MIC79110_07 [MICREL]
Simple 1.2A Linear Li-Ion Battery Charger; 简单的1.2A线性锂离子电池充电器
| 型号： | MIC79110_07 |
| 厂家： | 
MICREL SEMICONDUCTOR |
| 描述： | Simple 1.2A Linear Li-Ion Battery Charger |
| 文件： | 总14页 (文件大小：561K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
MIC79110
Simple 1.2A Linear Li-Ion Battery Charger
General Description
Features
The Micrel MIC79110 is a simple and accurate lithium ion
battery charger. The part features a built-in pass transistor,
precision programmable current limiting (±5%), and
precision voltage termination (±0.75% over temperature).
The MIC79110 packs full functionality into a small space.
• Input voltage range: 2.5V to 16V
• High output voltage accuracy of ±0.75%
over –5°C to +60˚C
• Current limit ±5% accurate from –5°C ≤ TJ ≤ + 125°C
• Programmable end-of-charge flag
• Analog output proportional to output current
• Adjustable and fixed 4.2V output
• Low dropout voltage of 550mV at 700mA load, over
temperature
• 1.2A max charge current
• Excellent line and load regulation specifications
• Reverse current protection
• Thermal shutdown and current limit protection
• Tiny 10-Pin 3mm × 3mm MLF® package
• Junction temperature range: –40°C to +125°C
Other features of the MIC79110 include two independent
indicators:
a
digital End-of-Charge signal that is
programmable with a resistor to ground, and an analog
current output that is proportional to the output current,
allowing for monitoring of the actual charging current.
Additional features include very low dropout (550mV over
the temperature range), thermal shutdown, and reverse
polarity protection. In the event the input voltage to the
charger is disconnected, the MIC79110 also provides
minimal reverse-current and reversed-battery protection.
Available in both fixed 4.2V and adjustable outputs, the
MIC79110 is offered in the leadless 10-pin 3mm x 3mm
MLF® with an operating junction temperature range of
–40˚C to +125˚C.
Applications
Data sheets and support documentation can be found on
Micrel’s web site at www.micrel.com.
•
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Cellular phones
PDAs
Digital cameras
Camcorders
MP3 players
Notebook PCs
Portable Meters
Cradle chargers
Car chargers
Battery packs
___________________________________________________________________________________________________________
Typical Application
MIC79110
VIN
VIN
BAT
SNS
DEOC
ACHG
4.2VBAT
4.2V
Li-Ion
Cell
SHUTDOWN
ENABLE
SD
REOC
RSET
GND
MIC79110 Typical Application
MLF and MicroLeadFrame are registered trademarks of Amkor Technology, Inc.
Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel +1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com
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Micrel, Inc.
MIC79110
Ordering Information
Part Number
Junction
Temp. Range
Voltage
Package
Standard
Marking
L942
Pb-Free
Marking
L942*
MIC79110-4.2BML
MIC79110BML
MIC79110-4.2YML
MIC79110YML
4.2V
Adj.
–40° to +125°C
–40° to +125°C
10-pin 3×3 MLF®
10-pin 3×3 MLF®
L9AA
L9AA*
* Pb-Free “Y” indicator is added to the device mark after LOGO.
Pin Configuration
SD
RSET
1
10 GND
SD
RSET
ADJ
BAT
VIN
1
10 GND
2
9
8
7
6
REOC
DEOC
ACHG
VIN
2
3
4
5
9
8
7
6
REOC
SNS
BAT
VIN
3
4
5
DEOC
ACHG
VIN
Fixed Output
10-Pin 3mm × 3mm MLF® (ML)
Adjustable Output
10-Pin 3mm × 3mm MLF® (ML)
Pin Description
Pin Number
Pin Name
SD
Pin Function
1
2
Shutdown Input. Logic High = Off; Logic Low = On.
RSET
Current limit: Sets constant current limit via an external resistor to ground.
IRSET = (0.2V/RSET) × 1000.
3
3
SNS
ADJ
(Fixed voltage only): Sense output, connect directly to battery.
(Adjustable voltage only): Feedback input.
Battery Terminal. Connect to single-cell lithium-ion battery.
Input supply pin.
4
BAT
5, 6
7
VIN
ACHG
Analog Charge Indicator Output: Current source who’s output current is equal to
1/1000 of the BAT pin current.
8
DEOC
Digital End-of-Charge Output: N-Ch open drain output. Low indicates charging,
a current that is higher than the programmed current set by REOC is charging the
battery. When the current drops to less than the current set by REOC, the output
goes high impedance, indicating end-of-charge.
9
REOC
GND
End-of-Charge Set: Sets end-of-charge current threshold via an external resistor
to ground. IEOC = (0.2V/REOC) × 1000.
10
Ground
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MIC79110
Absolute Maximum Ratings(1)
Operating Ratings(2)
Input Supply Voltage (VIN).................................... 0V to 18V
Shutdown Input Voltage (V) ................................. 0V to 10V
Output Voltage (ADJ).....................................................10V
Power Dissipation ...................................Internally Limited
Junction Temperature ...............................–40°C to +125°C
Input Supply Voltage ........................................ 2.5V to 16V
Shutdown Input Voltage (V)................................... 0V to 7V
Output Voltage (ADJ)....................................................9.6V
Junction Temperature Range (TJ).............–40°C to +125°C
θ
θ
JA (MLF-10) .......................................................... 60°C
JC (MLF-10) ............................................................ 2°C
Electrical Characteristics(4)
TA = 25°C with VIN = VOUT + 1V; ILOAD = 100µA; CBATT = 10µF; SD = 0V; RSET=1kΩ. Bold values indicate –40ºC < TJ < +125°C; unless
otherwise specified.
Parameter
Condition
Min
Typ
Max
Units
Variation from VOUT = 4.2V; TJ = –5°C to +60°C; ILOAD = 50mA
Output Voltage Accuracy
-0.75
-1.5
+0.75
+1.5
%
%
ADJ Pin Voltage Accuracy
Line Regulation
0.5955
-0.1
0.6
0.6045
+0.1
V
V
IN = VOUT + 1V to 16V @ ILOAD = 50mA
%/V
I
LOAD = 0.1mA to 1A
Load Regulation
0.3
160
375
2
%
mV
mV
mA
mA
µA
µA
V
ILOAD = 100mA, RSET = 167Ω
ILOAD = 700mA, RSET = 167Ω
ILOAD = 10mA, RSET = 167Ω
ILOAD = 700mA, RSET = 167Ω
SD = VIN
Dropout Voltage(3)
250
550
3
Ground Current
24
35
300
5
VIN Pin Current
120
0.1
Shutdown Pin Current
Shutdown Input Threshold
SD = 5.2V, VBAT = 0
Logic High, regulator off
Logic Low, regulator on
1.1
0.9
V
Shutdown Hysteresis
Current Limit Accuracy(4, 5)
60
mV
%
V
R
OUT = 0.9 × VNOM; IOUT = 1.2A,
SET = 167Ω, TJ = –40°C to +85°C
-5
+5
VOUT = 0.9 × VNOM; IOUT = 0.1A,
RSET = 2kΩ
-20
+20
%
A
Current Limit Setpoint
Range(5)
0.1
1.2
Maximum Current Limit
VBAT Reverse Current
R
SET shorted to ground, VBAT = 0.9 × VNOM
1.25
1.65
4.2
2.5
20
A
VIN = High impedance or ground
µA
Digital End–of–Charge (DEOC) Output
(6, 7)
IEOC
REOC = 4kꢀ Current Falling
35
30
50
70
65
70
mA
mA
(6, 7)
IEOC
REOC = 4kꢀ Current Rising
50
40
95
100
mA
mA
DEOC Logic–Low Voltage
DEOC Leakage Current
DEOC On Resistance
IDEOC = 5mA, IBAT = 700mA
Logic High = VIN = 16V
VIN = +5V
0.74
0.1
0.95
V
µA
ꢀ
150
1.0
190
REOC Maximum Current Limit
REOC shorted to ground
0.5
2.0
mA
Analog Charge Indicator (ACHG) Output
(8)
ISOURCE
IBAT = 50mA
IBAT = 1.2A, TJ = –40°C to +85°C
37
46
55
µA
µA
800
950
1150
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MIC79110
Notes:
1. Exceeding the absolute maximum rating may damage the device.
2. The device is not guaranteed to function outside its operating rating.
3. Dropout Voltage is defined as the input to output differential at which the output voltage drops 2% below its nominal value measured at 1V
differential. For outputs below 2.5V, dropout voltage is the input-to-output voltage differential with the minimum input voltage 2.5V. Minimum input
operating voltage is 2.5V.
4.
VNOM denotes the nominal output voltage.
5. IRSET = (0.2V/RSET) × 1000
6. Output Current IEOC when Digital End-of-Charge output goes high impedance. Currents greater than IEOC, the DEOC output is low, currents lower
than IEOC, DEOC is high impedance.
7.
8.
I
I
EOC = (0.2V/REOC) × 1000
SOURCE is the current output from ACHG pin. A resistor to ground from the ACHG pin will program a voltage that is proportional to the output current.
Block Diagram
VIN
BAT
SNS
Current
Limit Sense
Thermal
Protection
Li-Ion
+
DEOC
VREF
Shutdown
Control
SD
End of
Charge
Detect
RSET
Current
Limit Set
ACHG
REOC GND
MIC79110 Block Diagram
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MIC79110
Typical Characteristics
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MIC79110
Typical Characteristics (continued)
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MIC79110
Functional Characteristics
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MIC79110
active low, there is reverse battery current protection
built in. The current is limited to less than 10µA over
temperature.
Application Information
Detailed Description
The MIC79110 forms a complete charger for 1-cell
Lithium-ion batteries. It includes precision voltage control
(0.75% over temperature) to optimize both cell
performance and cycle life. All are compatible with
common 4.2V Lithium-ion chemistries. Voltages other
than 4.2V can be obtained with the adjustable version.
Other features include current limit, end-of-charge flag
and end-of-charge current limit using an external
resistor. The shutdown pin enables low quiescent
current when not charging.
Constant Output Voltage/Current Charging
The MIC79110 features constant voltage and constant
current output to correctly charge lithium-ion batteries.
The constant voltage is either 4.2V or adjustable. The
constant current is set by the Rset pin and is constant
down to around 300mV. Since Rset can be set below
500mA, the minimum output current is set at 500mA for
output voltages below 100mV. This minimum voltage
starts the charging process in lithium-ion batteries. If the
output current is too low, the battery will not begin
charge.
Current Limit Mode
MIC79110 features an internal current limit that is set by
the RSET pin with a resistor-to-ground. The maximum
current is calculated by the following equation:
IRset = (0.2/Rset) × 1000
Using a 167ꢀ Rset resistor will achieve the maximum
current limit for the MIC79110 at 1.2 amperes.
End of Charge
I Current
REOC pin is connected to a resistor-to-ground. This
resistor is used to set the end of charge current for the
lithium ion battery as follows:
IREOC = (0.2/REOC) × 1000
Using a 4kꢀ REOC resistor will set the end-of-charge
current at 50mA.
IMAX = (0.2/RSET)×1000
IREOC should be set at 10% of the battery’s rated current.
Digital End-of-Charge Output
0.7V
500mA
I Current
This pin is the output of an open drain. When tied high to
the supply using a resistor, the output will toggle high or
low depending on the output current of IBAT
Lithium Ion Batteries
.
Lithium-ion batteries are charged in two stages to reach
full capacity. The first stage charges the battery with
maximum charge current until 90% of the battery cell’s
voltage limit is reached. The second stage tops off the
charge with constant voltage charge as the charge
current slowly decreases. End of charge is reached
when the current is less than 3% of the rated current. A
third stage will occasionally top off with charge with
constant voltage charge if the battery voltage drops
below a certain threshold.
•
Low state indicates that the IBAT current is higher
than the programmed current set by REOC
.
•
High state indicates that the IBAT current is lower
than the programmed current set by REOC. The
output goes high impedance indicating end-of-
charge.
Analog End-Of-Charge Output
The ACHG pin provides a small current that is proportional
to the charge current. The ratio is set at 1/1000th of the
output current.
Shutdown
The SD pin serves as a logic input (active low) to enable
the charger.
Built-in hysteresis for the shutdown pin is 50mV over
temperature.
Reverse Polarity Protection
In the event that VBAT > VIN and the shutdown pin is
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MIC79110
Lithium-Ion Safety Precautions
Every lithium-ion battery pack should have a safety
circuit which monitors the charge and discharge of the
pack and prevents dangerous occurrences. The
specifications of these safety circuits are dictated by the
cell manufacturer and may include the following:
•
•
Reverse polarity protection
Charge temperature must not be charged when
temperature is lower than 0°C or above 45°C.
•
•
•
•
•
Charge current must not be too high, typically below
0.7°C
Discharge current protection to prevent damage due
to short circuits.
Protection circuitry for over voltage applied to the
battery terminals.
All lithium-ion batteries take approximately 3 hours to
charge with the second stage taking twice as long as the
first stage. Some chargers claim to be fast chargers by
skipping the second stage and just charges the battery
until the cell voltage is reached. This only charges the
battery to 70% capacity.
Overcharge protection circuitry to stop charge when
the voltage per cell rises above 4.3V.
Over discharge protection circuitry to stop discharge
when the battery voltage falls below 2.3V (varies
with manufacturer).
•
Thermal shutdown protection for the battery if the
ambient temperature is above 100°C.
An increase in the charge current during stage 1 does
not shorten the total charge time. It will only shorten the
time for stage 1 to complete and lengthen the time in
stage 2.
The lithium-ion loses charge due to aging whether it is
used or not. Do not store the batteries at full charge and
high heat because it will accelerate the aging process.
Try and store with 40% charge and in a cool
environment.
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MIC79110
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MIC79110
Simple Charger - External Trigger to Reset Charge
Cycle reset
External Trigger to Reset Charger
1. VIN steps up to a voltage greater than VBAT
.
Reset charge cycle.
2. SD held low by CSD until active high DEOC pulls
shutdown low.
3. DEOC releases SD, resistor pull-up from SD pin,
VIN pulls VSD to VIN.
SD
GND
Reoc
DEOC
AEOC
VIN
4. An external signal applied to the gate of the
external NCH pulls SD pin-to-ground.
RSET
SNS
BAT
VIN
5. IBAT is near zero (2 to 4µA) because VIN is below
VBAT and the reverse shutoff circuit is turning the
charge to the battery off.
CDELAY
0.1µF
6. IBAT is decreased as VBAT approaches VBAT set
volt-age. IBAT decreases below the DEOC
threshold and DEOC is released high allowing VSD
to go high.
7. External NCH turns part on, after a small delay
The VIN voltage steps up to a voltage greater than VBAT
.
IBAT turns on.
When VIN is below VBAT, the IBAT current is near zero and
the reverse shutoff circuit is turning the charge to the
battery off. The IBAT slowly increases as VIN rises above
VBAT. DEOC is pulled low when the IBAT current is above
the Ieoc current set by REOC. When the DEOC is low, the
shutdown pin is also forced low and helps discharge
CSD. When the VBAT reaches the set voltage, the IBAT
begins to slowly drop. When the IBAT is less than the IEOC
threshold, the DEOC output goes high impedance,
indicating end-of-charge. When an external signal is
applied to the gate, the external NCH pulls the SD and
8. Active high DEOC pin goes high because of
reverse shutoff. DEOC remains high until IBAT
exceeds DEOC threshold, then goes low.
9. IBAT decreases below (see #5) DEOC threshold.
10. Active low DEOC is high because VIN is below
VBAT and reverse shutoff holds DEOC comparator
off. As VIN increases above VBAT, the reverse
volt-age shutoff turns off, DEOC comparator
becomes active. While IBAT is below DEOC
threshold DEOC active low goes low, when IBAT
exceeds DEOC threshold IBAT goes high.
D
EOC pins to ground. This restarts the charging process.
11. Legitimate Activation of active low DEOC until SD
shuts down part and DEOC AL (active low) goes
high.
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MIC79110
Signal Diagram
Vin
VSD
Vbat set voltage
Vbat
SD threshold
1
2
2
3
Vgate
6
5
4
Ibattery
7
8
Active high DEOC pin
9
9
Active low DEOC pin
10
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MIC79110
Auto Top-Off-Charger - Application Circuit
1. SD not held low by active high DEOC because
DEOC Comparator’s inputs do not common-mode
to ground. Divider holds SD low so part can
start.
2. SD held low by divider.
3. SD held low by active high DEOC
.
4. Divider voltage above SD threshold and DEOC
open.
5. Divider voltage drops below SD threshold and
charging begins again.
Top-Off-Charger with Internal Reset - Application
Circuit
Lithium-Ion batteries will begin to lose their charge over
time. The MIC79110 can be configured to automatically
recharge the battery if the voltage drops below a certain
voltage. This minimum voltage is set by a resistor divider
at the battery and connected to the SD pin. When the
battery voltage falls below the minimum voltage, the SD
pin is pulled low to start the normal charging process.
SD
GND
REOC
DEOC
AEOC
VIN
RSET
SNS
BAT
VIN
R1
R2
3M
1M
Battery
LI-ion Battery
Self discharge
charging
VIN
This circuit is similar to the auto top off charger circuit
mentioned above except that the DEOC pin is externally
triggered to restart the charging cycle. It still uses the
same resistor divider to set the minimum battery voltage
before the lithium-ion needs to be recharged.
4.2 V
VBattery
VBat min
Deoc trip
IBattery
Auto-Shutdown Using Shutdown Pin
Vs
R1
R2
V
0.975
1
R2
VBat min=0.975V
(
+1)
R2=1meg
R1=
(
Bat min -1
)
Vbat set (4.2V)
The shutdown pin on the MIC79110 can be used to
automatically shutdown the battery charger when the
input voltage rises above a safe operating voltage. To
keep the part from heating up and entering thermal
shutdown, we can connect the shutdown pin to VIN using
a resistor divider. Use the following equation to setup the
maximum VIN.
Vbat
Vbat low set
by divider.
4
2
VIN(MAX)
VSD
R1
R2
=
+ 1
3
The MIC79110 can be connected to a wall wart with a
rectified DC voltage and protected from over voltages at
the input.
1
SD Voltage
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MIC79110
Package Information
10-Pin 3mm × 3mm MLF® (ML)
MICREL, INC. 2180 FORTUNE DRIVE SAN JOSE, CA 95131 USA
TEL +1 (408) 944-0800 FAX +1 (408) 474-1000 WEB http://www.micrel.com
The information furnished by Micrel in this data sheet is believed to be accurate and reliable. However, no responsibility is assumed by Micrel for its
use. Micrel reserves the right to change circuitry and specifications at any time without notification to the customer.
Micrel Products are not designed or authorized for use as components in life support appliances, devices or systems where malfunction of a product
can reasonably be expected to result in personal injury. Life support devices or systems are devices or systems that (a) are intended for surgical implant
into the body or (b) support or sustain life, and whose failure to perform can be reasonably expected to result in a significant injury to the user. A
Purchaser’s use or sale of Micrel Products for use in life support appliances, devices or systems is a Purchaser’s own risk and Purchaser agrees to fully
indemnify Micrel for any damages resulting from such use or sale.
© 2004 Micrel, Incorporated.
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