Liteon Semiconductor Corporation
LSP4054
Standalone Linear Li-ion Battery Charger with Thermal Regulation
Rev1.1
1/17
APPLICATIONS
Cellular phones, PDAs
Bluetooth applications
Charging docks and Cradles
MP3 players
PIN CONFIGURATION
(Top View) (Top View)
SOT23-5L SOT89-5L
PIN DESCRIPTION
Pin Number Pin Name Pin Function
1 CHRG Open-drain charge status output
2 GND Ground
3 BAT Charge current output
4 Vcc Positive input supply voltage
5 PROG Charge current program, Charge current monitor and shutdown pin
GENERAL DESCRIPTION
The LSP4054 is a complete constant-current
/
constant-voltage linear charger for cell lithium-ion
batteries. Its Thin SOT23-5L package and low external
component count make the LSP4054 ideally suited fo
r
portable applications. Furthermore, the LSP4054 is
specifically designed to work within USB powe
r
specifications.
No external sense resistor is needed, and no blocking
diode is required due to the internal MOSFET architecture.
Thermal feedback regulators 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 programmed externally with
a single resistor. The LSP4054 automatically terminates
the charge cycle when the charge current drops to 1/10th
the programmed value after the final float voltage is
reached.
When the input supply (wall adapter or USB supply) is
removed, the LSP4054 automatically enters a low curren
t
state, dropping the battery drain current to less than 2uA.
The LSP4054 can be put into shutdown mode, reducing
the supply current to 25uA.
Other features include charge current monitor,
undervoltage lockout, automatic recharge and a status pin
to indicate charge termination and the presence of an inpu
t
voltage.
FEATURES
Programmable charge current up to 800mA
No MOSFET, sense resistor or blocking diode
required
Complete linear charger in thin SOT package for
single cell lithium–ion batteries
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
Preset 4.2V charge voltage with ±1% accuracy
Charge current monitor output for gas gauging
Automatic recharge
Charge status output pin
C/10 charge termination
25uA supply current in shutdown
2.9V trickle charge threshold
Soft-start limits inrush current
Available in SOT23-5L and SOT89 packages
TYPICAL APPLICATIONS CIRCUITS
600mA single cell Li-ion charger
Liteon Semiconductor Corporation
LSP4054
Standalone Linear Li-ion Battery Charger with Thermal Regulation
Rev1.1
2/17
BLOCK DIAGRAM
PIN FUNCTION
CHRG: When the battery is charging, the CHRG pin is pulled low by an internal N-channel MOSFET. When the
charge cycle is completed, a weak pull-down of approximately 20uA is connected to the CHRG pin, including an “AC
present” condition. When the LSP4054 detects an undervoltage lockout condition, CHRG is forced high impedance.
GND: Ground.
BAT: Provides charge current to the battery and regulators the final voltage to 4.2V. An internal precision resistor
divider from this pin sets the float voltage which is disconnected in shutdown mode.
Vcc: Provides power to the charger. Vcc can range from 4.25V to 6.5V and should be bypassed with at least a 1uF
capacitor. When Vcc drops to within 30mV of the BAT pin voltage, the LSP4054 enters shutdown mode, dropping
IBAT to less than 2uA.
PROG: The charge current is programmed by connected 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:
The PROG pin can also be used to shut down the charger. Disconnecting the program resistor from ground allows a
3uA 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 25uA. This pin is also clamped to
approximately 2.4V. Driving this pin to voltages beyond the clamp voltage will draw current as high as 1.5mmA.
Reconnected RPROG to ground will return the charger to normal operation.
Liteon Semiconductor Corporation
LSP4054
Standalone Linear Li-ion Battery Charger with Thermal Regulation
Rev1.1
3/17
OPERATION
The LSP4054 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 voltage accuracy of ±1%. The
LSP4054 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 LSP4054 is capable of operating from a USB power source.
Normal charge cycle
A charge cycle begins when the voltage at the Vcc pin rises above the UVLO threshold level and a 1% program
resistor is connected from the PROG 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 LSP4054 supplies approximately
1/10 the programmed charge current to bring the battery voltage up to a safe level for full current charging.
When the BAT pin voltage rises above 2.9V, the charger enters constant-current mode, where the programmed
charge current is supplied to the battery. When the BAT pin approaches the final float voltage (4.2V), the LSP4054
enters constant-voltage mode and the charge current begins to decrease. When the charge current drops to 1/10 of
the programmed value, the charge cycle ends.
Programmed charge current
The charge current is programmed using a single resistor from the PROG pin to ground. The battery charge current
is 900 times the current out of the PROG pin. The program resistor and the current are calculated using the following
equations:
The charge current out of the BAT pin can be determined at any time by monitoring the PROG pin voltage using the
following equation:
Charge termination
A charge cycle is terminated when the charge current falls to 1/10th the programmed value after the final float voltage
is reached. This condition is detected by using an internal, filtered comparator to monitor the PROG pin. When the
PROG pin voltage falls below 100mV for longer than tTERM, charging is terminated. The charge current is latched off
and the LSP4054 enters standby mode, where the input supply current drops to 200uA. (Note: C/10 termination is
disabled in trickle charging and thermal limiting modes)
When charging, transient loads on the BAT pin can cause the PROG pin to fall below 100mV for short periods of
time before the DC charge current has dropped to 1/10th the programmed value. The 1ms filter time 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 programmed value, the LSP4054 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 LSP4054 constantly monitor the BAT pin voltage in standby mode. If this voltage drops below the 4.05V
recharge threshold, 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 PROG pin. The figure 1shows the state diagram of a typical charge cycle.
Charge status indicator
The charge status output has three different states: strong pull-down(10mA), weak pull-down (20uA) and high
impedance. The strong pull-down state indicates that the LSP4054 is in a charge cycle. Once the charge cycle has
terminated, the pin state is determined by undervoltage lockout conditions. A weal pull-down indicates that Vcc
meets the UVLO conditions and the LSP4054 is ready to charge. High impedance indicates that the LSP4054 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 programmed charge current if the die temperature attempts to rise
above a preset value of approximately 120°C. This feature protects the LSP4054 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 LSP4054. The charge current can be set according to typical (not worst-case) ambient temperature with the
Liteon Semiconductor Corporation
LSP4054
Standalone Linear Li-ion Battery Charger with Thermal Regulation
Rev1.1
4/17
assurance that the charger will automatically reduce the current in worst-case conditions. ThinSOT 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 shut down
At any point in the charge cycle, the LSP4054 can be put into shutdown mode by removing RPROG thus floating the
PROG pin. This reduces the battery drain current to less than 2mA and the supply current to less than 50mA. A new
charge cycle can be initiated by reconnecting the program resistor.
In manual shutdown, the CHRG pin is in a weak pull-down state as long as VCC is high enough to exceed the UVLO
conditions. The CHRG pin is in a high impedance state if the LSP4054 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 LSP4054 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. CHRG output enters a strong
pulldown state during recharge cycles.
Figure 1:the state diagram of a typical charge cycle
Liteon Semiconductor Corporation
LSP4054
Standalone Linear Li-ion Battery Charger with Thermal Regulation
Rev1.1
5/17
ABSOLUTE MAXIMUM RATINGS(NOTE 1)
Parameter Rating Unit
Input Supply Voltage -0.3 to 10 V
PROG -0.3 to Vcc + 0.3
V
BAT -0.3 to 7 V
CHRG -0.3 to 10 V
BAT short-circuit duration continuous
BAT pin current 800 mA
PROG pin current 800 uA
Operating temperature(Note 2) -40 to 85 °C
Maximum Junction Temperature 125 °C
Storage Temperature -65 to 150 °C
Lead Temperature (Soldering, 10 sec) 300 °C
Note 1: Absolute Maximum Ratings are those values beyond which the life of a device may be impaired.
Note 2: The LSP4054 is guaranteed to meet performance specifications from 0°C ~ 70°C. Specifications over the
-40°C ~85°C operating temperature range are assured by design, characterization and correlation with
statistical process controls.
ELECTRICAL CHARACTERISTICS
The * denotes specifications which apply over the full operating temperature range, otherwise specifications are at
TA=25°C. Vcc=5V, unless otherwise noted.
PARAMETER SYMBO
L TEST CONDITIONS MIN TYP MAX UNIT
Input Voltage Vcc * 4.25 6.5 V
*Charge mode(Note3) RPROG=10k 300 2000
*Standby mode(Charge terminated) 200 500
Input supply current Icc *Shutdown mode(RPROG not
connected, VCC＜VBAT, or VCC＜VUV) 25 50
uA
Regulated output (Float)
voltage VFLOAT 0°C＜TA＜85°C, IBAT=40mA 4.158 4.2 4.342 V
*RPROG=10k, current mode 93 100 107 mA
*RPROG=2k, current mode 465 500 535 mA
*VBAT=4.2V, Standby mode 0 -2.5 -6 uA
Shutdown mode(RPROG not
connected, ±1 ±2 uA
BAT pin current IBAT
VCC=0V, Sleep mode ±1 ±2 uA
Trickle charge current ITRIKL *VBAT＜VTRIKL, RPROG=2k 20 45 70 mA
Trickle charge threshold
voltage VTRIKL RPROG=10k, VBAT Rising 2.8 2.9 3.0 V
Trickle charge hystersis
voltage VTRHYS RPROG=10k 60 80 110 mV
Vcc undervoltage lockout
threshold VUV *From Vcc low to high 3.7 3.8 3.93 V
Vcc undervoltage lockout
hystersis VUVHYS * 150 200 300 mV
*PROG pin rising 1.15 1.21 1.30
Manual shutdown threshold
voltage VMSD *PROG pin falling 0.9 1.0 1.1 V
Vcc from low to high 70 100 140
VCC – VBAT lockout threshold
voltage VASD
Vcc from high to low 5 30 50
mV
Liteon Semiconductor Corporation
LSP4054
Standalone Linear Li-ion Battery Charger with Thermal Regulation
Rev1.1
6/17
ELECTRICAL CHARACTERISTICS (CONTINUED)
The * denotes specifications which apply over the full operating temperature range, otherwise specifications are at
TA=25°C. Vcc=5V, unless otherwise noted.
PARAMETER SYMBO
L TEST CONDITIONS MIN TYP MAX UNIT
*RPROG=10k (Note 4)
C/10 termination current
threshold ITERM *RPROG=2k 0.085 0.10 0.115 mA/mA
PROG pin voltage VPROG *RPROG=10k, current mode 0.93 1.0 1.07 V
CHRG pin weak pull-down
current ICHRG VCHRG=5V 8 20 35 uA
CHRG pin output low voltage I
CHRG=5mA 0.35 0.6 V
Recharge battery threshold
voltage ∆VRECHRG VFLOAT -VRECHRG 100 200 mV
Junction temperature in
constant temperature mode TLIM 120
°C
Power FET “ON” resistance
(between Vcc and VBAT) RON 600 mΩ
Soft-start time tss =0 to IBAT=1000V/RPROG 100 us
Recharge comparator filter
time tRECHARGE VIBAT high to low 0.75 2 4.5 ms
Termination comparator filter
time TTERM IBAT falling below ICHRG/10 400 1000 2500 us
PROG pin pull-up current IPROG 3 uA
Note 3: Supply current includes PROG pin current (approximately 100uA) but does not include any current delivered
to the battery through the BAT pin (approximately 100mA)
Note 4: ITERM is expressed as a function of measured full charge current with indicated PROG resistor
Liteon Semiconductor Corporation
LSP4054
Standalone Linear Li-ion Battery Charger with Thermal Regulation
Rev1.1
7/17
APPLICATION INFORMATION
Stability Considerations
The constant-voltage mode feedback loop is stable without an output capacitor provided a battery is connected to
the charger output. With no battery present, an output capacitor is recommended to reduce ripple voltage. When
using high value, low ESR ceramic capacitors, it is recommended to add a 1W resistor in series with the capacitor.
No series resistor is needed if tantalum capacitors are used. In constant-current mode, the PROG pin is in the
feedback loop, not the battery. The constant-current mode stability is affected by the impedance at the PROG pin.
With no additional capacitance on the PROG pin, the charger is stable with program resistor values as high as 20k.
However, additional capacitance on this node reduces the maximum allowed program resistor. The pole frequency
at the PROG pin should be kept above 100kHz. Therefore, if the PROG pin is loaded with a capacitance, CPROG, the
following equation can be used to calculate the maximum resistance value for RPROG:
Average, rather than instantaneous, charge current may be of interest to the user. For example, if a switching power
supply operating in low current mode is connected in parallel with the battery, the average current being pulled out of
the BAT pin is typically of more interest than the instantaneous current pulses. In such a case, a simple RC filter can
be used on the PROG pin to measure the average battery current as shown in Figure 2. A 10k resistor has been
added between the PROG pin and the filter capacitor to ensure stability.
Figure 2: Isolating capacitive load on PROG pin and filtering
Power Dissipation
The conditions that cause the LSP4054 to reduce charge current through thermal feedback can be approximated by
considering the power dissipated in the IC. Nearly all of this power dissipation is generated by the internal MOSFET
-this is calculated to be approximately:
where PD is the power dissipated, VCC is the input supply voltage, VBAT is the battery voltage and IBAT is the charge
current. The approximate ambient temperature at which the thermal feedback begins to protect the IC is:
Example: An LSP4054 operating from a 5V USB supply is programmed to supply 400mA full-scale current to a
discharged Li-Ion battery with a voltage of 3.75V. Assuming θJA is 150°C/W, the ambient temperature at which
the LSP4054 will begin to reduce the charge current is approximately:
The LSP4054 can be used above 45°C ambient, but the charge current will be reduced from 400mA. The
approximate current at a given ambient temperature can be approximated by:
Using the previous example with an ambient temperature of 60°C, the charge current will be reduced to
approximately:
Liteon Semiconductor Corporation
LSP4054
Standalone Linear Li-ion Battery Charger with Thermal Regulation
Rev1.1
8/17
Moreover, when thermal feedback reduces the charge current, the voltage at the PROG pin is also reduced
proportionally as discussed in the Operation section. It is important to remember that LSP4054 applications do not
need to be designed for worst-case thermal conditions since the IC will automatically reduce power dissipation when
the junction temperature reaches approximately 120°C.
Increasing Thermal Regulation Current
Reducing the voltage drop across the internal MOSFET can significantly decrease the power dissipation in the IC.
This has the effect of increasing the current delivered to the battery during thermal regulation. One method is by
dissipating some of the power through an external component, such as a resistor or diode.
Example: An LSP4054 operating from a 5V wall adapter is programmed to supply 800mA full-scale current to a
discharged Li-Ion battery with a voltage of 3.75V. Assuming θJA is 125°C/W, the approximate charge current at an
ambient temperature of 25°C is:
By dropping voltage across a resistor in series with a 5V wall adapter (shown in Figure 3), the on-chip power
dissipation can be decreased, thus increasing the thermally regulated charge current
Figure 3: A circuit to maximize thermal mode charge current
Solving for IBAT using the quadratic formula.
Using RCC = 0.25W, VS = 5V, VBAT = 3.75V, TA = 25°C and θJA = 125°C/W we can calculate the thermally
regulated charge current to be:
IBAT = 708.4mA
While this application delivers more energy to the battery and reduces charge time in thermal mode, it may actually
lengthen charge time in voltage mode if VCC becomes low enough to put the LSP4054 into dropout. Figure 4 shows
how this circuit can result in dropout as RCC becomes large.
This technique works best when RCC values are minimized to keep component size small and avoid dropout.
Remember to choose a resistor with adequate power handling capability.
Liteon Semiconductor Corporation
LSP4054
Standalone Linear Li-ion Battery Charger with Thermal Regulation
Rev1.1
9/17
Figure 4: Charge current vs RCC
VCC Bypass Capacitor
Many types of capacitors can be used for input bypassing, however, caution must be exercised when using
multilayer ceramic capacitors. Because of the self-resonant and high Q characteristics of some types of ceramic
capacitors, high voltage transients can be generated under some start-up conditions, such as connecting the
charger input to a live power source. Adding a 1.5W resistor in series with an X5R ceramic capacitor will minimize
start-up voltage transients. For more information, refer to Application Note 88.
Charge Current Soft-Start
The LSP4054 includes a soft-start circuit to minimize the inrush current at the start of a charge cycle. When a charge
cycle is initiated, the charge current ramps from zero to the full-scale current over a period of approximately 100ms.
This has the effect of minimizing the transient current load on the power supply during start-up.
CHRG Status Output Pin
The CHRG pin can provide an indication that the input voltage is greater than the undervoltage lockout threshold
level. A weak pull-down current of approximately 20mA indicates that sufficient voltage is applied to VCC to begin
charging. When a discharged battery is connected to the charger, the constant current portion of the charge cycle
begins and the CHRG pin pulls to ground. The CHRG pin can sink up to 10mA to drive an LED that indicates that a
charge cycle is in progress.
When the battery is nearing full charge, the charger enters the constant-voltage portion of the charge cycle and the
charge current begins to drop. When the charge current drops below 1/10 of the programmed current, the charge
cycle ends and the strong pull-down is replaced by the 20mA pull-down, indicating that the charge cycle has ended.
If the input voltage is removed or drops below the undervoltage lockout threshold, the CHRG pin becomes high
impedance. Figure 5 shows that by using two different value pull-up resistors, a microprocessor can detect all three
states from this pin.
Figure 5: Microprocessor to determine CHRG state
To detect when the LSP4054 is in charge mode, force the digital output pin (OUT) high and measure the voltage at
the CHRG pin. The N-channel MOSFET will pull the pin voltage low even with the 2k pull-up resistor. Once the
charge cycle terminates, the N-channel MOSFET is turned off and a 20mA current source is connected to the
CHRG pin. The IN pin will then be pulled high by the 2k pull-up resistor. To determine if there is a weak pull-down
current, the OUT pin should be forced to a high impedance state. The weak current source will pull the IN pin low
through the 800k resistor; if CHRG is high impedance, the IN pin will be pulled high, indicating that the part is in a
UVLO state.
Liteon Semiconductor Corporation
LSP4054
Standalone Linear Li-ion Battery Charger with Thermal Regulation
Rev1.1
10/17
Reverse Polarity Input Voltage Protection
In some applications, protection from reverse polarity voltage on VCC is desired. If the supply voltage is high
enough, a series blocking diode can be used. In other cases, where the voltage drop must be kept low a Pchannel
MOSFET can be used (as shown in Figure 6).
Figure 6: Low loss input reverse polarity protection
USB and Wall Adapter Power
The LSP4054 allows charging from both a wall adapter and a USB port. Figure 7 shows an example of how to
combine wall adapter and USB power inputs. A P-channel MOSFET, MP1, is used to prevent back conducting into
the USB port when a wall adapter is present and a Schottky diode, D1, is used to prevent USB power loss through
the 1k pull-down resistor.
Typically a wall adapter can supply more current than the 500mA-limited USB port. Therefore, an N-channel
MOSFET, MN1, and an extra 10k program resistor are used to increase the charge current to 600mA when the wall
adapter is present.
Figure 7: Combining wall adapter and USB power
TYPICAL APPLICATIONS
USB/wall adapter power Li-ion charger Full featured single cell Li-ion charger
Liteon Semiconductor Corporation
LSP4054
Standalone Linear Li-ion Battery Charger with Thermal Regulation
Rev1.1
11/17
800mA Li-ion charger with external power dissipation Basic Li-ion charger with reverse polarity input protection
TYPICAL PERFORMANCE CHARACTERISTICS
Liteon Semiconductor Corporation
LSP4054
Standalone Linear Li-ion Battery Charger with Thermal Regulation
Rev1.1
12/17
TYPICAL PERFORMANCE CHARACTERISTICS（CONTINUED）
Liteon Semiconductor Corporation
LSP4054
Standalone Linear Li-ion Battery Charger with Thermal Regulation
Rev1.1
13/17
TYPICAL PERFORMANCE CHARACTERISTICS（CONTINUED）
Liteon Semiconductor Corporation
LSP4054
Standalone Linear Li-ion Battery Charger with Thermal Regulation
Rev1.1
14/17
TYPICAL PERFORMANCE CHARACTERISTICS（CONTINUED）
Liteon Semiconductor Corporation
LSP4054
Standalone Linear Li-ion Battery Charger with Thermal Regulation
Rev1.1
15/17
ORDERING INFORMATION
MARKING INFORMATION
Liteon Semiconductor Corporation
LSP4054
Standalone Linear Li-ion Battery Charger with Thermal Regulation
Rev1.1
16/17
PACKAGE INFORMATION
(1) SOT23-5L
L1
L
A
2
A
A
1
M1
E1
e
e1
D
b
c
SEATING PLANE
GAUGE PLANE
E
M2
L2
Dimensions In Millimeters
Symbol Min Typ Max
A 1.05 1.20 1.35
A1 0.05 0.10 0.15
A2 1.00 1.10 1.20
b 0.30 - 0.50
c 0.08 - 0.22
D 2.80 2.90 3.00
E 2.60 2.80 3.00
E1 1.50 1.60 1.70
e 0.95 BSC
e1 1.90 BSC
L 0.30 0.45 0.55
L1 0.60 REF
L2 0.25 BSC
∠M1 3° 5° 7°
∠M2 6° 8° 10°
Liteon Semiconductor Corporation
LSP4054
Standalone Linear Li-ion Battery Charger with Thermal Regulation
Rev1.1
17/17
(2) SOT89-5L
