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PDF MAX8903B Data sheet ( Hoja de datos )
| Número de pieza | MAX8903B | |
| Descripción | 1-Cell Li+ DC-DC Charger | |
| Fabricantes | Maxim Integrated Products | |
| Logotipo |  |
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19-4502; Rev 1; 11/09
EVAALVUAAILTAIOBNLEKIT
www.DataSheet4U.com
2A, 1-Cell Li+ DC-DC Charger for USB
and Adapter Power
General Description
The MAX8903B is an integrated 1-cell Li+ charger and
Smart Power Selector™ with dual (AC adapter and
USB) power inputs. The switch mode charger uses a
high switching frequency to eliminate heat and allow for
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 on-chip. No external
MOSFETs, blocking diodes, or current-sense resistors
are required.
The MAX8903B 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 cur-
rent can be set to 100mA or 500mA. Automatic input
selection switches the system load 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 4.1V to 6.5V range of with up to 8V protection.
The MAX8903B internally blocks current from the bat-
tery and system back to the DC and USB inputs when
no input supply is present. Other features include pre-
qual charging and timer, fast charge timer, taper cur-
rent detection for charge status, 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
MAX8903B is available in a 4mm x 4mm, 28-pin thin
QFN package.
Applications
PDA, Palmtop, and Wireless Handhelds
Personal Navigation Devices
Smart Cell Phones
Portable Multimedia Players
Mobile Internet Devices
Smart Power Selector is a trademark of Maxim Integrated
Products, Inc.
Features
o Efficient DC-DC Converter Powers System Load
and Charger
o 4MHz Switching for Tiny External Components
o Instant On—Works with No Battery or Low
Battery
o Dual Current-Limiting Input Circuits—AC Adapter
or USB
Automatic Adapter/USB/Battery Switchover to
Support Load Transients
50mΩ System-to-Battery Switch
Supports USB Spec
o Thermistor Monitor
o Integrated Current-Sense Resistor
o No External MOSFETS or Diodes
o 4.1V to 16V Input Operating Voltage Range
Ordering Information
PART
TEMP RANGE PIN-PACKAGE
MAX8903BETI+
-40°C to +85°C
28 Thin QFN-EP
(4mm x 4mm)
+Denotes a lead(Pb)-free/RoHS-compliant package.
**EP = Exposed pad.
Typical Operating Circuit
AC
ADAPTER
OR USB DC
LX
CS
Q1
SYS
PWM
STEP-DOWN
USB USB
Q2
CHARGE
CURRENT
Q3
LOAD
CURRENT
CHARGE AND
SYS LOAD
SWITCH
SYSTEM
LOAD
BAT BATTERY
MAX8903B
GND
Pin Configuration appears 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.
1 page  
www.DataSheet4U.com
2A, 1-Cell Li+ DC-DC Charger 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
Logic Input Leakage Current
(CEN, USUS, IUSB)
Logic Input Leakage Current
(DCM)
Logic Output Voltage, Low
(CHG, FLT, DOK, UOK)
VINPUT = 0V to 5.5V (Note 5)
VDCM = 0V to 16V,
VDC = 16V
Sinking 1mA
Sinking 10mA
TA = +25°C
TA = +85°C
-0.2 0.001 +0.2
0.001
0.01
8
80
1
50
μA
μA
mV
Logic Output Leakage Current,
High (CHG, FLT, DOK, UOK)
VOUT = 5.5V (Note 5)
0.001
1
μA
VL Output Voltage
Thermal Shutdown Temperature
Thermal Shutdown Hysteresis
VDC = VUSB = 6V, IVL = 0 to 10mA
4.6 5 5.4
160
15
V
°C
°C
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 by the VIN/VOUT ratio 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.
Note 5: Limits over the operating temperature range are generated by design only.
(TA = +25°C, unless otherwise noted.)
Typical Operating Characteristics
BATTERY CHARGER EFFICIENCY
vs. BATTERY VOLTAGE
100
90 VDC = 5V
80
70 VDC = 8V
60
50
40 VDC = 12V
30
20 IBATT = 0.15A
IBATT = 1.5A
10
0
1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0
BATTERY VOLTAGE (V)
4.5
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0
4
SWITCHING FREQUENCY
vs. DC VOLTAGE
VBAT = 3V
VBAT = 4V
RISET = 1.2kΩ
VCEN = 0V
6 8 10 12 14 16
VDC (V)
SYS EFFICIENCY vs. SYS OUTPUT CURRENT
100
90
80
70
60 VDC = 16V
50 VDC = 11V
40
30 VDC = 6V
20
10 VDC = 4.5V
0
1 10 100 1000 10,000
SYS OUTPUT CURRENT (mA)
_______________________________________________________________________________________ 5
5 Page 
www.DataSheet4U.com
PIN
22
23, 24
25, 26
27, 28
—
2A, 1-Cell Li+ DC-DC Charger for USB
and Adapter Power
NAME
CHG
SYS
CS
LX
EP
Pin Description (continued)
FUNCTION
Charger Status Output. Active-low, open-drain output pulls low when the battery is in fast-charge or
prequal. Otherwise, CHG is high impedance.
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 4.325V. When the system load (ISYS)
exceeds the DC or USB current limit, SYS is regulated to 50mV below BAT and both the USB input and
the battery service SYS.
Bypass SYS to GND with a 22μF X5R or X7R ceramic capacitor. Both SYS pins must be connected
together externally.
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.
Inductor Connection. Connect the inductor between LX and CS. Both LX pins must be connected together
externally.
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.
______________________________________________________________________________________ 11
11 Page | ||
| Páginas | Total 26 Páginas | |
| PDF Descargar | [ Datasheet MAX8903B.PDF ] | |
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