ETC MH4056

1A Lithium Ion Battery Linear Charger
MH4056
Description
Features
MH4056 is a complete constant-current/constant voltage
●
linear charger for single cell lithium-ion batteries. With a
connection
thermally enhanced 8-PIN SOP package on the bottom
●
Programmable charge current up to 1A
and low external component count make the MH4056
●
No MOSFET sense resistor or blocking
id ll suited
ideally
i d for
f portable
bl applications.
li i
Furthermore
F h
the
h
diode required
MH4056 is specifically designed to work within USB
●
power specifications.
Package
Applications
● Cellular
● Digital
● MP3
Telephones
● USB
S
●
for single Cell Lithium-Ion Batteries.
●
Constant-Current/Constant-Voltage
maximize Rate Without risk of overheating.
Players
● Portable
Complete linear Charger in SOP8
operation with thermal regulation to
Still Cameras
● Bluetooth
Protection of battery cell reverse
●
Applications
Preset 4.2V charge voltage with ±1%
accuracy
Devices
● Automatic
Bus-Poweredd Chargers
Ch
●
Typical charge cycle（1000mAh battery）
Two Status Indication for Charge status,
no battery and battery failure indicators
●
C/10 charge termination
●
55μA supply current in shutdown
●
2.9V trickle current charge
g threshold
●
Soft-Start limits inrush current
●
Battery Temperature Sensing
● Available
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Recharge
in SOP8-PP package
1／16
1A Lithium Ion Battery Linear Charger
MH4056
Pin Configuration
Pin No.
Pin Name
Descripition
1
VCC
Positive input supply voltage Provides power to the internal circuit. When
VCC drops to within 80mV of the BAT pin voltage, the MH4056 enters
low power sleep mode, dropping IBAT to less than 2μA.
2
GND
Ground
3
PROG
C
Constant
Ch
Charge C
Current S
Setting
i and
d Ch
Charge C
Current M
Monitor
i Pi
Pin Th
The
charge current is programmed by connecting a resistor RPROG from this
pin to GND. When in precharge mode, the PROG pin’s voltage is regulated
to 0.1V. When charging in constant-current mode this pin’s voltage is
regulated to 1V. In all modes during charging, the voltage on this pin can
be used to measure the charge current using the following formula:
IBAT=VPROG/RPROG × 1300
4
TEMP
Temperature sense input Connecting TEMP pin to NTC thermistor’s
output in Lithium ion battery pack. If TEMP pin’s voltage is below 45% or
above 80% of supply voltage VCC, this means that battery’s temperature is
too low or too high, charging is suspended. The temperature sense function
can be disabled by grounding the TEMP pin.
5
CE
Chip enable input A high input will put the device in the normal operating
mode. Pulling the CE pin to low level will put the MH4056 into disable
mode. The CE pin can be driven by TTL or CMOS logic level.
6
_____
CHRG
Open-Drain charge status output
______
When the battery is being charged, the CHRG pin is pulled low by an
______
internal switch, otherwise, CHRG pin is in high impedance state.
7
______
STDBY
Charge terminated status output is pulled low by an internal switch to
indicate a battery charge terminated; this means Charge termination.
termination
Otherwise pin is in high impedance state.
8
BAT
Battery connection Pin Connect the positive terminal of the battery to this
pin. Dropping BAT pin’s current to less than 2μA when IC in disable mode
or in sleep mode. BAT pin provides charge current to the battery and
provides regulation voltage of 4.2V.
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1A Lithium Ion Battery Linear Charger
MH4056
Absolute Maximum Ratings
Parameter
Rating
Unit
Input supply voltage : VCC
-0.3～8
V
PROG pin voltage
-0.3～VCC+0.3
V
BAT pin voltage
-0.3～7
V
TEMP pin voltage
-0.3～10
V
______
STDBY pin voltage
-0.3～10
V
_____
CHRG pin voltage
-0.3～10
V
CE pin voltage
-0.3～10
V
BAT pin current
1200
mA
PROG pin current
1200
uA
Maximum junction temperature
145
℃
p
g ambient
Operating
temperature :Topa
-40～85
℃
Storage temperature :Tstr
-65～125
℃
Soldering temperature and time
+260（Recommended 10S）
℃
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MH4056
1A Lithium Ion Battery Linear Charger
Electrical Characteristics
Symbol
Parameter
VCC
Input supply voltage
ICC -IBAT
static current
Condition
Min
Typ.
Max
Unit
4
5
8
V
Charge mode, RPROG=1.3K
-
150
500
uA
Standby mode(charge end)
-
55
100
uA
Shutdown mode（RPROG not
connected, VCC<VBAT, or VCC<VUV）
-
55
100
uA
VFLOAL
Regulated output voltage
0℃≤TA≤85℃ IBAT=40mA
4.15
8
4.2
4.242
V
IBAT
BAT pin current (The
condition of current mode is
VBAT=3.9V)
RPROG=2.6K, current mode
450
500
550
mA
RPROG=1.3K,current mode
950
1000
1050
mA
Standby mode: VBAT=4.2V
0
-2.5
-6
uA
Sh d
Shutdown
mode,
d RPROG not connected
d
-
±1
±2
uA
A
Sleep mode, VCC=0V
-
-1
-2
uA
ITRIKL
Trickle charge current
VBAT<VTRIKL, RPROG=1.3K
120
130
140
mA
VTRIKL
Trickle charge threshold
voltage
RPROG=1.3K, VBAT rising
2.8
2.9
3.0
V
VTRHYS
Trickle voltage hysteresis
voltage
g
RPROG=1.3K
150
200
250
mV
VUV
VCC under voltage lockout
threshold
VCC from low to high
3.5
3.7
3.9
V
VUVHYS
VCC under voltage lockout
hysteresis
-
150
200
300
mV
VASD
VCC-VBAT lockout
threshold voltage
VCC from low to high
100
140
180
mV
VCC from high to low
50
80
110
mV
C/10 termination current
threshold
RPROG=2.6K
60
70
80
mA
RPROG=1.3K
120
130
140
mA
0.9
1.0
1.1
V
ITERM
VPROG
PROG pin voltage
RPROG=1.3K，current mode
VCHRG
______
CHRG Pin output low
voltage
______
ICHRG = 5mA
-
0.3
0.6
V
VSTDBY
_______
STDBY Pin output low
voltage
VCSN = VIN, increase DIM until
VDRV > (VCC - 0.5V)
-
0.3
0.6
V
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MH4056
1A Lithium Ion Battery Linear Charger
VTEMP-H
The voltage at TEMP increase
VTEMP-L
The voltage at TEMP decrease
ΔVRECHRG
Recharge battery threshold
voltage
TLIM
VCSN = VIN, decrease DIM until
VDRV < 0.5V
-
80
83
%VCC
42
45
-
%VCC
120
180
240
mV
Thermal
h
l protection
i temperature
-
145
-
℃
RON
The resistance of power
FET ”ON”（between VCC
and BAT）
-
650
-
mΩ
tSS
Soft-start time
IBAT=0 to IBAT=1300V/RPROG
-
20
-
uS
tRECHARGE
Recharge comparator filter
time
VBAT from high to low
0.8
1.8
4
mS
tTERM
Termination comparator filter
time
IBAT below ICHG/10
0.8
1.8
4
mS
IPROG
PROG pin pull-up current
-
2
-
uA
VFLOAT -VRECHRG
Typical
yp
p
performance characteristics
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1A Lithium Ion Battery Linear Charger
MH4056
Programming charge current
The charge current is programmed using a single resistor from the PROG pin to ground. The program resistor
and the charge current are calculated using the following equations.
RPROG = 1300 / IBAT
In application, according the charge current to determine RPROG ,the relation between RPROG and charge
current can reference the following
g chart:
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RPROG (K)
IBAT (mA)
30
43
24
54
12
108
6
216
5
260
4
325
3
433
2
650
1.3
1000
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1A Lithium Ion Battery Linear Charger
MH4056
Charge
g 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 tTEMP (typically 1.8mS), Charging is terminated.
The charge current is latched off and the MH4056 enters standby mode, where the input supply current drops to
55μA (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 1.8mS filter time (tTEMP)
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 MH4056 terminated
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 MH4056 constantly monitors the BAT pin voltage in standby mode. If this voltage drops below the
4.02V 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
cycle.
Charge status indicator
______
_______
MH4056 has two open-drain status indicator output CHRG and STDBY . is pull-down when the MH4056 in a
charge cycle. In other status in high impedance. and are all in high impedance when the battery out of the normal
temperature. Represent in failure state, when TEMP pin in typical connecting, or the charger with no battery: red LED
and green LED all don’t light. The battery temperature sense function is disabled by connecting TEMP pin to GND.
If bbattery
tt
iis nott connected
t d tto charger,
h
pin
i outputs
t t a PWM llevell tto indicate
i di t no battery.
b tt
If BAT pin
i connects
t a 10μF
10 F
capacitor, the frequency of flicker about 1-4S, If not use status indicator should set status indicator output connected
to GND.
Charger’s status
______
Red led CHRG
______
Green led STDBY
Charging
light
dark
Battery in full state
dark
light
Under-voltage, battery’s temperature is
to high or too low, or not connect to
battery(use TEMP)
dark
dark
Green LED bright,
g , Red LED flicker F=1-4 S
BAT p
pin is connected to 10uF capacitor，
p
No battery mode (TEMP=GND)
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1A Lithium Ion Battery Linear Charger
MH4056
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 140℃ . The feature protects the MH4056 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 MH4056. 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.
To prevent the damage caused by the very high or very low temperature done to the battery pack, the MH4056
continuously senses battery pack temperature by measuring the voltage at TEMP pin determined by the voltage
divider circuit and the battery
battery’ss internal NTC thermistor as shown in Figure 11.
The MH4056 compares the voltage at TEMP pin (VTEMP) against its internal VLOW and VHIGH thresholds to
determine if charging is allowed. In MH4056, VLOW is fixed at (45%×Vcc), while VHIGH is fixed at
(80%×Vcc). If VTEMP<VLOW or VTEMP>VHIGH , it indicates that the battery temperature is too high or too
low and the charge cycle is suspended. When VTEMP is between VLOW and VHIGH, charge cycle resumes.
The battery temperature sense function can be disabled by connecting TEMP pin to GND.
Selecting R1 and R2
Th values
The
l
off R1 and
d R2 in
i the
h application
li i circuit
i i can be
b determined
d
i d according
di to the
h assumedd temperature
monitor range and thermistor’s values. The Follows is an example: Assume temperature monitor range is TL～TH，
（ TL＜TH)；the thermistor in battery has negative temperature coefficient（NTC），RTL is thermistor’s
resistance at TL， RTH is the resistance at TH，so RTL＞RTH，then at temperature TL, the voltage at TEMP
pin is:
At temperature TH, the voltage at TEMP pin is:
We know VTEMPL＝VHIGH＝K2×Vcc (K2=0.8)；VTEMPH＝VLOW＝K1×Vcc (K1=0.45)
Then we can have：
Likewise, for positive temperature coefficient thermistor in battery, we have RTH＞RTL and we can calculate:
We can conclude that temperature monitor range is independent of power supply voltage VCC and it only depends
on R1
R1, R2
R2, RTL and RTH: The values of RTH and RTL can be found in related battery handbook or deduced from
testing data. In actual application, if only one terminal temperature is concerned (normally protecting overheating),
there is no need to use R2 but R1. It becomes very simple to calculate R1 in this case.
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1A Lithium Ion Battery Linear Charger
MH4056
Under Voltage lockout (UVLO)
An internal under voltage lockout circuit monitors the input voltage and keeps the charger in shutdown mode
until VCC rises above the under voltage lockout threshold . If the UVLO comparator is tripped, the charger will
not come out of shutdown mode until VCC rises 140mV above the battery voltage.
Manual terminate
At any time of the cycle of charging will put the MH4056 into disable mode to pull CE pin to GND, or
remove RPROG （PROG pin is float）. This made the battery drain current to less than 2μA and reducing the
supply
l currentt to
t 55μA.
55 A T
To restart
t t th
the charge
h
cycle,
l sett CE pin
i iin hi
high
h llevell or connectt a programming
i resistor.
it
_____
______
If MH4056 in the under voltage Lockout mode, the CHRG and STDBY are all in high impedance state, or VCC
is above BAT pin 140mV, or VCC is too low.
Auto restart
Once charge is been terminated, MH4056 immediately use a 1.8ms filter time（ tRECHARGE ）on the
termination comparator to constant monitor the voltage on BAT pin. If this voltage drops below the 4.02V
recharge threshold (about between 80% and 90% of VCC), another charge cycle begins. This ensured the battery
maintained (or approach) to a charge full status and avoid the requirement of restarting the periodic charging
cycle. In the recharge cycle, pin enters a pulled down status.
Fig.2 Isolating with capacitive load on PROG Pin
Stability Considerations
In constant
constant-current
current mode, the PROG pin is in the feedback loop, not the battery. The constant
constant-current
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. Therefore, if IPROG pin is loaded with a capacitance
C, the following equation should be used to calculate the maximum resistance value for RPROG：
As user,
user may think charge current is important,
important not instantaneous current.
current For example,
example to run a low current
mode switch power which parallel connected with battery, the average current from BAT pin usually importance
to instantaneous current. In this case, In order to measure average charge current or isolate capacitive load from
IPROG pin, a simple RC filter can be used on PROG pin as shown in Figure 2. In order to ensure the stability
add a 10K resistor between PROG pin and filter capacitor.
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1A Lithium Ion Battery Linear Charger
MH4056
Fig 1 State diagram of a typical charge cycle
Fig.1
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1A Lithium Ion Battery Linear Charger
MH4056
Power dissipation
The conditions that cause the MH4056 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: PD =(VCC -VBAT ) ×I BAT
The approximate ambient temperature at which the thermal feedback begins to protect the IC is:
TA = 145℃-PDθJA;
TA = 145℃ - (VCC -VBAT ) ×IBAT× θJA
Thermal considerations
Because of the small size of the thin SOP8 package, it is 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 possible and expand
out to larger copper areas to spread and dissipate the heat to the surrounding ambient. Other heat sources
on the board, not related to the charger, must also be considered when designing a PC board layout because
they will affect overall temperature rise and the maximum charge current.
current
Add thermal regulation current
It will effective to decrease the power dissipation through reduce the voltage of both ends of the inner
MOSFET. In the thermal regulation, this action of transporting current to battery will raise. One of the
measure is through an external component(as a resistor or diode) to consume some power dissipation.
For example: The MH4056 with 5V supply voltage through programmable provides full limiting current
800mA to a charge lithium-ion battery with 3.75V voltage. If 　JA is 125℃/W, so that at 25℃ ambient
t
temperature,
t
the
th charge
h
currentt iis calculated
l l t d tto be
b approximately
i t l :
In order to increase the thermal regulation charge current, can decrease the power dissipation of the IC
through reducing the voltage (as show fig.3) of both two ends of the resistor which connecting in series with
a 5V AC adapter. With square equation to calculate I BAT ：
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1A Lithium Ion Battery Linear Charger
MH4056
If RCC=0.25Ω, VS=5V, VBAT=3.75V, TA=25℃ and JA =125℃/W, we can calculate the thermal regulation
charge current: IBAT
IBAT＝948mA.
948mA. It means that in this structure it can output 800mA full limiting charge current at
more high ambient temperature environment.
Although it can transport more energy and reduce the charge time in this application, but actually spread
charge time, if MH4056 stay in under-voltage state, when VCC becomes too low in voltage mode. Fig.4 shows
how the voltage reduced with increase RCC value in this circuit. This technique will act the best function when
in order to maintain the minimize the dimension of the components and avoid voltage decreased to minimize RCC .
Fig.3:A circuit to maximum the thermal
regulation charge current
Fig.4:The relationship curve between charge
current with 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 1.5Ω resistor in series with a ceramic capacitor
will
ill minimize
i i i start-up voltage
l
transients.
i
Charging Current Soft Start
MH4056 includes a soft start circuit which used to maximize to reduce the surge current in the begging of
charge cycle. When restart a new charge cycle, the charging current ramps up from 0 to the full charging
current within 20μs. In the start process it can maximize to reduce the action which caused by surge current load.
USB and Wall Adapter Power
MH4056 allows charging from a USB port, a wall adapter can also be used to charge Li-Ion/Li-polymer
batteries.Figure 5 shows an example of how to combine wall adapter and USB power inputs. A P-channel
MOSFET, M1, is used to prevent back conducting into the USB port when a wall adapter is present and
Schottky diode, D1, is used to prevent USB power loss through the 1KΩ pull-down resistor.
Generally, AC adaptor is able to provide bigger much current than the value of specific current limiting
which is 500mA for USB port. So can rise charge current to 600mA with using a N-MOSFET (MN1) and an
additional set resistor value as high as 10K.
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1A Lithium Ion Battery Linear Charger
MH4056
Fig.5:Combining Wall Adapter and USB Power
Typical Application
Mainly used in Cellular telephones, MP3, MP4 players, digital still cameras, electronic dictionary, GPS,
portable devices and vary chargers.
1. Suitable for the function of battery’s temperature detection, the application of the indicator of battery’s
temperature anomaly and charge status.
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1A Lithium Ion Battery Linear Charger
MH4056
2. Suitable for the application of USB power and the charge of wall adapter
3. Suitable for charge status indicator, which the application not need battery’s temperature detection.
4 Suitable
4.
S it bl for
f the
th application
li ti which
hi h nott needd charge
h
status
t t indicator
i di t andd battery’s
b tt ’ temperature
t
t
detection.
d t ti
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1A Lithium Ion Battery Linear Charger
MH4056
5. Add a resistor for p
power dissipation,
p
Red LED for charge
g status, ggreen LED for charge
g terminate state
Board Layout Considerations
● RPROG at PROG pin should be as close to MH4056 as possible, also the parasitic capacitance at PROG pin
should be kept as small as possible.
● The capacitance at VCC pin and BAT pin should be as close to MH4056 as possible.
● During charging, MH4056’s temperature may be high, the NTC thermistor should be placed far enough to
MH4056 so that the thermistor can reflect the battery’s temperature correctly.
● It is very important to use a good thermal PC board layout to maximize charging current. The thermal path
for the heat generated by the IC is from the die to the copper lead frame through the package lead (especially
the ground lead) to the PC board copper
copper, the PC board copper is the heat sink.
sink The footprint copper pads should
be as wide as possible and expand out to larger copper areas to spread and dissipate the heat to the surrounding
ambient. Feed through vias to inner or backside copper layers are also useful in improving the overall thermal
performance of the charger. Other heat sources on the board, not related to the charger, must also be considered
when designing a PC board layout because they will affect overall temperature rise and the maximum charge current.
● The ability to deliver maximum charge current under all conditions require that the exposed metal pad on the back
side of the MH4056 package be soldered to the PC board ground. Failure to make the thermal contact between
the exposed pad on the backside of the package and the copper board will result in larger thermal resistance.
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1A Lithium Ion Battery Linear Charger
MH4056
SOP8 Package Outline
Symbol
Dimensions In Millimoters
Dimensions In Inches
Min
Max
Min
Max
A
1.350
1.750
0.053
0.069
A1
0.100
0.250
0.004
0.010
A2
1.350
1.550
0.053
0.061
b
0.330
0.510
0.013
0.020
c
0.170
0.250
0.006
0.010
D
4.700
5.100
0.185
0.200
E
3.800
4.000
0.150
0.157
E1
5.800
6.200
0.228
0.244
e
1.270（BSC）
0.050（BSC）
L
0.400
1.270
0.016
0.050
θ
0°
8°
0°
8°
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