EVALUATION KIT AVAILABLE
MAX8903A–E/G/H/J/N/Y
2A 1-Cell Li+ DC-DC Chargers
for USB and Adapter Power
General Description
The MAX8903A–MAX8903E/MAX8903G/MAX8903H/
MAX8903J/MAX8903N/MAX8903Y are integrated 1-cell
Li+ chargers and Smart Power Selectors™ with dual
(AC adapter and USB) power inputs. The switch mode
charger uses a high switching frequency to eliminate
heat and allow tiny external components. It can operate
with either separate inputs for USB and AC adapter
power, or from a single input that accepts both. All
power switches for charging and switching the load
between battery and external power are included onchip. No external MOSFETs, blocking diodes, or current-sense resistors are required.
The MAX8903_ features optimized smart power control
to make the best use of limited USB or adapter power.
Battery charge current and SYS output current limit are
independently set. Power not used by the system
charges the battery. Charge current and SYS output current limit can be set up to 2A while USB input current can
be set to 100mA or 500mA. Automatic input selection
switches the system from battery to external power. The
DC input operates from 4.15V to 16V with up to 20V protection, while the USB input has a range of 4.1V to 6.3V
with up to 8V protection.
The MAX8903_ internally blocks current from the battery and system back to the DC and USB inputs when
no input supply is present. Other features include prequal charging and timer, fast charge timer, overvoltage
protection, charge status and fault outputs, power-OK
monitors, and a battery thermistor monitor. In addition,
on-chip thermal limiting reduces battery charge rate
and AC adapter current to prevent charger overheating. The MAX8903_ is available in a 4mm x 4mm, 28-pin
thin QFN package.
The various versions of the MAX8903_ allow for design
flexibility to choose key parameters such as system
regulation voltage, battery prequalification threshold,
and battery regulation voltage. The MAX8903B/
MAX8903E/MAX8903G also includes power-enable on
battery detection. See the Selector Guide section for
complete details.
Features
o
o
o
o
o
o
o
o
Efficient DC-DC Converter Eliminates Heat
4MHz Switching for Tiny External Components
Instant On—Works with No/Low Battery
Dual Current-Limiting Inputs—AC Adapter or USB
Automatic Adapter/USB/Battery Switchover to
Support Load Transients
50mΩ System-to-Battery Switch
Supports USB Spec
Thermistor Monitor
Integrated Current-Sense Resistor
No External MOSFETs or Diodes
4.1V to 16V Input Operating Voltage Range
Ordering Information
TEMP RANGE
PIN-PACKAGE
MAX8903AETI+T
PART
-40°C to +85°C
28 Thin QFN-EP*
MAX8903BETI+T
-40°C to +85°C
28 Thin QFN-EP*
MAX8903CETI+T
-40°C to +85°C
28 Thin QFN-EP*
MAX8903DETI+T
-40°C to +85°C
28 Thin QFN-EP*
MAX8903EETI+T
-40°C to +85°C
28 Thin QFN-EP*
MAX8903GETI+T
-40°C to +85°C
28 Thin QFN-EP*
MAX8903HETI+T
-40°C to +85°C
28 Thin QFN-EP*
MAX8903JETI+T
-40°C to +85°C
28 Thin QFN-EP*
MAX8903NETI+T
-40°C to +85°C
28 Thin QFN-EP*
MAX8903YETI+T
-40°C to +85°C
28 Thin QFN-EP*
+Denotes a lead(Pb)-free/RoHS-compliant package.
*EP = Exposed pad.
T = Tape and reel.
Typical Operating Circuit
AC
ADAPTER
OR USB
LX
SYS
DC
CHARGE
CURRENT
Applications
PDAs, Palmtops, and
Wireless Handhelds
Personal Navigation
Devices
Smart Cell Phones
Portable Multimedia
Players
Mobile Internet Devices
Ultra Mobile PCs
CS
PWM
STEP-DOWN
USB
LOAD
CURRENT
CHARGE
AND
SYS LOAD
SWITCH
BAT
USB
SYSTEM
LOAD
BATTERY
Selector Guide appears at end of data sheet.
Visit www.maximintegrated.com/products/patents for
product patent marking information.
Smart Power Selector is a trademark of Maxim Integrated
Products, Inc.
MAX8903_
GND
Pin Configuration appears at end of data sheet.
For pricing, delivery, and ordering information, please contact Maxim Direct
at 1-888-629-4642, or visit Maxim’s website at www.maximintegrated.com.
19-4410; Rev 5; 9/11
MAX8903A–E/G/H/J/N/Y
2A 1-Cell Li+ DC-DC Chargers
for USB and Adapter Power
ABSOLUTE MAXIMUM RATINGS
DC, LX to GND .......................................................-0.3V to +20V
DCM to GND ..............................................-0.3V to (VDC + 0.3V)
DC to SYS .................................................................-6V to +20V
BST to GND ...........................................................-0.3V to +26V
BST TO LX ................................................................-0.3V to +6V
USB to GND .............................................................-0.3V to +9V
USB to SYS..................................................................-6V to +9V
VL to GND ................................................................-0.3V to +6V
THM, IDC, ISET, CT to GND........................-0.3V to (VVL + 0.3V)
DOK, FLT, CEN, UOK, CHG, USUS,
BAT, SYS, IUSB, CS to GND ................................-0.3V to +6V
SYS to BAT ...............................................................-0.3V to +6V
PG, EP (exposed pad) to GND .............................-0.3V to +0.3V
DC Continuous Current (total in two pins)......................2.4ARMS
USB Continuous Current.......................................................1.6A
LX Continuous Current (total in two pins).......................2.4ARMS
CS Continuous Current (total in two pins) ......................2.4ARMS
SYS Continuous Current (total in two pins) .......................3ARMS
BAT Continuous Current (total in two pins) .......................3ARMS
VL Short Circuit to GND .............................................Continuous
Continuous Power Dissipation (TA = +70°C)
28-Pin Thin QFN-EP
Multilayer (derate 28.6mW/°C above +70°C) ..........2286mW
28-Pin Thin QFN-EP
Single-Layer (derate 20.8mW/°C above +70°C)...1666.7mW
Operating Temperature Range ...........................-40°C to +85°C
Junction Temperature Range ............................-40°C to +150°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
Soldering Temperature (reflow) .......................................+260°C
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
ELECTRICAL CHARACTERISTICS
(VDC = VUSB = 5V, VBAT = 4V, circuit of Figure 2, TA = -40°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.)
(Note 1)
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
16
V
3.9
4.0
4.0
4.3
4.1
4.4
V
16.5
17
17.5
V
Charger enabled, no switching, VSYS = 5V
2.3
4
Charger enabled, f = 3MHz, VDC = 5V
15
Charger enabled, VCEN = 0V, 100mA USB mode (Note 2)
1
2
Charger enabled, VCEN = 5V, 100mA USB mode (Note 2)
VDCM = 0V, VUSUS = 5V
1
0.10
2
0.25
DC INPUT
DC Operating Range
4.15
No valid USB input
Valid USB input
DC Undervoltage Threshold
When VDOK goes low, VDC
rising, 500mV typical hysteresis
DC Overvoltage Threshold
When VDOK goes high, VDC rising, 500mV typical
hysteresis
DC Supply Current
DC High-Side Resistance
0.15
Ω
DC Low-Side Resistance
0.15
Ω
0.31
Ω
DC-to-BAT Dropout Resistance
Assumes a 40mΩ inductor resistance (RL)
DC-to-BAT Dropout Voltage
When SYS regulation and charging stops, VDC falling,
200mV hysteresis
0
15
30
mV
Minimum Off Time (tOFFMIN)
100
ns
Minimum On Time (tONMIN)
ns
VDC = 8V, VBAT = 4V
70
4
MAX8903A/B/C/D/E/H/J/Y
Switching Frequency (fSW)
MAX8903G
VDC = 5V, VBAT = 3V
3
VDC = 9V, VBAT = 4V
1
VDC = 9V, VBAT = 3V
1
DC Step-Down Output CurrentLimit Step Range
DC Step-Down Output Current
Limit (ISDLIM)
2
mA
0.5
VDC = 6V, VSYS = 4V
MHz
2
RIDC = 3kΩ
1900
2000
2100
RIDC = 6kΩ
RIDC = 12kΩ
950
450
1000
500
1050
550
A
mA
Maxim Integrated
MAX8903A–E/G/H/J/N/Y
2A 1-Cell Li+ DC-DC Chargers
for USB and Adapter Power
ELECTRICAL CHARACTERISTICS (continued)
(VDC = VUSB = 5V, VBAT = 4V, circuit of Figure 2, TA = -40°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.)
(Note 1)
PARAMETER
DC Soft-Start Time
DC Output Current
500mA USB Mode (Note 3)
DC Output Current
100mA USB Mode (Note 2)
SYS to DC Reverse Current
Blocking
CONDITIONS
MIN
TYP
MAX
UNITS
No valid USB input
1
ms
Valid USB input before soft-start
20
µs
VDCM = 0V, VIUSB = 5V
450
475
500
mA
VDCM = 0V, VIUSB = 0V
90
95
100
mA
VSYS = 5.5V, VDC = 0V
0.01
µA
USB INPUT
USB Operating Range
4.1
6.3
USB Standoff Voltage
V
8
V
USB Undervoltage Threshold
When VUOK goes low, VUSB rising, 500mV hysteresis
3.95
4.0
4.05
V
USB Overvoltage Threshold
When VUOK goes high, VUSB rising, 500mV hysteresis
6.8
6.9
7.0
V
USB Current Limit
VIUSB = 0V (100mA setting)
90
95
100
VIUSB = 5V (500mA setting)
450
475
500
1.3
3
ISYS = IBAT = 0mA, VCEN = 0V
USB Supply Current
ISYS = IBAT = 0mA, VCEN = 5V
VUSUS = 5V (USB suspend mode)
Minimum USB to BAT Headroom
0
USB to SYS Dropout Resistance
USB Soft-Start Time
0.8
2
0.115
0.25
15
30
0.2
0.35
mA
mA
mV
Ω
VUSB rising
1
ms
VDC falling below DC UVLO to initiate USB soft-start
20
µs
SYS OUTPUT
Minimum SYS Regulation Voltage
(VSYSMIN)
ISYS = 1A,
VBAT < VSYSMIN
Regulation Voltage
ISYS = 0A
MAX8903A/B/E/G/Y
3.0
MAX8903C/D/H/J/N
3.4
MAX8903A/C/D/H/N/Y
MAX8903B/E/G
MAX8903J
V
4.3
4.4
4.5
4.265
4.325
4.395
4.4
4.5
4.55
MAX8903A/C/D/H
40
MAX8903B/E/G/J/N/Y
25
V
Load Regulation
ISYS = 0 to 2A
CS to SYS Resistance
VDC = 6V, VDCM = 5V, VSYS = 4V, ICS = 1A
0.07
SYS to CS Leakage
VSYS = 5.5V, VDC = VCS = 0V
0.01
BAT to SYS Resistance
VDC = VUSB = 0V, VBAT = 4.2V, ISYS = 1A
0.05
0.1
Ω
BAT to SYS Reverse Regulation
Voltage
VUSB = 5V, VDC = 0V, VIUSB = 0V, ISYS = 200mA
50
75
100
mV
SYS Undervoltage Threshold
SYS falling, 200mV hysteresis (Note 4)
1.8
1.9
2.0
V
Maxim Integrated
mV/A
Ω
µA
3
MAX8903A–E/G/H/J/N/Y
2A 1-Cell Li+ DC-DC Chargers
for USB and Adapter Power
ELECTRICAL CHARACTERISTICS (continued)
(VDC = VUSB = 5V, VBAT = 4V, circuit of Figure 2, TA = -40°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.)
(Note 1)
PARAMETER
CONDITIONS
MIN
TYP
MAX
TA = +25°C
4.179
4.200
4.221
UNITS
BATTERY CHARGER
MAX8903A/B/C/G/H
MAX8903D/E
BAT Regulation Voltage
(VBATREG)
IBAT = 0mA
MAX8903J
BAT Prequal Threshold (VBATPQ)
Prequal Charge Current
Fast-Charge Current
DONE Threshold (ITERM)
4.158
4.200
4.242
4.079
4.100
4.121
TA = -40°C to +85°C
4.059
4.100
4.141
TA = +25°C
4.328
4.350
4.372
TA = -40°C to +85°C
4.307
4.350
4.394
TA = +25°C
4.129
4.150
4.171
TA = -40°C to +85°C
4.109
4.150
4.192
-150
-100
-60
MAX8903A/C/D/H/J/N/Y
2.9
3.0
3.1
MAX8903B/E/G
2.4
2.5
2.6
RISET = 600Ω
1800
2000
2200
RISET = 1.2kΩ (MAX8903A/C/D)
900
1000
1100
RISET = 2.4kΩ
450
500
550
MAX8903Y/N
Charger Restart Threshold
TA = -40°C to +85°C
TA = +25°C
Change in VBAT from DONE to fast-charge
VBAT rising 180mV
hystersis
Percentage of fast-charge current set at ISET
10
Percentage of fast-charge, IBAT decreasing
RISET Resistor Range
mV
V
%
10
0.6
V
mA
%
2.4
kΩ
ISET Output Voltage
1.5
V
ISET Current Monitor Gain
1.25
mA/A
BAT Leakage Current
No DC or USB input
With valid input power, VCEN = 5V
0.05
4
3
6
µA
Charger Soft-Start Time
1.0
ms
Charger Thermal Limit
Temperature
100
°C
5
%/°C
Charger Thermal Limit Gain
Charge current = 0 at +120°C
CHARGER TIMER
Prequalification Time
CCT = 0.15µF
33
min
Fast-Charge Time
CCT = 0.15µF
660
min
MAX8903A/C/D/H/J/N/Y (fixed)
15
s
Top-Off Timer (tTOP-OFF)
MAX8903B/E/G, CCT = 0.15µF
Timer Accuracy
132
-15
min
+15
%
Timer Extend Current Threshold
Percentage of fast-charge current below which the timer
clock operates at half-speed
40
50
60
%
Timer Suspend Current Threshold
Percentage of fast-charge current below which timer
clock pauses
16
20
24
%
4
Maxim Integrated
MAX8903A–E/G/H/J/N/Y
2A 1-Cell Li+ DC-DC Chargers
for USB and Adapter Power
ELECTRICAL CHARACTERISTICS (continued)
(VDC = VUSB = 5V, VBAT = 4V, circuit of Figure 2, TA = -40°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.)
(Note 1)
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
THERMISTOR MONITOR
THM Threshold, Hot
When charging is suspended, 1% hysteresis
0.27 x
VVL
0.28 x
VVL
0.29 x
VVL
V
THM Threshold, Cold
When charging is suspended, 1% hysteresis
0.73 x
VVL
0.74 x
VVL
0.75 x
VVL
V
THM Threshold, Disabled
THM function is disabled below this voltage
0.0254
x VVL
0.03 x
VVL
0.036 x
VVL
V
THM Threshold DC, USB Enable
MAX8903B/MAX8903E/MAX8903G
0.83 x
VVL
0.87 x
VVL
0.91 x
VVL
V
-0.100
±0.001
+0.200
MAX8903A/C/D/H/J/N/Y
THM = GND or VL;
TA = +25°C
THM = GND or VL;
TA = +85°C
THM Input Leakage
MAX8903B/E/G
THM = GND or VL;
TA = -40°C to +85°C
µA
±0.010
-0.200
±0.001
+0.200
THERMAL SHUTDOWN, VL, AND LOGIC I/O: CHG, FLT, DOK, UOK, DCM, CEN, USUS, IUSB
High level
Logic-Input Thresholds
(DCM, CEN, USUS, IUSB)
Logic-Input Leakage Current
(CEN, USUS, IUSB)
1.3
Low level
0.4
Hysteresis
VINPUT = 0V to 5.5V
(MAX8903A/C/D/H/J/N/Y)
VINPUT = 0V to 5.5V
(MAX8903B/E/G)
50
TA = +25°C
-1.000
TA = +85°C
TA = -40°C to +85°C
±0.001
+0.200
TA = +25°C
0.001
1
TA = +85°C
0.01
VDCM = 0V to 16V
VDC = 16V
Logic Output Voltage, Low
(CHG, FLT, DOK, UOK)
Sinking 1mA
8
Sinking 10mA
80
Maxim Integrated
µA
±0.001
Logic-Input Leakage Current
(DCM)
Open-Drain Output Leakage
VOUT = 5.5V
Current, High (CHG, FLT, DOK, UOK)
mV
+1.000
±0.010
-0.200
TA = +25°C
0.001
TA = +85°C
0.01
V
50
1
µA
mV
µA
5
ELECTRICAL CHARACTERISTICS (continued)
(VDC = VUSB = 5V, VBAT = 4V, circuit of Figure 2, TA = -40°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.)
(Note 1)
PARAMETER
CONDITIONS
VL Output Voltage
MIN
TYP
MAX
IVL = 0 to 1mA
(MAX8903A/C/D/H/J/N/Y)
4.6
5.0
5.4
IVL = 0 to 10mA
(MAX8903B/E/G)
4.6
5.0
5.4
UNITS
V
VDC = VUSB = 6V
VL UVLO Threshold
3.2
V
Thermal Shutdown Temperature
160
°C
Thermal Shutdown Hysteresis
15
°C
VVL falling; 200mV hysteresis
Note 1: Limits are 100% production tested at TA = +25°C. Limits over the operating temperature range are guaranteed by design.
Note 2: For the 100mA USB mode using the DC input, the step-down regulator is turned off and its high-side switch operates as a
linear regulator with a 100mA current limit. The linear regulator’s output is connected to LX and its output current flows
through the inductor into CS and finally to SYS.
Note 3: For the 500mA USB mode, the actual current drawn from USB is less than the output current due to the input/output current
ratio of the DC-DC converter.
Note 4: For short-circuit protection, SYS sources 25mA below VSYS = 400mV, and 50mA for VSYS between 400mV and 2V.
Typical Operating Characteristics
(TA = +25°C, unless otherwise noted.)
MAX8903A/B/C/D/E/H/J/N/Y
BATTERY CHARGER EFFICIENCY
vs. BATTERY VOLTAGE
EFFICIENCY (%)
VDC = 8V
60
50
VDC = 12V
40
30
70
VDC = 9V
60
50
VDC = 12V
40
30
IBAT = 0.15A
20
IBAT = 1.5A
IBATT = 0.15A
20
10
IBATT = 1.5A
1.5
2.0
2.5
3.0
3.5
4.0
BATTERY VOLTAGE (V)
4.5
5.0
3.5
VBAT = 3V
3.0
2.5
VBAT = 4V
2.0
1.5
1.0
RISET = 1.2kΩ
VCEN = 0V
0.0
0
1.0
4.0
0.5
10
0
6
VDC = 6V
80
4.5
MAX8903A toc02
VDC = 5V
70
90
SWITCHING FREQUENCY (MHz)
80
100
MAX8903A toc01a
90
MAX8903A/B/C/D/E/H/J/N/Y
SWITCHING FREQUENCY vs. VDC
MAX8903G BATTERY CHARGER
EFFICIENCY vs. BATTERY VOLTAGE
MAX8903A toc01
100
EFFICIENCY (%)
MAX8903A–E/G/H/J/N/Y
MAX8903A–E/G/H/J/N/Y
2A 1-Cell Li+ DC-DC Chargers
for USB and Adapter Power
1.0
1.5
2.0
2.5
3.0
3.5
4.0
BATTERY VOLTAGE (V)
4.5
5.0
4
6
8
10
12
14
16
DC VOLTAGE (V)
Maxim Integrated
MAX8903A–E/G/H/J/N/Y
2A 1-Cell Li+ DC-DC Chargers
for USB and Adapter Power
Typical Operating Characteristics (continued)
(TA = +25°C, unless otherwise noted.)
MAX8903A/B/C/D/E/H/J/N/Y
SYS EFFICIENCY
vs. SYS OUTPUT CURRENT
VBAT = 4V
VBAT = 3V
0.4
VDC = 11V
50
VDC = 16V
40
30
VDC = 6V
20
RISET = 1.2kI
VCEN = 0V
0.2
10
6
8
10
12
14
VDC = 12V
40
VDC = 9V
30
VDC = 6V
10
10
100
10000
1000
1
10
100
SYS OUTPUT CURRENT (mA)
USB SUPPLY CURRENT
vs. USB VOLTAGE
USB SUPPLY CURRENT
vs. USB VOLTAGE (SUSPEND)
BATTERY LEAKAGE CURRENT
vs. BATTERY VOLTAGE
0.6
CHARGER
DISABLED
0.4
120
100
80
60
40
80
BATTERY LEAKAGE CURRENT (nA)
0.8
140
MAX8903A toc05
MAX8903A toc04
1.0
20
0.2
70
60
50
40
30
20
10
NO DC OR USB INPUT
USB SUSPEND
0
1
2
3
4
5
6
7
0
1
2
3
4
5
6
0
7
2
3
4
5
USB VOLTAGE (V)
BATTERY VOLTAGE (V)
BATTERY LEAKAGE CURRENT
vs. AMBIENT TEMPERATURE
CHARGE CURRENT
vs. BATTERY VOLTAGE—USB MODE
CHARGE CURRENT
vs. BATTERY VOLTAGE—DC MODE
60
50
40
30
20
350
300
VIUSB = VUSB
250
200
VIUSB = 0V
150
100
10
NO DC OR USB INPUT
-15
10
35
TEMPERATURE (°C)
Maxim Integrated
60
85
800
MAX8903A toc09
6
CHARGER ENABLED
IBAT SET TO 1A
IDC SET TO 2A
MAX8903A/C/H
VBAT RISING
600
400
200
50
0
0
1000
CHARGE CURRENT (mA)
400
CHARGE CURRENT (mA)
70
CHARGE ENABLED
IBAT SET TO 1.5A
MAX8903D
VBAT RISING
450
1200
MAX8903A toc08
500
MAX8903A toc07
80
-40
1
USB VOLTAGE (V)
90
BATTERY LEAKAGE CURRENT (nA)
0
0
0
10,000
1000
SYS OUTPUT CURRENT (mA)
CHARGER
ENABLED
1.2
VDC = 16V
50
DC VOLTAGE (V)
1.6
1.4
60
0
1
16
USB QUIESCENT CURRENT (µA)
4
70
20
VDC = 4.5V
0
0
USB SUPPLY CURRENT (mA)
60
80
MAX8903A toc06
0.6
70
VCEN = 1
90
SYS EFFICIENCY (%)
1.0
0.8
80
SYS EFFICIENCY (%)
1.2
VCEN = 1V
VSYS = 4.4V
90
100
MAX8903A toc03
1.4
SWITCHING FREQUENCY (MHz)
100
MAX8903A toc02a
1.6
MAX8903G SYS EFFICIENCY
vs. SYS OUTPUT CURRENT
MAX8903A toc03a
MAX8903G SWITCHING
FREQUENCY vs. VDC
0
1.5
2.0
2.5
3.0
3.5
BATTERY VOLTAGE (V)
4.0
4.5
1.5
2.0
2.5
3.0
3.5
4.0
4.5
BATTERY VOLTAGE (V)
7
MAX8903A–E/G/H/J/N/Y
2A 1-Cell Li+ DC-DC Chargers
for USB and Adapter Power
Typical Operating Characteristics (continued)
(TA = +25°C, unless otherwise noted.)
NORMALIZED BATTERY
REGULATION VOLTAGE
vs. AMBIENT TEMPERATURE
1.005
1.000
0.995
0.990
0.985
-15
-40
10
35
60
100.3
4.0
100.1
100.0
99.9
2.0
99.7
1.0
0.5
22ppm/°C
10
35
0
85
60
RSYS = 1MΩ
0
99.5
-15
VUSB RISING
1
2
3
4
5
6
7
USB VOLTAGE (V)
MAX8903A/C/D/H/N/Y
SYS VOLTAGE vs. DC VOLTAGE
SYS VOLTAGE
vs. SYS OUTPUT CURRENT, DC INPUT
SYS VOLTAGE
vs. SYS OUTPUT CURRENT, USB INPUT
VDC FALLING
1.5
4.3
MAX8903A/C/D/H, MAX8903N/Y,
VDC = 5.75V
VDC = 5.75V
MAX8903B/E/G,
VDC = 5.75V
4.1
4.0
1.0
VCEN = 5V
VBAT = 0V
VUSB = 0V
0.5
2
4
6
8
10
12
14
16
0
0.5
1.0
1.5
MAX8903_, VUSB = 0V
3.8
2.0
100
0
VL WITH
NO LOAD AND
DCDC OFF
(VUSUS = 5V)
VL AND DCDC
WITH
FULL LOAD
(VUSUS = 0V)
2
1
VBAT = 3.6V
VUSB = 0V
0
VBAT (V)
5
MAX8903A toc17
6.0
5.5
5.0
4.5
4.0
3.5
3.0
IDC SET TO 1A
IBAT SET TO 2A
VBAT
2
4
6
8
10 12 14 16 18 20
DC VOLTAGE (V)
400
500
1.2
1.0
0.8
0.6
2.5
2.0
1.5
1.0
0.5
IBAT
0.4
0.2
MAX8903A/B/C/G/H
0
0
300
CHARGE PROFILE—1400mAh BATTERY
ADAPTER INPUT—1A CHARGE
MAX8903A toc16
6
200
SYS OUTPUT CURRENT (mA)
VL VOLTAGE vs. DC VOLTAGE
3
MAX8903B/E/G,
VUSB = 5V
4.1
SYS OUTPUT CURRENT (A)
DC VOLTAGE (V)
4
MAX8903A /C/D/H, MAX8903N/Y,
VUSB = 5V
VUSB = 5V
4.2
3.9
MAX8903_, VDC = 0V
3.8
18
4.3
4.0
3.9
0
MAX8903J, VUSB = 5V
4.4
4.2
MAX8903A toc15
VDC = 0V, VBATT = 4V
4.5
IBAT (A)
2.0
4.6
SYS VOLTAGE (V)
2.5
MAX8903J, VDC = 5.75V
4.4
SYS VOLTAGE (V)
VDC RISING
3.0
VUSB = 0V
4.5
MAX8903A toc14
4.6
MAX8903A toc13
3.5
VL VOLTAGE (V)
2.5
1.5
-40
VUSB FALLING
3.0
TEMPERATURE (°C)
4.0
0
3.5
99.8
99.6
VCEN = 5V
VBAT = 0V
VDC = 0V
4.5
100.2
85
4.5
8
5.0
MAX8903A toc12
100.4
TEMPERATURE (°C)
5.0
SYS VOLTAGE (V)
100.5
SYS VOLTAGE (V)
1.010
MAX8903A/C/D/H/N/Y
SYS VOLTAGE vs. USB VOLTAGE
MAX8903A toc11
VUSB = 5V, VBAT = 4V
NORMALIZED BATTERY REGULATION VOLTAGE (%)
NORMALIZED CHARGE CURRENT
1.015
MAX8903A toc10
NORMALIZED CHARGE CURRENT
vs. AMBIENT TEMPERATURE
0
20
40
60
80
100
0.0
120 140
TIME (min)
Maxim Integrated
MAX8903A–E/G/H/J/N/Y
2A 1-Cell Li+ DC-DC Chargers
for USB and Adapter Power
Typical Operating Characteristics (continued)
(TA = +25°C, unless otherwise noted.)
MAX8903A/B/C/G/H
CHARGE PROFILE—1400mAh BATTERY
USB INPUT—500mA CHARGE
MAX8903A toc18
5.0
MAX8903A toc19
0.50
4.5
0.45
4.0
0.40
3.5
20mV/div
AC-COUPLED
VOUT
0.35
VBAT
3.0
0.30
2.5
0.25
IBAT
2.0
0.20
1.5
0.15
1.0
MAX8903A/MAX8903B/MAX8903C
IUSB SET TO 500mA
IBAT SET TO 2A
0.5
0
0
IBAT (A)
VBAT (V)
MAX8903A/B/C/D/E/H/J/N/Y DC SWITCHING
WAVEFORMS—LIGHT LOAD
0.10
5V/div
VLX
0V
ILX
0.05
RSYS = 44Ω
0
20 40 60 80 100 120 140 160 180 200
500mA/div
0A
200ns/div
TIME (min)
MAX8903A/B/C/D/E/H/J/N/Y DC SWITCHING
WAVEFORMS—HEAVY LOAD
MAX8903G DC SWITCHING
WAVEFORMS—LIGHT LOAD
MAX8903A toc20
MAX8903A toc19a
50mV/div
AC-COUPLED
VSYS
VDC = 9V, L = 2.2µH
CSYS = 22µF,
RSYS = 44I
VLX
10V/div
20mV/div
AC-COUPLED
VOUT
5V/div
0V
VLX
0V
1A/div
ILX
0A
ILX
500mA/div
RSYS = 5Ω
0A
1µs/div
200ns/div
MAX8903G DC SWITCHING
WAVEFORMS—HEAVY LOAD
DC CONNECT WITH
USB CONNECTED (RSYS = 25Ω)
MAX8903A toc21
MAX8903A toc20a
3.6V
VSYS
VDC = 9V, L = 2.2µH
CSYS = 22µF, RSYS = 5I
CEN = 1
50mV/div
AC-COUPLED
IDC
10V/div
VLX
0V
2V/div
VSYS
IUSB
347mA
475mA
500mA/div
500mA/div
-IBAT = CHARGING
IBAT
ILX
0A
500mA/div
-335mA
1A/div
0A
1µs/div
Maxim Integrated
200µs/div
9
MAX8903A–E/G/H/J/N/Y
2A 1-Cell Li+ DC-DC Chargers
for USB and Adapter Power
Typical Operating Characteristics (continued)
(TA = +25°C, unless otherwise noted.)
DC CONNECT WITH NO USB
(RSYS = 25Ω)
DC DISCONNECT WITH NO USB
(RSYS = 25Ω)
MAX8903A toc22
3.84V
3.6V
VSYS
3.6V
VBAT
IBAT
2V/div
3.44V
5V/div
CDC
CHARGING
IDC
MAX8903A toc23
CSYS
CHARGING 850mA
3.68V
3.6V
VSYS
3.6V
VBAT
5V/div
1A/div
IDC
0A
-IBAT = CHARGING
IBAT
144mA BATTERY
CHARGER
SOFT-START
144mA
-1A
1A/div
40µs/div
MAX8903B/E SYS LOAD TRANSIENT
MAX8903A toc24a
MAX8903A toc24b
4.400V
MAX8903A
VDC = 10.5V
L = 2.2µH
CSYS = 10µF
RIDC = 3kI (2A)
DCM = HIGH
CEN = 1
20mV/div
AC-COUPLED
4.360V
4.325V
VSYS
MAX8903B
VDC = 10.5V
L = 2.2µH
CSYS = 22µF
RIDC = 3kI (2A)
DCM = HIGH
CEN = 1 4.305V
1A
20mV/div
1A
500mA/div
0A
0A
ISYS
500mA/div
0A
0A
100µs/div
100µs/div
MAX8903G SYS LOAD TRANSIENT
USB CONNECT WITH NO DC
(RSYS = 25Ω)
MAX8903A toc25
MAX8903A toc24c
3.6V
VSYS
4.325V
VSYS
4.305V
1A
ISYS
50mV/div
VDC = 9V
L = 2.2µH
CSYS = 22µF
RIDC = 3kI (2A)
DCM = 1
CEN = 1
0A
100µs/div
10
1A/div
-IBAT = CHARGING
-1A
MAX8903A/C/D/H SYS LOAD TRANSIENT
ISYS
1A/div
0A
850mA
400µs/div
VSYS
2V/div
3.75V
3.5V
2V/div
5V
5V/div
VUSB
CUSB
CHARGING
475mA
500mA/div
IUSB
500mA/div
0A
IBAT
144mA
BATTERY
CHARGER
SOFT-START
500mA/div
-330mA
400µs/div
Maxim Integrated
MAX8903A–E/G/H/J/N/Y
2A 1-Cell Li+ DC-DC Chargers
for USB and Adapter Power
Typical Operating Characteristics (continued)
(TA = +25°C, unless otherwise noted.)
USB DISCONNECT WITH NO DC
(RSYS = 25Ω)
USB SUSPEND
MAX8903A toc26
VSYS
3.6V
VUSB
2V/div
5V/div
5V
USB RESUME
MAX8903A toc27
VUSUS
IUSB
0V
475mA
3V
MAX8903A toc28
5V/div
0A
VUSUS
500mA/div
IUSB
0V
3V
500mA/div VSYS
IBAT
-330mA
144mA
100µs/div
2V/div
3.7V
500mA/div IBAT -475mA
0A
3.6V
VSYS
IBAT
500mA/div
475mA
0A
475mA
IUSB
5V/div
CUSB
CHARGING
3.8V
500mA/div
3.6V
2V/div
0A
200µs/div
BATTERY
CHARGER
SOFT-START
-475mA
500mA/div
200µs/div
Pin Description
PIN
NAME
1, 2
PG
FUNCTION
Power Ground for Step-Down Low-Side Synchronous n-Channel MOSFET. Both PG pins must be
connected together externally.
DC Power Input. DC is capable of delivering up to 2A to SYS. DC supports both AC adapter and USB
inputs. The DC current limit is set through DCM, IUSB, or IDC depending on the input source used. See
Table 2. Both DC pins must be connected together externally. Connect at least a 4.7µF ceramic capacitor
from DC to PG.
Current-Limit Mode Setting for the DC Power Input. When logic-high, the DC input current limit is set by
the resistance from IDC to GND. When logic-low, the DC input current limit is internally programmed to
500mA or 100mA, as set by the IUSB logic input. There is an internal diode from DCM (anode) to DC
(cathode) as shown in Figure 1.
3, 4
DC
5
DCM
6
BST
High-Side MOSFET Driver Supply. Bypass BST to LX with a 0.1µF ceramic capacitor.
7
IUSB
USB Current-Limit Set Input. Drive IUSB logic-low to set the USB current limit to 100mA. Drive IUSB logichigh to set the USB current limit to 500mA.
8
DOK
DC Power-OK Output. Active-low open-drain output pulls low when a valid input is detected at DC. DOK
is still valid when the charger is disabled (CEN high).
9
VL
Logic LDO Output. VL is the output of an LDO that powers the MAX8903_ internal circuitry and charges
the BST capacitor. Connect a 1µF ceramic capacitor from VL to GND.
10
CT
Charge Timer Set Input. A capacitor (CCT) from CT to GND sets the fast-charge and prequal fault timers.
Connect to GND to disable the timer.
11
IDC
DC Current-Limit Set Input. Connect a resistor (RIDC) from IDC to GND to program the current limit of the
step-down regulator from 0.5A to 2A when DCM is logic-high.
12
GND
Ground. GND is the low-noise ground connection for the internal circuitry.
Maxim Integrated
11
MAX8903A–E/G/H/J/N/Y
2A 1-Cell Li+ DC-DC Chargers
for USB and Adapter Power
Pin Description (continued)
PIN
NAME
13
ISET
Charge Current Set Input. A resistor (RISET) from ISET to GND programs the fast-charge current up to 2A.
The prequal charge current is 10% of the fast-charge current.
14
CEN
Charger Enable Input. Connect CEN to GND to enable battery charging when a valid source is connected
at DC or USB. Connect to VL, or drive high to disable battery charging.
15
USUS
USB Suspend Input. Drive USUS logic-high to enter USB suspend mode, lowering USB current to 115µA,
and internally shorting SYS to BAT.
16
THM
Thermistor Input. Connect a negative temperature coefficient (NTC) thermistor from THM to GND.
Connect a resistor equal to the thermistor +25°C resistance from THM to VL. Charging is suspended
when the thermistor is outside the hot and cold limits. Connect THM to GND to disable the thermistor
temperature sensor.
17
USB
USB Power Input. USB is capable of delivering 100mA or 500mA to SYS as set by the IUSB logic input.
Connect a 4.7µF ceramic capacitor from USB to GND.
18
FLT
Fault Output. Active-low, open-drain output pulls low when the battery timer expires before prequal or
fast-charge completes.
19
UOK
USB Power-OK Output. Active-low, open-drain output pulls low when a valid input is detected at USB.
UOK is still valid when the charger is disabled (CEN high).
20, 21
BAT
Battery Connection. Connect to a single-cell Li+ battery. The battery charges from SYS when a valid
source is present at DC or USB. BAT powers SYS when neither DC nor USB power is present, or when the
SYS load exceeds the input current limit. Both BAT pins must be connected together externally.
22
CHG
Charger Status Output. Active-low, open-drain output pulls low when the battery is in fast-charge or
prequal. Otherwise, CHG is high impedance.
23, 24
SYS
System Supply Output. SYS connects to BAT through an internal 50mΩ system load switch when DC or
USB are invalid, or when the SYS load is greater than the input current limit.
When a valid voltage is present at DC or USB, SYS is limited to VSYSREG. When the system load (ISYS)
exceeds the DC or USB current limit, SYS is regulated to 50mV below BAT, and both the powered input
and the battery service SYS.
Bypass SYS to GND with an X5R or X7R ceramic capacitor. See Table 6 for the minimum recommended
SYS capacitor (CSYS). Both SYS pins must be connected together externally.
25, 26
CS
70mΩ Current-Sense Input. Connect the step-down inductor from LX to CS. When the step-down
regulator is on, there is a 70mΩ current-sense MOSFET from CS to SYS. When the step-down regulator is
off, the internal CS MOSFET turns off to block current from SYS back to DC.
27, 28
LX
Inductor Connection. Connect the inductor between LX and CS. Both LX pins must be connected together
externally.
—
EP
Exposed Pad. Connect the exposed pad to GND. Connecting the exposed pad does not remove the
requirement for proper ground connections to the appropriate pins.
12
FUNCTION
Maxim Integrated
MAX8903A–E/G/H/J/N/Y
2A 1-Cell Li+ DC-DC Chargers
for USB and Adapter Power
PG
AC
ADAPTER
DC
LX
BST
CS
MAX8903_
DC POWER
MANAGEMENT
SYS
PWR
OK
Li+ BATTERY
CHARGER
AND SYS LOAD SWITCH
PWM
STEP-DOWN
REGULATOR
DOK
CHARGER
CURRENTVOLTAGE
CONTROL
SET
INPUT
LIMIT
TO
SYSTEM
LOAD
ISET
BATTERY
CONNECTOR
BAT
BAT+
+
BAT-
USB POWER
MANAGEMENT
USB
USB
PWR
OK
T
THERMISTOR
MONITOR
(SEE FIGURE 7)
CURRENTLIMITED
VOLTAGE
REGULATOR
UOK
IC
THERMAL
REGULATION
NTC
VL
CHARGE
TERMINATION
AND MONITOR
SET
INPUT
LIMIT
THM
CHG
DC
DCM
FLT
DC MODE
USB
LIMIT
500mA
IUSB
100mA
USB
SUSPEND
USUS
CHARGE
TIMER
INPUT AND
CHARGER
CURRENT-LIMIT
SET LOGIC
CEN
IDC
DC
LIMIT
CT
GND
EP
Figure 1. Functional Block Diagram
Maxim Integrated
13
MAX8903A–E/G/H/J/N/Y
2A 1-Cell Li+ DC-DC Chargers
for USB and Adapter Power
RPU
4 x 100kΩ
TO VL
1
2
PG
PG
MAX8903_
CDC
4.7µF
UOK
3 DC
ADAPTER
DOK
4 DC
6
CBST
0.1µF
FLT
CHG
BST
27 LX
18
FAULT
OUTPUT
19
USB PWR OK
8
DC PWR OK
22
CHARGE
INDICATOR
13
RISET
11
RIDC
ISET
28 LX
IDC
L1
1µH
25
CS
(SEE TABLE 5 FOR
INDUCTOR SELECTION)
26
CS
SYS
24
SYS
23
BAT
21
BAT
20
TO SYSTEM
LOAD
CSYS
(SEE TABLE 6 FOR CSYS SELECTION)
USB
17
VBUS
USB
CUSB
4.7µF
GND
TO DC
5
OFF
CHARGE ON
14
500mA
100mA
7
USB SUSPEND
15
10
CCT
0.15µF
CBAT
10µF
1-CELL
LI+
DCM
VL
9
CVL
1µF
CEN
THM
IUSB
RT
10kΩ
16
NTC
10kΩ
USUS
CT
GND
12
EP
Figure 2. Typical Application Circuit Using a Separate DC and USB Connector
Circuit Description
The MAX8903_ is a dual input charger with a 16V input
for a wide range of DC sources and USB inputs. The IC
includes a high-voltage (16V) input DC-DC step-down
converter that reduces charger power dissipation while
also supplying power to the system load. The stepdown converter supplies up to 2A to the system, the
battery, or a combination of both.
14
A USB charge input can charge the battery and power
the system from a USB power source. When powered
from USB or the DC input, system load current peaks
that exceed what can be supplied by the input are supplemented by the battery.
The MAX8903_ also manages load switching from the
battery to and from an external power source with an
on-chip 50mΩ MOSFET. This switch also helps support
load peaks using battery power when the input source
is overloaded.
Maxim Integrated
MAX8903A–E/G/H/J/N/Y
2A 1-Cell Li+ DC-DC Chargers
for USB and Adapter Power
RPU
4 x 100kΩ
TO VL
1
2
PG
PG
MAX8903_
CDC
4.7µF
DOK
4 DC
D-
6
D+
CBST
0.1µF
ID
GND
CHG
BST
27 LX
18
FAULT
OUTPUT
19
USB PWR-OK
8
DC PWR-OK
22
CHARGE
INDICATOR
13
RISET
11
RIDC
ISET
28 LX
L1
1µH
499kΩ
IDC
25
CS
26
CS
(SEE TABLE 5 FOR
INDUCTOR VALUE
SELECTION)
17
DC MODE
UOK
3 DC
VBUS
FLT
USB
ADAPTER
5
OFF
CHARGE ON
14
500mA
100mA
7
USB SUSPEND
15
10
CCT
0.15µF
USB
SYS
24
SYS
23
BAT
21
BAT
20
TO SYSTEM
LOAD
CSYS
(SEE TABLE 6 FOR CSYS SELECTION)
CBAT
10µF
1-CELL
LI+
DCM
VL
9
CVL
1µF
CEN
THM
IUSB
RT
10kΩ
16
NTC
10kΩ
USUS
CT
GND
12
EP
Figure 3. Typical Application Circuit Using a Mini 5 Style Connector or Other DC/USB Common Connector
As shown in Figure 1, the IC includes a full-featured
charger with thermistor monitor, fault timer, charger
status, and fault outputs. Also included are power-OK
signals for both USB and DC. Flexibility is maintained
with adjustable charge current, input current limit, and
a minimum system voltage (when charging is scaled
back to hold the system voltage up).
The MAX8903_ prevents overheating during high ambient temperatures by limiting charging current when the
die temperature exceeds +100°C.
Maxim Integrated
DC Input—Fast Hysteretic
Step-Down Regulator
If a valid DC input is present, the USB power path is
turned off and power for SYS and battery charging is
supplied by the high-frequency step-down regulator
from DC. If the battery voltage is above the minimum
system voltage (VSYSMIN, Figure 4), the battery charger
connects the system voltage to the battery for lowest
power dissipation. The step-down regulation point is
then controlled by three feedback signals: maximum
step-down output current programmed at IDC, maximum
charger current programmed at ISET, and maximum
15
MAX8903A–E/G/H/J/N/Y
2A 1-Cell Li+ DC-DC Chargers
for USB and Adapter Power
Table 1. External Components List for Figures 2 and 3
COMPONENT
(FIGURES 2 AND 3)
CDC, CUSB
FUNCTION
Input filter capacitor
4.7µF ceramic capacitor
CVL
VL filter capacitor
1.0µF ceramic capacitor
CSYS
SYS output bypass capacitor
10µF (MAX8903A/MAX8903C/MAX8903D/MAX8903H/MAX8903J) or
22µF (MAX8903B/MAX8903E/MAX8903G/MAX8903Y) ceramic capacitor
CBAT
Battery bypass capacitor
10µF ceramic capacitor
CCT
Charger timing capacitor
0.15µF low TC ceramic capacitor
Logic output pullup resistors
100kΩ
RPU (X4)
THM
RT
RIDC
RISET
L1
Negative TC thermistor
Philips NTC thermistor, P/N 2322-640-63103, 0kΩ ±5% at +25°C
THM pullup resistor
10kΩ
DC input current-limit programming resistor 3kΩ ±1%, for 2A limit
Fast-charge current programming resistor 1.2kΩ ±1%, for 1A charging
DC input step-down inductor
die temperature. The feedback signal requiring the
smallest current controls the average output current in
the inductor. This scheme minimizes total power dissipation for battery charging and allows the battery to
absorb any load transients with minimum system voltage disturbance.
If the battery voltage is below VSYSMIN, the charger does
not directly connect the system voltage to the battery
and the system voltage (VSYS) is slightly above VSYSMIN
as shown in Figure 4. The battery charger independently
controls the battery charging current. VSYSMIN is set to
either 3.0V or 3.4V based on the version of MAX8903_.
See Table 6.
After the battery charges to 50mV above VSYSMIN, the
system voltage is connected to the battery. The battery
fast-charge current then controls the step-down converter to set the average inductor current so that both
the programmed input current limit and fast-charge current limit are satisfied.
DC-DC Step-Down Control Scheme
A proprietary hysteretic current PWM control scheme
ensures fast switching and physically tiny external components. The feedback control signal that requires the
smallest input current controls the center of the peak
and valley currents in the inductor. The ripple current is
internally set to provide 4MHz operation. When the
input voltage decreases near the output voltage, very
high duty cycle occurs and, due to minimum off-time,
4MHz operation is not achievable. The controller then
provides minimum off-time, peak current regulation.
Similarly, when the input voltage is too high to allow
4MHz operation due to the minimum on-time, the con16
PART
1µH inductor with ISAT > 2A
troller becomes a minimum on-time, valley current regulator. In this way, ripple current in the inductor is always
as small as possible to reduce ripple voltage on SYS for
a given capacitance. The ripple current is made to vary
with input voltage and output voltage in a way that
reduces frequency variation. However, the frequency
still varies somewhat with operating conditions. See the
Typical Operating Characteristics.
DC Mode (DCM)
As shown in Table 2, the DC input supports both AC
adapters (up to 2A) and USB (up to 500mA). With the
DCM logic input set high, the DC input is in adapter
mode and the DC input current limit is set by the resistance from IDC to GND (RIDC). Calculate RIDC according to the following equation:
RIDC = 6000V/IDC-MAX
With the DCM logic input set low, the DC input current
limit is internally programmed to 500mA or 100mA as
set by the IUSB logic input. With the IUSB logic input
set high, the DC input current limit is 500mA and the
DC input delivers current to SYS through the step-down
regulator. With the IUSB logic input set low, the DC
input current limit is 100mA. In this 100mA mode, the
step-down regulator is turned off and its high-side
switch operates as a linear regulator with a 100mA current limit. The linear regulator’s output is connected to
LX and its output current flows through the inductor into
CS and finally to SYS.
The DCM pin has an internal diode to DC as shown in
Figure 1. To prevent current from flowing from DCM
through the internal diode and to the DC input, DCM
cannot be driven to a voltage higher than DC. The
Maxim Integrated
MAX8903A–E/G/H/J/N/Y
2A 1-Cell Li+ DC-DC Chargers
for USB and Adapter Power
circuit of Figure 3 shows a simple MOSFET and resistor
on DCM to prevent any current from flowing from DCM
through the internal diode to DC. This circuit of Figure 3
allows a microprocessor to drive the gate of the MOSFET to any state at any time.
An alternative to the simple MOSFET and resistor on
DCM as shown in Figure 3 is to place a 1MΩ resistor in
series with the DCM input to the microprocessor. The
microprocessor can then monitor the DOK output and
make sure that whenever DOK is high DCM is also low.
In the event that DCM is driven to a higher voltage than
DC, the 1MΩ series resistance limits the current from
DCM through the internal diode to DC to a few µA.
USB Input—Linear Regulator
If a valid USB input is present with no valid DC input,
current for SYS and battery charging is supplied by a
low-dropout linear regulator connected from USB to
SYS. The SYS regulation voltage shows the same characteristic as when powering from the DC input (see
Figure 4). The battery charger operates from SYS with
any extra available current, while not exceeding the
maximum-allowed USB current. If both USB and DC
inputs are valid, power is only taken from the DC input.
The maximum USB input current is set by the logic
state of the IUSB input to either 100mA or 500mA.
Power Monitor Outputs (UOK, DOK)
DOK is an open-drain, active-low output that indicates
the DC input power status. With no source at the USB
pin, the source at DC is considered valid and DOK is
driven low when: 4.15V < VDC < 16V. When the USB
voltage is also valid, the DC source is considered valid
and DOK is driven low when: 4.45V < VDC < 16V. The
higher minimum DC voltage with USB present helps
guarantee cleaner transitions between input supplies. If
the DC power-OK output feature is not required, connect DOK to ground.
UOK is an open-drain, active-low output that indicates
the USB input power status. UOK is low when a valid
VSYSREG
VBATREG
MAX8903_
VSYS
IBAT x RON
VSYSMIN
VBAT
VCEN = 0V
VDC AND/OR VUSB = 5.0V
Figure 4. SYS Tracking VBAT to the Minimum System Voltage
Maxim Integrated
source is connected at USB. The source at USB is valid
when 4.1V < VUSB < 6.6V. If the USB power-OK output
feature is not required, connect UOK to ground.
Both the UOK and the DOK circuitry remain active in
thermal overload, USB suspend, and when the charger
is disabled. DOK and UOK can also be wire-ORed
together to generate a single power-OK (POK) output.
Thermal Limiting
When the die temperature exceeds +100°C, a thermal
limiting circuit reduces the input current limit by 5%/°C,
bringing the charge current to 0mA at +120°C. Since
the system load gets priority over battery charging, the
battery charge current is reduced to 0mA before the
input limiter drops the load voltage at SYS. To avoid
false charge termination, the charge termination detect
function is disabled in this mode. If the junction temperature rises beyond +120°C, no current is drawn from
DC or USB, and VSYS regulates at 50mV below VBAT.
System Voltage Switching
DC Input
When charging from the DC input, if the battery is
above the minimum system voltage, SYS is connected
to the battery. Current is provided to both SYS and the
battery, up to the maximum program value. The stepdown output current sense and the charger current
sense provide feedback to ensure the current loop
demanding the lower input current is satisfied. The
advantage of this approach when powering from DC is
that power dissipation is dominated by the step-down
regulator efficiency, since there is only a small voltage
drop from SYS to BAT. Also, load transients can be
absorbed by the battery while minimizing the voltage
disturbance on SYS. If both the DC and USB inputs are
valid, the DC input takes priority and delivers the input
current, while the USB input is off.
After the battery is done charging, the charger is turned
off and the SYS load current is supplied from the DC
input. The SYS voltage is regulated to VSYSREG. The
charger turns on again after the battery drops to the
restart threshold. If the load current exceeds the input
limiter, SYS drops down to the battery voltage and the
50mΩ SYS-to-BAT PMOS switch turns on to supply the
extra load current. The SYS-to-BAT switch turns off again
once the load is below the input current limit. The 50mΩ
PMOS also turns on if valid DC input power is removed.
USB Input
When charging from the USB input, the DC input stepdown regulator turns off and a linear regulator from
USB to SYS powers the system and charges the battery. If the battery is greater than the minimum system
17
MAX8903A–E/G/H/J/N/Y
2A 1-Cell Li+ DC-DC Chargers
for USB and Adapter Power
Table 2. Input Limiter Control Logic
POWER SOURCE
AC Adapter at DC Input
DC STEP-DOWN
OUTPUT
CURRENT LIMIT
USB INPUT
CURRENT LIMIT
UOK
DCM***
L
X
H
X
X
6000V/RIDC
L
X
L
L
L
100mA
L
X
L
H
L
500mA
Lesser of
1200V/RISET and
500mA
L
X
L
X
H
USB suspend
0
H
L
X
L
L
H
L
X
H
L
H
L
X
X
H
USB suspend
Lesser of
1200V/RISET and
500mA
0
H
H
X
X
X
No USB input
0
IUSB USUS
Lesser of
1200V/RISET and
6000V/RIDC
USB input off. DC
input has priority.
USB Power at DC Input
USB Power at USB Input,
DC Unconnected
DC and USB Unconnected
MAXIMUM
CHARGE
CURRENT**
DOK
100mA
No DC input
500mA
Lesser of
1200V/RISET and
100mA
Lesser of
1200V/RISET and
100mA
**Charge current cannot exceed the input current limit. Charge may be less than the maximum charge current if the total SYS load
exceeds the input current limit.
***There is an internal diode from DCM (anode) to DC (cathode) as shown in Figure 1. If the DCM level needs to be set by a µP, use
a MOSFET for isolation as shown in FIgure 3.
X = Don’t care.
voltage, the SYS voltage is connected to the battery.
The USB input then supplies the SYS load and charges
the battery with any extra available current, while not
exceeding the maximum-allowed USB current. Load
transients can be absorbed by the battery while minimizing the voltage disturbance on SYS. When battery
charging is completed, or the charger is disabled, SYS
is regulated to VSYSREG. If both USB and DC inputs are
valid, power is only taken from the DC input.
USB Suspend
Driving USUS high and DCM low turns off charging as
well as the SYS output and reduces input current to
170µA to accommodate USB suspend mode. See
Table 2 for settings.
Charge Enable (CEN)
When CEN is low, the charger is on. When CEN is high,
the charger turns off. CEN does not affect the SYS output. In many systems, there is no need for the system
controller (typically a microprocessor) to disable the
18
charger, because the MAX8903_ smart power selector
circuitry independently manages charging and
adapter/battery power hand-off. In these situations, CEN
may be connected to ground.
Soft-Start
To prevent input transients that can cause instability in
the USB or AC adapter power source, the rate of change
of the input current and charge current is limited. When
an input source is valid, SYS current is ramped from
zero to the set current-limit value in typically 50µs. This
also means that if DC becomes valid after USB, the
SYS current limit is ramped down to zero before switching from the USB to DC input. At some point, SYS is no
longer able to support the load and may switch over to
BAT. The switchover to BAT occurs when VSYS < VBAT.
This threshold is a function of the SYS capacitor size
and SYS load. The SYS current limit then ramps from
zero to the set current level and SYS supports the load
again as long as the SYS load current is less than the
set current limit.
Maxim Integrated
MAX8903A–E/G/H/J/N/Y
2A 1-Cell Li+ DC-DC Chargers
for USB and Adapter Power
When the charger is turned on, the charge current ramps
from 0A to the ISET current value in typically 1.0ms.
Charge current also soft-starts when transitioning to fastcharge from prequal, when the input power source is
switched between USB and DC, and when changing the
USB charge current from 100mA to 500mA with the IUSB
logic input. There is no di/dt limiting, however, if RISET is
changed suddenly using a switch.
Battery Charger
While a valid input source is present, the battery charger attempts to charge the battery with a fast-charge
current determined by the resistance from ISET to
GND. Calculate the RISET resistance according to the
following equation:
RISET = 1200V/ICHGMAX
Monitoring Charge Current
The voltage from ISET to GND is a representation of the
battery charge current and can be used to monitor the
current charging the battery. A voltage of 1.5V represents the maximum fast-charge current.
If necessary, the charge current is reduced automatically to prevent the SYS voltage from dropping.
Therefore, a battery never charges at a rate beyond the
capabilities of a 100mA or 500mA USB input, or overloads an AC adapter. See Figure 5.
When VBAT is below VBATPQ, the charger enters prequal mode and the battery charges at 10% of the maximum fast-charge rate until the voltage of the deeply
discharged battery recovers. When the battery voltage
MONITORING THE BATTERY
CHARGE CURRENT WITH VISET
1.5
VISET (V)
0
DISCHARGING
0
1200V/RISET
BATTERY CHARGING CURRENT (A)
reaches VBATREG and the charge current drops to 10%
of the maximum fast-charge current, the charger enters
the DONE state. The charger restarts a fast-charge
cycle if the battery voltage drops by 100mV.
Charge Termination
When the charge current falls to the termination threshold (ITERM) and the charger is in voltage mode, charging is complete. Charging continues for a brief 15s
top-off period and then enters the DONE state where
charging stops.
Note that if charge current falls to ITERM as a result of
the input or thermal limiter, the charger does not enter
DONE. For the charger to enter DONE, charge current
must be less than ITERM, the charger must be in voltage mode, and the input or thermal limiter must not be
reducing charge current.
Charge Status Outputs
Charge Output (CHG)
CHG is an open-drain, active-low output that indicates
charger status. CHG is low when the battery charger is
in its prequalification and fast-charge states. CHG goes
high impedance if the thermistor causes the charger to
go into temperature suspend mode.
When used in conjunction with a microprocessor (µP),
connect a pullup resistor between CHG and the logic
I/O voltage to indicate charge status to the µP.
Alternatively, CHG can sink up to 20mA for an LED
charge indicator.
Fault Output (FLT)
FLT is an open-drain, active-low output that indicates
charger status. FLT is low when the battery charger has
entered a fault state when the charge timer expires.
This can occur when the charger remains in its prequal
state for more than 33 minutes or if the charger remains
in fast-charge state for more than 660 minutes (see
Figure 6). To exit this fault state, toggle CEN or remove
and reconnect the input source.
When used in conjunction with a microprocessor (µP),
connect a pullup resistor between FLT and the logic I/O
voltage to indicate charge status to the µP.
Alternatively, FLT can sink up to 20mA for an LED fault
indicator. If the FLT output is not required, connect FLT
to ground or leave unconnected.
Charge Timer
A fault timer prevents the battery from charging indefinitely. The fault prequal and fast-charge timers are controlled by the capacitance at CT (CCT).
Figure 5. Monitoring the Battery Charge Current with the
Voltage from ISET to GND
Maxim Integrated
19
MAX8903A–E/G/H/J/N/Y
2A 1-Cell Li+ DC-DC Chargers
for USB and Adapter Power
NOT READY
UOK AND DOK = HIGH IMPEDANCE
CHG = HIGH IMPEDANCE
FLT = HIGH IMPEDANCE
ICHG = 0mA
CEN = HI OR
REMOVE AND RECONNECT
THE INPUT SOURCE(S)
ANY STATE
UOK AND/OR DOK = LOW
CEN = 0
RESET TIMER
PREQUALIFICATION
UOK AND/OR DOK = LOW
CHG = LOW
FLT = HIGH IMPEDANCE
0 < VBAT < VBATPQ
ICHG ≤ ICHGMAX/10
VBAT < VBATPQ - 180mV
RESET TIMER = 0
ICHG > ITERM
RESET TIMER
ANY CHARGING
STATE
THM OK
TIMER RESUME
THM NOT OK
TIMER SUSPEND
TEMPERATURE SUSPEND
ICHG = 0mA
UOK OR DOK PREVIOUS STATE
CHG = HIGH IMPEDANCE
FLT = HIGH IMPEDANCE
TIMER > tPREQUAL
FAULT
UOK AND/OR DOK = LOW
CHG = HIGH IMPEDANCE
FLT = LOW
ICHG = 0mA
VBAT > VBATPQ
RESET TIMER
FAST-CHARGE
UOK AND/OR DOK = LOW
CHG = LOW
FLT = HIGH IMPEDANCE
VBATPQ < VBAT < VBATREG
ICHG ≤ ICHGMAX
VBAT < VBATPQ - 180mV
RESET TIMER
TOGGLE CEN OR
REMOVE AND RECONNECT
THE INPUT SOURCE(S)
TIMER > tFSTCHG
(TIMER SLOWED BY 2x IF
ICHG < ICHGMAX/2, AND
PAUSED IF ICHG < ICHGMAX/5 WHILE VBAT < VBATREG)
ICHG < ITERM
AND VBAT = VBATREG
AND THERMAL
OR INPUT LIMIT
NOT EXCEEDED;
RESET TIMER
TOP-OFF
UOK AND/OR DOK = LOW
CHG = HIGH IMPEDANCE
FLT = HIGH IMPEDANCE
VBAT = VBATREG
ICHG = ITERM
VBAT < VBATREG + VRSTRT
RESET TIMER
TIMER > tTOP-OFF
DONE
UOK AND/OR DOK = 0
CHG = HIGH IMPEDANCE
FLT = HIGH IMPEDANCE
VBATREG + VRSTRT < VBAT < VBATREG
ICHG = 0mA
Figure 6. MAX8903A Charger State Flow Chart
CCT
0.15µF
CCT
tFST -CHG = 660min ×
0.15µF
t TOP -OFF = 15s (MAX8903 A/D /H/ J/N/ Y)
tPREQUAL = 33min ×
t TOP -OFF = 132min ×
20
CCT
(MAX8903B/E / G)
0.15µF
While in fast-charge mode, a large system load or device
self-heating may cause the MAX8903_ to reduce charge
current. Under these circumstances, the fast-charge
timer is slowed by 2x if the charge current drops below
50% of the programmed fast-charge level, and suspended if the charge current drops below 20% of the programmed level. The fast-charge timer is not affected at
any current if the charger is regulating the BAT voltage
at VBATREG (i.e., the charger is in voltage mode).
Maxim Integrated
MAX8903A–E/G/H/J/N/Y
2A 1-Cell Li+ DC-DC Chargers
for USB and Adapter Power
CEN
VL
THERMISTOR
CIRCUITRY
VL
MAX8903_
0.87 VL
RTB
ALTERNATE
THERMISTOR
CONNECTION
0.74 VL
MAX8903B/MAX8903E/
MAX8903G ONLY
THERMISTOR
DETECTOR
COLD
THM
RTS
0.28 VL
RTP
HOT
RT
ENABLE THM
0.03 VL
RT
THM
OUT OF
RANGE
DISABLE
CHARGER
ALL COMPARATORS
60mV HYSTERESIS
GND
Figure 7. Thermistor Monitor Circuitry
Table 3. Fault Temperatures for Different
Thermistors
Thermistor β (K)
3000
3250
3500
3750
4250
RTB (kΩ) (Figure 7)
10
10
10
10
10
Resistance at +25°C
(kΩ)
10
10
10
10
10
Resistance at +50°C
(kΩ)
4.59
4.30
4.03
3.78
3.316
Resistance at 0°C (kΩ)
25.14
27.15
29.32 31.66
36.91
Nominal Hot Trip
Temperature (°C)
55
53
50
49
46
Nominal Cold Trip
Temperature (°C)
-3
-1
0
2
4.5
VL Regulator
VL is a 5V linear regulator that powers the MAX8903’s
internal circuitry and charges the BST capacitor. VL is
used externally to bias the battery’s thermistor. VL takes
its input power from USB or DC. When input power is
available from both USB and DC, VL takes power from
DC. VL is enabled whenever the input voltage at USB
or DC is greater than ~1.5V. VL does not turn off when
the input voltage is above the overvoltage threshold.
Similarly, VL does not turn off when the charger is disabled (CEN = high). Connect a 1µF ceramic capacitor
from VL to GND.
Maxim Integrated
Thermistor Input (THM)
The THM input connects to an external negative temperature coefficient (NTC) thermistor to monitor battery
or system temperature. Charging is suspended when
the thermistor temperature is out of range. The charge
timers are suspended and hold their state but no fault is
indicated. When the thermistor comes back into range,
charging resumes and the charge timer continues from
where it left off. Connecting THM to GND disables the
thermistor monitoring function. Table 3 lists the fault
temperature of different thermistors.
Since the thermistor monitoring circuit employs an external bias resistor from THM to VL (RTB, Figure 7), the thermistor is not limited only to 10kΩ (at +25°C). Any
resistance thermistor can be used as long as the value is
equivalent to the thermistor’s +25°C resistance. For
example, with a 10kΩ at +25°C thermistor, use 10kΩ at
RTB, and with a 100kΩ at +25°C thermistor, use 100kΩ.
For a typical 10kΩ (at +25°C) thermistor and a 10kΩ
RTB resistor, the charger enters a temperature suspend
state when the thermistor resistance falls below 3.97kΩ
(too hot) or rises above 28.7kΩ (too cold). This corresponds to a 0°C to +50°C range when using a 10kΩ
NTC thermistor with a beta of 3500. The general relation
of thermistor resistance to temperature is defined by
the following equation:
RT = R25 × e
⎧ ⎛
1
1 ⎞⎫
−
⎨β ⎜
⎟⎬
298°C ⎠ ⎭⎪
⎩⎪ ⎝ T + 273°C
21
MAX8903A–E/G/H/J/N/Y
2A 1-Cell Li+ DC-DC Chargers
for USB and Adapter Power
where:
RT = The resistance in Ω of the thermistor at temperature T in Celsius
R25 = The resistance in Ω of the thermistor at +25°C
β = The material constant of the thermistor, which typically ranges from 3000K to 5000K
T = The temperature of the thermistor in °C
Table 3 shows the MAX8903_ THM temperature limits
for different thermistor material constants.
and let the system continue to operate with external power.
If the THM pin is tied to GND (voltage at THM is below 3%
of VL), the thermistor option is disabled and the system
does not respond to the thermistor input. In those cases, it
is assumed that the system has its own temperature sensing, and halts changing through CEN when the temperature is outside of the safe charging range.
Some designs might prefer other thermistor temperature
limits. Threshold adjustment can be accommodated by
changing RTB, connecting a resistor in series and/or in
parallel with the thermistor, or using a thermistor with different β. For example, a +45°C hot threshold and 0°C
cold threshold can be realized by using a thermistor
with a β of 4250 and connecting 120kΩ in parallel. Since
the thermistor resistance near 0°C is much higher than it
is near +50°C, a large parallel resistance lowers the
cold threshold, while only slightly lowering the hot
threshold. Conversely, a small series resistance raises
the hot threshold, while only slightly raising the cold
threshold. Raising RTB lowers both the cold and hot
thresholds, while lowering RTB raises both thresholds.
Note that since VL is active whenever valid input power
is connected at DC or USB, thermistor bias current
flows at all times, even when charging is disabled (CEN
= high). When using a 10kΩ thermistor and a 10kΩ
pullup to VL, this results in an additional 250µA load.
This load can be reduced to 25µA by instead using a
100kΩ thermistor and 100kΩ pullup resistor.
28-PIN 4mm x 4mm THIN QFN
Power Enable on Battery Detection
The power enabled on battery detection function allows
the MAX8903B/MAX8903E/MAX8903G to automatically
enable/disable the USB and DC power inputs when the
battery is applied/removed. This function utilizes the
battery pack’s integrated thermistor as a sensing mechanism to determine when the battery is applied or
removed. With this function, MAX8903B/MAX8903E/
MAX8903G-based systems shut down when the battery
is removed regardless of whether external power is
available at the USB or DC power inputs.
The MAX8903B/MAX8903E/MAX8903G implement the
power enabled on battery detection function with the thermistor detector comparator as shown in Figure 7. If no battery is present, the absence of the thermistor allows RTB to
pull THM to VL. When the voltage at the THM pin increases
above 87% of VL, it is assumed that the battery has been
removed and the system powers down. However, there is
also the option to bypass this thermistor sensing option
completely, and so retain the ability to remove the battery
22
Power Dissipation
Table 4. Package Thermal Characteristics
SINGLE-LAYER PCB
MULTILAYER PCB
1666.7mW
2286mW
Derate 20.8mW/°C
above +70°C
Derate 28.6mW/°C
above +70°C
θJA
48°C/W
35°C/W
θJC
3°C/W
3°C/W
Continuous
Power
Dissipation
Minimum SYS Output Capacitor
Based on the version of the MAX8903_, the SYS load
regulation is either 25mV/A or 40mV/A. The 25mV/A versions achieve better load regulation by increasing the
feedback loop gain. To ensure feedback stability with
this higher gain, a larger SYS output capacitor is
required. Devices with 25m/V SYS load regulation
require 22µF SYS output capacitor whereas devices
with 40m/V only require 10µF. See Table 6 for more
information about the various versions of the
MAX8903_.
Inductor Selection for
Step-Down DC-DC Regulator
The MAX8903_'s control scheme requires an external
inductor (LOUT) from 1.0µH to 10µH for proper operation.
This section describes the control scheme and the considerations for inductor selection. Table 5 shows recommended inductors for typical applications. For assistance with
the calculations needed to select the optimum inductor for
a given application, refer to the spreadsheet at:
www.maximintegrated.com/design/tools/calculators/files/MAX8903-INDUCTOR-DESIGN.xls.
The MAX8903 step-down DC-DC regulator implements a
control scheme that typically results in a constant switching frequency (fSW). When the input voltage decreases to
a value near the output voltage, high duty cycle operation
occurs and the device can operate at less than fSW due
to minimum off-time (tOFFMIN) constraints. In high duty
cycle operation, the regulator operates with tOFFMIN and
a peak current regulation. Similarly, when the input
voltage is too high to allow fSW operation due to minimum
Maxim Integrated
MAX8903A–E/G/H/J/N/Y
2A 1-Cell Li+ DC-DC Chargers
for USB and Adapter Power
on-time constraints (tONMIN), the regulator becomes a
fixed minimum on-time valley current regulator.
Versions of the MAX8903 with fSW = 4MHz offer the
smallest LOUT while delivering good efficiency with low
input voltages (5V or 9V). For applications that use high
input voltages (12V), the MAX8903G with fSW = 1MHz
is the best choice because of its higher efficiency.
For a given maximum output voltage, the minimum
inductor ripple current condition occurs at the lowest
input voltage that allows the regulator to maintain fSW
operation. If the minimum input voltage dictates an offtime less than tOFFMIN, then the minimum inductor ripple condition occurs just before the regulator enters
fixed minimum off-time operation. To allow the currentmode regulator to provide a low-jitter, stable duty factor
operation, the minimum inductor ripple current
(IL_RIPPLE_MIN) should be greater than 150mA in the
minimum inductor ripple current condition. The maximum allowed output inductance LOUT_MAX is therefore
obtained using the equations (1) and (2) below.
(1)
⎛ VSYS(MAX) ⎞
1
tOFF = tOFFMIN if ⎜ 1 −
≤ tOFFMIN ,
⎟×
VDC(MIN) ⎠ fSW
⎝
( VDC(MAX) − VSYS(MIN) ) × tON
K × ISDLIM
where VDC(MAX) is maximum input voltage, VSYS(MIN) is
the minimum charger output voltage, and tON is the ontime at high input voltage, as given by the following
equation:
(5)
⎛ VSYS(MIN)
1 ⎞
tON = tONMIN if ⎜
×
⎟ ≤ tONMIN ,
V
f
⎝ DC(MAX) SW ⎠
⎝
otherwise,
tON =
VSYS(MIN)
VDC(MAX)
×
1
fSW
The saturation current DC rating of the inductor (ISAT)
must be greater than the DC step-down output current
limit (ISDLIM) plus one-half the maximum ripple current,
as given by equation (6).
(6)
ISAT > ISDLIM +
ILRIPPLE _ MAX
2
where ILRIPPLE_MAX is the greater of the ripple currents
obtained from (7) and (8).
otherwise,
⎛ VSYS(MAX) ⎞
1
tOFF = ⎜ 1 −
⎟×
VDC(MIN) ⎠ fSW
⎝
where tOFF is the off-time, VSYS(MAX) is maximum charger
output voltage, and VDC(MIN) is minimum DC input voltage.
(2)
(4) LOUT _ MIN _ t
=
ON
LOUT _ MAX =
VSYS(MAX) × tOFF
IL _ RIPPLE _ MIN
where LOUT_MAX is the maximum allowed inductance.
To obtain a small-sized inductor with acceptable core
loss, while providing stable, jitter-free operation at the
advertised fSW, the actual output inductance (LOUT), is
obtained by choosing an appropriate ripple factor K, and
picking an available inductor in the range inductance
yielded by equations (2), (3), and (4). LOUT should also
not be lower than the minimum allowable inductance as
shown in Table 6. The recommended ripple factor ranges
from (0.2 ≤ K ≤ 0.45) for (2A ≥ ISDLIM ≥ 1A) designs.
(3)
VSYS(MAX) × tOFF
LOUT _ MIN _ TOFF =
K × ISDLIM
(7)
(8)
ILRIPPLE _ MIN _ TOFF =
ILRIPPLE _ MIN _ TON =
VSYS(MAX) × tOFF
LOUT
( VDC(MAX) − VSYS(MIN) ) × tON
LOUT
PCB Layout and Routing
Good design minimizes ground bounce and voltage gradients in the ground plane, which can result in instability
or regulation errors. The GND and PGs should connect to
the power-ground plane at only one point to minimize the
effects of power-ground currents. Battery ground should
connect directly to the power-ground plane. The ISET
and IDC current-setting resistors should connect directly
to GND to avoid current errors. Connect GND to the
exposed pad directly under the IC. Use multiple tightly
spaced vias to the ground plane under the exposed pad
to help cool the IC. Position input capacitors from DC,
SYS, BAT, and USB to the power-ground plane as close
as possible to the IC. Keep high current traces such as
those to DC, SYS, and BAT as short and wide as possible. Refer to the MAX8903A Evaluation Kit for a suitable
PCB layout example.
where tOFF is the minimum off-time obtained from (1).
Maxim Integrated
23
MAX8903A–E/G/H/J/N/Y
2A 1-Cell Li+ DC-DC Chargers
for USB and Adapter Power
Table 5. Recommended Inductor Examples
DC INPUT
VOLTAGE
RANGE
5V ±10%
5V ±10%
5V ±10%
5V ±10%
9V ±10%
9V ±10%
24
DC STEP-DOWN
OUTPUT
CURRENT LIMIT
(ISDMAX)
PART NUMBER,
SWITCHING
FREQUENCY*
RECOMMENDED INDUCTOR
MAX8903H/J/N/Y, 4MHz
1.0µH, IFSC1008ABER1R0M01, Vishay
2.5mm x 2mm x 1.2mm, 43mΩ (max), 2.6A
or 1.0µH, LQH32PN1R0-NN0, Murata,
3.2mm x 2.5mm x 1.55mm, 54mΩ (max), 2.3A
1A
MAX8903H/J/N/Y, 4MHz
1.5µH inductor, MDT2520-CN1R5M, TOKO
2.5mm x 2.0mm x 1.2mm, 123.5mΩ (max), 1.25A
or 1.5uH Inductor, IFSC1008ABER1R5M01, Vishay
2.5mm x 2mm x 1.2mm, 72mΩ (max), 2.2A
2A
MAX8903A/B/C/D/E,
4MHz
2.2µH inductor, DFE322512C-2R2N, TOKO
3.2mm x 2.5mm x 1.2mm, 91mΩ (max), 2.4A
or 2.2µH inductor, IFSC1515AHER2R2M01, Vishay
3.8mm x 3.8mm x 1.8mm, 45mΩ (max), 3A
1A
MAX8903A/B/C/D/E,
4MHz
2.2µH inductor, IFSC1008ABER2R2M01, Vishay
2.5mm x 2mm x 1.2mm, 90mΩ (max), 2.15A
or 2.2µH Inductor, LQH32PN2R2-NN0, Murata
3.2mm x 2.5mm x 1.55mm, 91mΩ (max), 1.55A
MAX8903H/J/N/Y, 4MHz
1.5uH inductor, IFSC1008ABER1R5M01, Vishay
2.5mm x 2mm x 1.2mm, 72mW (max), 2.2A
or 1.5µH Inductor, VLS4012ET-1R5N, TDK
4mm x 4mm x 1.2mm, 72mW (max), 2.1A
MAX8903H/J/N/Y, 4MHz
2.2µH inductor, IFSC1008ABER2R2M01, Vishay
2.5mm x 2mm x 1.2mm, 90mΩ (max), 2.15A
or 2.2µH inductor, LQH3NPN2R2NJ0, Murata
3mm x 3mm x 1.1mm, 83mΩ (max), 1.15A
2A
2A
1A
Maxim Integrated
MAX8903A–E/G/H/J/N/Y
2A 1-Cell Li+ DC-DC Chargers
for USB and Adapter Power
Table 5. Recommended Inductor Examples (continued)
DC INPUT
VOLTAGE
RANGE
9V ±10%
9V ±10%
9V ±10%
9V ±10%
12V ±10%
12V ±10%
DC STEP-DOWN
OUTPUT
CURRENT LIMIT
(ISDMAX)
PART NUMBER,
SWITCHING
FREQUENCY*
2A
MAX8903A/B/C/D/E,
4MHz
2.2µH inductor, DFE322512C-2R2N, TOKO
3.2mm x 2.5mm x 1.2mm, 91mΩ (max), 2.4A
or 2.2µH Inductor, IFSC1515AHER2R2M01, Vishay
3.8mm x 3.8mm x 1.8mm, 45mΩ (max), 3A
1A
MAX8903A/B/C/D/E,
4MHz
2.2µH Inductor, IFSC1008ABER2R2M01, Vishay
2.5mm x 2mm x 1.2mm, 90mΩ (max), 2.15A
or 2.2µH Inductor, LQH3NPN2R2NJ0, Murata
3mm x 3mm x 1.1mm, 83mΩ (max), 1.15A
2A
1A
2A
1A
RECOMMENDED INDUCTOR
MAX8903G, 1MHz
4.3uH Inductor, DEM4518C (1235AS-H-4R3M), TOKO
4.7mm x 4.5mm x 1.8mm, 84mΩ (max), 2.0A
or 4.7µH Inductor, IFSC1515AHER4R7M01, Vishay
3.8mm x 3.8mm x 1.8mm, 90mΩ (max), 2.0A
MAX8903G, 1MHz
4.7µH inductor, DEM2818C (1227AS-H-4R7M), TOKO
3.2mm x 2.8mm x 1.8mm, 92mΩ (max), 1.1A
or 4.7µH inductor, IFSC1008ABER4R7M01, Vishay
2.5mm x 2mm x 1.2mm, 212mΩ (max), 1.2A
MAX8903G, 1MHz
4.3µH inductor, DEM4518C (1235AS-H-4R3M), TOKO
4.7mm x 4.5mm x 1.8mm, 84mΩ (max), 2.0A
or 4.7µH inductor, IFSC1515AHER4R7M01, Vishay
3.8mm x 3.8mm x 1.8mm, 90mΩ (max), 2.0A
MAX8903G, 1MHz
6.8µH, IFSC1515AHER6R8M01, Vishay
3.8mm x 3.8mm x 1.8mm, 115mΩ (max), 1.5A
or 6.8µH, LQH44PN6R8MP0, Murata
4mm x 4mm x 1.65mm, 144mΩ (max), 1.34A
*See the Selector Guide for more information about part numbers.
Maxim Integrated
25
MAX8903A–E/G/H/J/N/Y
2A 1-Cell Li+ DC-DC Chargers
for USB and Adapter Power
Selector Guide
The MAX8903_ is available in several options designated by the first letter following the root part number. The
basic architecture and functionality of the
MAX8903A–MAX8903E/MAX8903G/MAX8903Y are the
same. Their differences lie in certain electrical and
operational parameters. Table 6 outlines these differences.
Table 6. Selector Guide
PARAMETER MAX8903A MAX8903B MAX8903C MAX8903D MAX8903E MAX8903G MAX8903H MAX8903J MAX8903N MAX8903Y
Minimum SYS
Regulation
Voltage
(VSYSMIN)
3.0V
3.0V
3.4V
3.4V
3.0V
3.0V
3.4V
3.4V
3.4V
3.0V
SYS Regulation
Voltage
(VSYSREG)
4.4V
4.325V
4.4V
4.4V
4.325V
4.325V
4.4V
4.5V
4.4V
4.4V
Minimum
Allowable
Inductor
2.2µH
2.2µH
2.2µH
2.2µH
2.2µH
2.2µH
1µH
1µH
1µH
1µH
Switching
Frequency
4MHz
4MHz
4MHz
4MHz
4MHz
1MHz
4MHz
4MHz
4MHz
4MHz
SYS Load
Regulation
40mV/A
25mV/A
40mV/A
40mV/A
25mV/A
25mV/A
40mV/A
25mV/A
25mV/A
25mV/A
Minimum SYS
Output
Capacitor (CSYS)
10µF
22µF
10µF
10µF
22µF
22µF
10µF
10µF
22µF
22µF
BAT Regulation
Voltage
(VBATREG)
(Note 5)
4.2V
4.2V
4.2V
4.1V
4.1V
4.2V
4.2V
4.35V
4.15V
4.15V
BAT Prequal
Threshold
(VBATPQ)
(Note 5)
3V
2.5V
3V
3V
2.5V
2.5V
3V
3V
3V
3V
Top-Off Timer
(Note 6)
15s (fixed)
132min
15s (fixed)
15s (fixed)
132min
132min
VL Output
Current Rating
1mA
10mA
1mA
1mA
10mA
10mA
1mA
1mA
1mA
1mA
Power-Enable
On Battery
Detection
(Note 7)
No
Yes
No
No
Yes
Yes
No
No
No
No
Comments
—
—
—
—
—
—
(Note 8)
—
—
—
Note 5:
Note 6:
Note 7:
Note 8:
26
15s (fixed) 15s (fixed) 15s (fixed) 15s (fixed)
Typical values. See the Electrical Characteristics table for min/max values.
Note that this also changes the timing for the prequal and fast-charge timers.
See the Power Enable on Battery Detection section for details.
The MAX8903H is a newer version of the MAX8903C that is a recommended for new designs.
Maxim Integrated
MAX8903A–E/G/H/J/N/Y
2A 1-Cell Li+ DC-DC Chargers
for USB and Adapter Power
Pin Configuration
Chip Information
USB
THM
USUS
20
UOK
21
FLT
BAT
TOP VIEW
BAT
PROCESS: BiCMOS
19
18
17
16
15
CHG 22
14
CEN
SYS 23
13
ISET
12
GND
11
IDC
CS 26
10
CT
LX 27
9
VL
8
DOK
SYS 24
MAX8903_
CS 25
5
6
7
IUSB
DC
4
BST
3
DCM
2
DC
1
PG
+
PG
LX 28
EP
TQFN
Maxim Integrated
27
MAX8903A–E/G/H/J/N/Y
2A 1-Cell Li+ DC-DC Chargers
for USB and Adapter Power
Package Information
For the latest package outline information and land patterns (footprints), go to www.maximintegrated.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.
28
PACKAGE TYPE
PACKAGE CODE
OUTLINE NO.
LAND
PATTERN NO.
28 TQFN-EP
T2844-1
21-0139
90-0035
Maxim Integrated
MAX8903A–E/G/H/J/N/Y
2A 1-Cell Li+ DC-DC Chargers
for USB and Adapter Power
Package Information (continued)
For the latest package outline information and land patterns (footprints), go to www.maximintegrated.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.
Maxim Integrated
29
MAX8903A–E/G/H/J/N/Y
2A 1-Cell Li+ DC-DC Chargers
for USB and Adapter Power
Revision History
REVISION
NUMBER
REVISION
DATE
0
12/08
Initial release
1
8/09
Added MAX8903C/MAX8903D to data sheet
2
11/09
Made various corrections
3
10/10
Added MAX8903B, MAX8903E, MAX8903G, and MAX8903Y
1–29
4
5/11
Added MAX8903H and MAX8903J and updated components
1–29
5
9/11
Added the MAX8903N, and removed future product designation for MAX8903J
1–29
DESCRIPTION
PAGES
CHANGED
—
1–20
1–7, 9, 11–21
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. The parametric values (min and max limits) shown in
the Electrical Characteristics table are guaranteed. Other parametric values quoted in this data sheet are provided for guidance.
30 ________________________________Maxim Integrated 160 Rio Robles, San Jose, CA 95134 USA 1-408-601-1000
© 2011 Maxim Integrated Products, Inc.
The Maxim logo and Maxim Integrated are trademarks of Maxim Integrated Products, Inc.
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