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Preliminary Datasheet
LP28011
1A Single-chip Li-ion and Li-POL Charge with OVP
General Description
The LP28011 is a complete constant-current/ constantvoltage linear charger for single cell lithium-ion batteries. Its TDFN-10 package and low external component count make the LP28011 ideally suited for portable applications. Furthermore, the LP28011 is specifically designed to work within USB power specifications. Its have a over voltage protection in input with 6V and support over zero voltages of battery can charge enable. No external sense resistor is needed, and no blocking diode is required due to the internal MOSFET architecture. Thermal feedback regulates the charge current to limit the die temperature during high power operation or high ambient temperature. The charge voltage is fixed at 4.2V, and the charge current can be ISET rammed externally with a single resistor. The LP28011 automatically terminates the charge cycle when the charge current drops to 1/10th the ISET rammed value after the final float voltage is reached. When the input supply (wall adapter or USB supply) is removed, the LP28011 automatically enters a low current state, dropping the battery drain current to less than 2A. The LP28011 can be put into shutdown mode, reducing the supply current to 25A. Other features include charge current monitor, undervoltage lockout, automatic recharge and a status pin to indicate charge termination and the presence of an input voltage.
Features
Very Low Power Dissipation Vin Over Voltage Protection:6V Short-circuit protection Programmable Charge Current Up to 1000mA No MOSFET, Sense Resistor or Blocking Diode Required Constant-Current/Constant-Voltage Operation with Thermal Regulation* to Maximize Charge Rate Without Risk of Overheating Charges Single Cell Li-Ion Batteries Directly from USB Port 25A Supply Current in Shutdown Time Pre-charge Conditioning With Safety Timer Reverse Leakage Protection Prevents Battery Drainage Charge Current Thermal Regulation Status Outputs for LED or System Interface Indicates Charge and Fault Conditions Optional Battery Temperature Monitoring Before and During Charge Automatic Sleep Mode for Low-Power Consumption Available in 3mm x 3mm TDFN-10 Package
RoHS Compliant and 100% Lead (Pb)-Free
Typical Application Circuit Order Information
LP28011 F: Pb-Free Package Type QV: TDFN-10
Vin 1 2 3 4 5 VIN VIN STAT1 STAT2 VSS LP28011 BATT BATT VSS VSS ISET 10 9 8 7 6 Rset 1uF BT3 BATT VBAT
BATTERY
Applications
Portable Media Players/MP3 players Cellular and Smart mobile phone PDA/DSC
ISTAT=830/Rset
Marking Information
Please see website.
Bluetooth Applications
LP28011 - 01 Ver. 1.1 Datasheet
Nov.-2007
Page 1 of 10
Preliminary Datasheet Functional Pin Description
P a c k a g e Ty p e Pin Configurations
LP28011
VIN
1 2 3 4 5 11
10 9 8 7 6
BATT BATT VSS VSS ISET
TDFN- 10
VIN STAT STAT VSS
Pi n Desc ript ion
PIN VIN STAT NC VSS
PIN Number 1,2 3 4 5,7,8,11
DESCRIPTION VIN is the input power source. Connect to a wall adapter. Open-Drain Charge Status Output. When the battery is charging, the STAT pin is pulled low by an internal N-channel MOSFET. When the charge cycle is completed, a weak pull-down of approximately 20A is connected to the STAT pin, indicating an "AC present" condition. When the LP28011 detects an under voltage lockout condition, STAT is forced high impedance. No connector. VSS is the connection to system ground. Charge Current Program, Charge Current Monitor and Shutdown Pin. The charge current is programmed by connecting a 1% resistor(RPROG)to ground. When charging in constant-current mode, this pin servos to 1V. In all modes, the voltage on this pin can be used to measure the charge current using the following formula:
IBAT = (VPROG/RPROG) * 830
ISET
6
The PROG pin can also be used to shut down the charger. Disconnecting the program resistor from ground allows a 3A current to pull the PROG pin high. When it reaches the 1.21V shutdown threshold voltage, the charger enters shutdown mode, charging stops and the input supply current drops to 25A. This pin is also clamped to approximately 2.4V. Driving this pin to voltages beyond the clamp voltage will draw currents as high as 1.5mA. Reconnecting RPROG to ground will return the charger to normal operation. VBAT is the connection to the battery. Typically a 1F Tantalum capacitor is needed for stability when there is no battery attached. When a battery is attached, only a 0.1F ceramic capacitor is required.
VBAT
9,10
LP28011 - 01 Ver. 1.1 Datasheet
Nov.-2007
Page 2 of 10
Preliminary Datasheet
LP28011
LP28011 - 01 Ver. 1.1 Datasheet
Nov.-2007
Page 3 of 10
Preliminary Datasheet Function Block Diagram
VIN
LP28011
VSS
ISET
STAT LP28011
Absolute Maximum Ratings
Input Voltage to GND (VIN) ----------------------------------------------------------------------------- 2.6V to 8V BAT, ISET, STAT (VX) ---------------------------------------------------------------------- 0.3V to VIN+0.3V BAT Short-Circuit Duration ---------------------------------------------------------------------------- Continuous BAT Pin Current ------------------------------------------------------------------------------------------ 1200mA ISET Pin Current --------------------------------------------------------------------------------------------- 800A Maximum Junction Temperature ---------------------------------------------------------------------------- 125C Operating Junction Temperature Range (TJ) ----------------------------------------------------- -40 to 85C Maximum Soldering Temperature (at leads, 10 sec) ------------------------------------------------------ 260C Thermal Information Maximum Power Dissipation (PD,TA<40C) -------------------------------------------------------------- 1.5W Thermal Resistance (JA) --------------------------------------------------------------------------------- 46/W
LP28011 - 01 Ver. 1.1 Datasheet Nov.-2007 Page 4 of 10
Preliminary Datasheet Electrical Characteristics
SYMBOL
VIN
ICC
LP28011
(The specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25C. VCC = 5V, unless otherwise noted.)
PARAMETER
Adapter/USB Voltage Range
Input Supply Current
CONDITIONS
Charge Mode (Note 4), RISET = 10k Standby Mode (Charge Terminated) Shutdown Mode (RISET Not Connected, VCC < VBAT, or VCC < VUV) 0C TA 85C, IBAT = 40mA RISET = 1k, Current Mode RISET = 2k, Current Mode
MIN 2.65
TYP. 5
300 200
MAX UNITS 6 V
2000 500 50 4.242 871 455 -6 2 2 70 3.0 110 3.95 300 1.30 1.1 140 50 0.115 0.115 1.1 35 0.6 200 120 600 4.5 2500
6.5
uA V mA
VFLOAT
Regulated Output (Float) Voltage
IBAT
BAT Pin Current
Standby Mode, VBAT = 4.2V Shutdown Mode (RISET Not Connected) Sleep Mode, VCC = 0V VBAT < VTRIKL, RISET = 2k (Note 5) RISET = 10k, VBAT Rising (Note 5) RISET = 10k (Note 5)
4.158 788 386 0
ITRIKL VTRIKL VTRHYS VUV VUVHYS VMSD VASD ITERM VISET ISTAT VSTAT VRESTAT TLIM RON tSS tRECHARGE tTERM IISET VIN OVP
Trickle Charge Current Trickle Charge Threshold Voltage Trickle Charge Hysteresis Voltage VCC Undervoltage Lockout Hysteresis Manual Shutdown Threshold Voltage VCC - VBAT Lockout Threshold Voltage C/10 Termination Current Threshold ISET Pin Voltage STAT Pin Weak Pull-Down Current STAT Pin Output Low Voltage
VCC Undervoltage Lockout Threshold From VCC Low to High ISET Pin Rising ISET Pin Falling VCC from Low to High VCC from High to Low RISET = 10k (Note 6) RISET = 2k RISET = 10k, Current Mode VSTAT = 5V ISTAT = 5mA
20 2.8 60 3.7 150 1.15 0.9 70 5 0.085 0.085 0.9 8 100
Recharge Battery Threshold Voltage VFLOAT - VRESTAT Junction Temperature in Constant Temperature Mode Power FET "ON" Resistance (Between VCC and BAT) Soft-Start Time Recharge Comparator Filter Time Termination Comparator Filter Time ISET Pin Pull-Up Current Over voltage protection IBAT = 0 to IBAT =830V/RISET VBAT High to Low IBAT Falling Below ICHG/10
25 4.2 830 415 -2.5 1 1 45 2.9 80 3.8 200 1.21 1.0 100 30 0.10 0.10 1.0 20 0.35 150
uA mA V mV V mV V V mV mV
mA/mA mA/mA
V uA V mV
C m
0.75 400
5.9
100 2 1000 3
6.2
uS mS uS uA
V
LP28011 - 01 Ver. 1.1 Datasheet
Nov.-2007
Page 5 of 10
Preliminary Datasheet
LP28011
LP28011 - 01 Ver. 1.1 Datasheet
Nov.-2007
Page 6 of 10
Preliminary Datasheet Typical Operating Characteristics
LP28011
LP28011 - 01 Ver. 1.1 Datasheet
Nov.-2007
Page 7 of 10
Preliminary Datasheet Operation
The LP28011 is a single cell lithium-ion battery charger using a constant-current/constant-voltage algorithm. It can deliver up to 800mA of charge current (using a good thermal PCB layout) with a final float voltage accuracy of 1%. The LP28011 includes an internal P-channel power MOSFET and thermal regulation circuitry. No blocking diode or external current sense resistor is required; thus, the basic charger circuit requires only two external components. Furthermore, the LP28011 is capable of operating from a USB power source.
LP28011
tTERM (typically 1ms), charging is terminated. The charge current is latched off and the LP28011 enters standby mode, where the input supply current drops to 200A. (Note: C/10 termination is disabled in trickle charging and thermal limiting modes). When charging, transient loads on the BAT pin can cause the ISET pin to fall below 100mV for short periods of time before the DC charge current has dropped to 1/10th the ISET rammed value. The 1ms filter time (tTERM) on the termination comparator ensures that transient loads of this nature do not result in premature charge cycle termination. Once the average charge current drops below 1/10th the ISET rammed value, the LP28011 terminates the charge cycle and ceases to provide any current through the BAT pin. In this state, all loads on the BAT pin must be supplied by the battery. The LP28011 constantly monitors the BAT pin voltage in standby mode. If this voltage drops below the 4.05V recharge threshold (VRESTAT), another charge cycle begins and current is once again supplied to the battery. To manually restart a charge cycle when in standby mode, the input voltage must be removed and reapplied, or the charger must be shut down and restarted using the ISET pin. Figure 1 shows the state diagram of a typical charge cycle. Charge Status Indicator (STAT) The charge status output has three different states: strong pull-down (~10mA), weak pull-down (~20A) and high impedance. The strong pull-down state indicates that the LP28011 is in a charge cycle. Once the charge cycle has terminated, the pin state is determined by undervoltage lockout conditions. A weak pull-down indicates that VCC meets the UVLO conditions and the LP28011 is ready to charge. High impedance indicates that the LP28011 is in undervoltage lockout mode: either VCC is less than 100mV above the BAT pin voltage or insufficient voltage is applied to the VCC pin. A microprocessor can be used to distinguish between these three states--this method is discussed in the Applications Information section. Thermal Limiting An internal thermal feedback loop reduces the ISET rammed charge current if the die temperature attempts to rise above a preset value of approximately 120C. This feature protects the LP28011 from excessive temperature and allows the user to push the limits of the power handling capability of a given circuit board without risk of damaging the LP28011. The charge current can be set according to typical (not worst-case) ambient temperature with the
Page 8 of 10
Normal Charge Cycle
A charge cycle begins when the voltage at the VCC pin rises above the UVLO threshold level and a 1% ISET ram resistor is connected from the ISET pin to ground or when a battery is connected to the charger output. If the BAT pin is less than 2.9V, the charger enters trickle charge mode. In this mode, the LP28011 supplies approximately 1/10 the ISET rammed charge current to bring the battery voltage up to a safe level for full current charging. (Note: The LP28011X does not include this trickle charge feature). When the BAT pin voltage rises above 2.9V, the charger enters constant-current mode, where the ISET rammed charge current is supplied to the battery. When the BAT pin approaches the final float voltage (4.2V), the LP28011 enters constant-voltage mode and the charge current begins to decrease. When the charge current drops to 1/10 of the ISET rammed value, the charge cycle ends. ISET ramming Charge Current The charge current is ISET rammed using a single resistor from the ISET pin to ground. The battery charge current is 1000 times the current out of the ISET pin. The ISET ram resistor and the charge current are calculated using the following equations:
RSET=830V/ICHGICHG= 830V/RSET
The charge current out of the BAT pin can be determined at any time by monitoring the ISET pin voltage using the following equation:
IBAT= VSET x 830/RSET
Charge Termination A charge cycle is terminated when the charge current falls to 1/10th the ISET rammed value after the final float voltage is reached. This condition is detected by using an internal, filtered comparator to monitor the ISET pin. When the ISET pin voltage falls below 100mV for longer than
LP28011 - 01 Ver. 1.1 Datasheet Nov.-2007
1
Preliminary Datasheet
assurance that the charger will automatically reduce the current in worst-case conditions. TDFN power considerations are discussed further in the Applications Information section. Undervoltage Lockout (UVLO) An internal undervoltage lockout circuit monitors the input voltage and keeps the charger in shutdown mode until VCC rises above the undervoltage lockout threshold. The UVLO circuit has a built-in hysteresis of 200mV. Furthermore, to protect against reverse current in the power MOSFET, the UVLO circuit keeps the charger in shutdown mode if VCC falls to within 30mV of the battery voltage. If the UVLO comparator is tripped, the charger will not come out of shutdown mode until VCC rises 100mV above the battery voltage. Manual Shutdown At any point in the charge cycle, the LP28011 can be put into shutdown mode by removing RISET thus floating the ISET pin. This reduces the battery drain current to less than 2A and the supply current to less than 50A. A new charge cycle can be initiated by reconnecting the ISETram resistor. In manual shutdown, the STAT pin is in a weak pull-down state as long as VCC is high enough to exceed the UVLO conditions. The STAT pin is in a high impedance state if the LP28011 is in undervoltage lockout mode: either VCC is within 100mV of the BAT pin voltage or insufficient voltage is applied to the VCC pin. Automatic Recharge Once the charge cycle is terminated, the LP28011 continuously monitors the voltage on the BAT pin using a comparator with a 2ms filter time (tRECHARGE). A charge cycle restarts when the battery voltage falls below 4.05V (which corresponds to approximately 80% to 90% battery capacity). This ensures that the battery is kept at or near a fully charged condition and eliminates the need for periodic charge cycle initiations. STAT output enters a strong pull-down state during recharge cycles. Power Dissipation The conditions that cause the LP28011 battery charger to reduce charge current through thermal feedback can be approximated by considering the total power dissipated in the IC. For high charge currents, the LP28011 power dissipation is approximately:
LP28011
Where PD is the total power dissipated within the IC, ADP is the input supply voltage, VBAT is the battery voltage, IBAT is the charge current and PD_BUCK is the power dissipation due to the regulator. PD_BUCK can be calculated as:
Where VOUTB is the regulated output of the switching regulator, IOUTB is the regulator load and is the regulator efficiency at that particular load. It is not necessary to perform worst-case power dissipation scenarios because the LP28011 will automatically reduce the charge current to maintain the die temperature at approximately 125C. However, the approximate ambient temperature at which the thermal feedback begins to rotect the IC is:
Example: Consider the extreme case when an LP28011 is operating from a 6V supply providing 250mA to a 3V Li-Ion battery, the switching regulator and the LDO are off. The ambient temperature above which the LP28011 will begin to reduce the 250mA charge current is approximately: (Correctly soldered to a 2500mm2 double-sided 1 oz. copper board, the LP28011 has a thermal resistance of approximately 43C/W.)
T= If there is more power dissipation due to the switching regulator or the LDO, the thermal regulation will kick in at a somewhat lower temperature than this. In the above circumstances, the LP28011 can be used above 82.75C, but the charge current will be reduced from 250mA. The approximate current at a given ambient temperature can be calculated:
o
o
o
Note: 1V = 1J/C = 1W/A Furthermore, the voltage at the ISET pin will change proportionally with the charge current as discussed in the ISET ramming Charge Current section.
LP28011 - 01 Ver. 1.1 Datasheet
Nov.-2007
Page 9 of 10
Preliminary Datasheet Packaging Information
LP28011
LP28011 - 01 Ver. 1.1 Datasheet
Nov.-2007
Page 10 of 10

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