________ 13
Complete Backup-Management ICs
for Lithium and NiMH Batteries
Pullup resistors, R3 and R4 in Figure 7, should be select-
ed to ensure that when OD1 and OD2 go high imped-
ance, the gate of the external MOSFET discharges within
IN
CHGI
50µs to 100µs. This time allows the backup converters to
start and provide power to I/O and MEM. Discharges
1MΩ
R
CHGI
longer than 50µs to 100µs could cause the main supply
to back drain current from the MAX8568 and allow the
I/O OUT and MEM OUT voltage to droop. The MOSFET
MAX1586
MAX8568
n-CHANNEL
MOSFET OR
OPEN-DRAIN
INVERTER
LBO
DBO
gate-source resistor, R , is calculated from the follow-
GS
ing formulas:
τ = R x C
GS
ISS
1MΩ
−
50µs
τ =
INOK
V
GS(TH)
−
ln 1
V
BKSU
where the MOSFET gate-source threshold, V
,
Figure 5. Using a MAX1586 Power-Supply IC to Trigger
Backup Switchover and to Disable Backup Battery Charging
Prior to Switchover
GS(TH)
and MOSFET input capacitance, C , are provided on
ISS
the MOSFET data sheet.
Connection with MAX1586
When the MAX8568 is used with the MAX1586 system
power supply, it may be preferable to employ the
MAX1586’s voltage monitors to determine when backup
should start. The connection for this is shown in Figure 5
where the dead-battery output (DBO) of the MAX1586
drives the INOK input of the MAX8568. This, in effect,
overrides the voltage-sensing circuit on the MAX8568
and uses the DBO monitor on the MAX1586. Refer to the
MAX1586 data sheet for information on how to set the
DBO threshold. The CHG connection in Figure 5 is
described in the next section.
open-drain logic inverter) and disconnects the current
path through R
. Backup charging can be stopped
ICHG
for any reason using this method.
PC Board Layout and Routing
Careful PC board layout is important for minimizing
ground bounce and noise. Ensure that C1 (IN input
capacitor), C2 (BK input capacitor), C3 (BKSU bypass
capacitor), and C4 (LDO output capacitor) are as close
as possible to the IC. Avoid using vias to connect C2 or
C3 to their respective pins or GND. C2 and C3 grounds
should be next to each other, and this connection can
then be used as the star ground point. All other grounds
should connect to the star ground. PGND should star at
C2 and C3, and should not connect directly to the
exposed pad (EP) of the MAX8568. Connect EP to the
bottom layer ground plane, and then connect the
ground plane to the star ground. Vias on the inductor
path are acceptable if necessary. IN, BK, BKSU, and
LDO traces should be as wide as possible to minimize
inductance. Refer to the MAX8568 evaluation kit for a
PC board layout example.
Terminating Charging at a Voltage Other
than the Switchover Voltage
In normal operation, the MAX8568 charger is always
active as long as the INOK voltage is valid (above
2.43V). In some systems, however, it may be desirable to
terminate backup battery charging when the main bat-
tery is somewhat depleted but not so low as to trigger
backup. An external voltage monitor, or a voltage moni-
tor in a power-supply IC, such as the MAX1586, can dis-
able charging by disconnecting the CHGI resistor. If
CHGI is open, no charging current flows. This can be
accomplished with the circuit in Figure 5. The low-battery
output (LBO) of the MAX1586 pulls low when the battery
falls below a user-set level (refer to the MAX1586 data
sheet). This turns off the external n-channel MOSFET (or
Chip Information
TRANSISTOR COUNT: 7902
PROCESS: BiCMOS
14 ______________________________________________________________________________________
Complete Backup-Management ICs
for Lithium and NiMH Batteries
MAX8568
REF
NI/LI
REF
GND
TERMV
IN
BK
CHARGE
CURRENT
SOURCE
STRTV
0.286
0.67
BK
1
0.86
UVLO
1.13
LI
NI
INOK
STEP-UP CONVERTER
2.43V
LX
BKSU
PGND
UVLO
2.25
PFM
BKV
OD1
BKSU
LDO
LDO
OD2
Figure 6. Functional Diagram
______________________________________________________________________________________ 15
Complete Backup-Management ICs
for Lithium and NiMH Batteries
MAIN BATTERY
2.8V TO 5.5V
1
2
IN
C1
4.7µF
16
15
BACKUP BATTERY
REF
BK
C5
0.22µF
C2
10µF
R6
50kΩ
L1
10µH
MAX8568A
TERMV
4
5
LX
I/O OUT
3.3V, 50mA
R7
0Ω
BKSU
14
13
R1
OPEN
STRTV
GND
C3
10µF
R8
1.2MΩ
MAIN
BATTERY
3
PGND
BKV
I/O IN
Q1
R2
0Ω
10
R9
357kΩ
R3
100kΩ
11
INOK
7
6
OD1
LDO
MEM OUT
2.5V, 10mA
R10
1MΩ
NI
9
LI
NI/LI
CHGI
C4
4.7µF
MEM IN
Q2
12
R4
100kΩ
R5
169kΩ
8
OD2
Figure 7. Typical Application Circuit
16 ______________________________________________________________________________________
Complete Backup-Management ICs
for Lithium and NiMH Batteries
Package Information)
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information,
go to www.maxim-ic.com/packages.)
D2
b
0.10 M
C
A
B
D
D2/2
D/2
E/2
E2/2
(NE - 1)
X e
C
E2
E
L
L
k
e
C
L
(ND - 1)
X e
C
L
C
L
0.10
C
0.08 C
A
A2
A1
L
L
e
e
PACKAGE OUTLINE
12, 16L, THIN QFN, 3x3x0.8mm
1
21-0136
E
2
PKG
12L 3x3
16L 3x3
NOM.
0.75
REF. MIN. NOM.
MAX.
0.80
MIN.
0.70
MAX.
EXPOSED PAD VARIATIONS
DOWN
BONDS
ALLOWED
0.70
0.75
0.80
A
b
D2
E2
PKG.
PIN ID
JEDEC
CODES
MIN. NOM. MAX. MIN. NOM. MAX.
0.20
2.90
2.90
0.25
3.00
0.30
3.10
3.10
0.20
2.90
2.90
0.25
3.00
3.00
0.30
3.10
3.10
T1233-1
T1233-3
T1633-1
T1633-2
T1633F-3
T1633-4
0.95
0.95
0.95
0.95
0.65
0.95
1.10
1.10
1.10
1.10
0.80
1.10
1.25
1.25
1.25
1.25
0.95
1.25
0.95
0.95
0.95
0.95
0.65
0.95
1.10
1.10
1.10
1.10
0.80
1.10
1.25
1.25
1.25
1.25
0.95
1.25
0.35 x 45∞ WEED-1
0.35 x 45∞ WEED-1
0.35 x 45∞ WEED-2
0.35 x 45∞ WEED-2
0.225 x 45∞ WEED-2
0.35 x 45∞ WEED-2
NO
YES
NO
D
E
e
L
3.00
0.50 BSC.
0.55
0.50 BSC.
0.40
0.45
0.65
0.30
0.50
YES
N/A
NO
N
12
3
16
4
ND
NE
3
4
A1
A2
k
0
0.02
0.05
-
0
0.02
0.05
-
0.20 REF
-
0.20 REF
-
0.25
0.25
NOTES:
1. DIMENSIONING & TOLERANCING CONFORM TO ASME Y14.5M-1994.
2. ALL DIMENSIONS ARE IN MILLIMETERS. ANGLES ARE IN DEGREES.
3. N IS THE TOTAL NUMBER OF TERMINALS.
4. THE TERMINAL #1 IDENTIFIER AND TERMINAL NUMBERING CONVENTION SHALL CONFORM TO
JESD 95-1 SPP-012. DETAILS OF TERMINAL #1 IDENTIFIER ARE OPTIONAL, BUT MUST BE LOCATED
WITHIN THE ZONE INDICATED. THE TERMINAL #1 IDENTIFIER MAY BE EITHER A MOLD OR
MARKED FEATURE.
5. DIMENSION b APPLIES TO METALLIZED TERMINAL AND IS MEASURED BETWEEN 0.20 mm AND 0.25 mm
FROM TERMINAL TIP.
6. ND AND NE REFER TO THE NUMBER OF TERMINALS ON EACH D AND E SIDE RESPECTIVELY.
7. DEPOPULATION IS POSSIBLE IN A SYMMETRICAL FASHION.
8. COPLANARITY APPLIES TO THE EXPOSED HEAT SINK SLUG AS WELL AS THE TERMINALS.
9. DRAWING CONFORMS TO JEDEC MO220 REVISION C.
PACKAGE OUTLINE
12, 16L, THIN QFN, 3x3x0.8mm
2
21-0136
E
2
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are
implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 ____________________ 17
© 2005 Maxim Integrated Products
Printed USA
is a registered trademark of Maxim Integrated Products, Inc.
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