MAXIM MAX8900BEWV+T

19-5063; Rev 3; 1/11
TION KIT
EVALUA BLE
A
IL
A
V
A
1.2A Switch-Mode Li+ Chargers with ±22V Input
Rating and JEITA Battery Temperature Monitoring
The MAX8900_ is a high-frequency, switch-mode charger for a 1-cell lithium ion (Li+) or lithium polymer
(Li-Poly) battery. It delivers up to 1.2A of current to the
battery from 3.4V to 6.3V (MAX8900A/MAX8900C) or
3.4V to 8.7V (MAX8900B). The 3.25MHz switch-mode
charger is ideally suited to small portable devices such
as headsets and ultra-portable media players because it
minimizes component size and heat.
Several features make the MAX8900_ perfect for highreliability systems. The MAX8900_ is protected against
input voltages as high as +22V and as low as -22V.
Battery protection features include low voltage prequalification, charge fault timer, die temperature monitoring,
and battery temperature monitoring. The battery temperature monitoring adjusts the charge current and termination voltage as described in the JEITA* specification for
safe use of secondary lithium-ion batteries.
Charge parameters are easily adjustable with external
components. An external resistance adjusts the charge
current from 50mA to 1200mA. Another external resistance adjusts the prequalification and done current
thresholds from 10mA to 200mA. The done current threshold is very accurate achieving Q1mA at the 10mA level.
The charge timer is adjustable with an external capacitor.
Features
S 3.25MHz Switching Li+/Li-Poly Battery Charger
S JEITA Battery Temperature Monitor Adjusts
Charge Current and Termination Voltage
S 4.2V ±0.5% Battery Regulation Voltage (Alternate
4.1V Target Available on Request)
S Adjustable Done Current Threshold
Adjustable from 10mA to 200mA
±1mA Accuracy at 10mA
S High-Efficiency and Low Heat
S Uses a 2.0mm x 1.6mm Inductor
S Positive and Negative Input Voltage Protection
(±22V)
S Up to +20V Operating Range (Alternate OVLO
Ranges Available on Request)
S Supports No-Battery Operation
S Fault Timer
S Charge Status Outputs
S 2.44mm x 2.67mm x 0.64mm Package
Simplified Applications Circuit
1FH
The MAX8900_ is available in a 0.4mm pitch, 2.44mm x
2.67mm x 0.64mm WLP package.
Applications
USB Charging
Headsets and Media
Players
Smartphones
Digital Cameras
GPS, PND
eBook
VIN
(-22V TO +22V) 0.47FF
25V
0603
TEMP PINRANGE PACKAGE
OFF
-40NC to
30 WLP
+85NC
VOVLO = 6.5V
T1 = 0NC
2-pin status indicators
VPQUTH = 2.8V
-40NC to
MAX8900BEWV+T
30 WLP
+85NC
VOVLO = 9.0V
T1 = -15NC
3-pin status indicators
VPQUTH = 2.8V
MAX8900AEWV+T
ON
OPTIONS
+Denotes a lead(Pb)-free/RoHS-compliant package.
T = Tape and reel.
1.0FF
6.3V
0402
CS
LX
BAT
0.47FF
25V
0603
2.2FF
6.3V
0603
IN
PGND
STAT1
STAT2
STAT3
CEN
Ordering Information
PART
BST
AVL
MAX8900_
GND
SYSTEM
LOAD
Li+/
Li-POLY
THM
T
PVL
INBP
CT
SETI
DNI
*JEITA (Japan Electronics and Information Technology
Industries Association) standard, “A Guide to the Safe Use
of Secondary Lithium Ion Batteries in Notebook-type Personal
Computers” April 20, 2007.
Ordering Information continued 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.
MAX8900A/MAX8900B/MAX8900C
General Description
MAX8900A/MAX8900B
1.2A Switch-Mode Li+ Chargers with ±22V Input
Rating and JEITA Battery Temperature Monitoring
TABLE OF CONTENTS
Absolute Maximum Ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Electrical Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Typical Operating Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Pin Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Pin Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Detailed Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Control Scheme . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Soft-Start . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Setting the Fast-Charge Current (SETI) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Setting the Prequalification Current and Done Threshold (DNI) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Charge Enable Input (CEN) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Charger States . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Charger Disabled State . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Dead-Battery State . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Dead Battery + Prequalification State . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Prequalification State . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Fast-Charge Constant Current State . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Fast-Charge Constant Voltage State . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Top-Off State . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Done State . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Timer Fault State . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Battery Hot/Cold State . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
VIN Too High State . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Charge Timer (CT) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Thermal Management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Thermistor Monitor (THM) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Thermal Foldback . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Thermal Shutdown . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
PVL and AVL Regulator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Charge Status Outputs (3 Pin) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Charge Status Outputs (2 Pin + > T4) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Inductor Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
BAT Capacitor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
INBP Capacitor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Other Capacitors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Applications Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Dynamic Charge Current Programming . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
No-Battery Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
2
1.2A Switch-Mode Li+ Chargers with ±22V Input
Rating and JEITA Battery Temperature Monitoring
Charge-Source Issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Charge-Source Impedance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Inductive Kick . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Overvoltage and Reverse Input Voltage Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
PCB Layout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Chip Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Package Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Revision History . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
LIST OF FIGURES
Figure 1. Applications Circuit: Single SETI Resistor, Status Indicators Connected to LEDs . . . . . . . . . . . . . . . . . . . . . 15
Figure 2. Applications Circuit: Multiple Charge Rates Managed by µP to Be USB Compliant, Status Indicators
Connected to a µP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Figure 3. Functional Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Figure 4. Fast-Charge Current vs. RSETI (www.maxim-ic.com/tools/other/software/MAX8900-RSETI.XLS) . . . . 18
Figure 5. Prequalification Current and Done Threshold vs. RDNI (www.maxim-ic.com/tools/other/software/
MAX8900-DNI.XLS) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Figure 6. Li+/Li-Poly Charge Profile . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Figure 7. Charger State Diagram (3-Pin Status) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Figure 8. Charger State Diagram (2-Pin Status) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Figure 9. Charge Times vs. CCT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
23
Figure 10. JEITA Battery Safety Regions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Figure 11. Thermistor Monitor Detail . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Figure 12. Charge Current vs. Junction Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Figure 13. Calculated Fast-Charge Current vs. Dropout Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Figure 14. Power PCB Layout Example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Figure 15. Recommended Land Pattern . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Figure 16. Bump Cross Section and Copper Pillar Detail . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
LIST OF TABLES
Table 1. 2.44mm x 2.67mm x 0.64mm, 0.4mm Pitch WLP Thermal Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Table 2. Trip Temperatures for Different Thermistors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Table 3. 3-Pin Status Output Truth Table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Table 4. 2-Pin Status Output Truth Table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Table 5. Recommended Inductor Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Table 6. Recommended Inductor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
3
MAX8900A/MAX8900B
TABLE OF CONTENTS (continued)
MAX8900A/MAX8900B/MAX8900C
1.2A Switch-Mode Li+ Chargers with ±22V Input
Rating and JEITA Battery Temperature Monitoring
ABSOLUTE MAXIMUM RATINGS
IN to PGND..............................................................-22V to +22V
INBP to PGND........................................... (VBAT - 0.3V) to +22V
IN to INBP...............................................................-30V to +1.2V
STAT1, STAT2 to GND...........................................-0.3V to +30V
BST to PGND..........................................................-0.3V to +36V
BST to LX...............................................................-0.3V to +6.0V
BST to PVL.............................................................-0.3V to +30V
PVL, BAT, CS to PGND.........................................-0.3V to +6.0V
AVL, STAT3, CEN, THM to GND...........................-0.3V to +6.0V
PVL to AVL............................................................-0.3V to +0.3V
CT to GND..................................................-0.3V to (AVL + 0.3V)
SETI, DNI to GND..................................... -0.3V to (VBAT + 0.3V)
PGND to GND.......................................................-0.3V to +0.3V
IN Continuous Current.................................................... 2.4ARMS
LX Continuous Current (Note 1)..................................... 1.6ARMS
CS Continuous Current................................................. 1.3ARMS
BAT Continuous Current................................................ 1.3ARMS
Continuous Power Dissipation (TA = +70NC)
30-Bump WLP (derate 20.4mW/NC above +70NC).....1616mW
Operating Temperature Range........................... -40NC to +85NC
Junction Temperature....................................... -40NC to +150NC
Storage Temperature Range............................. -65NC to +150NC
Soldering Temperture (reflow).........................................+260NC
Note 1: LX has an internal clamp diode to PGND and INBP. Applications that forward bias these diodes should take care not to
exceed the power dissipation limits of the device.
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
(VIN = 6V, VBAT = 4V, RSETI = 2.87kI, RDNI = 3.57kI, VTHM = VAVL/2, circuit of Figure 1, TA = -40NC to +85NC, unless otherwise
noted. Typical values are at TA = +25NC.) (Note 2)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
V
GENERAL
Withstand voltage
IN Input Voltage Range (Note 3)
IN Undervoltage Threshold
IN to BAT Shutdown Threshold
IN Overvoltage Threshold
(Note 3)
IN Supply Current
VIN
VUVLO
VIN2BAT
VOVLO
IIN
Operating voltage
-20
+20
MAX8900B
3.4
8.7
MAX8900A/
MAX8900C
3.4
6.3
VIN falling, 400mV hysteresis (Note 4)
3.1
3.2
3.3
V
0
15
30
mV
0.40V hysteresis (MAX8900B)
8.80
9.00
9.20
0.26V hysteresis (MAX8900A/
MAX8900C)
6.35
6.50
6.65
Charger enabled, no switching
1
2
Charger enabled, f = 3.25MHz, VIN = 6V
20
When charging stops, VIN falling, 200mV
hysteresis
VIN rising
Charger disabled, CEN = high
0.04
LX High-Side Resistance
RHS
0.10
LX Low-Side Resistance
RLS
0.15
LX Leakage Current
LX = GND or IN
BST Leakage Current
VBST - VLX = 6V
Current-Sense Resistor
IN to BAT Dropout Resistance
Switching Frequency
4
RSNS
RIN2BAT
fSW
V
TA = +25NC
0.01
TA = +85NC
0.1
TA = +25NC
0.01
TA = +85NC
0.1
VBAT = 2.6V
V
mA
0.2
I
I
10
10
FA
FA
0.045
I
Calculation estimates a 40mI inductor
resistance (RL), RIN2BAT = RIN2INBP + RHS
+ RL + RSNS
0.3
I
VBAT = 2.6V
3.25
MHz
1.2A Switch-Mode Li+ Chargers with ±22V Input
Rating and JEITA Battery Temperature Monitoring
(VIN = 6V, VBAT = 4V, RSETI = 2.87kI, RDNI = 3.57kI, VTHM = VAVL/2, circuit of Figure 1, TA = -40NC to +85NC, unless otherwise
noted. Typical values are at TA = +25NC.) (Note 2)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
Minimum On-Time
tON-MIN
90
ns
Maximum On-Time
tON-MAX
9
Fs
Minimum Off-Time
tOFF
75
ns
BAT Regulation Voltage (Note 3)
VBATREG
Charger Restart Threshold
(Note 6)
VRSTRT
BAT Prequalification Lower
Threshold (Figure 6)
BAT Prequalification Upper
Threshold (Figure 6) (Note 3)
IBAT = 0mA,
MAX8900A/
MAX8900B/
MAX8900C
(Figure 10)
TA = +25NC, VTHM between
T1 and T3
4.179
4.200
4.221
TA = -40NC to +85NC, VTHM
between T1 and T3
4.158
4.200
4.242
TA = +25NC, VTHM between
T3 and T4 (Note 5)
4.055
4.075
4.095
TA = -40NC to +85NC, VTHM
between T3 and T4 (Note 5)
4.034
4.075
4.100
-70
-100
-125
VTHM between T1 and T3
VTHM between T3 and T4
-75
VPQLTH
VBAT rising,180mV hysteresis
2.1
VPQUTH
VBAT rising, 180mV MAX8900A/MAX8900B
typical hysteresis
MAX8900C
VTHM between T2
and T4 (Figure 10)
Fast-Charge Current
IFC
Fast-Charge Current Set Range
Fast-Charge Setting Resistor
Range
Done Current
Prequalification Current
V
(Figure 5)
RSETI
IDN
IPQ
(Figure 5)
V
2.7
2.8
2.9
2.9
3.0
3.1
RSETI = 2.87kI
1166
1190
1214
RSETI = 6.81kI
490
500
510
RSETI = 34.0kI
99
101
103
VTHM between T1 and T2 (Figure 10); the
fast-charge current is reduced to 50% the
value programmed by RSETI
50
Minimum
50
Maximum
1200
Minimum
Maximum
2.87
68.1
RDNI = 3.83kI (Note 5)
VTHM between T2
RDNI = 7.68kI (Note 5)
and T4 (Figure 10)
RDNI = 38.3kI
VTHM between T2 RDNI = 3.83kI (Note 5)
and T4 (Figure 10), RDNI = 7.68kI (Note 5)
VBAT = 2.6V
RDNI = 38.3kI (Note 5)
VTHM between T1 and T2 (Figure 10); the
prequalification current is reduced to 50%
the value programmed by RDNI
kI
99
50
53
9.5
10.5
11.5
105
50
mA
%
105
115
49
54
59
10
11.5
13
50
mA
mA
47
95
V
%
93
VTHM between T1 and T2 (Figure 10); the
done current threshold is reduced to 50%
the value programmed by RDNI
mV
mA
%
5
MAX8900A/MAX8900B/MAX8900C
ELECTRICAL CHARACTERISTICS (continued)
MAX8900A/MAX8900B/MAX8900C
1.2A Switch-Mode Li+ Chargers with ±22V Input
Rating and JEITA Battery Temperature Monitoring
ELECTRICAL CHARACTERISTICS (continued)
(VIN = 6V, VBAT = 4V, RSETI = 2.87kI, RDNI = 3.57kI, VTHM = VAVL/2, circuit of Figure 1, TA = -40NC to +85NC, unless otherwise
noted. Typical values are at TA = +25NC.) (Note 2)
PARAMETER
SYMBOL
Done and Prequalification
Current Set Range
CONDITIONS
(Figure 5)
Done and Prequalification
Setting Resistor Range
RDNI
(Figure 5)
Dead-Battery Charge Current
IDBAT
0V P VBAT P VDBAT
Dead-Battery Voltage Threshold
(Figure 6)
VDBAT
TYP
MAX
9.8
200
1.91
39.2
VIN = 0V, VBAT = 4.2V,
TA = +25NC
includes LX leakage current
TA = +85NC
through the inductor
BAT Leakage Current
Charger Soft-Start Time (Note 3)
MIN
Minimum
Maximum
Minimum
Maximum
mA
kI
45
mA
2.5
V
0.02
1
FA
0.05
tSS
UNITS
1.5
ms
CHARGE TIMER
Prequalification/Dead-Battery
Time
tPQ
CCT = 0.1FF
30
min
Fast-Charge Time
tFC
CCT = 0.1FF
180
min
Top-Off Time
tTO
16
Timer Accuracy
-15
s
+15
%
THERMISTOR MONITOR
THM Hot Shutoff Threshold
(60NC)
T4
VTHM/AVL falling, 1% hysteresis
(thermistor temperature rising)
21.24
22.54
23.84
%AVL
THM Hot Voltage Foldback
Threshold (45NC)
T3
VTHM/AVL falling, 1% hysteresis
(thermistor temperature rising)
32.68
34.68
36.68
%AVL
THM Cold Current Foldback
Threshold (15NC)
T2
VTHM/AVL rising, 1% hysteresis
(thermistor temperature falling)
57.00
60.00
63.00
%AVL
THM Cold Shutoff Threshold
(-15NC/0NC)
T1
VTHM/AVL rising, 1% 0NC, MAX8900A/
hysteresis (thermistor MAX8900C
temperature falling)
-15NC, MAX8900B
71.06
74.56
78.06
81.43
86.07
90.98
-0.2
0.001
+0.2
THM Input Leakage
THM = GND or AVL
TA = +25NC
0.001
TA = +85NC
CHARGE ENABLE INPUT (CEN)
CEN Input Voltage Low
VIL
CEN Input Voltage High
VIH
1.4
RCEN
100
CEN Internal Pulldown Resistance
6
%AVL
FA
0.6
V
400
kI
V
200
1.2A Switch-Mode Li+ Chargers with ±22V Input
Rating and JEITA Battery Temperature Monitoring
(VIN = 6V, VBAT = 4V, RSETI = 2.87kI, RDNI = 3.57kI, VTHM = VAVL/2, circuit of Figure 1, TA = -40NC to +85NC, unless otherwise
noted. Typical values are at TA = +25NC.) (Note 2)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
ISINK = 1mA
0.025
0.05
ISINK = 15mA
0.38
UNITS
STATUS OUTPUTS (STAT1, STAT2, STAT3)
STAT1 and STAT2 Output
Voltage Low
STAT1 and STAT2 Output High
Leakage
VSTAT_= 28V
STAT3 Output Voltage Low
STAT3 Output High Leakage
TA = +25NC
0.001
TA = +85NC
0.01
1
ISINK = 1mA
0.01
ISINK = 15mA
0.15
0.25
TA = +25NC
0.001
1
TA = +85NC
0.01
VSTAT3 = 5.5V
V
FA
V
FA
PVL AND AVL
0 to 30mA internal load, VIN = 6V,
TA = 0NC to +85NC
PVL and AVL Output Voltage
0 to 23mA internal load, VIN = 6V,
TA = -40NC to +85NC
4.6
5.0
5.1
V
THERMAL
TREG
Junction temperature when charge current
is reduced
95
NC
Thermal Regulation Gain
TTREG
The charge current is decreased 6.7% of
the fast-charge current setting for every
degree that the junction temperature
exceeds the thermal regulation temperature
6.7
%/NC
Thermal-Shutdown Temperature
TSHDN
Junction temperature rising, 15NC hysteresis
+155
NC
Thermal Regulation Temperature
Note 2: Parameters are production tested at TA = +25NC. Limits over the operating temperature range are guaranteed through
correlation using statistical quality control (SQC) methods.
Note 3: Contact factory for alternative values.
Note 4: VIN must be greater than VUVLO-RISING for the part to operate when CEN is pulled low. For example, if CEN is low and the
MAX8900_ is operating with VUVLO-FALLING < VIN < VUVLO-RISING, then toggling CEN results in a nonoperating condition.
Note 5: Guaranteed by design, not production tested.
Note 6: When the charger is in its DONE state, it restarts when the battery voltage falls to the charger restart threshold. The battery
voltage that causes a restart (VBAT-RSTRT) is VBAT-RSTRT = 4.2V - VRSTRT. For example, with the MAX8900A, VBAT-RSTRT
= 4.2V - 100mV = 4.1V.
7
MAX8900A/MAX8900B/MAX8900C
ELECTRICAL CHARACTERISTICS (continued)
Typical Operating Characteristics
(Circuit of Figure 1, VIN = 6V, VBAT = 3.6V, TA = +25NC, unless otherwise noted.)
20
80
40
VIN RISING
20
0
-20
-20
-20
-10
0
10
20
30
-10
VIN (V)
20
30
MAX8900A
RL = 90mI
1.0
1.2
1.0
0.6
VCEN = 0V
VBAT = 4.0V
RSETI = 3.01kI
0.6
0.4
0.4
VIN RISING
0.2
VIN FALLING
0.2
0
0.8
RSETI = 2.87kI
VCEN = 0V
VIN = 6.0V
RSETI = 3.40kI
MAX8900A/
MAX8900B
RSETI = 6.81kI
0.6
VIN RISING
0.4
VIN FALLING
0.2
0
15
10
15
1.4
IBAT (A)
0.8
5
10
CHARGE CURRENT
vs. BATTERY VOLTAGE
0.8
0
5
0
VIN (V)
1.2
IIN (A)
RSETI = 34.0kI
RDNI = 3.83kI
0
3.5
4.5
5.5
6.5
7.5
0
1
2
3
4
5
VIN (V)
VIN (V)
VBAT (V)
INPUT SUPPLY CURRENT AND
CHARGE CURRENT vs. INPUT VOLTAGE
BATTERY REGULATION VOLTAGE
vs. AMBIENT TEMPERATURE
BATTERY REGULATION VOLTAGE
vs. INPUT VOLTAGE
1.0
MAX8900A
VCEN = 0V
VBAT = 4.0V
RSETI = 3.01kI
VIN FALLING
0.6
0.4
IBAT
IIN
0.2
0
3.5
4.5
5.5
VIN (V)
6.5
1.008
1.006
NORMALIZED VBAT
0.8
7.5
VCEN = 0V
VBAT = UNCONNECTED
VIN = 5.0V
VTHM = VAVL/2
1.004
1.010
1.002
1.000
0.998
0.996
MAX8900B
VCEN = 0V
VBAT = UNCONNECTED
1.008
1.006
NORMALIZED VBAT
1.010
MAX8900A toc07
1.2
MAX8900A toc08
IIN (A)
1.0
10
INPUT SUPPLY CURRENT
vs. INPUT VOLTAGE (VIN2BAT DETAIL)
MAX8900A toc04
MAX8900A
VCEN = 0V
VBAT = 3.1V
RSETI = 2.87kI
1.2
0
VIN (V)
INPUT SUPPLY CURRENT
vs. INPUT VOLTAGE (CHARGING AT 1.2A)
1.4
VIN FALLING
0
-20
-30
MAX8900A toc05
-30
60
40
20
0
8
100
MAX8900A toc06
60
MAX8900A
VCEN = 0V
VBAT = 2.6V
RDNI = 3.83kI
6
MAX8900A toc09
60
IIN (uA)
80
120
MAX8900A toc03
100
80
40
VCEN = 3.0V
IIN (mA)
VCEN = 3.0V
100
IIN (uA)
120
MAX8900A toc01
120
INPUT SUPPLY CURRENT
vs. INPUT VOLTAGE (PREQUALIFICATION)
INPUT SUPPLY CURRENT
vs. INPUT VOLTAGE (DISABLED, VBAT = 3.6V)
MAX8900A toc02
INPUT SUPPLY CURRENT
vs. INPUT VOLTAGE (DISABLED, VBAT = 0V)
CURRENT (A)
MAX8900A/MAX8900B/MAX8900C
1.2A Switch-Mode Li+ Chargers with ±22V Input
Rating and JEITA Battery Temperature Monitoring
1.004
1.002
1.000
0.998
0.996
0.994
0.994
0.992
0.992
0.990
0.990
-40
-15
10
35
60
AMBIENT TEMPERATURE (°C)
85
4
5
6
7
VIN (V)
8
9
1.2A Switch-Mode Li+ Chargers with ±22V Input
Rating and JEITA Battery Temperature Monitoring
(Circuit of Figure 1, VIN = 6V, VBAT = 3.6V, TA = +25NC, unless otherwise noted.)
SWITCHING FREQUENCY
vs. INPUT VOLTAGE
SWITCHING FREQUENCY
vs. CHARGE CURRENT
3.5
VBAT = 4V
3.0
2.5
2.0
MAX8900x
VIN RISING
VOVLO = 28V
VCEN = 0V
RISET = 2.87kI
1.5
1.0
0.5
MAX8900A toc11
SWITCHING FREQUENCY (MHz)
VBAT = 3V
5
4
3
VIN = 5V, VBAT = 3V
VIN = 6V, VBAT = 4V
VIN = 4.5V, VBAT = 4V
2
1
0
0
4
8
12
16
20
24
0
28
0.2
0.4
0.6
0.8
1.0
INPUT VOLTAGE (V)
CHARGE CURRENT (A)
MAX8900B DC SWITCHING
WAVEFORMS (IBAT = 100mA)
MAX8900B DC SWITCHING
WAVEFORMS (IBAT = 440mA)
MAX8900A toc12
VOUT
20mV/div
VLX
VOUT
20mV/div
VLX
5V/div
0V
200mA/div
0A
ILX
1.2
MAX8900A toc13
5V/div
0V
ILX
500mA/div
200ns/div
MAX8900B DC SWITCHING
WAVEFORMS (IBAT = 1.2A)
CHARGE CURRENT
vs. AMBIENT TEMPERATURE
MAX8900A toc14
VOUT
1.4
VTHM = VAVL/2
1.2
20mV/div
RSETI = 2.87kI
MAX8900A toc15
0A
200ns/div
1.0
VLX
5V/div
0V
IBAT (A)
SWITCHING FREQUENCY (MHz)
4.5
4.0
6
MAX8900A toc10
5.0
0.8
0.6
RSETI = 6.81kI
0.4
ILX
500mA/div
0A
200ns/div
0.2
0
-40 -15 10
35
60
85 110 135 160 185
TA (°C)
9
MAX8900A/MAX8900B/MAX8900C
Typical Operating Characteristics (continued)
Typical Operating Characteristics (continued)
(Circuit of Figure 1, VIN = 6V, VBAT = 3.6V, TA = +25NC, unless otherwise noted.)
THM NORMAL TO COLD CURRENT
FOLDBACK (T2) TO COLD SHUTOFF (T1)
THM NORMAL TO HOT VOLTAGE FOLDBACK
(T3) TO HOT SHUTOFF (T4) THRESHOLD
MAX8900A toc16
MAX8900A toc17
60% OF AVL (T2)
VTHM
34.7% OF AVL (T3)
VTHM
1V/div
74.5% OF AVL (T1)
2V/div
2V/div
22.5% OF AVL (T4)
VBAT
2V/div
0V
0V
1200mA (T2 < T < T3)
10I RESISTOR LOAD
600mA
200mA/div
0mA
200mA/div
IBAT
0A
0A
20ms/div
20ms/div
EFFICIENCY vs. BATTERY VOLTAGE
(CONSTANT-CURRENT MODE)
CHARGER ENABLE
MAX8900A toc18
VCEN
85
5V/div
MAX8900A toc19
IBAT
4.075V
4.2V
3.6V
VBAT
VIN = 5.0V
83
81
VLX
EFFICIENCY (%)
5V/div
VPVL
5V/div
79
77
75
IBAT = 100mA
73
71
1.2A
IBAT
69
1A/div
67
0A
65
400µs/div
2.5
3.0
3.5
4.0
4.5
VBAT (V)
80
75
IBAT = 500mA
IBAT = 800mA
IBAT = 1200mA
70
65
2.5 2.7 2.9 3.1 3.3 3.5 3.7 3.9 4.1 4.3 4.5
VBAT (V)
10
85
80
VBAT = 3.0V
95
90
VBAT = 3.6V
75
IBAT = 1200mA, RSETI = 2.87kI
MAX8900A/MAX8900B
85
80
75
VIN = 5V
VIN = 8V
VIN = 7V
VIN = 6V
VIN = 8.5V
70
70
65
65
0
0.5
1.0
IBAT (A)
1.5
MAX8900A toc22
90
EFFICIENCY (%)
85
VBAT = 4.0V
VIN = 5.0V
EFFICIENCY (%)
VIN = 5.0V
MAX8900A/
MAX8900B
MAX8900A toc21
90
95
MAX8900A toc20
95
EFFICIENCY vs. BATTERY VOLTAGE
(CONSTANT-CURRENT MODE, IBAT = 1200mA)
EFFICIENCY vs. CHARGE CURRENT
(CONSTANT-CURRENT MODE)
EFFICIENCY vs. BATTERY VOLTAGE
(CONSTANT-CURRENT MODE)
EFFICIENCY (%)
MAX8900A/MAX8900B/MAX8900C
1.2A Switch-Mode Li+ Chargers with ±22V Input
Rating and JEITA Battery Temperature Monitoring
2.5 2.7 2.9 3.1 3.3 3.5 3.7 3.9 4.1 4.3 4.5
VBAT (V)
1.2A Switch-Mode Li+ Chargers with ±22V Input
Rating and JEITA Battery Temperature Monitoring
(Circuit of Figure 1, VIN = 6V, VBAT = 3.6V, TA = +25NC, unless otherwise noted.)
EFFICIENCY vs. CHARGE CURRENT
(CONSTANT-VOLTAGE MODE)
90
VBAT = 3.6V
80
85
80
78
76
75
VBAT = 3.0V
70
74
6
5
7
8
9
BATTERY + LX LEAKAGE CURRENT
vs. BATTERY VOLTAGE
BATTERY + LX LEAKAGE CURRENT
vs. AMBIENT TEMPERATURE
20
15
10
100
0
1
2
3
MAX8900A toc27
IN UNCONNECTED
STAT INDICATOR CURRENT
NOT INCLUDED
5
VOVLO
4
30
3
20
2
10
1
MAX8900x
VOVLO = 28V
VCEN = 0V
VBAT = 3.6V
RSETI = 2.87kI
5
0
0
1
2
3
4
-15
-40
6
5
10
35
60
MAX8900A toc29
4.3
CC
CV
DONE
1.4
4.3
1.2
4.2
0.8
0.6
VIN = 5V
RSETI = 4.02kI
RDNI = 3.57kI
CCT = 0.47µF
1300mAh BATTERY
3.8
3.7
IBAT
3.6
500
2500
4500
0.4
0.2
IIN
6500
TIME (s)
8500
20
25
30
0
10,500
MAX8900A toc30
DONE
CV
4.1
DONE
VBAT
4.0
1.4
1.2
1.0
0.8
3.9
0.6
VIN = 5V
RSETI = 4.02kI
RDNI = 3.57kI
CCT = 0.47µF
1300mAh BATTERY
3.8
3.7
IBAT
0.2
IIN
3.6
0
2000
4000
0.4
BATTERY CURRENT (A)
1.0
4.0
15
MAX8900_ CHARGE PROFILE
(CHARGER RESTART)
BATTERY CURRENT (A)
VBAT
4.1
3.9
10
VIN (V)
MAX8900_ CHARGE PROFILE
(CONSTANT-CURRENT TO DONE MODES)
4.2
5
0
85
TEMPERATURE (°C)
BATTERY VOLTAGE (V)
VOLTAGE (V)
0
5
AVL VOLTAGE vs. INPUT VOLTAGE
40
0
4
6
VAVL (V)
25
BATTERY LEAKAGE CURRENT (nA)
MAX8900A toc26
30
VOLTAGE (V)
BATTERY LEAKAGE CURRENT (nA)
35
VBAT = 3.2V
INPUT VOLTAGE (V)
60
50
VBAT = 4.0V
10
1500
IBAT (A)
IN UNCONNECTED
STAT INDICATOR CURRENT
NOT INCLUDED
40
1000
VIN (V)
50
45
500
0
10
CEN = 1
MAX8900A toc28
82
95
1000
BATTERY LEAKAGE CURRENT (nA)
VBAT = 4.0V
84
VIN = 5V, VBAT = 4.2V
EFFICIENCY (%)
EFFICIENCY (%)
86
MAX8900A toc24
IBAT = 1200mA, RSETI = 2.87kI
88
100
MAX8900A toc23
90
BATTERY + LX LEAKAGE CURRENT
vs. INPUT VOLTAGE
MAX8900A toc25
EFFICIENCY vs. INPUT VOLTAGE
(CONSTANT-CURRENT MODE)
6000
8000
0
10,000
TIME (s)
11
MAX8900A/MAX8900B/MAX8900C
Typical Operating Characteristics (continued)
MAX8900A/MAX8900B/MAX8900C
1.2A Switch-Mode Li+ Chargers with ±22V Input
Rating and JEITA Battery Temperature Monitoring
Typical Operating Characteristics (continued)
(Circuit of Figure 1, VIN = 6V, VBAT = 3.6V, TA = +25NC, unless otherwise noted.)
5V IN CONNECT
BATTERY CONNECT
MAX8900A toc31
MAX8900A toc32
6V
VIN
VIN
2V/div
5V/div
4.2V
3.6V
VBAT
VLX
2V/div
5V/div
IBAT
RSETI = 6.81kI
1.2A
IBAT
500mA/div
0A
500mA/div
RSETI = 2.87kI
400µs/div
20µs/div
BATTERY DISCONNECT
SOFT-START INTO RESISTIVE
SOURCE, RSETI = 6.81kI
MAX8900A toc33
0A
MAX8900A toc34
6V
VIN
VIN
5V/div
VSOURCE = 4.8V,
VBAT = 4V
1I BETWEEN
SOURCE AND IN
4.2V
3.6V
2V/div
VBAT
VLX
2V/div
1.2A
IBAT
500mA/div
RSETI = 2.87kI
IBAT
500mA/div
0A
0A
400µs/div
2ms/div
SOFT-START INTO RESISTIVE
SOURCE (RSETI = 2.87kI)
MAX8900A toc35
VIN
5V/div
VSOURCE = 4.8V, VBAT = 4V
1I BETWEEN SOURCE AND IN
VLX
2V/div
IBAT
500mA/div
0A
2ms/div
12
2V/div
1.2A Switch-Mode Li+ Chargers with ±22V Input
Rating and JEITA Battery Temperature Monitoring
TOP VIEW (BUMPS DOWN)
+
BAT
CS
LX
PGND
BST
PVL
A1
A2
A3
A4
A5
A6
BAT
CS
LX
PGND
PGND
PGND
B1
B2
B3
B4
B5
B6
STAT2
CEN
INBP
INBP
INBP
INBP
C1
C2
C3
C4
C5
C6
STAT1
STAT3
IN
IN
IN
IN
D1
D2
D3
D4
D5
D6
DNI
SETI
CT
THM
AVL
GND
E1
E2
E3
E4
E5
E6
30 WLP
(0.4mm PITCH)
Pin Description
PIN
NAME
A1, B1
BAT
Connection to Battery. Connect to a single-cell Li+/Li-Poly battery from BAT to PGND. Connect both
BAT pins together externally. Bypass BAT to PGND with a 2.2FF ceramic capacitor.
A2, B2
CS
40mI Current-Sense Node. Connect the inductor from LX to CS. Connect both CS pins together
externally.
A3, B3
LX
Inductor Switching Node. Connect the inductor between LX and CS. Connect both LX pins together
externally. When enabled (CEN = 0), LX switches between INBP and PGND to control the battery
charging. When disabled (CEN = 1), the LX switches are high-impedance however they still have
body diodes as shown in Figure 3.
A4, B4,
B5, B6
PGND
A5
BST
Supply for High-Side n-Channel Gate Driver. Bypass BST to LX with a 0.1FF ceramic capacitor.
A6
PVL
5V Linear Regulator to Power Internal Circuits. PVL also charges the BST capacitor. Bypass PVL to
PGND with a 1.0FF ceramic capacitor. Powering external loads from PVL is not recommended.
C1
C2
FUNCTION
Power Ground for Step-Down Low-Side Synchronous n-Channel MOSFET. Connect all PGND pins
together externally.
STAT2
Status Output 2. STAT2 is an open-drain output that has a 30V absolute maximum rating and a typical
pulldown resistance of 25I. For the MAX8900A, STAT1 and STAT2 indicate different states as shown
in Table 4. For the MAX8900B/MAX8900C, STAT1, STAT2, and STAT3 indicate different operating
states of the MAX8900_ as shown in Table 3.
CEN
Charge Enable Input. CEN has an internal 200kI pulldown resistor. Pull CEN low or leave it
unconnected to enable the MAX8900_. Drive CEN high to disable the MAX8900_. Note: VIN must be
greater than VUVLO-RISING for the MAX8900_ to operate when CEN is pulled low. For example, if CEN
is low and the MAX8900_ is operating with VUVLO-FALLING < VIN < VUVLO-RISING, then toggling CEN
results in a nonoperating condition.
13
MAX8900A/MAX8900B/MAX8900C
Pin Configuration
1.2A Switch-Mode Li+ Chargers with ±22V Input
Rating and JEITA Battery Temperature Monitoring
MAX8900A/MAX8900B/MAX8900C
Pin Description (continued)
PIN
C3–C6
INBP
FUNCTION
Power Input Bypass. Connect all INBP pins together externally. Bypass INBP to PGND with a 0.47FF
ceramic capacitor.
STAT1
Status Output 1. STAT1 is an open-drain output that has a 30V absolute maximum rating and a typical
internal pulldown resistance of 25I. For the MAX8900A, STAT1 and STAT2 indicate different states
as shown in Table 4. For the MAX8900B/MAX8900C, STAT1, STAT2, and STAT3 indicate different
operating states of the MAX8900_ as shown in Table 3.
D2
STAT3
Status Output 3. STAT3 is an open-drain output that is a 6V absolute maximum rating and a typical
pulldown resistance of 10I. For the MAX8900A, STAT1 and STAT2 indicate different states as shown
in Table 4. For the MAX8900B/MAX8900C, STAT1, STAT2, and STAT3 indicate different operating
states of the MAX8900_ as shown in Table 3.
D3–D6
IN
Power Input. IN is capable of delivering 1.2A to the battery and/or system. Connect all IN pins
together externally. Bypass IN to PGND with a 0.47FF ceramic capacitor.
E1
DNI
Done/Prequalification Program Input. DNI is a dual function pin that sets both the done current
threshold and the prequalification charge rate. Connect a resistor from DNI to GND to set the
threshold between 10mA and 200mA. DNI is pulled to GND during shutdown.
E2
SETI
Fast-Charge Current Program Input. Connect a resistor from SETI to GND to set the fast-charge
current from 0.05A to 1.2A. SETI is pulled to GND during shutdown.
E3
CT
D1
14
NAME
Charge Timer Set Input. A capacitor (CCT) from CT to GND sets the prequalification/dead-battery
and fast-charge fault timers. Use 0.1FF for 180-minute fast-charge time limit and 30-minute
prequalification/dead-battery time limit. Connect to GND to disable the timer.
E4
THM
Thermistor Input. Connect a negative temperature coefficient (NTC) thermistor from THM to GND.
Connect a resistor equal to the thermistor’s +25NC resistance from THM to AVL. Thermistor adjusts
the charge current and termination voltage as described in the JEITA specification for safe use of
secondary Li+ batteries. See Figure 10. To disable the THM operation, bias VTHM midway between
AVL and GND.
E5
AVL
5V Linear Regulator to Power Low-Noise Internal Circuits. Bypass AVL to GND with a 0.1FF ceramic
capacitor. Powering external loads from AVL is not recommended.
E6
GND
Ground. GND is the low-noise ground connection for the internal circuitry. See the PCB Layout
section for more details.
1.2A Switch-Mode Li+ Chargers with ±22V Input
Rating and JEITA Battery Temperature Monitoring
MAX8900A/MAX8900B/MAX8900C
1FH
1.5A
0.1FF
10V
0402
VIN RANGE:
-22V TO +22V
BST
IN
0.47FF
25V
0603
BAT
422I
*
422I
BAT
PGND
BAT
2.2FF
6.3V
0603
PGND
MAX8900_
*
AVL
STAT1
STAT2
STAT3
OFF
ON
0.47FF
25V
0603
GND
SYSTEM
LOAD
Li+/
Li-POLY
422I
*
1.0FF
6.3V
0402
CS
LX
IN
CEN
PVL
INBP
CT
0.47FF
6.3V
0402
0.1FF
6.3V
0201
GND
10kI
0201
THM
SETI
2.87kI
0201
10kI
3380k
0402
T
DNI
3.57kI
0201
THE MINIMUM ACCEPTABLE EIA
COMPONENT SIZES AS OF LATE 2009
ARE LISTED: 0201, 0402, 0603.
* STATUS INDICATORS ARE UNCONNECTED FOR THE ELECTRICAL CHARACTERISTICS TABLE.
Figure 1. Applications Circuit: Single SETI Resistor, Status Indicators Connected to LEDs
*PULLUP RESISTORS ARE INTERNAL TO THE µP.
GPIO4
CEN
1
0
0
0
0
1FH
1.5A
USB
CONNECTOR
VBUS
DD+
ID
0.1FF
10V
0402
BST
CS
SUSPEND IS 0mA FAST-CHARGE CURRENT
(IFC) AND 40FA OF INPUT CURRENT (IIN).
LX
IN
BAT
0.47FF
25V
0603
GND
0.47FF
25V
0603
USB
TRANSCEIVER
35.7kI
0201
FP
GPIO5
9.09kI
0201
PGND
AVL
GND
4.75kI
0201
0.1FF
6.3V
0201
10kI
0201
THM
T
375mA_EN
717mA_EN
SYSTEM
LOAD
Li+/
Li-POLY
MAX8900_
CT
GPIO6
2.2FF
6.3V
0603
INBP
STAT1
STAT2
STAT3
CEN
SETI
GPIO1*
GPIO2*
GPIO3*
GPIO4*
GPIO5 GPIO6
RTH (I) IFC (A)
9090 4750
SUSPEND
x
x
x
0
0
35700
0.095
1
0
7245
0.470
0
1
4192
0.812
1
1
2869
1.187
PVL
0.47FF
6.3V
0402
DNI
1.0FF
6.3V
0402
3.57kI
0201
10kI
3380K
0402
PGND
GND
THE MINIMUM ACCEPTABLE EIA
COMPONENT SIZES AS OF LATE 2009
ARE LISTED: 0201, 0402, 0603.
Figure 2. Applications Circuit: Multiple Charge Rates Managed by µP to Be USB Compliant, Status Indicators Connected to a µP
15
MAX8900A/MAX8900B/MAX8900C
1.2A Switch-Mode Li+ Chargers with ±22V Input
Rating and JEITA Battery Temperature Monitoring
STAT1: D1
BV = 30V
STAT2: C1
BV = 30V
BAT_T
STAT3: D1
BV = 6V
INPUT
OVERVOLTAGE
OVLO
LOGIC
VOVLO
GND: E6
CT: E3
CHARGER
TIMER
INPUT
UNDERVOLTAGE
UVLO
CTS
VUVLO
IN: D3
IN: D4
IN: D5
CEN: C2
RCEN
IN
RAVL
12.5I
AVL: E5
OUT
EN
5V 30mA
LDO
AVL IS THE
INTERNAL
ANALOG SUPPLY
REVERSEINPUT
PROTECTION
INBP: C3
VIN2BAT
INBP: C4
SHDN
IBAT
IN: D6
LOW IN TO
BAT
VOLTAGE
DC-DC
CHARGE
CONTROLLER
AVL
BAT_I
BAT
INBP: C5
PVL
INBP: C6
FC_I
DNI: E1
BST: A5
PQ_I
AVL
THM: E4
LI2B
IN
PVL: A6
SETI: E2
PVL
TO_I
BAT
RHS
DRV_OUT
BAT_V
BAT_T
DIE_T
LX: A3
LX: B3
PVL
BAT_T
T
RLS
COLD: T1
PGND: A4
PGND: B4
THERMOMETER
DECODE LOGIC
PGND: B5
DIE
TEMPERATURE
COOL: T2
PGND: B6
CS: A2
CS: B2
IBAT
PGND
GND
RSNS
WARM: T3
BAT: A1
IN
BAT
IN
BAT: B1
OUT
DEAD-BATTERY
CHARGER (IDBAT)
HOT: T4
EN
MAX8900_
Figure 3. Functional Diagram
16
VDBAT
1.2A Switch-Mode Li+ Chargers with ±22V Input
Rating and JEITA Battery Temperature Monitoring
The MAX8900_ is a full-featured, high-frequency switchmode charger for a 1-cell Li+ or Li-Poly battery. It
delivers up to 1.2A to the battery from 3.4V to 6.3V
(MAX8900A/MAX8900C) or 3.4V to 8.7V (MAX8900B).
Contact the factory for input operating voltage ranges
up to +20V. The 3.25MHz switch-mode charger is ideally suited to small portable devices such as headsets
and ultra-portable media players because it minimizes
component size and heat.
Several features make the MAX8900_ ideal for high reliability systems. The MAX8900_ is protected against input
voltages as high as +22V and as low as -22V. Battery
protection features include low voltage prequalification,
charge fault timer, die temperature monitoring, and battery temperature monitoring. The battery temperature
monitoring adjusts the charge current and termination
voltage as described in the JEITA (Japan Electronics and
Information Technology Industries Association) specification for safe use of secondary Li+ batteries. The
full title of the standard is A Guide to the Safe Use
of Secondary Lithium Ion Batteries in Notebook-Type
Personal Computers, April 20, 2007.
Charge parameters are easily adjustable with external
components. An external resistance adjusts the charge
current from 50mA to 1200mA. Another external resistance adjusts the prequalification and done current
thresholds from 10mA to 200mA. The done current threshold is very accurate achieving Q1mA at the 10mA level.
The charge timer is adjustable with an external capacitor.
Control Scheme
A proprietary hysteretic current PWM control scheme
ensures high efficiency, fast switching, and physically tiny
external components. Inductor ripple current is internally
set to provide 3.25MHz. At very high duty factors, when
the input voltage is lowered close to the output voltage, the steady-state duty ratio does not allow 3.25MHz
operation because of the minimum off-time. The controller
then provides minimum off-time, peak current regulation. Similarly, when the input voltage is too high to allow
3.25MHz operation due to the minimum on-time, the controller becomes a minimum on-time, valley current regulator. In this way, the ripple current in the inductor is always
as small as possible to reduce the output ripple voltage.
The inductor ripple current is made to vary with input and
output voltage in a way that reduces frequency variation.
Soft-Start
To prevent input current transients, the rate of change
of the input current (di/dt) and charge current is limited.
When the input is valid, the charge current ramps from
0mA to the fast-charge current value in 1.5ms. Charge
current also soft-starts when transitioning from the
prequalification state to the fast-charge state. There is
no di/dt limiting when transitioning from the done state
to the fast-charge state (Figures 7 and 8). Similarly, if
RSETI is changed suddenly when using a switch or variable resistor at SETI as shown in Figure 2 there is no di/
dt current limiting.
Setting the Fast-Charge Current (SETI)
As shown in Figure 4, a resistor from SETI to ground
(RSETI) sets the fast-charge current (IFC). The MAX8900_
supports values of IFC from 50mA to 1200mA. Select
RSETI as follows:
IFC = 3405V/RSETI
Determine the optimal IFC for a given system by considering the characteristics of the battery and the capabilities of the charge source.
Example 1: If you are using a 5V Q5% 1A charge
source along with an 800mAh battery that has a 1C
fast-charge rating, then choose RSETI to be 4.42kI
Q1%. This value provides a typical charge current
of 770mA. Given the Q2% six sigma limit on the
MAX8900_ fast-charge current accuracy along with
the Q1% accuracy of the resistor, we can reasonably
expect that the 770mA typical value has an accuracy
of Q2.2% (2.2 ≈ sqrt(22 + 12)) or Q17mA. Furthermore,
since the MAX8900_ charger uses a step-down converter topology, we can guarantee that the input current is less than or equal to the output current so we
do not violate the 1A rating of the charge source.
Depending on its mode of operation, the MAX8900_
controls the voltage at SETI to be between 0V and 1.5V.
Avoid adding capacitance directly to the SETI pin that
exceeds 10pF.
As a protection feature, if the battery temperature is
between the T2 and T4 thresholds and SETI is shorted
to ground, then the MAX8900_ latches off the battery
charger and enters the timer fault state. This protection
feature is disabled outside of fast-charge, top-off, done
mode and inside thermal foldback. Furthermore, if SETI is
unconnected, then the battery fast-charge current is 0A.
17
MAX8900A/MAX8900B/MAX8900C
Detailed Description
Setting the Prequalification Current
and Done Threshold (DNI)
As shown in Figure 5, a resistor from DNI to ground
(RDNI) sets the prequalification current (IPQ) and done
current (IDN). The MAX8900_ supports values of RDNI
from 1.19kI to 38.2kI. Select RDNI as follows:
IDN = 384V/RDNI
IPQ = 415V/RDNI
Determine the optimal IPQ and IDN for a given system by
considering the characteristics of the battery.
FAST-CHARGE CURRENT
vs. RSETI
1.4
1.2
FAST-CHARGE CURRENT (A)
Depending on its mode of operation, the MAX8900_ controls
the voltage at DNI from 0 to 1.5V. Avoid adding capacitance
directly to the SETI pin that exceeds 10pF.
As shown in Figure 10, the prequalification current and
done threshold is set to 50% of programmed value when
T1 < THM < T2, and 100% of programmed value when
T2 < THM < T4.
As a protection feature, if the battery temperature is
between the T2 and T4 thresholds and DNI is shorted
to ground, then the MAX8900_ latches off the battery
charger and enters the timer fault state. This protection
feature is disabled inside of dead-battery mode and
thermal foldback. Furthermore, if DNI is unconnected,
then the prequalification and done current is 0A and the
charge timer prevents the MAX8900_ from indefinitely
operating in its done state.
1.0
Charge Enable Input (CEN)
0.8
CEN is a digital input. Driving CEN high disables the
battery charger. Pull CEN low or leave it unconnected
0.6
0.4
PREQUALIFICATION AND DONE CURRENT
vs. RDNI
0.2
250
0
0
20
40
60
80
200
RSETI (kI)
RSETI
(kI)
IFC
(A)
RSETI
(kI)
IFC
(A)
RSETI
(kI)
IFC
(A)
2.87
1.186
7.15
0.476
24.9
0.137
3.01
1.131
7.32
0.465
27.4
0.124
3.16
1.078
7.87
0.433
30.1
0.113
3.32
1.026
8.25
0.413
32.2
0.106
3.57
0.954
9.09
0.375
34.0
0.100
3.92
0.869
10.0
0.341
35.7
0.095
4.12
0.826
11.0
0.310
39.2
0.087
4.32
0.788
12.1
0.281
43.2
0.079
4.42
0.770
13.0
0.262
45.5
0.075
4.75
0.717
14.0
0.243
49.9
0.068
4.99
0.682
15.0
0.227
51.1
0.067
5.11
0.666
16.2
0.210
56.2
0.061
5.62
0.606
18.2
0.187
61.9
0.055
6.19
0.550
20.0
0.170
66.5
0.051
6.81
0.500
22.1
0.154
68.1
0.050
7.5
0.454
24.3
0.140
Figure 4. Fast-Charge Current vs. RSETI (www.maxim-ic.com/
tools/other/software/MAX8900-RSETI.XLS)
18
CURRENT (mA)
MAX8900A/MAX8900B/MAX8900C
1.2A Switch-Mode Li+ Chargers with ±22V Input
Rating and JEITA Battery Temperature Monitoring
150
IPQ
100
IDN
50
0
0
10
100
RDNI (kI)
RDNI
(kI)
IPQ
(mA)
IDN
(mA)
RDNI
(kI)
IPQ
(mA)
IDN
(mA)
1.91
217.3
2.37
175.1
201.0
7.5
55.3
51.2
162.0
7.68
54.0
3.48
50.0
119.3
110.3
7.87
52.7
48.8
3.57
116.2
107.6
10.0
41.5
38.4
3.83
108.4
100.3
14.3
29.0
26.9
4.42
93.9
86.9
20.0
20.8
19.2
5.9
70.3
65.1
28.0
14.8
13.7
7.32
56.7
52.5
39.2
10.6
9.8
Figure 5. Prequalification Current and Done Threshold vs. RDNI
(www.maxim-ic.com/tools/other/software/MAX8900-DNI.XLS)
1.2A Switch-Mode Li+ Chargers with ±22V Input
Rating and JEITA Battery Temperature Monitoring
VIN must be greater than VUVLO-RISING for the MAX8900_
to operate when CEN is pulled low. For example, if CEN is
low and the MAX8900_ is operating with VUVLO-FALLING
< VIN < VUVLO-RISING, then toggling CEN results in a
nonoperating condition.
Charger States
DONE
TOP-OFF
FAST-CHARGE
(CONSTANT VOLTAGE)
The MAX8900_ utilizes several charging states to safely
and quickly charge batteries as shown in Figure 7.
Figure 6 shows an exaggerated view of a Li+/Li-Poly
battery progressing through the following charge states
when the die and battery are close to room temperature:
dead battery è prequalification è fast-charge è top-off
è done.
FAST-CHARGE
(CONSTANT CURRENT)
PREQUALIFICATION
DEAD BATTERY +
PREQUALIFICATION
DEAD
BATTERY
In many systems, there is no need for the system controller (typically a microprocessor (FP)) to disable the charger because the MAX8900_ independently manages the
charger. In these situations, CEN can be connected to
ground or left unconnected. Note: if CEN is permanently
connected to ground or left unconnected, the input
power must be cycled to escape from a timer fault state
(see Figures 7 and 8 for more information).
BATTERY VOLTAGE
VBATREG
VPQUTH
VDBAT
VPQLTH
TIME
BATTERY CHARGE CURRENT
ICHG P ISET
IDBAT + IPQ
IPQ
IDBAT
0
TIME
Figure 6. Li+/Li-Poly Charge Profile
19
MAX8900A/MAX8900B/MAX8900C
to enable the MAX8900_. CEN has an internal 200kI
pulldown resistor. When disabled, the MAX8900_ supply
current is reduced, the step-down converter high-side and
low-side switches are off, and the AVL is disabled.
MAX8900A/MAX8900B/MAX8900C
1.2A Switch-Mode Li+ Chargers with ±22V Input
Rating and JEITA Battery Temperature Monitoring
NO PWR OR
CHARGER DISABLED
STAT1 = HI-Z
STAT2 = HI-Z
STAT3 = HI-Z
IBAT = 0
CEN = LOGIC-HIGH
OR TJ > TSHDN
VIN > VUVLO
AND VIN > VBAT + VIN2BAT
AND TJ < TSHDN
(SET TIMER = 0)
VIN < VUVLO
OR < VBAT + VIN2BAT
ANY STATE
DEAD BAT
STAT1 = LOW
STAT2 = HI-Z
STAT3 = LOW
IBAT = IDBAT
VIN TOO HIGH
STAT1 = LOW
STAT2 = LOW
STAT3 = HI-Z
IBAT = 0
VIN < VOVLO
TIMER = RESUME
VBAT < VPQLTH
VIN > VOVLO
TIMER = SUSPEND
ANY CHARGING STATE
THERMISTOR > T1
TIMER = RESUME
THERMISTOR < T4
TIMER = RESUME
TIMER > tPQ
VBAT > VDBAT
VBAT < VDBAT
PREQUAL
TIMER FAULT
STAT1 = LOW
STAT2 = HI-Z
STAT3 = LOW
IBAT = IPQ
TIMER > tPQ
STAT1 = HI-Z
STAT2 = HI-Z
STAT3 = LOW
IBAT = 0
VBAT > VPQUTH
SOFT-START
(SET TIMER = 0)
VBAT < VPQUTH
(SET TIMER = 0)
BATTERY COLD
STAT1 = LOW
STAT2 = LOW
STAT3 = LOW
IBAT = 0 IF VBAT > VDBAT
THERMISTOR > T4
TIMER = SUSPEND
VBAT > VPQLTH
DEAD BAT +
PREQUAL
STAT1 = LOW
STAT2 = HI-Z
STAT3 = LOW
IBAT = IDBAT + IPQ
(DEAD BAT, PREQUAL,
FAST CHG,
OR TOP-OFF)
THERMISTOR < T1
TIMER = SUSPEND
TIMER > tPQ
FAST CHG
STAT1 = LOW
STAT2 = HI-Z
STAT3 = LOW
IBAT = IFC
IBAT > IDN + 1mA
(SET TIMER = 0)
TIMER > tFC
IBAT < IDN
TOP-OFF
BATTERY HOT
STAT1 = LOW
STAT2 = HI-Z
STAT3 = HI-Z
IBAT = 0 IF VBAT > VDBAT
STAT1 = LOW
STAT2 = HI-Z
STAT3 = LOW
TIMER > tTO
DONE
STAT1 = HI-Z
STAT2 = LOW
STAT3 = LOW
IBAT = 0
Figure 7. Charger State Diagram (3-Pin Status)
20
VBAT < VRSTRT
NO SOFT-START
(SET TIMER = 0)
1.2A Switch-Mode Li+ Chargers with ±22V Input
Rating and JEITA Battery Temperature Monitoring
MAX8900A/MAX8900B/MAX8900C
NO PWR OR
CHARGER DISABLED
STAT1 = HI-Z
STAT2 = HI-Z
IBAT = 0
VIN > VUVLO
AND VIN > VBAT + VIN2BAT
AND TJ < TSHDN
(SET TIMER = 0)
CEN = LOGIC-HIGH
OR TJ > TSHDN
VIN < VUVLO
OR < VBAT + VIN2BAT
ANY STATE
DEAD BAT
STAT1 = LOW
STAT2 = HI-Z
IBAT = IDBAT
VIN TOO HIGH
TIMER > tPQ
STAT1 = HI-Z
STAT2 = LOW
IBAT = 0
VIN < VOVLO
TIMER = RESUME
VBAT < VPQLTH
VIN > VOVLO
TIMER = SUSPEND
ANY CHARGING STATE
DEAD BAT +
PREQUAL
STAT1 = LOW
STAT2 = HI-Z
IBAT = IDBAT + IPQ
VBAT < VDBAT
(DEAD BAT, PREQUAL,
FAST CHG,
OR TOP-OFF)
THERMISTOR > T4 OR
THERMISTOR < T1
TIMER = SUSPEND
T1 < THERMISTOR < T4
TIMER = RESUME
BATTERY COLD/
BATTERY HOT
VBAT > VPQLTH
TIMER > tPQ
VBAT > VDBAT
PREQUAL
STAT1 = LOW
STAT2 = HI-Z
IBAT = IPQ
TIMER FAULT
TIMER > tPQ
STAT1 = HI-Z
STAT2 = LOW
IBAT = 0
VBAT > VPQUTH
SOFT-START
(SET TIMER = 0)
VBAT < VPQUTH
(SET TIMER = 0)
FAST CHG
STAT1 = HI-Z
STAT2 = LOW
IBAT = 0 IF VBAT > VDBAT
STAT1 = LOW
STAT2 = HI-Z
IBAT = IFC
IBAT > IDN + 1mA
(SET TIMER = 0)
TIMER > tFC
IBAT < IDN
TOP-OFF
STAT1 = LOW
STAT2 = HI-Z
VBAT < VRSTRT
NO SOFT-START
(SET TIMER = 0)
TIMER > tTO
DONE
STAT1 = HI-Z
STAT2 = HI-Z
IBAT = 0
Figure 8. Charger State Diagram (2-Pin Status)
21
MAX8900A/MAX8900B/MAX8900C
1.2A Switch-Mode Li+ Chargers with ±22V Input
Rating and JEITA Battery Temperature Monitoring
Charger Disabled State
When CEN is high or the input voltage is out of range, the
MAX8900_ disables the charger. To exit this state, CEN must
be low and the input voltage must be within its valid range.
Dead-Battery State
When a deeply discharged battery is inserted with a
voltage of less than VPQLTH, the MAX8900_ disables the
switching charger and linearly charges with IDBAT. If the
MAX8900_ remains in this dead-battery state for longer
than tPQ, then it transitions to the timer fault state. This
dead-battery state prevents the MAX8900_ from dissipating excessive power in the event of a shorted battery.
Once VBAT increases beyond VPQLTH, the MAX8900_
transitions to the dead battery + prequalification state.
Dead Battery + Prequalification State
The dead battery + prequalification state occur when
the battery voltage is greater than VPQLTH and less than
VDBAT. In this state, both the linear dead-battery charger
and the switching charger are on and delivering current
to the battery. The total battery current is IDBAT + IPQ. If
the MAX8900_ remains in this state for longer than tPQ,
then it transitions to the timer fault state. A normal battery typically stays in the dead-battery + prequalification
state for several minutes or less and when the battery
voltage rises above VDBAT, the MAX8900_ transitions to
the prequalification state.
Prequalification State
The prequalification state occurs when the battery voltage is greater than VDBAT and less than VPQUTH.
In this state, the linear dead-battery charger is turned
off and only the switching charger is on and delivering
current to the battery. The total battery current is IPQ. If
the MAX8900_ remains in this state for longer than tPQ,
then the MAX8900_ transitions to the timer fault state. A
normal battery typically stays in the prequalification state
for several minutes or less and when the battery voltage
rises above VPQUTH, the MAX8900_ transitions to the
fast-charge constant current state.
As shown in Figure 10, the prequalification current and
done threshold is set to 50% of programmed value when
T1 < THM < T2, and 100% of programmed value when
T2 < THM < T4.
Fast-Charge Constant Current State
The fast-charge constant current state occurs when the
battery voltage is greater than VPQUTH and less than
VBATREG. In this state, the switching charger is on and
22
delivering current to the battery. The total battery current
is IFC. If the MAX8900_ remains in this state and the fastcharge constant voltage state for longer than tFC, then
the MAX8900_ transitions to the timer fault state. When
the battery voltage rises to VBATREG, the MAX8900_
transitions to the fast-charge constant voltage state. As
shown in Figure 10, the fast-charge constant current is
set to 50% of programmed value when T1 < THM < T2,
and 100% of programmed value when T2 < THM < T4.
The MAX8900_ dissipates the most power in the fastcharge constant current state. This power dissipation
causes the internal die temperature to rise. If the die temperature exceeds TREG, IFC is reduced. See the Thermal
Foldback section for more detail.
If there is low input voltage headroom (VIN - VBAT), then
IFC decreases due to the impedance from IN to BAT. See
Figure 13 for more detail.
Fast-Charge Constant Voltage State
The fast-charge constant voltage state occurs when the
battery voltage is at the VBATREG and the charge current
is greater than IDN. In this state, the switching charger is
on and delivering current to the battery. The MAX8900_
maintains VBATREG and monitors the charge current to
detect when the battery consumes less than the IDN current. When the charge current decreases below the IDN
threshold, the MAX8900_ transitions to the top-off state.
If the MAX8900_ remains in the fast-charge constant
current state and this state for longer than tFC, then the
MAX8900_ transitions to the timer fault state. Please note
when the battery temperature is between T3 and T4 the
BAT regulation voltage is reduced to 4.075V.
The MAX8900_ offers an adjustable done current threshold (IDN) from 10mA to 200mA. The accuracy of the
top-off current threshold is Q1mA when it is set for 10mA.
This accurate threshold allows the maximum amount of
charge to be stored in the battery before the MAX8900_
transitions into done state.
Top-Off State
The top-off state occurs when the battery voltage is
at VBATREG and the battery current decreases below
IDN. In this state, the switching charger is on and delivers current to the battery. The MAX8900_ maintains
VBATREG for a specified time (tTO). When tTO expires,
the MAX8900_ transitions to the done state. If the charging current increases to IDN + 1mA before tTO expires,
then the charger re-enters the fast-charge constant voltage state.
1.2A Switch-Mode Li+ Chargers with ±22V Input
Rating and JEITA Battery Temperature Monitoring
Timer Fault State
The timer fault state occurs when either the prequalification or fast-charge timers expire, or SETI/DNI is shorted
to ground (see the Setting the Fast-Charge Current
(SETI) and Setting the Prequalification Current and Done
Threshold (DNI) sections for more details). In this state
the charger is off. The charger can exit the timer fault
state by either cycling CEN or input power.
Battery Hot/Cold State
The battery hot/cold state occurs when the MAX8900_ is
in any of its charge states (dead battery, prequalification,
fast-charge, top-off) and thermistor temperature is either
less than T1 or greater than T4. In this state, the charger
is off and timers are suspended. The MAX8900_ exits
the temperature suspend state and returns to the state
it came from once the thermistor temperature is greater
than T1 and less than T4. The timer resumes once the
MAX8900_ exits this state.
VIN Too High State
The VIN too high state occurs when the MAX8900_ is in
any of its charge states (dead battery, prequalification,
fast-charge, top-off) and VIN exceeds VOVLO. In this
state, the charger is off and timers are suspended. The
MAX8900_ exits the VIN too high state and returns to the
state it came from when VIN decreases below VOVLO.
The timer resumes once the MAX8900_ exits this state.
Charge Timer (CT)
As shown in Figure 7, a fault timer prevents the battery
from charging indefinitely. In the dead-battery, prequalification, and fast-charge states, the timer is controlled
by the capacitance at CT (CCT). The MAX8900_ supports values of CCT from 0.01FF to 1.0FF. Calculate the
prequalification time (tPQ) and fast-charge time (tFC) as
follows (Figure 9):
MAX8900A/MAX8900B/MAX8900C
Done State
The MAX8900_ enters its done state after the charger
has been in the top-off state for tTO. In this state, the
switching charger is off and no current is delivered to
the battery. Although the charger is off, the SETI and
DNI pins are biased in the done state and the MAX8900_
consumes the associated current from the battery (IBAT
= 1.5V/RSETI + 1.5V/RDNI + 3FA). If the system load
presented to the battery is low (<< 100FA), then a typical system can remain in the done state for many days.
If left in the done state long enough, the battery voltage
decays below the restart threshold (VRSTRT) and the
MAX8900_ transitions back into the fast-charge state.
There is no soft-start (di/dt limiting) during the done-tofast-charge state transition.
CHARGE TIMES
vs. CHARGE TIMER CAPACITOR
2000
1800
CHARGE TIMES (min)
1600
1400
1200
tFC
1000
800
600
tPQ
400
200
0
0
200
400
600
800
1000
CCT (nF)
tFC
CCT
(nF)
tPQ
(min)
(min)
(hrs)
tTO
(s)
68
20.4
122.4
2
16
100
30.0
180.0
3
16
150
45.0
270.0
4.5
16
220
66.0
396.0
6.6
16
470
141.0
846.0
14.1
16
1000
300.0
1800.0
30.0
16
Figure 9. Charge Times vs. CCT
t PQ = 30min ×
C CT
0.1FF
t FC = 180min ×
C CT
0.1FF
The top-off time (tTO) is fixed at 16s:
t TO = 16s
Connect CT to GND to disable the prequalification/deadbattery and fast-charge timers. With the internal timers of
the MAX8900_ disabled, an external device, such as a
FP can control the charge time through the CEN input.
Thermal Management
The MAX8900_ is packaged in a 2.44mm x 2.67mm x
0.64mm, 0.4mm pitch WLP package and withstands
a junction temperature of +150NC. The MAX8900_ is
rated for the extended ambient temperature range from
-40NC to +85NC. Table 1 and Application Note 1891:
Wafer-Level Packaging (WLP) and Its Applications
(www.maxim-ic.com/ucsp) show the thermal characteristics of this package. The MAX8900_ uses several
23
MAX8900A/MAX8900B/MAX8900C
1.2A Switch-Mode Li+ Chargers with ±22V Input
Rating and JEITA Battery Temperature Monitoring
Table 1. 2.44mm x 2.67mm x
0.64mm, 0.4mm Pitch WLP Thermal
Characteristics
FOUR-LAYER PCB
(JESD51-9:2s2p)
Continuous Power
Dissipation
BJA
BJC
Board Parameters
1619mW
Derate 20.2mW/NC above
+70NC/W
49.4NC/W
9NC/W
•
•
•
•
•
•
•
•
Still air
4-layer board
1.5oz copper on outer layers
1oz copper on inner layers
1.6mm thick board (62mil)
4in x 4in board
Four center thermal vias
FR-4
thermal management techniques to prevent excessive
battery and die temperatures.
Thermistor Monitor (THM)
The MAX8900_ adjusts the charge current and termination voltage as described in the JEITA specification for
safe use of secondary Li+ batteries (A Guide to the Safe
Use of Secondary Lithium Ion Batteries in Notebook-type
Personal Computers, April 20, 2007). As shown in Figure
10, there are four temperature thresholds that change
the battery charger operation: T1, T2, T3, and T4. When
the thermistor input exceeds the extreme temperatures
(< T1 or > T4), the charger shuts off and all respective
charging timers are suspended. While the thermistor
remains out of range, no charging occurs, and the timer
counters hold their state. When the thermistor input
comes back into range, the charge timers continue to
count. The middle thresholds (T2 and T3) do not shut
the charger off, but adjust the current/voltage targets
to maximize charging while reducing battery stress.
Between T3 and T4, the voltage target is reduced (see
VBATREG in the Electrical Characteristics table); however, the charge timers continue to count. Between T1
and T2, the charging current target is reduced to 50%
of its normal operating value; and similarly the charge
timers continue to count.
24
If the thermistor functionality is not required, connect a
1MI resistor from THM to AVL and another 1MI resistor from THM to GND. This biases the THM node to be
½ of the AVL voltage telling the MAX8900_ that the battery temperature is between the T2 and T3 temperature
range. Furthermore, the high 2MI impedance presents
a minimal load to AVL.
Table 2 shows that the MAX8900_ is compatible with
several standard thermistor values. When using a 10kI
thermistor with a beta of 3380K, the configuration of
Figure 11A provides for temperature trip thresholds that
are very close to the nominal T1, T2, T3, and T4 (see the
Electrical Characteristics table). When using alternate
resistance and/or beta thermistors, the circuit of Figure
11A may result in temperature trip thresholds that are different from the nominal values. In this case, the circuit of
Figure 11B allows for compensating the thermistor to shift
the temperature trip thresholds back to the nominal value.
In general, smaller values of RTP shift all the temperature
trip thresholds down; however, the lower temperature
thresholds are affected more then the higher temperature
thresholds. Furthermore, larger values of RTS shift all
the temperature trip thresholds up; however, the higher
temperature thresholds are affected more than the lower
temperature thresholds. For assistance with thermistor
calculations, use the spreadsheet at the following link:
www.maxim-ic.com/tools/other/software/MAX8900THERMISTOR.XLS
The general relation of thermistor resistance to temperature is defined by the following equation:
R THRM = R 25
 
1
1 
β 

+
N
NC  
T
273
C
298

xe 
where:
RTHRM = The resistance in I of the thermistor at tem
perature T in Celsius.
R25 = The resistance in I of the thermistor at TA =
+25NC.
ß = The material constant of the thermistor, which
typically ranges from 3000K to 5000K.
T = The temperature of the thermistor in NC.
1.2A Switch-Mode Li+ Chargers with ±22V Input
Rating and JEITA Battery Temperature Monitoring
THERMISTOR
RTHRM at TA = +25NC
Thermistor Beta (ß[I])
RTB (I)
TEMPERATURE
10,000
10,000
10,000
47,000
47,000
100,000
100,000
3380
3940
3940
4050
4050
4250
4250
10,000
10,000
10,000
47,000
47,000
100,000
100,000
OPEN
OPEN
301,000
OPEN
1,200,000
OPEN
1,800,000
RTS (I)
SHORT
SHORT
499
SHORT
2,400
SHORT
6,800
Resistance at T1_n15 (I)
61,788
61,788
77,248
290,410
380,716
617,913
934,027
Resistance at T1_0 (I)
29,308
29,308
31,971
137,750
153,211
293,090
343,283
Resistance at T2 (I)
15,000
15,000
15,288
70,500
72,500
150,002
156,836
Resistance at T3 (I)
5,309
5,309
4,906
24,954
23,083
53,093
47,906
Resistance at T4 (I)
2,910
2,910
2,439
13,676
11,434
29,099
22,777
Temperature at T1_n15 (NC) [-15NC nom]
-16.2
-11.1
-14.9
-10.2
-14.8
-8.7
-15.4
Temperature at T1_0 (NC) [0NC nom]
-0.8
2.6
0.9
3.2
1.2
4.1
1.3
Temperature at T2 (NC) [+15NC nom]
14.7
16.1
15.7
16.4
15.8
16.8
15.9
Temperature at T3 (NC) [+45NC nom]
42.6
40.0
42.0
39.6
41.5
38.8
41.2
Temperature at T4 (NC) [+60NC nom]
61.4
55.7
60.6
54.8
59.6
53.2
59.2
BAT REGULATION VOLTAGE (V)
RTP (I)
*CONTACT FACTORY FOR A 4.1V
OPTION FOR VBATREG.
4.2V
4.2
4.1V*
4.1
4.075V
4.0
15
T2
-40
T1
25
45
T3
60
T4
85
BATTERY TEMPERATURE (°C)
IFC =
3405V
RSETI
CHARGE CURRENT (A)
T1 = 0°C for MAX8900A/MAX8900C
T1 = -15°C for MAX8900B
IFC =
3405V
2 x RSETI
IPQ =
IPQ =
415V
RDNI
415V
2 x RDNI
IDBAT
-40
T1
15
T2
25
45
T3
60
T4
85
BATTERY TEMPERATURE (°C)
Figure 10. JEITA Battery Safety Regions
25
MAX8900A/MAX8900B/MAX8900C
Table 2. Trip Temperatures for Different Thermistors
A. BASIC THERMISTOR CONFIGURATION
AVL: E5
RTB
AVL
B. ADVANCED THERMISTOR CONFIGURATION
AVL: E5
AVL IS THE
INTERNAL
ANALOG SUPPLY
MAX8900_
THM: E4
RTHRM
T
AVL
RTB
AVL IS THE
INTERNAL
ANALOG SUPPLY
MAX8900_
THM: E4
RTP
COLD: T1
THERMOMETER
DECODE LOGIC
RTS
T
BAT_T
COLD: T1
RTHRM
THERMOMETER
DECODE LOGIC
COOL: T2
BAT_T
COOL: T2
TO DC-DC
CHARGE
CONTROLLER
TO DC-DC
CHARGE
CONTROLLER
WARM: T3
WARM: T3
HOT: T4
HOT: T4
Figure 11. Thermistor Monitor Detail
Thermal Foldback
Thermal foldback maximizes the battery charge current
while regulating the MAX8900_ junction temperature. As
shown in Figure 12, when the die temperature exceeds
TREG, a thermal limiting circuit reduces the battery
charge-current target by ATREG, until the charge current reaches 25% of the fast-charge current setting. The
charger maintains 25% of the fast-charge current until
the die temperature reaches TSHDN. Please note that
the MAX8900_ is rated for a maximum ambient temperature of +85NC. Furthermore, although the maximum die
temperature of the MAX8900_ is +150NC, it is common
industry practice to design systems in such a way that
the die temperature never exceeds +125NC. Limiting the
maximum die temperature to +125NC extends long-term
reliability.
Thermal Shutdown
As shown in Figure 12, when the MAX8900_ die temperature exceeds TSHDN, the IC goes into thermal shutdown.
During shutdown, the step-down charger is off and all
internal blocks except the bias circuitry is turned off. Once
the junction has cooled by 15NC, the IC resumes operation.
CHARGE CURRENT
vs. JUNCTION TEMPERATURE
1.4
T2 < VTHM < T3
1.2
1.0
ICHG (A)
MAX8900A/MAX8900B/MAX8900C
1.2A Switch-Mode Li+ Chargers with ±22V Input
Rating and JEITA Battery Temperature Monitoring
IFC = 1.19A
0.8
0.6
IFC = 0.756A
0.4
0.2
0
50
75
100
125
150
175
TJ (°C)
Figure 12. Charge Current vs. Junction Temperature
26
1.2A Switch-Mode Li+ Chargers with ±22V Input
Rating and JEITA Battery Temperature Monitoring
When the status outputs are used to drive LED indicators,
a series resistor should limit the LED current to be less
than 30mA (Figure 1). The STAT1 and STAT2 typical pulldown resistance is 25I and the absolute maximum rating
is +30V. This +30V rating allows IN to be used to bias
STAT1 and STAT2. The STAT3 typical pulldown resistance is 10I and the absolute maximum rating is +6V.
As shown in Figure 3, AVL is a filtered output from the
PVL linear regulator that the MAX8900_ uses to power its
internal analog circuits. The filter consists of an internal
12.5I resistor and the AVL external bypass capacitor
(0.1FF). This filter creates a 127kHz lowpass filter that
cleans the 3.25MHz switching noise from the analog portions of the MAX8900_. Connect a 0.1FF ceramic capacitor from AVL to GND. Powering external loads with AVL
is not recommended.
STAT1 and STAT2 are open-drain outputs that indicate
the status of the MAX8900A as shown in Table 4.
Charge Status Outputs (3 Pin)
When the status outputs are used to drive LED indicators, a series resistor should limit the LED current to
be less than 30mA (Figure 1). Note that the STAT1 and
STAT2 typical pulldown resistance is 25I and the absolute maximum rating is +30V. This +30V rating allows IN
to be used to bias STAT1 and STAT2.
STAT1, STAT2, and STAT3 are open-drain outputs that
indicate the status of the MAX8900B/MAX8900C as
shown in Table 3.
When the status outputs are used to communicate with a
FP, pull them up to the system logic voltage (VLOGIC) to
create a signal that has a logic-high and logic-low state that
the FP can easily interpret (Figure 2). Since more than one
status signal may change when the MAX8900B/MAX8900C
changes states, the FP must implement a deglitching
routine for the interpretation of the status signals.
Table 3. 3-Pin Status Output Truth Table
STAT1
STAT2
STAT3
INDICATION
0
0
0
Battery cold (THM < T1)
0
0
1
VIN > VOVLO
0
1
0
Charging (dead-battery state or
dead battery + prequalification
state or prequalification state or
fast-charge state)
0
1
1
Battery hot (THM >T4)
1
0
0
Done state
1
0
1
Undefined. This
state does not occur.
1
1
0
Timer fault
1
1
1
VIN < VUVLO or CEN = 1 or
VIN < (VBAT + VIN2BAT) or
thermal shutdown
Note: STAT1, STAT2, and STAT3 are open-drain outputs. “0”
indicates that the output device is pulling low. “1” indicates
that the output is high impedance.
Charge Status Outputs (2 Pin + > T4)
When the status outputs are used to communicate with a
FP, pull them up to the system logic voltage (VLOGIC) to
create a signal that has a logic-high and logic-low state
that the FP can easily interpret (Figure 2). Since more
than one status signal may change when the MAX8900A
changes states, the FP must implement a deglitching
routine for the interpretation of the status signals.
STAT3 pulls low when the battery temperature monitor detects that the battery temperature is greater than
the T4 threshold, otherwise, STAT3 is high impedance.
Some systems may want to reduce the battery loading
when STAT3 pulls low to prevent the battery from getting
excessively hot.
Table 4. 2-Pin Status Output Truth Table
STAT1
STAT2
INDICATION
0
0
Undefined. This does not occur
when the MAX8900_ is powered.
0
1
Charging (dead-battery state or
dead battery + prequalification state
or prequalification state or fastcharge state)
1
0
Timer fault or VIN > VOVLO or battery cold (THM < T1) or battery hot
(THM > T4)
1
1
Done state or CEN = 1 or VIN <
VUVLO or VIN < (VBAT + VIN2BAT) or
thermal shutdown
Note: STAT1 and STAT2 are open-drain outputs. “0” indicates
that the output device is pulling low. “1” indicates that the output is high impedance.
27
MAX8900A/MAX8900B/MAX8900C
PVL and AVL Regulator
PVL is a 5V linear regulator that the MAX8900_ uses to
power the gate drivers for its step-down charger. PVL
also charges the BST capacitor. The PVL linear regulator
is on when CEN is low, VIN is greater than ~2V, and VIN
is above VBAT by the VIN2BAT threshold, otherwise it is
off. Bypass PVL with a 1FF ceramic capacitor to GND.
Powering external loads from PVL is not recommended.
MAX8900A/MAX8900B/MAX8900C
1.2A Switch-Mode Li+ Chargers with ±22V Input
Rating and JEITA Battery Temperature Monitoring
Inductor Selection
Consider inductance, current rating, series resistance,
physical size, and cost when selecting an inductor.
These factors affect the converter’s efficiency, maximum
output current, transient response time, and output voltage ripple. Tables 5 and 6 show suggested inductor
values based upon input voltage and laboratory tests.
When using the MAX8900_ with IN voltages below 8.5V,
select the inductor to be 1.0FH. This keeps the inductor
peak-to-peak ripple current to the average DC inductor
current at the full load (LIR) between 40% to 50%. If a
lower ripple is desired, select an inductance from 2.2FH
Table 5. Recommended Inductor Selection
DC INPUT VOLTAGE
RANGE (V)
RECOMMENDED INDUCTOR
FOR 40% LIR
3.4 to 8.7
1FH inductor, LQM2HPN1R0G0, Murata,
2.5mm x 2.0mm x 0.9mm, 55mI, 1.6A.
8.7 to 15.8
1.5FH inductor, LQM2HPN1R5G0, Murata,
2.5mm x 2.0mm x 0.9mm, 70mI, 1.5A
15.8 to 27.4
2.2FH inductor, LQM2HPN2R2G0, Murata,
2.5mm x 2.0mm x 0.9mm, 80mI, 1.3A.
to 10FH. Higher input voltages require higher inductors
to maintain the same inductor current ripple.
The trade-off between inductor size and converter efficiency for step-down regulators varies as the LIR varies.
LIR is the ratio of the inductor peak-to-peak ripple current
to the average DC inductor current at the full-load current. A higher LIR value allows for smaller inductance, but
result in higher losses and higher output voltage ripple.
To reduce the power dissipation and improve transient
response, choose an inductor that has a low DC series
resistance as well as a low AC resistance at 3.25MHz.
Note that it is typical for low inductance inductors such
as 1FH to have a Q30% initial variation in inductance.
Furthermore, some physically smaller inductors show a
substantial degradation in inductance with increased DC
current. It is typical for inductor manufacturers to specify
their saturation current at the level when the initial inductance decreases by 30% or at the level where the internal inductor temperature rises +40NC above the ambient
temperature. Because of differences in the way inductor
manufacturers specify saturation current (ISAT), it is critical that you study and understand your manufacturer’s
specification criteria.
Table 6. Recommended Inductor
MANUFACTURER
SERIES
Coilcraft
EPL2014
LQM2MPN_G0
Murata
LQM2HPN_G0
MLP2520S
TDK
CPL2512
MDT2520-CH
TOKO
MDT2520-CN
28
INDUCTANCE (μH)
1.0
1.5
2.2
1.0
1.5
2.2
3.3
1.0
1.5
2.2
3.3
1.0
1.5
1.0
2.2
1.0
1.5
2.2
1.0
1.5
2.2
3.3
ESR (I)
0.059
0.075
0.120
0.085
0.110
0.110
0.120
0.055
0.070
0.080
0.100
0.060
0.070
0.090
0.135
0.110
0.140
0.16
0.085
0.095
0.105
0.115
CURRENT RATINGS (A)
1.68
1.60
1.30
1.40
1.20
1.20
1.20
1.60
1.50
1.30
1.20
1.50
1.50
1.20
0.90
1.20
1.10
1.05
1.35
1.25
1.20
1.15
DIMENSIONS
2.0 x 2.0 x 1.4 = 5.6mm3
2.0 x 1.6 x 0.9 = 2.88mm3
2.5 x 2.0 x 0.9 =4.5mm3
2.0 x 2.5 x 1.0 = 5mm3
2.5 x 1.5 x 1.2 = 3.6mm3
2.5 x 2.0 x 1.0 = 5mm3
2.5 x 2.0 x 1.2 = 6mm3
1.2A Switch-Mode Li+ Chargers with ±22V Input
Rating and JEITA Battery Temperature Monitoring
RDROPOUT = RIN2INBP + RHS + RL +
RSNS = 0.120I + 0.100I + RL + 0.040I
RDROPOUT heavily depends upon the inductor ESR (RL).
A low RL is required to maximize performance.
BAT Capacitor
Choose the nominal BAT capacitance to be 2.2FF. The
BAT capacitor is required to keep the BAT voltage ripple
small and to ensure regulation loop stability. The BAT
capacitor must have low impedance at the switching
frequency. Ceramic capacitors with X5R or X7R dielectric
are highly recommended due to their small size, low ESR,
and small temperature coefficients. For optimum loadtransient performance and very low output voltage ripple,
the BAT capacitor value can be increased above 2.2FF.
As the case sizes of ceramic surface-mount capacitors decreases, their capacitance vs. DC bias voltage
characteristic becomes poor. Due to this characteristic,
it is possible for 0603 capacitors to perform well while
0402 capacitors of the same value perform poorly. The
MAX8900_ require a nominal BAT capacitance of 2.2FF,
however, after initial tolerance, bias voltage, aging, and
temperature derating, the capacitance must be greater
than 1.5FF. With the capacitor technology that is available
at the time the MAX8900_ was released to production, the
BAT capacitance is best achieved with a single ceramic
capacitor (X5R or X7R) in an 0603 or 0805 case size. The
capacitor voltage ratings should be 6.3V or greater.
CALCULATED FAST-CHARGE CURRENT
vs. DROPOUT VOLTAGE
1.4
FAST-CHARGE CURRENT (A)
1.2
RL = 40mI
1.0
IFC = 1200mA
0.8
0.6
0.4
RL = 300mI
0.2
IFC = 500mA
0
0
0.2
0.4
0.6
0.8
1.0
VIN - VBAT (V)
Figure 13. Calculated Fast-Charge Current vs. Dropout Voltage
INBP Capacitor
Choose the INBP capacitance (CINBP) to be 0.47FF.
Larger values of CINBP improve the decoupling for the
DC-DC step-down converter, but they cause a larger IN to
INBP inrush current when the input adapter is connected.
To limit the IN inrush current (IIN) to the 2.4A maximum
(see the Absolute Maximum Ratings section), limit CINBP
by the maximum input voltage slew rate (VINSR) on IN:
CINBP < 2.4A/VINSR.
CINBP reduces the current peaks drawn from the battery
or input power source during switch-mode operation and
reduces switching noise in the MAX8900_. The impedance
of the input capacitor at the switching frequency should be
very low. Ceramic capacitors with X5R or X7R dielectric are
highly recommended due to their small size, low ESR, and
small temperature coefficients. For optimum noise immunity
and low input voltage ripple, the input capacitor value can
be increased. To fully utilize the Q22V input capability of the
MAX8900_, the INBP capacitor voltage rating must be 25V
or greater. Note that if VIN falls below VBAT, VINBP remains
at the VBAT potential (i.e., a -20V at IN does not pull down
INBP). Because VINBP never goes negative, it is possible to
use a polarized capacitor (Maxim recommends a ceramic
capacitor).
INBP is a critical discontinuous current path that requires
careful bypassing. In the PCB layout, place CINBP as
close as possible to the power pins (INBP and PGND)
to minimize parasitic inductance. If making connections
to the INBP capacitor through vias, ensure that the vias
are rated for the expected input current so they do not
contribute excess inductance and resistance between the
bypass capacitor and the power pins. The expected INBP
current is the same as the ISAT (see the Inductor Selection
section). See the PCB Layout section for more details.
The input capacitor must meet the input ripple current
requirement imposed by the step-down converter. Ceramic
capacitors are preferred due to their low ESR and resilience
to surge currents. Choose the INBP capacitor so that its temperature rise due to ripple-current does not exceed approximately TA = +10NC. For a step-down regulator, the maximum input ripple current is half of the output current. This
maximum input ripple current occurs when the step-down
converter operates as 50% duty cycle (VIN = 2 x VBAT).
Other Capacitors
The minimum IN capacitor (CIN) is 0.47FF with a voltage
rating of 25V or greater. Note that although the MAX8900_
needs only 0.47FF, larger capacitors can be used. Some
specifications from USB-IF require a 2.2FF capacitor to
have proper handshaking during OTG operation. The BST
29
MAX8900A/MAX8900B/MAX8900C
If the input voltage approaches the BAT voltage during
fast-charge constant current state, the maximum current
is no longer limited by the current loop, but by the dropout resistance. The total dropout resistance is:
MAX8900A/MAX8900B/MAX8900C
1.2A Switch-Mode Li+ Chargers with ±22V Input
Rating and JEITA Battery Temperature Monitoring
capacitor (CBST) is a 0.1FF with a voltage rating of 10V or
greater. If CBST is increased then maintain a ratio of less
than 1:10 between CBST and CPVL. CBST stores charge
to drive the high-side n-channel gate. The minimum AVL
capacitor is 0.1FF with a voltage rating of 6.3V. The minimum PVL capacitor is 1.0FF with a voltage rating of 6.3V.
Ceramic capacitors with X5R or X7R dielectric are highly
recommended due to their small size, low ESR, and small
temperature coefficients.
Applications Information
Dynamic Charge Current Programming
Certain applications require dynamic programming of the
charge current. For example, if the input supply is a USB
source, then the system might need to adjust the charge
current to support the 100mA and 500mA input current
ratings dictated by the USB-IF. Figure 2 illustrates one
approach to dynamically program the charge current. By
driving the gates of two MOSFET switches to logic-high
or logic-low, a microprocessor (FP) connects or disconnects different program resistors. This method allows for
four different charge current values ranging from 95mA
to 1187mA. When a MOSFET is turned on, its associated
resistor is connected to SETI. As resistors are added
in parallel, the total resistance from SETI to ground
decreases, which causes IFC to increase.
In the particular example of a USB input, the circuit of
Figure 2 could be leveraged as follows: When a VBUS
connect event is detected, the FP can immediately initiate the USB 100mA current mode by setting GPIO[6:4]
= 0b000. After the USB transceiver has enumerated with
500mA permission, the FP can initiate the USB 500mA
current mode by setting GPIO[6:4] = 0b010. If the USB
transceiver detects that a USB suspend is needed, then
the FP can reduce the input current to 40FA by setting GPIO[6:4] = 0b001. Alternatively, it is possible that
after the VBUS connect event that the USB transceiver
determines that there is a dedicated USB wall charger
(D+ and D- shorted together) and then the FP can set
the charge current to the full capability of the MAX8900_
(1.2A) by setting GPIO[6:4] = 0b110.
No-Battery Operation
No-battery operation may be necessary in the application and/or end-of-line testing during production. The
MAX8900_ can operate a system without a battery as
long as the following conditions are satisfied:
U The system must not draw load currents that are
greater than IFC.
30
U The system must not draw load currents that are
greater than IPQ when the battery is less than VPQUTH.
U The thermistor node (THM) must be satisfied. Note
that if the thermistor is in the battery pack and the
pack is removed, the MAX8900_ THM node voltage
goes high and disables the charger. If the MAX8900_
is expected to deliver charge without a battery then
VTHM must be forced to AVL/2.
U The battery node should have enough capacitance
to hold the battery voltage to some minimum acceptable system value (VSYSRST) during the done-to-fastcharge state transition time of 100Fs (tDONE2FC).
C BAT ≥ ILOAD ×
t DONE2FC
VBATREG - VSYSRST
For example, if the maximum system load without a
battery could be 300mA (ILOAD) and the minimum
acceptable system voltage is 3.4V (VSYSRST), then
the battery node should have at least 37.5FF.
C BAT ≥ 300mA ×
100Fs
= 35.7FF
4.2V - 3.4V
Charge-Source Issues
A battery charger’s input is typically very accessible to
the end-user (i.e., available on a connector) and can
potentially be exposed to very harsh conditions. The
MAX8900_ provides for high-reliability solution that can
survive harsh conditions seen on its input.
Charge-Source Impedance
Charge source impedance can vary due to quality of
the charge source and the associated connectors. The
MAX8900_ operates very nicely with input impedance
up to 1I. When high input impedances cause the input
voltage to drop, the MAX8900_ simply reduces the
charge current to a sustainable level and tries to put as
much energy into the battery as possible. If the input
voltage falls within the VIN2BAT threshold of the battery
voltage, the MAX8900_ shuts down to prevent any current flowing from the battery back to the charger source.
The MAX8900_ does not suffer from the self-oscillation
problems that plague other chargers when exposed to
high-impedance sources.
Inductive Kick
Often the input source has long leads connecting to the
MAX8900_, which, during connection and disconnect,
can cause voltage spikes. The lead inductance and the
input capacitor create an LC tank circuit. In the event
that the LC tank circuit has a high Q (i.e., low series
1.2A Switch-Mode Li+ Chargers with ±22V Input
Rating and JEITA Battery Temperature Monitoring
In the event that an application may see a high-Q LC
tank circuit in the cabling for a supply that is > +11V, a
resistor (RIN) must be added in series with CIN to reduce
the Q of the tank circuit. The resistor value can be found
experimentally by assuming the parasitic inductance
(LPAR) of the input cabling is 1FH/m, then use the following equation give a good starting value for RIN:
RIN = 2 ×
L PAR
CIN
An alternative method for estimating LPAR is to measure
the frequency of the input voltage spike ringing and then
calculate LPAR from the following equation.
L PAR =
1
(2 × π × fR ) × CIN
Overvoltage and Reverse Input Voltage Protection
The MAX8900_ provides for a +22V absolute maximum
positive input voltage and a -22V absolute maximum
negative input voltage. Excursions to the absolute maximum voltage levels should be on a transient basis only,
but can be withstood by the MAX8900_ indefinitely.
Situations that typically require extended input voltage
ratings include but are not limited to the following:
U Inductive kick
U Charge source failure
U Power surge
U Improperly wired wall adapter
U Improperly set universal wall adapter
U Wall adapter with the correct plug, but wrong voltage
U Home-built computer with USB wiring harness connected backwards (negative voltage)
U USB connector failure
U Excessive ripple voltage on a switch-mode wall charger
U USB powered hub that is powered by a wall charger
(typically through a barrel connector) that has any of
the aforementioned issues
U Unregulated charger (passively regulated by the
turns ratio of the magnetic’s turns ratio)
U Automotive environment (9V, 12V, any of the aforementioned in reverse).
PCB Layout
The MAX8900_ WLP package and bump configuration
allows for a small-size low-cost PCB design. Figures 3
and 14 show that the MAX8900_ package’s 30 bumps
are combined into 18 functional nodes. The bump configuration places all like nodes adjacent to each other to
minimize the area required for routing. The bump configuration also allows for a layout that does not use any
vias within the WLP bump matrix (i.e., no micro vias). To
utilize this no via layout, CEN is left unconnected and the
STAT3 pin is not used (2-pin status version).
Figure 15 shows the recommended land pattern for the
MAX8900_. Figure 16 shows the cross section of the
MAX8900_’s bump with detail of the under-bump metal
(UBM). The diameter of each pad in the land pattern is
close to the diameter of the UBM. This land pattern to
UBM relationship is important to get the proper reflow of
each solder bump.
Underfill is not necessary for the MAX8900_’s package to pass the JESD22-B111 Board Level Drop Test
Method for Handheld Electronic Products. JESD22-B111
covers end applications such as cell phones, PDAs,
cameras, and other products that are more prone to
being dropped during their lifetime due to their size and
weight. Please consider using underfill for applications
that require higher reliability than what is covered in the
JESD22-B111 standard.
Careful printed circuit layout is important for minimizing
ground bounce and noise. Figure 14 is an example layout
of the critical power components for the MAX8900_. The
arrangement of the components that are not shown in
Figure 14 is less critical. Refer to the MAX8900 Evaluation
Kit for a complete PCB layout example. Use the following
list of guidelines in addition to Application Note 1891:
Wafer-Level Packaging (WLP) and Its Applications (www.
maxim-ic.com/ucsp) to layout the MAX8900_ PCB.
31
MAX8900A/MAX8900B/MAX8900C
impedance), the voltage spike could be twice that of
the nominal source voltage. In other words, a 6V source
with a high-Q LC tank circuit in the cabling can result in
a voltage spike as high as 12V. The MAX8900_’s high
input absolute maximum voltage rating of +22V to -22V
eliminates any concerns about the voltage spikes due to
inductive kicking for many applications.
MAX8900A/MAX8900B/MAX8900C
1.2A Switch-Mode Li+ Chargers with ±22V Input
Rating and JEITA Battery Temperature Monitoring
The guidelines at the top are the most critical:
1) When the step-down converter’s high-side MOSFET
turns on, CINBP delivers a high di/dt current pulse to
INBP. Because of this high di/dt current pulse, place
CINBP close to INBP to minimize the parasitic impedance in the PCB trace.
2) When the step-down converter is increasing the current in the inductor, the high-side MOSFET is on and
current flows in the following path: from CINBP into
INBP >> out of LX >> through the inductor >> into CS
>> out of BAT >> through CBAT and back to CINBP
through the ground plane. This current loop should
be kept small and the electrical length from the positive terminal of CINBP to INBP should be kept short to
minimize parasitic impedance. The electrical length
from the negative terminal of CBAT to the negative
terminal of CINBP should be short to minimize parasitic impedance. Keep all sensitive signals such as
feedback nodes or audio lines outside of this current
loop with as much isolation as your design allows.
3) When the step-down converter is decreasing the
inductor current, the low-side MOSFET is on and
the current flows in the following path: out of LX >>
through the inductor >> into CS >> out of BAT >>
through CBAT >> into PGND >> out of LX again. This
current loop should be kept small and the electrical
length from the negative terminal of CBAT to PGND
should be short to minimize parasitic impedance.
Keep all sensitive signals such as feedback nodes or
audio lines outside of this current loop with as much
isolation as your design allows.
6) Both CBST and CPVL deliver current pulses for the
MAX8900_’s MOSFET drivers. These components
should be placed as shown in Figure 14 to minimize
parasitic impedance.
7) Each of the MAX8900_ bumps has approximately the
same ability to remove heat from the die. Connect as
much metal as possible to each bump to minimize the
BJA associated with the MAX8900_. See the Thermal
Management section for more information on BJA.
In Figure 14, many of the top layer bump pads are connected together in top metal. When connecting bumps
together with top layer metal, the solder mask must
define the pads from 180Fm to 210Fm as shown in
Figure 15. When using solder mask defined pads, please
double check the solder mask openings on the PCB
Gerber files before ordering boards as some PCB layout tools have configuration settings that automatically
oversize solder mask openings. Also, explain in the PCB
fabrication notes that the solder mask is not to be modified. Occasionally, optimization tools are used at the
PCB fabrication house that modify solder masks. Layouts
that do not use solder mask defined pads are possible.
When using these layouts, adhere to the recommendations A through G above.
4) The LX node voltage switches between INBP and
PGND during the operation of the step-down converter. Minimize the stray capacitance on the LX node
to maintain good efficiency. Also, keep all sensitive
signals such as feedback nodes or audio lines away
from LX with as much isolation as your design allows.
5) In Figure 14, the CS node is connected to the second
layer of metal with vias. Use low-impedance vias that
are capable of handling 1.5A of current. Also, keep
the routing inductor current path on layer 2 just underneath the inductor current path on layer 1 to minimize
impedance.
32
Figure 14. Power PCB Layout Example
1.2A Switch-Mode Li+ Chargers with ±22V Input
Rating and JEITA Battery Temperature Monitoring
TOP VIEW SCALE DRAWING
5x6 BUMP ARRAY (30 BUMPS)
1
2
3
4
5
WAFER
6
A: FINISHED PAD DIAMETER:
180µm (min)
210µm (max)
A
B
C
A
D
B
C
E
B: PAD PITCH: 400µm
C: HEIGHT: 1.6mm
EPOXY
COPPER PILLAR (UBM)
EPOXY
D: WIDTH: 2.0mm
EPOXY
G
F
A
COPPER PILLAR (UBM)
B
E
D
1oz COPPPER PAD
1oz COPPPER PAD
PCB
Figure 15. Recommended Land Pattern
E: BUMP DIAMETER: 260µm
F: COPPER PILLAR (UBM) WIDTH: 210µm
G: COPPER PILLAR PITCH: 400µm
Figure 16. Bump Cross Section and Copper Pillar Detail
Ordering Information (continued)
PART
MAX8900CEWV+T
TEMP PINRANGE PACKAGE
-40NC to
30 WLP
+85NC
OPTIONS
Chip Information
PROCESS: BiCMOS
VOVLO = 6.5V
T1 = 0NC
3-pin status indicators
VPQUTH = 3.0V
+Denotes a lead(Pb)-free/RoHS-compliant package.
T = Tape and reel.
33
MAX8900A/MAX8900B/MAX8900C
EPOXY
MAX8900A/MAX8900B/MAX8900C
1.2A Switch-Mode Li+ Chargers with ±22V Input
Rating and JEITA Battery Temperature Monitoring
Package Information
For the latest package outline information and land patterns, go to www.maxim-ic.com/packages. Note that a “+”, “#”, or “-” in the
package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing pertains to the
package regardless of RoHS status.
34
PACKAGE TYPE
PACKAGE CODE
OUTLINE NO.
LAND PATTERN NO.
30 WLP
W302A2+1
21-0211
Refer to Application Note 1891
1.2A Switch-Mode Li+ Chargers with ±22V Input
Rating and JEITA Battery Temperature Monitoring
REVISION
NUMBER
REVISION
DATE
0
1/10
Initial release
1
3/10
Corrected various items
2
8/10
Updated Figures 2, 3, 7, and 8 and related text to indicate the charge timer
applies to the dead-battery state and corrected other various errors
3
1/11
Added MAX8900C to data sheet
DESCRIPTION
PAGES
CHANGED
—
1, 4, 5, 15, 30
6,14, 15, 16, 20–22,
27, 31
1–35
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
© 2011
Maxim Integrated Products 35
Maxim is a registered trademark of Maxim Integrated Products, Inc.
MAX8900A/MAX8900B/MAX8900C
Revision History