MP2674 [MPS]
Li-Ion Battery Charger Protection Circuit;
| 型号： | MP2674 |
| 厂家： | 
MONOLITHIC POWER SYSTEMS |
| 描述： | Li-Ion Battery Charger Protection Circuit 电池 |
| 文件： | 总11页 (文件大小：353K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
MP2674
Li-Ion Battery Charger
Protection Circuit
The Future of Analog IC Technology
DESCRIPTION
FEATURES
The MP2674 is a high-performance single cell
Li-Ion/Li-Polymer battery charger protection
circuit. By integrating high voltage input
protection into the IC, the MP2674 can tolerate
an input surge up to +30V.
•
•
•
•
Input Surge up to 30V
Input Over voltage protection in 1µs.
Proprietary Battery Over-Voltage Protection
Programmable Charge Current Protection
Limit Value.
•
•
•
Temperature Monitoring and Protection
Fault Indication
2mmx2mm QFN Package
The device features input over voltage
protection (OVP), battery over voltage
protection (BOVP) and over charge current
protection (OCP). The device also provides
fault indications to the system when any of the
protection events happens.
APPLICATIONS
•
•
•
•
•
•
Cell Phones
MP3 Players
Smart Phones
PDA
Digital Cameras
Desktop Chargers
For guaranteed safe operation, the MP2674
monitors its own internal temperature and turns
off the MOSFET bridging VIN and OUT when
the die temperature exceeds 150oC.
The MP2674 is available in an 8-pin 2mmx2mm
QFN package.
“MPS” and “The Future of Analog IC Technology” are Registered Trademarks of
Monolithic Power Systems, Inc.
TYPICAL APPLICATION
LINEAR
BATTERY
CHARGER
INPUT
VIN
OUT
MP2674
C
IN
COUT
ILIM
VB
RILIM
RVB
GND
FLT
Battery
Pack
RFLT
MP2674 Rev. 0.9
11/8/2010
www.MonolithicPower.com
MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.
© 2010 MPS. All Rights Reserved.
1
MP2674 – CHARGE SYSTEM PROTECTION CIRCUIT
ORDERING INFORMATION
Part Number*
Package
Top Marking
Free Air Temperature (TA)
MP2674EG
QFN8 (2mm x 2mm)
2Q
-20°C to +85°C
*For Tape & Reel, add suffix –Z (e.g. MP2674EG–Z):
For RoHS compliant packaging, add suffix –LF (e.g. MP2674EG–LF–Z).
PACKAGE REFERENCE
TOP VIEW
8
7
6
5
VIN
GND
NC
1
2
3
4
OUT
ILIM
VB
GND
FLT
Thermal Resistance (4)
QFN8 (2mm x 2mm)..............100..... 55... °C/W
θJA
θJC
ABSOLUTE MAXIMUM RATINGS (1)
VIN to GND.......................................-0.3V to 30V
OUT and VB to GND.........................-0.3V to 7V
Notes:
Other Pins (ILIM, FLT )...................-0.3V to 5.5V
1) Exceeding these ratings may damage the device.
2) The maximum allowable power dissipation is a function of the
maximum junction temperature TJ (MAX), the junction-to-
ambient thermal resistance θJA, and the ambient temperature
TA. The maximum allowable continuous power dissipation at
any ambient temperature is calculated by PD (MAX) = (TJ
(MAX)-TA)/θJA. Exceeding the maximum allowable power
dissipation will cause excessive die temperature, and the
regulator will go into thermal shutdown. Internal thermal
shutdown circuitry protects the device from permanent
damage.
(2)
Continuous Power Dissipation...(TA = +25°C)
....................................................…....1.25W
Junction Temperature...............................150°C
Lead Temperature (Solder).......................260°C
Storage Temperature............... -65°C to +150°C
Recommended Operating Conditions (3)
Supply Voltage VIN ..........................4.3V to 5.5V
Operating Current Range…………….0A to 1.5A
Operating Junct. Temp (TJ)...... -20°C to +125°C
3) The device is not guaranteed to function outside of its
operating conditions.
4) Measured on JESD51-7, 4-layer PCB.
MP2674 Rev. 0.9
11/8/2010
www.MonolithicPower.com
MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.
© 2010 MPS. All Rights Reserved.
2
MP2674 – CHARGE SYSTEM PROTECTION CIRCUIT
ELECTRICAL CHARACTERISTICS
VIN = 5V, TA = +25°C, unless otherwise noted.
Parameter
Symbol Condition
Min
Typ
Max
Units
Power-On Reset
Rising VIN Threshold
POR Hysteresis
VPOR
2.35
2.43
110
0.6
2.50
V
mV
mA
µA
When enabled
When disabled
VIN Bias Current
IVIN
25
Protection
Input Over-voltage Protection
(OVP)
VOVP
5.6
5.80
50
6.0
V
Input OVP Hysteresis
mV
V
Input OVP Falling Threshold
Input OVP Propagation Delay
Over-current Protection
5.45
0.78
1
µs
A
IOCP
VVB = 3V, RILIM = 25kΩ
0.90
170
1.10
Overcurrent Protection Blanking
Time
BTOCP
µs
V
Battery Over-voltage Protection
Threshold
VBOVP
4.29
4.37
55
4.475
Battery OVP Threshold
Hysteresis
mV
Battery OVP Falling Threshold
Battery OVP Blanking Time
VB Pin Leakage Current
4.225
V
BTBOVP
180
µs
nA
VVB = 4.34V
20
Over Temperature Protection
Rising Threshold
150
110
°C
°C
Over Temperature Protection
Falling Threshold
Logic
FLT
Sink 5mA current
0.25
60
0.8
V
Output Logic Low
FLT
Ω
Parasitic Series Resistor
FLT
Output Logic High Leakage
1.5
µA
Current
Power MOSFET
On Resistance
RDS(ON)
Measured at 200mA,
200
300
mΩ
MP2674 Rev. 0.9
11/8/2010
www.MonolithicPower.com
MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.
© 2010 MPS. All Rights Reserved.
3
MP2674 – CHARGE SYSTEM PROTECTION CIRCUIT
PIN FUNCTIONS
8-pin
Name
QFN
Description
1
2, 5
3
VIN
GND
NC
Input Power Source. VIN can withstand 30V input.
System Ground.
No Connect. Keep it floating.
Open-Drain Logic Output. This pin turns LOW when any protection event occurs.
Connect a pull-up resistor to VIN pin. Higher than 10kΩ is recommended.
4
6
FLT
VB
Battery Voltage Monitoring Input. Connect this pin to the battery pack positive
terminal via an isolation resistor.
Over-current Protection Threshold Setting. Connect a resistor between this pin and
GND to set the OCP threshold.
7
8
ILIM
OUT
Output pin and input pin of the protected charger.
MP2674 Rev. 0.9
11/8/2010
www.MonolithicPower.com
MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.
© 2010 MPS. All Rights Reserved.
4
MP2674 – CHARGE SYSTEM PROTECTION CIRCUIT
TYPICAL PERFORMANCE CHARACTERISTICS
o
FLT
VIN=5V, RILIM=24.9kΩ, RVB=200kΩ, R =100kΩ, TA=25 C, unless otherwise noted.
Input OVP
Input OVP
Ramp Up V Slowly
IN
V
IN Steps from 5V to 20V
without Load
without Load
V
V
IN
IN
2V/div.
V
OUT
2V/div.
V
IN
2V/div.
OUT
2V/div.
V
IN
V
5V/div.
BAT
5V/div.
V
BAT
V
FLT
5V/div.
I
OUT
FLT
200mA/div.
5V/div.
Input OVP Start Up
Battery OVP
Ramp Up V Slowly from 0V to 6.6V
IN
No Load, Shut Dwon Permanently
after 16 Times
without Load
V
IN
2V/div.
VB
2V/div.
V
V
OUT
IN
2V/div.
2V/div.
V
V
OUT
OUT
2V/div.
2V/div.
I
I
OUT
OUT
FLT
5V/div.
200mA/div.
200mA/div.
I
FLT
5V/div.
FLT
5V/div.
OUT
200mA/div.
OCP Before Start Up
Zoom In of OCP
Before Start Up
Shut Dwon Permanently after 16 Times
V
IN
2V/div.
V
IN
2V/div.
V
OUT
V
OUT
2V/div.
2V/div.
I
I
OUT
OUT
500mA/div.
500mA/div.
FLT
FLT
5V/div.
5V/div.
MP2674 Rev. 0.9
11/8/2010
www.MonolithicPower.com
MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.
© 2010 MPS. All Rights Reserved.
5
MP2674 – CHARGE SYSTEM PROTECTION CIRCUIT
TYPICAL PERFORMANCE CHARACTERISTICS (Continued)
o
FLT
VIN=5V, RILIM=24.9kΩ, RVB=200kΩ, R =100kΩ, TA=25 C, unless otherwise noted.
Limit Current vs. R
Supply Current vs. V
IN
ILIM
1.4
1.2
1
500
450
400
350
300
250
200
150
100
50
0.8
0.6
0.4
0.2
0
0
0
50
100 150 200 250
0
1
2
3
4
5
6
7
INPUT VOLTAGE(V)
MP2674 Rev. 0.9
11/8/2010
www.MonolithicPower.com
MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.
© 2010 MPS. All Rights Reserved.
6
MP2674 – CHARGE SYSTEM PROTECTION CIRCUIT
BLOCK DIAGRAM
LINEAR
OUT
V
IN
INPUT
BATTERY
CHARGER
Q1
Q2
Q3
EA
ILIM
POR
PRE-REG
REF
FET
DRIVER
RILIM
- -
CP2
R1
R2
--
+
--
+
- -
0.8V
CP1
1.2V
LOGIC
CP3
RVB
VB
R
Q4
+
FLT
GND
Figure 1—Function Block Diagram
MP2674 Rev. 0.9
11/8/2010
www.MonolithicPower.com
MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.
© 2010 MPS. All Rights Reserved.
7
MP2674 – CHARGE SYSTEM PROTECTION CIRCUIT
When the input over-voltage condition is
removed, the power FET is turned on again by
running through the soft-start. Because of the
10ms second delay before the soft-start, the
output is never enabled if the input rises above
the OVP threshold quickly.
OPERATION
The MP2674 is designed to provide a
redundant safety protection to a Li-Ion battery
from failures of the charging system. The IC
continuously monitors the input voltage, the
battery voltage, and the charge current. When
any of the above three parameters exceeds its
limit, the IC turns off an internal N-channel
MOSFET to remove the power from the
charging system. The threshold of charge
current protection is user-programmable.
Additionally, the IC also monitors its own die
temperature and turns off the N-channel
MOSFET if the temperature exceeds 150°C.
Together with the battery charging IC and the
protection module in a battery pack, the
charging system has triple-level protection from
over-charging the Li-Ion battery and is two–fault
tolerant. The MP2674 protects up to 30V input
voltage.
Over-current Protection (OCP)
The current in the power FET is limited to
prevent charging the battery with an excessive
current. The current is sensed using the voltage
drop across the power FET after the FET is
turned on. The reference of the OCP is
generated using a sensing FET Q2, as shown
in Figure 1. The current in the sensing FET is
forced to a value which can be programmed by
an external resistor connected to the ILIM pin.
The size of the power FET Q1 is 31,250 times
the size of the sensing FET Q2. Therefore,
when the current in the power FET is 31,250
times the current in the sensing FET, the drain
voltage of the power FET falls below that of the
sensing FET. The comparator CP2 then outputs
a signal to turn off the power FET. The OCP
threshold can be programmed using the
following formula:
Power Up
The MP2674 has a power-on reset (POR)
threshold of 2.43V with a built-in hysteresis of
110mV. When the input voltage is below the
POR threshold, the internal power FET is off.
The IC resets itself and waits for approximately
10ms after the input voltage exceeds the POR
threshold, then, if the input voltage and battery
voltage are safe, the IC begins to soft-start the
internal power FET. The 10ms delay allows any
transient at the input during a hot insertion of
the power supply to settle down before the IC
starts to operate. The soft-start slowly turns on
the power FET to reduce the inrush current as
well as the input voltage drop during the
transition.
0. 8 V
25000
R
=
I
31250
LI
M
R
=
⋅
I LI
M
I LI M
The OCP comparator CP2 has a built-in 170µs
delay to prevent false triggering by transient
signals. When OCP happened, Vo shuts down
for about 40ms and take 10ms delay to soft
start as the OCP condition is removed. The
OCP function also has a 4-bit binary counter
that accumulates during an OCP event. When
the total count reaches 16, the power PFET is
turned off permanently unless the input power
is recycled.
Input Over-voltage Protection (OVP)
The input voltage is continuously monitored by
the comparator CP1 in the Block Diagram
(Figure 1). The OVP threshold is set by a
resistive divider consisting of R1 and R2 and an
accurate reference generated by the IC itself.
The protection threshold is set to 5.8V. When
the input voltage exceeds the threshold, the
CP1 outputs a logic signal to turn off the power
FET within 1µs to prevent the high input voltage
from damaging the electronics in the handheld
system. The hysteresis for the input OVP
threshold is given in the Electrical Specification.
Battery Over-voltage Protection (BOVP)
The battery voltage OVP threshold is internally
set to 4.37V. The threshold has 55mV built-in
hysteresis. The comparator CP3, as shown in
Figure 1, monitors the VB pin and issues an
over-voltage signal to turn off the internal power
FET when the battery voltage exceeds the
battery OVP threshold. The comparator CP3
has a built-in 180µs blanking time to prevent
any transient voltage from triggering the OVP. If
the OVP situation still exists after the blanking
MP2674 Rev. 0.9
11/8/2010
www.MonolithicPower.com
MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.
© 2010 MPS. All Rights Reserved.
8
MP2674 – CHARGE SYSTEM PROTECTION CIRCUIT
time, the power FET is turned off. There is an
internal 4-bit binary counter monitoring the
occurrence of the battery over-voltage event. If
the battery over-voltage occurs 16 times, the
power FET is turned off permanently. Recycling
the input power will reset the counter and
restart the MP2674.
The resistor between the VB pin and the
battery, RVB, as shown in the Typical
Applications circuit, is an important component.
This resistor provides a current limit in case the
VB pin is shorted to the input voltage under a
failure mode. The VB pin leakage current under
normal operation is negligible to allow a
resistance of 200kꢀ to 1Mꢀ being used.
Thermal Protection
The MP2674 monitors its own die temperature
to prevent thermal failures. When the internal
temperature reaches 150°C, the internal N-
channel power MOSFET is turned off. The IC
does not resume operation until the internal
temperature drops below 110°C.
Warning Indication Output
The FLT pin is an open-drain output that
indicates a LOW signal when any of the four
protection events happens.
1. Input over voltage
2. Battery over voltage
3. Output over current
4. Thermal protection
FLT
To pull the
pin voltage low when fault, a
recommended 10kꢀ to 200kꢀ resistor should
be used as the pull up resistor.
MP2674 Rev. 0.9
11/8/2010
www.MonolithicPower.com
MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.
© 2010 MPS. All Rights Reserved.
9
MP2674 – CHARGE SYSTEM PROTECTION CIRCUIT
the input decoupling capacitor is recommended
to use a dielectric ceramic capacitor with a
value between 1µF to 4.7µF.
The output of the MP2674 and the input of the
charging circuit typically share one decoupling
capacitor. The selection of that capacitor is
mainly determined by the requirement of the
charging circuit. When using the MP2602 family
chargers, a 1µF to 4.7uF ceramic capacitor is
recommended.
APPLICATION INFORMATION
For safe and effective charging, some strict
requirements have to be satisfied during
charging Li-Ion batteries such as high precise
power source for charging (4.2V±50mV), the
accuracy should be higher than 1%. For highly
used capacity, the voltage of the battery should
be charged to the value (4.2V) as possible as
could. Otherwise, the performance and the life
of the battery suffers overcharge. Additionally,
the pre-charge for depleted batteries, charging
voltage, charging current, as well as the
temperature detection and protection, are
required for linear battery chargers. The output
of most MPS linear chargers has a typical I-V
curve and provides overcharge, input over
voltage, over temperature protection. The
function of the MP2674 is to add a redundant
protection layer such that, under any fault
condition, the charging system output does not
exceed the I-V limits that the battery required.
Additionally, MP2674 provides full protection for
these chargers whose protection function is not
so complete especially those without input
surge voltage sustain. MP2674 guarantees the
safety of the charge system with its perfect 4
protection functions: OVP, BOVP, OCP and
OTP
RVB Selection
RVB limits the current from the VB pin to the
battery terminal in case the MP2674 fails. The
recommended value is between 200kꢀ to 1Mꢀ.
With 200kꢀ resistance, during the failure
operation, assuming the VB pin voltage is 30V
and the battery voltage is 4.2V. The worst case
the current flowing from the VB pin to the
charger output is,
(30V - 4.2V)/200kꢀ = 130µA,
Such small current can be easily absorbed by
the bias current of other components.
Increasing the RVB value reduces the worst
case current, but at the same time increases
the error for the 4.37V battery OVP threshold.
As the typical VB pin leakage current is 20nA,
the error of the battery OVP threshold can be
calculated as 4.37V+20nAxRVB. With the 200kꢀ
resistor, the worst-case additional error is 4mV
and with a 1Mꢀ resistor, the worst-case
additional error is 20mV.
The MP2674 is a simple device that requires
few external components, in addition to the
linear charger circuit as shown in the Typical
Application Circuit. The selection of MP2674’s
external components is shown as follow, and
the selection of the current limit resistor RILIM
has been introduced in the Over-current
Protection section.
.
CIN and COUT Selection
The input capacitor (CIN) is for decoupling.
Higher value of CIN reduces the voltage drop or
the over shoot during transients. The AC
adapter is inserted live (hot insertion) and
sudden step down of the current in the power
FET will cause the input voltage overshoot.
During an input OVP, the FET is turned off in
less than 1µs and can lead to significant over
shoot. Higher capacitance of CIN reduces this
type of over shoot. However, the over shoot
caused by a hot insertion is not very dependent
on the decoupling capacitance value. Usually,
MP2674 Rev. 0.9
11/8/2010
www.MonolithicPower.com
MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.
© 2010 MPS. All Rights Reserved.
10
MP2674 – CHARGE SYSTEM PROTECTION CIRCUIT
PACKAGE INFORMATION
QFN8 (2mmx2mm)
0.35
0.45
1.90
2.10
0.30
0.40
PIN 1 ID
0.10X45º TYP.
PIN 1 ID
MARKING
0.20
0.30
8
5
1
4
1.90
2.10
0.50
BSC
PIN 1 ID
INDEX AREA
TOP VIEW
BOTTOM VIEW
0.80
1.00
0.20 REF
0.00
0.05
SIDE VIEW
NOTE:
1.90
0.70
0.75
0.25
1) ALL DIMENSIONS ARE IN MILLIMETERS.
2) EXPOSED PADDLE SIZE DOES NOT INCLUDE MOLD FLASH.
3) LEAD COPLANARITY SHALL BE 0.10 MILLIMETER MAX.
4) JEDEC REFERENCE IS MO-220, VARIATION VCCD.
5) DRAWING IS NOT TO SCALE.
0.25
0.50
RECOMMENDED LAND PATTERN
NOTICE: The information in this document is subject to change without notice. Users should warrant and guarantee that third
party Intellectual Property rights are not infringed upon when integrating MPS products into any application. MPS will not
assume any legal responsibility for any said applications.
MP2674 Rev. 0.9
11/8/2010
www.MonolithicPower.com
MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.
© 2010 MPS. All Rights Reserved.
11
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