Standalone Linear Li-Ion Battery Charger with Thermal Regulation in ThinSOT ME4054
Ver01
Standalone Linear Li-Ion Battery Charger in ThinSOT ME4054-4.2V
DESCRIPTION FEATURES
ME4054 is a constant-current/constant-voltage
linear charger for single cell lithium-ion batteries.Its
ThinSOT package and low external component count
make the ME4054 ideally suited for portable
applications. Furthermore, the ME4054 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 ME4054 automatically terminates he
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 ME4054 automatically enters
a low current state, dropping the battery drain current
to less than 2µA.The ME4054 can be put into
shutdown mode, reducing the supply current to 25µA.
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.
APPLICATIONS
z Programmable Charge Current Up to 800mA
z No MOSFET, Sense Resistor or Blocking Diode
Required
z Complete Linear Charger in ThinSOT Package for
Single Cell Lithium-Ion Batteries
z Constant-Current/Constant-Voltage Operation with
Thermal Regulation to Maximize Charge Rate
Without Risk of Overheating
z Charges Single Cell Li-Ion Batteries Directly from
USB Port
z Preset 4.2V Charge Voltage with ±1% Accuracy
z Automatic Recharge
z Charge Status Output Pin
z C/10 Charge Termination
z 25µA Supply Current in Shutdown
z 2.9V Trickle Charge Threshold
z Soft-Start Limits Inrush Current
z Available in 5-Lead SOT-23 Package
z Cellular Telephones, PDAs, MP3 Players
z Charging Docks and Cradles
z Bluetooth Applications
TYPICAL APPLICA TION
Nanjing Micro One Electronics Inc. 1/11 TEL: 025-84731186 www. microne. com. cn
Standalone Linear Li-Ion Battery Charger with Thermal Regulation in ThinSOT ME4054
Ver01
Complete Charge Cycle(130mAh Battery)
90mA Single Cell Li-lon Charge
ABSOLUTE MAXIMUM RATINGS
Parameter Ratings
Input Supply Voltage (Vcc)
PROG
BAT
CHRG
BAT Short-Circuit Duration Continuous
BAT Pin Current 800mA
PROG Pin Current 800uA
Maximum Junction Temperature
Operating Ambient Temperature Range
Storage Temperature Range
Lead Temperature (Soldering, 10 sec)
－0.3V～10V
-0.3V～Vcc＋0.3V
-0.3V～7V
-0.3V～10V
125℃
-40℃～85℃
-65℃～125℃
260℃
Nanjing Micro One Electronics Inc. 2/11 TEL: 025-84731186 www. microne. com. cn
Standalone Linear Li-Ion Battery Charger with Thermal Regulation in ThinSOT ME4054
Ver01
ELECTRICAL CHARACTERISTIC
The●denotes specifications which apply over the full operating temperature range,otherwise specifications are at TA =
25°C. VCC = 5V, unless otherwise noted.
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
Vcc
Icc
V
FLOAT
I
BAT
I
TRILK
V
TRILK
V
TRHYS
V
V
UVHYS
V
MSD
V
ADS
I
TERM
V
PROG
I
CHRG
V
CHRG
V
RECHRG
T
LIM
R
ON
T
TRE
T
TERM
I
PROG
UV
SS
Input Supply Voltage
Input Supply Current
Standby Mode (Charge Terminated)
Charge Mode，R
Shutdown Mode（R
Vcc<V
BAT
）
=10K
PROG
Not Connected，
PROG
●
●
●
●
Regulated Output (Float)
≤85℃,I
Voltage
BAT Pin Current
Trickle Charge Current
0℃≤T
A
R
=10K，Current Mode
PROG
R
=2K，Current Mode
PROG
Standby Mode，V
Shutdown Mode（R
Sleep Mode，Vcc＝0V
V
BAT＜VTRILK，RPROG
BAT
=40mA
＝4.2V
BAT
Not Connected）
PROG
＝2K
●
●
●
●
Trickle Charge Threshold
Voltage
R
PROG
＝10K，V
BAT
Rising
Trickle Charge Hysteresis
R
Voltage
PROG
＝10K
VCC Undervoltage Lockout
Threshold From Vcc Low to High
●
VCC Undervoltage Lockout
Hysteresis
●
Manual Shutdown Threshold
Vcc-V
Voltage
Lockout Threshold
BAT
Voltage
Vcc from High to Low
PROG Pin Rising
PROG Pin Falling
from Low to High
Vcc
●
●
C/10 Termination Current
R
Threshold
PROG Pin Voltage
＝10K
PROG
R
＝2K
PROG
R
＝10K，Current Mode
PROG
●
●
●
CHRG Pin Weak
＝5V
Pull-Down Current
Pin Output Low
CHRG
V
I
CHRG
CHRG
＝5mA
Recharge Battery
Threshold Voltage
V
FLOAT－VRECHRG
Junction Temperature in
Constant
Temperature Mode
Power FET “ON”
Resistance
(Between VCC and BAT)
I
Soft-Start Time
BAT
＝0 to I
＝1000V/ R
BAT
PROG
Recharge Comparator
V
Filter Time
High to Low
BAT
Termination Comparator
Filter Time
I
Falling Below I
BAT
CHG
/10
PROG Pin Pull-Up
Current Current
4.25 6.5 V
300 2000 uA
200 500 uA
25 50 uA
4.158 4.2 4.242 V
93 100 107 mA
465 500 535 mA
0 -2.5 -6 uA
±1 ±2 uA
±1 ±2 uA
20 45 70 mA
2.8 2.9 3.0 V
60 80 110 mV
3.7 3.8 3.92 V
150 200 300 mV
1.15 1.21 1.30 V
0.9 1.0 1.1 V
70 100 140 mV
5 30 50 mV
0.085 0.10 0.115 mA /mA
0.085 0.10 0.115 mA /mA
0.93 1.0 1.07 V
8 20 35 uA
0.35 0.6 V
100 150 200 mV
120
600 m
100 uS
0.75 2 4.5 mS
400 1000 2500 uS
3 uA
℃
Ω
Nanjing Micro One Electronics Inc. 3/11 TEL: 025-84731186 www. microne. com. cn
Standalone Linear Li-Ion Battery Charger with Thermal Regulation in ThinSOT ME4054
Ver01
TYPICAL PERFORMANCE CHARACTERISTICS
Nanjing Micro One Electronics Inc. 4/11 TEL: 025-84731186 www. microne. com. cn
Standalone Linear Li-Ion Battery Charger with Thermal Regulation in ThinSOT ME4054
Ver01
Nanjing Micro One Electronics Inc. 5/11 TEL: 025-84731186 www. microne. com. cn
Standalone Linear Li-Ion Battery Charger with Thermal Regulation in ThinSOT ME4054
Ver01
PIN ASSIGNMENT
Pin
SOT23-5
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
Symbol
Description
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Standalone Linear Li-Ion Battery Charger with Thermal Regulation in ThinSOT ME4054
Ver01
PIN FUNCTIONS
CHRG (Pin 1): 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 20uA is
connected to the CHRG pin, indicating an “AC
present”condition. When the ME4054 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 4.25V 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 ME4054 enters shutdown mode, dropping
IBAT to less than 2mA.
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:
IBAT = (VPROG/RPROG) • 1000
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 currents as
high as 1.5mA.Reconnecting RPROG to ground
will return the charger to normal operation.
Nanjing Micro One Electronics Inc. 7/11 TEL: 025-84731186 www. microne. com. cn
Standalone Linear Li-Ion Battery Charger with Thermal Regulation in ThinSOT ME4054
Ver01
OPERATION
The ME4054 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 ME4054 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 ME4054 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 ME4054 supplies
approximately 1/10 the programmed charge current to
bring the battery voltage up to a safe level for full current
charging. (Note: The ME4054X 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 ME4054
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:
R
=1000V/I
The charge current out of the BAT pin can be determined
at any time by monitoring the PROG pin voltage using the
following equation:
PROG
CHG
, I
=1000V/ R
CHG
PROG
I
=1000* V
BAT
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 (typically 1ms),
charging is terminated. The charge current is latched
off and the ME4054 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 (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 ME4054 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 ME4054 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 1
shows the state diagram of a typical charge cycle.
PROG
/ R
PROG
Nanjing Micro One Electronics Inc. 8/11 TEL: 025-84731186 www. microne. com. cn
Standalone Linear Li-Ion Battery Charger with Thermal Regulation in ThinSOT ME4054
Ver01
Charge Status Indicator (CHRG)
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
ME4054 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 ME4054 is ready to
charge. High impedance indicates that the ME4054 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 ME4054 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 ME4054. 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 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 Shutdown
At any point in the charge cycle, the ME4054 can
be put into shutdown mode by removing RPROG
thus floating the PROG pin. This reduces the
battery drain current to less than 2uA and the
supply current to less than 50uA. 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 ME4054 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 ME4054
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.
Nanjing Micro One Electronics Inc. 9/11 TEL: 025-84731186 www. microne. com. cn
Standalone Linear Li-Ion Battery Charger with Thermal Regulation in ThinSOT ME4054
Ver01
PACKAGE DESCRIPTION
Nanjing Micro One Electronics Inc. 10/11 TEL: 025-84731186 www. microne. com. cn
Standalone Linear Li-Ion Battery Charger with Thermal Regulation in ThinSOT ME4054
Ver01
· The information described herein is subject to change without notice.
· Nanjing Micro One Electronics Inc is not responsible for any problems caused by circuits or diagrams
described herein whose related industrial properties, patents, or other rights belong to third parties. The
application circuit examples explain typical applications of the products, and do not guarantee the success of
any specific mass-production design.
· Use of the information described herein for other purposes and/or reproduction or copying without the
express permission of Nanjing Micro One Electronics Inc is strictly prohibited.
· The products described herein cannot be used as part of any device or equipment affecting the human
body, such as exercise equipment, medical equipment, security systems, gas equipment, or any apparatus
installed in airplanes and other vehicles, without prior written permission of Nanjing Micro One Electronics
Inc.
· Although Nanjing Micro One Electronics Inc exerts the greatest possible effort to ensure high quality and
reliability, the failure or malfunction of semiconductor products may occur. The user of these products
should therefore give thorough consideration to safety design, including redundancy, fire-prevention
measures, and malfunction prevention, to prevent any accidents, fires, or community damage that may
ensue.
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