EVALUATION KIT AVAILABLE
AVAILAB
LE
MAX8971
Industry's Smallest 1.55A
1-Cell Li+ DC-DC Charger
General Description
Benefits and Features
S
Switch-Mode Charger
High-Efficiency
Low Heat
Fast Charge Time
S
Small and Simple
S
Precise
Up to
Q5%
Current Regulation and 0.5% Voltage
Regulation
S
Safe
JEITA Battery Temperature Monitor
Over /Undervoltage Protection, Safety Timers,
Temperature Regulation
USB Friendly
S
Flexible
Programmable Voltage/Current
Status/ Interrupts Through I
2
C
Automatic Input Current Limit
S
I
2
C Interface
Input Current Limit (100mA to 1500mA)
Fast-Charge / Termination Current (250mA to
1550mA)
Charge Voltage (4.1V, 4.15V, 4.2V, 4.35V)
Safety Timer
Termination Enable
S
+22V Absolute Maximum Input Voltage Rating
S
Up to 7.5V Maximum Operating Input Voltage
S
5V USB/Safeout LDO for USB PHY
S
2.3A GSM RF Test Mode (Factory Testing)
S
Charge Current to Voltage Conversion (V
ICHG
) for
Baseband ADC
S
Reverse Battery Leakage Protection
S
Input /Output Overvoltage Protection
S
Interrupt Status Output
The MAX8971 is a compact, high-frequency, high-
efficiency switch-mode charger for a one-cell lithium-ion
(Li+) battery. It delivers up to 1.55A of current to the
battery from inputs up to 7.5V and withstands transient
inputs up to 22V. The 4MHz switch-mode charger is
ideally suited for small portable devices, such as head-
sets and ultra-portable media players. It minimizes
component size and heat.
Battery-protection features include: low-voltage prequali-
fication, charge fault timer, die temperature monitoring,
and battery temperature monitoring. The battery
temperature monitoring adjusts the charge current and
termination voltage for safe use of secondary lithium-ion
batteries.
The IC accepts either a general DC input or USB.
It has programmable automatic input-current limiting to pro-
tect upstream charging sources such as USB.
Charge parameters are easily adjustable through an I
2
C
interface. Charge is terminated based on user-selectable
minimum current level. A safety timer with reset control
provides a safety backup for I
2
C interface. Charge status
is provided to the application processor through an inter-
rupt pin.
The IC is available in a space-saving, 20-bump, 2.18mm
x 1.62mm WLP package.
Applications
USB Charging
Functional
Headsets and Media Players
Smartphones
Digital Cameras
GPS, PDAs
Diagrams
Ordering Information
appears at end of data sheet.
Pin Configurations appear at end of data sheet.
Functional Diagrams continued at end of data sheet.
UCSP is a trademark of Maxim Integrated Products, Inc.
For related parts and recommended products to use with this part,
refer to
www.maxim-ic.com/MAX8971.related.
Simplified Applications Circuit appears at end of data sheet.
For pricing, delivery, and ordering information, please contact Maxim Direct
at 1-888-629-4642, or visit Maxim’s website at www.maximintegrated.com.
19-4245; Rev 0; 1/12
MAX8971
Industry's Smallest 1.55A
1-Cell Li+ DC-DC Charger
TABLE OF CONTENTS
Absolute Maximum Ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Package Thermal Characteristics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Electrical Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Typical Operating Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Typical Operating Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Typical Operating Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Typical Operating Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Bump Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Bump Description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Detailed Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
DC Input—Fast-Hysteretic
Step-Down Regulator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Soft-Start . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
PVL and AVL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Thermistor Input (THM) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Thermal Foldback . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Charger States . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Charger-Disabled State . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Dead-Battery State. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Dead-Battery + Prequalification State . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Prequalification State . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Fast-Charge Constant-Current State . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Fast-Charge Constant Voltage State . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Top-Off State . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Done State . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Timer Fault State . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Overvoltage and Protection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Automatic Input Current
Limit Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
V
ICHG
Charging Current Monitor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
SAFEOUT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
JEITA Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Maxim Model Gauge M3 Support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Factory-Mode GSM Test Mode Support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Applications Information. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Inductor Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Input Capacitor Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Maxim Integrated
2
MAX8971
Industry's Smallest 1.55A
1-Cell Li+ DC-DC Charger
TABLE OF CONTENTS (continued)
Output Capacitor Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Charge Current Resistor Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
I
2
C Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Charger Interrupt Requests. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Charger Interrupt Masks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Charger Status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
DETAILS1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
DETAILS2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
USB Suspend . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Input Voltage Disable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Fast-Charge Current and Timer Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Input-Current Limit and Charger Restart Threshold . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Done Current, Timer, GSM Test Mode, and Battery Regulation Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Temperature Regulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
Charger Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
Simplified Applications Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Ordering Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Chip Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Package Information. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
Revision History . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
LIST OF TABLES
Table 1. Trip Temperatures for Different Thermistors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Table 2. Suggested Inductors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Table 3. Charge Current Settings for 47mΩ and 68mΩ Sense Resistors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Table 4. Topoff Current Settings for 47mΩ and 68mΩ Sense Resistors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Table 5. High-Level I
2
C Register Map. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Table 6. CHGCC[4:0] Decoding. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Table 7. DCILMT[5:0] Bit Code . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
LIST OF FIGURES
Figure 1. Typical Application Circuit. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Figure 2. Li/Li-Poly Charge Profile . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Figure 3. Functional State Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Figure 4. JEITA Safety Region . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Figure 5. MAX8971 with MAX17047. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Maxim Integrated
3
MAX8971
Industry's Smallest 1.55A
1-Cell Li+ DC-DC Charger
ABSOLUTE MAXIMUM RATINGS
BYP to PG_ ...........................................................-0.3V to +22V
DC_ to BYP ............................................................-6V to +0.3V
I2CIN, V
ICHG
, IRQB, SDA, SCL to GND .................-0.3V to +6V
BST to AVL ............................................................-0.3V to +16V
BST to LX_ ...............................................................-0.3V to +6V
PVL, SFO, BAT, CS to PG_ .....................................-0.3V to +6V
AVL, THM to GND ...................................................-0.3V to +6V
PG_ to GND..........................................................-0.3V to +0.3V
DC_, LX_, CS, BAT, BYP Continuous Current ............. 1.6A
RMS
Continuous Power Dissipation (T
A
= +70NC)
WLP derate 21.7mW/NC above +70NC .....................1736mW
Operating Temperature Range. ......................... -40NC to +85NC
Junction Temperature. ....................................................+150NC
Storage Temperature Range............................ -65NC to +150NC
Soldering Temperature (reflow) ......................................+260NC
*This device is constructed using a unique set of packaging techniques that impose a limit on the thermal profile the device can be
exposed to during board-level solder attach and rework. This limit permits only the use of the solder profiles recommended in the
industry-standard specification, JEDEC 020A, paragraph 7.6, Table 3 for IR / VPR and Convection reflow. Preheating is required.
Hand or wave soldering is not allowed.
PACKAGE THERMAL CHARACTERISTICS (Note 1)
WLP
Junction-to-Ambient Thermal Resistance (q
JA
) ..........46°C/W
Junction-to-Case Thermal Resistance (q
JC
) .................2°C/W
Note 1:
Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a four-
layer board. For detailed information on package thermal considerations, refer to
www.maxim-ic.com/thermal-tutorial.
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional opera-
tion 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
DC
= 5V, C
BYP
= 1FF, I
FCHG
= 500mA, C
AVL
= 4.7FF, V
THM
= AVL/2, T
A
= -40NC to +85NC, unless otherwise noted. Typical values
are at T
A
= +25NC.) (Note 2)
PARAMETER
DC INPUT
DC Operating Voltage Range
DC Undervoltage Lockout
DC OVP Interrupt Delay
DC to BAT Shutdown Threshold
DC Supply Current
BST Leakage Current
LX_ Leakage Current
BAT Reverse Leakage Current
Input-Current Limit Range
When charging stops, V
DC
falling, 150mV hysteresis
Charger enabled, V
DC
= 5.5V
V
BST
= 5.5V, LX_ = PG_
V
LX_
= 0 or 5.5V
V
DC
= 0V, V
BAT
= 4.2V
0.1
T
A
= +25°C
T
A
= -40°C to +85°C
T
A
= +25°C
T
A
= -40°C to +85°C
0
DC rising, 500mV hysteresis
DC Overvoltage Threshold (V
OVP
)* DC rising, 250mV hysteresis
4.0
3.6
7.25
3.8
7.5
16
50
2
0.01
0.1
0.01
0.1
1
5
1.5
FA
A
10
10
FA
100
V
OVP
4.0
7.75
V
V
V
ms
mV
mA
CONDITIONS
MIN
TYP
MAX
UNITS
Maxim Integrated
4
MAX8971
Industry's Smallest 1.55A
1-Cell Li+ DC-DC Charger
ELECTRICAL CHARACTERISTICS (continued)
(V
DC
= 5V, C
BYP
= 1FF, I
FCHG
= 500mA, C
AVL
= 4.7FF, V
THM
= AVL/2, T
A
= -40NC to +85NC, unless otherwise noted. Typical values
are at T
A
= +25NC.) (Note 2)
PARAMETER
USB 100mA mode
Input-Current Limit Accuracy
USB 500mA mode
Input limit programmed to 1.5A, I
FCHG
= 1500mA
Adaptive Input-Current Limit (AICL) DC voltage where charge current is regulated
(Note 4)
DC voltage where charge current is set to 75mA
Input Limit Switch
BUCK OPERATION
Switching Frequency
Maximum Duty Cycle
Minimum On-Time
Maximum On-Time
Minimum Off-Time
Soft-Start Time
High-Side Resistance
Low-Side Resistance
Thermal Regulation Temperature
(T
REG
)
Thermal Regulation Gain
I
LX
= 100mA, V
DC
= 5.5V
I
LX
= 100mA, V
DC
= 5.5V
I
2
C programmable 2-bits (90, 105, 120, and disable
selections, 105 default)
Percentage decrease in I
FCHG
above the thermal
regulation temperature
V
BAT
= 3.6V
4
99.5
55
10
65
1.5
120
150
105
5
250
220
MHz
%
ns
µs
ns
ms
mI
mI
°C
%/°C
V
DC
= 5.5V, I
BYP
= 100mA
CONDITIONS
MIN
90
450
1350
TYP
95
475
1500
4.5
4.4
35
80
MAX
100
500
1650
V
mI
mA
UNITS
BATTERY CHARGER PRECHARGE
Battery-Prequalification Lower
Threshold (V
PQLTH
)
Dead-Battery Charge Current
(I
DBAT
)
Battery-Prequalification Upper
Threshold (V
PQUTH
)
**
Prequalification Charge Current
(I
PQ
)
CONSTANT-CURRENT MODE
BAT Fast-Charge Current Range
(I
FC
)
Fast-Charge Current Accuracy
5 bits–50mA steps, R
CS
= 47mI
T
A
= +15NC to +45NC
JEITA safety region (Figure 6)
250
-5
-65
-50
1550
+5
-35
mA
%
%
V
BAT
rising, 130mV hysteresis
0V
≤
V
BAT
≤
2.1V
V
BAT
rising, 150mV hysteresis
Percentage of fast-charge current programmed
2.1
45
2.5
10
V
mA
V
%
Maxim Integrated
5
FPGA/CPLD
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