POWER LP4060A 800ma standalone linear li-ion battery charger with thermal regulation in thinsot Datasheet

Preliminary Datasheet
800mA Standalone Linear Li-Ion Battery Charger with
Thermal Regulation in ThinSOT
General Description
The LP4060A is a complete constant-current/constantvoltage linear charger for single cell lithium-ion batteries.
Its ThinSOT package and low external component count
make the LP4060A ideally suited for portable applications.
Furthermore, the LP4060A is specifically designed to work
within USB power specifications. 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
programmed externally with a single resistor. The
LP4060A automatically terminates the charge cycle when
the charge current drops to 1/10th the programmed value
after the final float voltage is reached. 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.
Programmable Charge Current Up to
No MOSFET, Sense Resistor or Blocking Diode
Complete Linear Charger in ThinSOT
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
Available in SOT23-5 Package
Charge Current Monitor Output for Gas
Automatic Recharge
2.9V Trickle Charge Threshold
C/10 Charge Termination
Order Information
LP4060A - □ □ □ □
Typical Application Circuit
F: Pb-Free
Package Type
B5: SOT23-5
1uF +
Portable Media Players/MP3 players
Cellular and Smart mobile phone
Bluetooth Applications
LP4060A – Ver. 1.0 Datasheet
Marking Information
Please see website.
Page 1 of 13
Preliminary Datasheet
Functional Pin Description
Pin Number
Pin Name
Pin Function
Open-Drain Status Output
Charge Current Output
Positive Input Supply Voltage
Charge Current Program, Charge Current Monitor and Shutdown Pin.
Open-Drain Charge Status Output. 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 12µA is connected
to the CHRG pin, indicating a “AC present” condition. When the LP4060A detects an undervoltage lockout
condition, CHRG is forced high impedance.
GND (PIN 2): Ground.
BAT (PIN 3): Charge Current Output. Provides charge current to the battery and regulates the final
float voltage to 4.2V. An internal precision resistor divider from this pin sets the float voltage which is
disconnected in shutdown mode.
VCC (PIN 4): Positive Input Supply Voltage. Provides power to the charger. VCC can range from 4.35V to 6.5V and
should be bypassed with at least a 1µF capacitor. When VCC drops to within 30mV of the BAT pin voltage, the
LP4060A enters shutdown mode, dropping IBAT to less than 2µA.
PROG (PIN 5): 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:
The PROG pin can also be used to shutdown the charger. Disconnecting the program resistor from
ground allows a 3µA current to pull the PROG pin high. When it reaches the 1.94V shutdown
threshold voltage, the charger enters shutdown mode, charging stops and the input supply current
drops to 25µA. This pin is also clamped to approximately 2.4V. Driving this pin to voltages beyond
the clamp voltage will draw currents as high as1.5mA. Reconnecting RPROG to ground will return the
charger to normal operation.
LP4060A – Ver. 1.0 Datasheet
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Preliminary Datasheet
Function Block Diagram
Absolute Maximum Ratings
Input Supply Voltage-------------------------------------------------------------------------------------- -0.3V to 6.5V
PROG----------------------------------------------------------------------------------------------- -0.3V to Vcc+0.3V
BAT---------------------------------------------------------------------------------------------------------- -0.3V to 6.5V
CHRG-------------------------------------------------------------------------------------------------------- -0.3V to 6.5V
BAT Pin Current--------------------------------------------------------------------------------------------------- 800mA
BAT Short-circuit Duration----------------------------------------------------------------------------------Continuous
PROG Pin Current---------------------------------------------------------------------------------------------------800uA
Operation Temperature Range------------------------------------------------------------------------ --40℃ to 85℃
Junction Temperature ----------------------------------------------------------------------------------------------- 125℃
Storage Temperture ------------------------------------------------------------------------------------- --65℃ to 125℃
Lead Temp(Soldering,10sec) -------------------------------------------------------------------------------------- 300℃
LP4060A – Ver. 1.0 Datasheet
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Preliminary Datasheet
Electrical Characteristics
((Over 0C ≤TJ ≤125°C and recommended supply voltage)
Note 1: Absolute Maximum Ratings are those values beyond which the life of the device may be impaired.
Note 2: The LP4060A are guaranteed to meet performance specifications from 0℃ to 70℃.
Specifications over the -40℃ to 85℃ operating temperature range are assured by design,
characterization and correlation with statistical process controls.
Note 3: See Thermal Considerations.
Note 4: Supply current includes PROG pin current (approximately 100µA) but does not include any current
delivered to the battery through the BAT pin (approximately 100mA).
Note 5: This parameter is not applicable to the LP4060AX.
Note 6: ITERM is expressed as a fraction of measured full charge current with indicated PROG resistor.
LP4060A – Ver. 1.0 Datasheet
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Preliminary Datasheet
Typical Operating Characteristics
LP4060A – Ver. 1.0 Datasheet
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Preliminary Datasheet
LP4060A – Ver. 1.0 Datasheet
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LP4060A – Ver. 1.0 Datasheet
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Preliminary Datasheet
Applications Information
The LP4060A 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 LP4060A 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 LP4060A 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 LP4060A
supplies approximately 1/10 the programmed charge
current to bring the battery voltage up to a safe level
for full current charging. (Note: The LP4060AX does
not include this trickle charge feature).
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 LP4060A 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.
Programming Charge Current
The charge current is programmed using a single
resistor from the PROG pin to ground. The battery
charge current is 1000 times the current out of the
PROG pin. The program resistor and the charge 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:
ISET = 830/ RSET
Charge Termination
A charge cycle is terminated when the charge current
LP4060A – Ver. 1.0 Datasheet
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 (typically 1ms),
charging is terminated. The charge current is latched
off and the LP4060A enters standby mode, where the
input supply current drops to 200µA. 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 (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 programmed value, the LP4060A
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
LP4060A constantly monitors the BAT pin voltage in
standby mode. If this voltage drops below the 4.05V
recharge threshold (VRECHRG), 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. Figure 7 shows the state diagram of a
typical charge cycle.
Charge Status Indicator(CHRG)
The charge status output has three different states:
strong pull-down(~10mA), weak pull-down (~12µA)
and high impedance. The strong pull-down state
indicates that the LP4060A 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 LP4060A is ready to charge. High
impedance indicates that the LP4060A 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.
Charge Termination
programmed charge current if the die temperature
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Preliminary Datasheet
attempts to rise above a preset value of
approximately 120℃. This feature protects the
LP4060A 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 LP4060A. The charge current can
be set according to typical (not worst-case)
ambient temperature with the assurance that the
charger will automatically reduce the current in
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 LP4060A can be
put into shutdown mode by removing RPROG thus
floating the PROG pin. This reduces the battery drain
current to less than 2µA and the supply current to less
than 50µA. 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
LP4060A is in under voltage 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 LP4060A
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
LP4060A – Ver. 1.0 Datasheet
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
pull-down state during recharge cycles.
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 1Ω
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, PROG, the following
equation can be used to calculate the maximum
resistance value for RPROG:
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Preliminary Datasheet
reduce the charge current is approximately:
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 8. A 10k resistor has been added
between the PROG pin and the filter capacitor to
ensure stability.
Power Dissipation
The conditions that cause the LP4060A 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
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:
TA=120℃-(VCC-VBAT) • IBAT • θJA
Example: An LP4060A 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 θ JA is 150 ℃ /W
(see Board Layout Considerations ), the ambient
temperature at which the LP4060A will begin to
LP4060A – Ver. 1.0 Datasheet
TA=120℃-(5V-3.75V) • (400mA) • 150℃/W
TA=120℃-0.5W • 150℃/W=120℃-75℃
The LP4060A can be used above 45℃ 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℃, the charge current will be reduced
to approximately:
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 LP4060A 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℃.
Thermal Considerations
Because of the small size of the ThinSOT package,
it is very important to use a good thermal PC
board layout to maximize the available charge
current. The thermal path for the heat generated
by the IC is from the die to the copper lead frame,
through the package leads, (especially the ground
lead) to the PC board copper. The PC board
copper is the heat sink. The footprint copper pads
should be as wide as One method is by dissipating
some of the power through an external component,
such as a resistor or diode. Example: An LP4060A
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℃/W, the approximate charge current
at an ambient temperature of 25 ℃
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Preliminary Datasheet
the effect of minimizing the transient current load on
the power supply during start-up.
By dropping voltage across a resistor in series with a
5V wall adapter (shown in Figure 9), the on-chip
power dissipation can be decreased, thus increasing the
thermally regulated charge current.:
Solving for IBAT using the quadratic formaula
Using RCC = 0.25Ω, VS = 5V, VBAT = 3.75V,
TA = 25℃ and θJA = 125℃/W we can calculate the
thermally regulated charge current to be:
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 LP4060A into
dropout. 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.
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 12µA 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 12µA pull-down,
indicating that the charge cycle has ended. If the input
voltage is removed or drops below the under voltage
lockout threshold, the CHRG pin becomes high
impedance. Figure 10 shows that by using two
different value pull-up resistors, a micro-processor can
detect all three states from this pin.
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 1.5Ω resistor in series with an
X5R ceramic capacitor will minimize start-up
voltage transients.
Charge Current Soft-Start
The LP4060A 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 100µs. This has
LP4060A – Ver. 1.0 Datasheet
To detect when the LP4060A 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 12µA 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.
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Preliminary Datasheet
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 P-channel MOSFET can be
used (as shown in Fig 11.)
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 extra 10k program resistor are used to
increase the charge current to 800mA when the wall adapter is
USB and Wall Adapter Power
The LP4060A allows charging from both a wall adapter and a
USB port. Figure 12 shows an example of how to combine
wall adapter and USB power inputs. A P-channel MOSFET,
Layout Considerations
— Follow the PCB layout guidelines for optimal performance of LP4060A.
— For the main current paths as indicated in bold lines, keep their traces short and wide.
— Put the input capacitor as close as possible to the device pins (VIN and GND).
— Connect all analog grounds to a command node and then connect the command node to the power
ground behind the output capacitors.
— Output not connect loading when charging
LP4060A – Ver. 1.0 Datasheet
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Preliminary Datasheet
Packaging Information
LP4060A – Ver. 1.0 Datasheet
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