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PDF EMC5755-00FF06NRR Data sheet ( Hoja de datos )
| Número de pieza | EMC5755-00FF06NRR | |
| Descripción | Standalone 1.2A Linear Li-Ion Battery Charger | |
| Fabricantes | Elite Semiconductor | |
| Logotipo |  |
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ESMT/EMP
EMC5755
Standalone 1.2A Linear Li-Ion Battery Charger
with Thermal Regulation in TDFN-6
General Description
The EMC5755 is a complete linear charger for single cell
lithium-ion batteries. With small TDFN-6 package and
few external components, EMC5755 is well suited for
portable applications. In addition, the EMC5755 is
specifically designed to work within USB power
specifications.
No external sense resistor and blocking diode are
required. Charging current can be programmed
externally with a single resistor. The built-in thermal
regulation facilitates charging with maximum power
without risk of overheating.
The EMC5755 always preconditions the battery with
1/10 of the programmed charge current at the
beginning of a charge cycle, until 40μs after it verifies
that the battery can be fast-charged. The EMC5755
automatically terminates the charge cycle when the
charge current drops to 1/10th the programmed value
after the final float voltage is reached.
The EMC5755 consumes zero reverse current from the
battery at standby, shutdown and sleep modes. This
feature reduces the charge and discharge cycles on
the battery, further prolonging the battery life. The
EMC5755 can also be used as a LDO when battery is
removed. Other features include shutdown mode,
charge current monitor, under voltage lockout,
automatic recharge and status indicator.
Features
Programmable charge current up to 1.2A
No MOSFET, sense resistor or blocking diode
required
Complete linear charger in TDFN-6 for single cell
Lithium-ion batteries
Typical zero reverse current from battery
Thermal regulation maximizes charge rate
without risk of overheating
Charges single cell Li-ion batteries directly from
USB port
Act as a LDO when battery is removed
Preset 4.2V charge voltage with ±1% accuracy
Automatic recharge
Charge status indicator
C/10 charge termination
45μA shutdown supply current
2.9V trickle charge threshold
Soft-start limits inrush current
RoHS compliant and Pb-free
Applications
Wireless handsets
Hand-held instruments
Portable information appliances
Bluetooth application
Charging docks and cradles
Typical Application Diagram
960 mA Charger
LDO Mode
(Battery Removed)
Typical Performance Characteristics
Complete Charge Cycle (850mAh Battery)
Elite Semiconductor Memory Technology Inc./Elite MicroPower Inc.
Time (1000s/DIV)
Publication Date: Oct. 2010
Revision: 2.2
1/17
1 page  
ESMT/EMP
Functional Block Diagram
EMC5755
State Diagram
Elite Semiconductor Memory Technology Inc./Elite MicroPower Inc.
Publication Date: Oct. 2010
Revision: 2.2
5/17
5 Page 
ESMT/EMP
EMC5755
Operation
The EMC5755 is a single cell lithium-ion battery charger
using a constant-current/constant-voltage algorithm. It
can deliver up to 1.2A of charge current with a final
float voltage accuracy of ±1%. The EMC5755 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 EMC5755 is capable 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 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 EMC5755 supplies
approximately 1/10 the programmed charge current to
bring the battery voltage up to a safe level for full
current charging. When the BAT pin voltage rises above
2.9V, the charger enters constant-current mode, where
the programmed charge current is supplied to the
battery. When the BAT pin approaches the final float
voltage (4.2V), the EMC5755 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.
Any external source (VPROG) that holds the PROG pin
above 100mV will prevent the EMC5755 from
terminating a charge cycle. However, if the PROG pin is
controlled by external source, current sourcing from the
BAT pin can be infinity (until the internal power MOSFET is
burned 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 by
external source below 1.1V should be avoided when a
battery is connected to BAT pin. However, with no
battery present, forcing VPROG to 0.2V~0.4V enables
EMC5755 to act as a LDO (LDO mode). In the LDO
mode, load current at the BAT pin is recommended to
be below 150mA to avoid overheating.
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 1.1ms
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 EMC5755 terminates the
charge cycle and ceases to provide any current
through the BAT pin. This is the standby mode, and all
loads 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 EMC5755.
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 calculated
using the following equations:
RPROG
=
960V
I CHG
,
I CHG
=
960V
RPROG
The 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
=
VPROG
RPROG
• 960
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 is
terminated. The charge current is latched off and the
EMC5755 enters standby mode, where the input supply
current drops to 106μA. (Note: C/10 termination is
disabled in trickle charging and thermal limiting modes).
The EMC5755 draws no current from the battery in
standby mode. This feature reduces the charge and
discharge cycles on the battery, further prolonging the
battery life.
The EMC5755 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.
Charge Status Indicator (CHGB)
The charge status output has three different states:
strong pull-down (~10mA), weak pull-down (~24μA) and
high impedance. The strong pull-down state indicates
that the EMC5755 is in a charge cycle. Once the
charge cycle has terminated, the pin state is
determined by under-voltage lockout conditions. A
weak pull-down indicates that VIN meets the UVLO
conditions and the EMC5755 is ready to charge. High
impedance indicates that the EMC5755 is in
under-voltage 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 temperature
attempts to rise above a preset value of approximately
120°C. This feature protects the EMC5755 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 EMC5755. The charge
current can be set according to typical (not worst-case)
ambient temperature with the assurance that the
Elite Semiconductor Memory Technology Inc./Elite MicroPower Inc.
Publication Date: Oct. 2010
Revision: 2.2
11/17
11 Page | ||
| Páginas | Total 17 Páginas | |
| PDF Descargar | [ Datasheet EMC5755-00FF06NRR.PDF ] | |
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