ESMTEMC5754

Standalone Linear Li-Ion Battery Charger with
Thermal Regulation in SOT-23-5 and E-SOP-8
General Description

Features

The EMC5754 is a complete linear charger for single cellProgrammable charge current up to 1A

lithium-ion batteries. With small SOT-23-5 package and

No MOSFET, sense resistor or blocking diodeComplete linear charger both in SOT-23-5 andTypical zero reverse current from battery

Thermal regulation maximizes charge rateCharges single cell Li-ion batteries directly fromfew external components, EMC5754 is well suited forrequired

portable applications. In addition, the EMC5754 is
specificallydesignedtoworkwithinUSB

power

E-SOP-8 for single cell Lithium-ion batteries

specifications.
No external sense resistor and blocking diode arewithout risk of overheating

required. Charging current can be programmed
externally with a single resistor. The built-in thermal

USB port

regulation facilitates charging with maximum powerAct as a LDO when battery is removed

Preset 4.2V/4.35V charge voltage with ±1%

1/10 of the programmed charge current at the
beginning of a charge cycle, until 40s after it verifies



Automatic rechargeCharge status indicatorthat the battery can be fast-charged. The EMC5754



C/10 charge termination



45A shutdown supply current

2.9V trickle charge thresholdSoft-start limits inrush current

RoHS compliant and Pb-free

without risk of overheating.
The EMC5754 always preconditions the battery withaccuracy

automatically terminates the charge cycle when the
charge current drops to 1/10th the programmed value
after the final float voltage is reached.
The EMC5754 consumes zero reverse current from thebattery at standby, shutdown and sleep modes. Thisfeature reduces the charge and discharge cycles on

Applications

the battery, further prolonging the battery life. The

Wireless handsets

EMC5754 can also be used as a LDO when battery isHand-held instruments

removed. Other features include shutdown mode,Portable information applianceschargeBluetooth application

Charging docks and cradles

current

monitor,under

voltagelockout,

automatic recharge and status indicator.

Typical Application Diagram

Typical Performance Characteristics
Complete Charge Cycle (850mAh Battery)LDO Mode(Battery Removed)

VBAT (V)IBAT (mA)

580 mA ChargerTime (1000s/DIV)

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Publication Date: Feb. 2014
Revision: 3.5
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EMC5754

Pin Configuration
SOT-23-5(Top View)
Order information
EMC5754--XXVF05GRR
XX

Charger Voltage

VF05

SOT-23-5 Package

GRR

RoHS &Halogen free
Rating: -40 to 85°C
Package in Tape & Reel

E-SOP-8(Top View)

EMC5754-xxSG08NRR
Charger Voltage
xx
SG08
E-SOP-8 Package
NRR
RoHS & Halogen free package
Rating: -40 to 85°C
Package in Tape & Reel

Order, Mark & Packing Information
ChargeVoltage

Package

Marking

Product ID

4.2V

SOT-23-5

EMC5754-00VF05GRR

4.35V

SOT-23-5

EMC5754-4DVF05GRR

Elite Semiconductor Memory Technology Inc.

Packing

3K units
Tape & Reel

3K units
Tape & Reel

Publication Date: Feb. 2014
Revision: 3.5
2/20

ESMT
4.2V

EMC5754

E-SOP-8

Elite Semiconductor Memory Technology Inc.

EMC5754-00SG08NRR

3K units
Tape & Reel

Publication Date: Feb. 2014
Revision: 3.5
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EMC5754

Pin Functions
Name
NC

E-SOP-8 SOT-23-5
1,6,8

NA

Function
Not connected.
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)*960

PROG

2

5

The PROG pin can also be used to shut down the charger. Disconnecting the program
resistor from ground allows a 0.4A current to pull the PROG pin high. When it reaches
the 1.18V shutdown threshold voltage, the charger enters shutdown mode. This pin isalso clamped to approximately 2.4V. Reconnecting RPROG to ground will return the
charger to normal operation. Connecting the PROG pin to a voltage between 0.2V
and 0.4V can force EMC5754 into LDO mode. The PROG pin must not be directly
shorted to ground at any condition.

GND

3

2

GroundPositive Input Supply Voltage. Provides power to the charger. VIN can range from

VIN

4

4

VBAT+0.5V to 5.5V and should be bypassed with at least a 1F capacitor. When VINdrops to within 30mV above the BAT pin voltage, the EMC5754 enters shutdown
mode, dropping IBAT to less than 1A.
Charge Current Output and battery voltage feedback. This pin provides charge

BAT

5

3

current to the battery and regulates the final float voltage to 4.2V/4.35V. An internal
precision resistor divider from this pin sets the float voltage which is disconnected instandby, shutdown and sleep modes.
Open-Drain Charge Status Output. An internal N-channel MOSFET connects CHGB pin
to ground when the battery is charging. After the charge cycle is completed, the

CHGB

7

1

internal N-channel MOSFET is replaced by a weak pull-down of approximately 24A,
indicating an “AC present” condition. When the EMC5754 detects an under voltage
lockout condition, CHGB is forced high impedance.

GND

9

NA

Thermal ground area.

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Publication Date: Feb. 2014
Revision: 3.5
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EMC5754

Absolute Maximum Ratings (Notes 1, 2)
VI N, V B A T , V C H G B-0.3 V to 6 .0 V

VPROG

(Note 3) -0.3V to VIN +0.3V

Junction Temperature (TJ)

150°C

Lead Temperature (10 sec.)

260°C

Thermal Resistance (JA)

Continuous

SOT-23-5

BAT Pin Current

1A

E-SOP-8L

PROG Pin Current

1mA

BAT Short-Circuit Duration

Storage Temperature Range-65°C to160°C(Note 5)75°C/W

Operating Ratings
Temperature Range-40°C to 85°C

Supply Voltage

VBAT+0.5V to 5.5V

Note: Devices are ESD sensitive. The leads should be shorted together or the device placed in conductive foam duringstorage or handling to prevent electrostatic damage to the device.

Electrical Characteristics
Unless otherwise specified, TA=25°C and VIN=5V.
SymbolVIN

Parameter
Input Voltage

Conditions

Input Supply Current

4.4

5.5

Charge Mode, RPROG=10K (Note 4)

150

260

330

A

50

106

150

A

20

45

75

A

Terminated)

VTRICKLEVTRHYSVUVVUVHYS
VMSD
VASD

V

Regulated Output (Float)

0°C ≦ TA ≦ 85°C (VFLOAT=4.2V)

4.158

4.2

4.242

V

Voltage

0°C ≦ TA ≦ 85°C (VFLOAT=4.35V)

4.30654.35

4.3935V

RPROG=2K, Current Mode

447

480

513

mA

Standby Mode, VBAT=4.2V

-1

0

1

A

-1

0

1

A

Sleep Mode, VIN=0V

-1

0

1

A

VBAT<VTRICKLE, RPROG=2K

21

50

75

mA

RPROG=10K, VBAT Rising

2.8

2.9

3.0

V

BAT Pin Current

Shutdown Mode (RPROG Not
Connected)

ITRICKLE

Units

VBAT=4.35V

Connected, VIN<VBAT or VIN <VUV)

IBAT

Max
5.5

Shutdown Mode (RPROG Not

VFLOAT

Typ

4.25

Standby Mode (Charge
ICC

Min

VBAT=4.2V

Trickle Charge Current
Trickle Charge Threshold
Voltage
Trickle Charge Hysteresis
Voltage
VIN Under voltage Lockout
Threshold

RPROG=10K
From VIN Low to High

210
2.45

VIN Under voltage Lockout

3.0

mV
3.75

180

Hysteresis
Manual Shutdown Threshold

PROG Pin Rising

Voltage

PROG Pin Falling

VIN-VBAT Lockout Threshold

VIN from Low to High

Voltage

VIN from High to Low

Elite Semiconductor Memory Technology Inc.

1.18
1.00
5

mV
1.25

1.04
80
30

V

V
V

140

mV
mV

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Revision: 3.5
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ITERM
VPROG
ICHGB
VCHGB
VRECHRG
TILM

C/10 Termination Current
Threshold
PROG Pin Voltage
CHGB Pin Weak Pull-Down
Current

Recharge Battery Threshold
Voltage

0.93

VCHGB=5V

Soft-Start Time
Recharge Comparator Filter
Time
Termination Comparator Filter
Time

1.0

mA/mA
1.07

24
0.23

VFLOAT-VRECHRG

Constant Temperature Mode

TSS

IPROG

RPROG=10K, Current Mode

0.1

Junction Temperature inPower FET “ON” Resistance

TTERM

RPROG=10K

CHGB Pin Output Low Voltage ICHGB =5mA

RON

TRECHARGE

EMC5754

IBAT=0 to IBAT=960V/RPROG

V
A

0.6

V

160

mV

120

o

550

m

100

s

C

VBAT High to Low

0.75

2.4

4.5

ms

IBAT Falling Below ICHG/10

0.4

1.1

2.5

ms

PROG Pin Pull-up Current

0.4

A

Note 1: Absolute Maximum ratings indicate limits beyond which damage may occur. Electrical specifications are notapplicable when the device is operated outside of its rated operating conditions.
Note 2: All voltages are defined and measured with respect to the potential at the ground pin.
Note 3: Can not exceed 6.0V.
Note 4: Supply current includes PROG pin current (approximately 100A) but does not include any current delivered
to the battery through the BAT pin (approximately 96mA).
Note 5: 80oC/W to150oC/W, depending on PCB Layout.

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EMC5754

Functional Block Diagram

State Diagram

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EMC5754

Typical Applications
USB/Wall Adapter Power Li-ion Charger

Full Featured Single Cell Li-ion Charger

Li-ion Charger with External Power Dissipation

Basic Li-ion Charger with Reverse Polarity Input Protection

Turn off the LED after Charge is Terminated*The formula for R1 is R1  V 1 , where V1 is the turn-on

35A

threshold voltage of the LED device.

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EMC5754

Typical Performance Characteristics
Unless otherwise specified, VIN = 5V, TA = 25°C.
Charge Current vs Battery Voltage

Regulated Output (Float) Voltage vs Temperature

VFLOAT (V)IBAT (mA)

RPROG=10K

ThermalRegulation

VBAT (V)

Temperature (oC)Charge Current vs Supply Voltage

Charge Current vs Ambient Temperature
VBAT=4V

IBAT (mA)

IBAT (mA)

ThermalRegulation

VBAT=4V

Temperature (oC)

VIN (V)CHGB Pin I-V Curve (Strong Pull-Down State)

VFLOAT (V)ICHGB (mA)

Regulated Output (Float) Voltage vs Supply Voltage

VBAT=4V

VIN (V)

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VCHGB (V)

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EMC5754

Typical Performance Characteristics
Unless otherwise specified, VIN = 5V, TA = 25°C. (Continued)
Load Transient (Battery Removed)Line Transient (Battery Removed)

VPROG=0.2V, IBAT=4mA

VIN (v), Tr=Tf=5s
VBAT (50mV/DIV)

5.5

VBAT (50mV/DIV) Tr=Tf=20s

IBAT (100mA/DIV),VPROG=0.2V, IBAT=2mA~150mA
4.5

400s/DIV

400s/DIVVBAT=4V
VCHGB=1V

CHGB Pin I-V Curve (Weak Pull-Down State)

ICHGB (A)

ICHGB (mA)

CHGB Pin Current vs Temperature(Strong Pull-Down State)

VBAT=4.3V

VCHGB (V)

Temperature (oC)
CHGB Pin Current vs Temperature(Weak Pull-Down State)

Trickle Charge Current vs Temperature

VBAT=4.3V
VCHGB=5V

Temperature (oC)Elite Semiconductor Memory Technology Inc.

ITRICKLE (mA)

ICHGB (A)

VBAT=2.5V

RPROG=2k
RPROG=10k

Temperature (oC)

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EMC5754

Typical Performance Characteristics
Unless otherwise specified, VIN = 5V, TA = 25°C. (Continued)
Trickle Charge Current vs Supply Voltage

Trickle Charge Threshold vs Temperature
RPROG=10k

RPROG=2k
RPROG=10k

VTRICKLE (V)ITRICKLE (mA)

VBAT=2.5V

Temperature (oC)

VIN (V)

Regulated Output (Float) Voltage
vs Charge Current

Recharge Voltage Threshold vs Temperature

RPROG=10k

VFLOAT (V)VRECHRG (V)RPROG=1.25k

Temperature (oC)IBAT (mA)

VBAT=4V
RPROG=10k

VIN (V)

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PROG Pin Voltage vs Temperature

VPROG (V)VPROG (V)PROG Pin Voltage vs Supply Voltage(Constant Current Mode)

VBAT=4V
RPROG=10k

Temperature (oC)

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EMC5754

Typical Performance Characteristics
Unless otherwise specified, VIN = 5V, TA = 25°C. (Continued)
PROG Pin Pull-Up Current vs
Temperature and Supply Voltage

Charge Current vs PROG Pin Voltage
VBAT=2.5V
RPROG=2k

IBAT (mA)

RPROG=2k
RPROG=10k

IPROG (A)

VBAT=4.3V
VPROG=0V

VIN=4.2V
VIN=5.5V

VPROG (V)

Temperature (oC)

PROG Pin Current vs PROG Pin Voltage(Pull-Up Current)

PROG Pin Current vs PROG Pin Voltage(Clamp Current)
VBAT=4.3V

IPROG (A)

IPROG (A)

VBAT=4.3V

VPROG (V)VPROG (V)RDS(ON) (m)Power FET “ON” Resistance vs Temperature
VIN=4.2V
IBAT=100mA
RPROG=2k

Temperature (oC)Elite Semiconductor Memory Technology Inc.

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EMC5754

Operation
The EMC5754 is a single cell lithium-ion battery charger
using a constant-current/constant-voltage algorithm. It
can deliver up to 1A of charge current (using a goodthermal PCB layout) with a final float voltage accuracyof ±1%. The EMC5754 includes an internal P-channel
power MOSFET and thermal regulation circuitry. No
blocking diode or external current sense resistor isrequired; thus, the basic charger circuit requires only
two external components. Furthermore, the EMC5754 iscapable of operating from a USB power source.
Normal Charge Cycle
A charge cycle begins when the voltage at the VIN pin
rises above the UVLO threshold level and a 1% program
resistor is connected from the PROG pin to ground orwhen 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 EMC5754 supplies
approximately 1/10 the programmed charge current tobring the battery voltage up to a safe level for fullcurrent charging. When the BAT pin voltage rises above
2.9V, the charger enters constant-current mode, where
the programmed charge current is supplied to thebattery. When the BAT pin approaches the final float
voltage (4.2V), the EMC5754 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 960 times the current out of the PROG pin. The
program resistor and the charge current are calculatedusing the following equations:

R PROG 

960V
960V, I CHG 
I CHG
R PROGThe charge current out of the BAT pin can be
determined at any time by monitoring the PROG pin
voltage using the following equation:

I BAT V PROG 960
R PROG

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 1.1ms), charging isterminated. The charge current is latched off and the
EMC5754 enters standby mode, where the input supply
current drops to 106A. (Note: C/10 termination isdisabled in trickle charging and thermal limiting modes).
The EMC5754 draws no current from the battery instandby mode. This feature reduces the charge anddischarge cycles on the battery, further prolonging thebattery life.
Any external source (VPROG) that holds the PROG pin

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above 100mV will prevent the EMC5754 fromterminating a charge cycle. However, if the PROG pin iscontrolled by external source, current sourcing from theBAT pin can be infinity (until the internal power MOSFET isburned out or the BAT pin voltage is close to its final float
voltage), and the formula for charge current is not valid
anymore. Therefore, controlling the PROG pin byexternal source below 1.1V should be avoided when abattery is connected to BAT pin. However, with nobattery present, forcing VPROG to 0.2V~0.4V enables
EMC5754 to act as a LDO (LDO mode). In the LDO
mode, load current at the BAT pin is recommended tobe below 150mA to avoid overheating.
When charging, transient loads on the BAT pin cancause the PROG pin to fall below 100mV for shortperiods of time before the DC charge current has
dropped to 1/10th the programmed value. The 1.1ms
filter time (TTERM) on the termination comparator ensuresthat transient loads of this nature do not result inpremature charge cycle termination. Once theaverage charge current drops below 1/10th theprogrammed value, the EMC5754 terminates the
charge cycle and ceases to provide any current
through the BAT pin. This is the standby mode, and allloads on the BAT pin must be supplied by the battery. In
the standby mode, any signal below the manual
shutdown threshold voltage (typically 1.18V) on the
PROG pin is transparent to EMC5754.
The EMC5754 constantly monitors the BAT pin voltage instandby mode. If this voltage drops below the 4.05V
recharge threshold (VRECHRG), another charge cycle
begins and current is once again supplied to thebattery. To manually restart a charge cycle when instandby mode, the input voltage must be removed andreapplied, or the charger must be shut down andrestarted using the PROG pin.
Charge Status Indicator (CHGB)
The charge status output has three different states:
strong pull-down (~10mA), weak pull-down (~24A) andhigh impedance. The strong pull-down state indicatesthat the EMC5754 is in a charge cycle. Once thecharge cycle has terminated, the pin state isdetermined by undervoltage lockout conditions. A
weak pull-down indicates that VIN meets the UVLO
conditions and the EMC5754 is ready to charge. High
impedance indicates that the EMC5754 is inundervoltage lockout mode: either VIN is less than
80mV above the BAT pin voltage or insufficient voltage
is applied to the VIN 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 temperatureattempts to rise above a preset value of approximately
120°C. This feature protects the EMC5754 from excessive
temperature and allows the user to push the limits of thepower handling capability of a given circuit board
without risk of damaging the EMC5754. 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 inworst-case conditions. SOT power considerations are

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EMC5754

discussed further in the Applications Information section.

program resistor.

Undervoltage Lockout (UVLO)

In manual shutdown, the CHGB pin is in a weakpull-down state as long as VIN is high enough to exceed
the UVLO conditions. The CHGB pin is in a highimpedance state if the EMC5754 is in undervoltage
lockout mode: either VIN is within 80mV of the BAT pin
voltage or insufficient voltage is applied to the VIN pin.

An internal undervoltage lockout circuit monitors the
input voltage and keeps the charger in shutdown mode
until VIN 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 VIN falls to within 30mV of the battery
voltage. If the UVLO comparator is tripped, the charger
will not come out of shutdown mode until VIN rises 80mV
above the battery voltage.
Manual Shutdown
At any point in the charge cycle, the EMC5754 can be
put into shutdown mode by removing RPROG thus floating
the PROG pin. This reduces the battery drain current toabout to 0A and the supply current to less than 45A. A
new charge cycle can be initiated by reconnecting theAutomatic Recharge
Once the charge cycle is terminated, the EMC5754
continuously monitors the voltage on the BAT pin using acomparator 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 theneed for periodic charge cycle initiations. CHGB output
enters a strong pulldown state during recharge cycles.

=============================================================================================

Application Information
Stability Considerations
The constant-voltage mode feedback loop is stablewithout an output capacitor provided a battery isconnected to the charger output. With no battery
present, an output capacitor is recommended toreduce ripple voltage. When using high value, low ESR
ceramic capacitors, it is recommended to add a 1resistor in series with the capacitor. No series resistor isneeded 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 100k. 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, thefollowing equation can be used to calculate themaximum resistance value for RPROG:

R PROG 

12  10  C PROG
5

Average, rather than instantaneous, charge current
may be of interest to the user. For example, if aswitching power supply operating in low current mode isconnected 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 asshown in Figure 1. A 10k resistor has been added
between the PROG pin and the filter capacitor toensure stability.
Power Dissipation

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The conditions that cause the EMC5754 to reduce
charge current through thermal feedback can beapproximated by considering the power dissipated in
the IC. Nearly all of this power dissipation is generated
by the internal MOSFET—this is calculated to beapproximately:
PD = (VIN – VBAT) • IBAT
where PD is the power dissipated, VIN is the input supply
voltage, VBAT is the battery voltage and IBAT is the charge
current. The approximate ambient temperature atwhich the thermal feedback begins to protect the IC is:
TA = 120oC – PDJA
TA = 120 oC – (VIN – VBAT) • IBAT •JA
Example: An EMC5754 operating from a 5V USB supply is
programmed to supply 500mA full-scale current to adischarged Li-Ion battery with a voltage of 3.7V.
Assuming JA is 100oC/W, the ambient temperature atwhich the EMC5754 will begin to reduce the charge
current is approximately:
TA = 120 oC – (5V – 3.7V) • (500mA) •100oC/W
TA = 120 oC – 0.65W •100oC/W = 120 oC – 65 oC
TA = 55 oC
The EMC5754 can be used above 55 oC ambient, but
the charge current will be reduced from 500mA. The

Figure 1. Isolating Capacitive load on PROG Pin and Filtering

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approximate current at a given ambient temperature
can be approximated by:

I BAT 120 o C  TA
(VIN  VBAT )   JA

Using the previous example with an ambient
temperature of 70oC, the charge current will be
reduced to approximately:

120 o C  70 o C
50 o C(5  3.7)  100 o C / W 130 o C / A
I BAT  384mA
I BAT 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 EMC5754 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 120oC.
Thermal Considerations
Because of the small size of the SOT package, it is very
important to use a good thermal PC board layout tomaximize the available charge current. The thermal
path for the heat generated by the IC is from the die tothe 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 theheat to the surrounding ambient. Feedthrough vias toinner or backside copper layers are also useful inimproving the overall thermal performance of thecharger. Other heat sources on the board, not related
to the charger, must also be considered when
designing a PC board layout because they will affectoverall temperature rise and the maximum charge
current.
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 isby dissipating some of the power through an external
component, such as a resistor or diode.
Example: An EMC5754 operating from a 5V wall

EMC5754
to a discharged Li-Ion battery with a voltage of 3.7V.
Assuming JA is 100oC/W, the approximate charge
current at an ambient temperature of 25oC is:I BAT 120 o C  25 o C 730mA(5V  3.7V )  100 o C / W

By dropping voltage across a resistor in series with a 5V
wall adapter (shown in Figure 2), the on-chip power
dissipation can be decreased, thus increasing thethermally regulated charge current

I BAT 120 o C  25 o C(V S  I BAT RCC  V BAT )   JA

Solving for IBAT using the quadratic formula.

I BAT 4 R (120 o C  T A )1[(VS  V BAT )  (VS  V BAT ) 2  CC
]
2 RCC
 JA

(Note: Large values of RCC will result in no solution for IBAT. This indicates that the
EMC5754 will not generate enough heat to require thermal regulation.)

Using RCC = 0.25, VS = 5V, VBAT = 3.7V, TA = 25°C and JA= 100°C/W we can calculate the thermally regulated
charge current to be:
IBAT = 879.5mA
While this application delivers more energy to thebattery and reduces charge time in thermal mode, it
may actually lengthen charge time in voltage mode if
VIN becomes low enough to put the EMC5754 into
dropout.
This technique works best when RCC values areminimized to keep component size small and avoid
dropout. Remember to choose a resistor with adequate
power handling capability.
VIN Bypass Capacitor
Many types of capacitors can be used for input
bypassing, however, caution must be exercised whenusing multilayer ceramic capacitors. Because of theself-resonant and high Q characteristics of some typesof ceramic capacitors, high voltage transients can begenerated under some start-up conditions, such as
connecting the charger input to a live power source.
Adding a 1.5 resistor in series with an X5R ceramic
capacitor will minimize start-up voltage transients.
Charge Current Soft-Start
The EMC5754 includes a soft-start circuit to minimize theinrush current at the start of a charge cycle. When acharge cycle is initiated, the charge current ramps fromzero to the full-scale current over a period of
approximately 100s. This has the effect of minimizing
the transient current load on the power supply during
start-up.

Figure 2. A Circuit to Maximize Thermal Mode Charge Current
adapter is programmed to supply 1A full-scale current

Elite Semiconductor Memory Technology Inc.

Publication Date: Feb. 2014
Revision: 3.5
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ESMT
CHGB Status Output Pin

Figure 3. Using a Microprocessor to Determine CHGB State

EMC5754
USB and Wall Adapter PowerThe EMC5754 allows charging from both a wall adapter
and a USB port. Figure 5 shows an example of how to
combine wall adapter and USB power inputs. A
P-channel MOSFET, MP1, is used to prevent backconducting into the USB port when a wall adapter ispresent 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 areused to increase the charge current to 580mA when thewall adapter is present.

The CHGB pin can provide an indication that the input
voltage is greater than the undervoltage lockout
threshold level. A weak pull-down current ofapproximately 24A indicates that sufficient voltage isapplied to VIN to begin charging. When a discharged
battery is connected to the charger, the constantcurrent portion of the charge cycle begins and theCHGB pin pulls to ground. The CHGB 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 24A pull-down, indicatingthat the charge cycle has ended. If the input voltage isremoved or drops below the undervoltage lockout
threshold, the CHGB pin becomes high impedance.
Figure 3 shows that by using two different value pull-up
resistors, a microprocessor can detect all three statesfrom this pin.
To detect when the EMC5754 is in charge mode, force
the digital output pin (OUT) high and measure thevoltage at the CHGB pin. The internal N-channel
MOSFET will pull the pin voltage low even with the 2k
pull-up resistor. Once the charge cycle terminates, theN-channel MOSFET is turned off and a 24A current
source is connected to the CHGB pin. The IN pin willthen 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 CHGB is high impedance, the IN pin will
be pulled high, indicating that the part is in a UVLO
state.

Figure 5. Combining Wall Adapter and USB Power

Reverse Polarity Input Voltage Protection
In some applications, protection from reverse polarity
voltage on VIN is desired. If the supply voltage is highenough, a series blocking diode can be used. In othercases, where the voltage drop must be kept low a
P-channel MOSFET can be used (as shown in Figure 4).

Figure 4. Low Loss Input Reverse Polarity Protection

Elite Semiconductor Memory Technology Inc.

Publication Date: Feb. 2014
Revision: 3.5
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ESMT

EMC5754

Package Outline Drawing
SOT-23-5

5

4

E

PIN#1
MARK

1

DETAIL A

E13c

TOP VIEW
D

A

1
b

3

A1

e

L

DETAIL A

SIDE VIEW
Symbol
A
A1
b
c
D
E
E1
e
L

Elite Semiconductor Memory Technology Inc.

Dimension in mm
Min.
Max.
0.90
1.45
0.00
0.15
0.30
0.50
0.08
0.25
2.70
3.10
1.40
1.80
2.60
3.00
0.95 BSC
0.30
0.60

Publication Date: Feb. 2014
Revision: 3.5
17/20

ESMT

EMC5754

Package Outline Drawing
SOP-8 (E) (150 mil)Symbol
A
A1
b
c
D
E
E1
e
L

Dimension in mm
Min
Max
1.35
1.75
0.00
0.25
0.33
0.51
0.17
0.25
4.80
5.00
3.81
4.00
5.79
6.20
1.27 BSC
0.41
1.27

Elite Semiconductor Memory Technology Inc.

Exposed pad

D2
E2

Dimension in mm
Min
Max
1.93
2.39
1.93
2.39

Publication Date: Feb. 2014
Revision: 3.5
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ESMT

EMC5754

Revision History
Revision

Date

3.0

2009.05.12

EMP transferred from version 2.1

3.1

2011.08.11

1.Revise outline spec in Jedec dimension
2.Revise GRR definition

3.2

2011.11.01

Added 4.1V and 4.3V charge voltage options into thisdatasheet.

3.3

2012.08.14

1.Add 4.35V charge voltage options into this datasheet
2.Update package outline drawing

3.4

2013.08.06

Remove 4.1V and 4.3V charge voltage options

3.5

2014.03.04

Add SOP-8E package option

Elite Semiconductor Memory Technology Inc.

Description

Publication Date: Feb. 2014
Revision: 3.5
19/20

ESMT

EMC5754
Important Notice

All rights reserved.
No part of this document may be reproduced or duplicated in any
form or by any means without the prior permission of ESMT.
The contents contained in this document are believed to be accurate
at the time of publication. ESMT assumes no responsibility for any error
in this document, and reserves the right to change the products or
specification in this document without notice.
The information contained herein is presented only as a guide or
examples for the application of our products. No responsibility is
assumed by ESMT for any infringement of patents, copyrights, or otherintellectual property rights of third parties which may result from its use.
No license, either express , implied or otherwise, is granted under any
patents, copyrights or other intellectual property rights of ESMT orothers.
Any semiconductor devices may have inherently a certain rate of
failure. To minimize risks associated with customer's application,adequate design and operating safeguards against injury, damage,or loss from such failure, should be provided by the customer when
making application designs.
ESMT's products are not authorized for use in critical applications suchas, but not limited to, life support devices or system, where failure or
abnormal operation may directly affect human lives or cause physicalinjury or property damage. If products described here are to be used
for such kinds of application, purchaser must do its own quality
assurance testing appropriate to such applications.

Elite Semiconductor Memory Technology Inc.

Publication Date: Feb. 2014
Revision: 3.5
20/20