MICROCHIP MCP73827

MCP73827
Single Cell Lithium-Ion Charge Management Controller
with Mode Indicator and Charge Current Monitor
Features
Description
• Linear Charge Management Controller for Single
Lithium-Ion Cells
• High Accuracy Preset Voltage Regulation:
+ 1% (max)
• Two Preset Voltage Regulation Options:
- 4.1V - MCP73827-4.1
- 4.2V - MCP73827-4.2
• Programmable Charge Current
• Automatic Cell Preconditioning of Deeply
Depleted Cells, Minimizing Heat Dissipation During Initial Charge Cycle
• Charge Status Output for LED Drive or Microcontroller Interface
• Charge Current Monitor Output
• Automatic Power-Down when Input Power
Removed
• Temperature Range: -20°C to +85°C
• Packaging: 8-Pin MSOP
The MCP73827 is a linear charge management controller for use in space-limited, cost sensitive applications. The MCP73827 combines high accuracy
constant voltage, controlled current regulation, cell preconditioning, and charge status indication in a space
saving 8-pin MSOP package. The MCP73827 provides
a stand-alone charge management solution.
Applications
•
•
•
•
•
•
Typical Application Circuit
500 mA Lithium-Ion Battery Charger
VIN
5V
10 µF
100 mΩ
332Ω
8
100 kΩ
NDS8434
+ Single
Lithium-Ion
- Cell
6
7
VSNS VDRV
1
3
VIN
VBAT
SHDN GND
MODE IMON
MCP73827
Following the preconditioning phase, the MCP73827
enters the controlled current phase. The MCP73827
allows for design flexibility with a programmable charge
current set by an external sense resistor. The charge
current is ramped up, based on the cell voltage, from
the foldback current to the peak charge current established by the sense resistor. This phase is maintained
until the battery reaches the charge-regulation voltage.
Then, the MCP73827 enters the final phase, constant
voltage. The accuracy of the voltage regulation is better
than +1% over the entire operating temperature range
and supply voltage range. The MCP73827-4.1 is preset
to a regulation voltage of 4.1V, while the
MCP73827-4.2 is preset to 4.2V. The charge status
output, MODE, indicates when the charge cycle has
transitioned to constant voltage mode. The charge
cycle can be terminated by a timer that is started when
the MODE pin goes to a logic High or by monitoring the
charge current monitor output, IMON, for a minimum
current.
Single Cell Lithium-Ion Battery Chargers
Personal Data Assistants
Cellular Telephones
Hand Held Instruments
Cradle Chargers
Digital Cameras
MA2Q705
The MCP73827 charges the battery in three phases:
preconditioning, controlled current, and constant voltage. If the battery voltage is below the internal low-voltage threshold, the battery is preconditioned with a
foldback current. The preconditioning phase protects
the lithium-ion cell and minimizes heat dissipation.
The MCP73827 operates with an input voltage range
from 4.5V to 5.5V. The MCP73827 is fully specified
over the ambient temperature range of -20°C to +85°C.
5
2
4
10 µF
Package Type
MSOP
8 VIN
SHDN 1
7 VSNS
GND 2
MODE 3
IMON 4
© 2007 Microchip Technology Inc.
MCP73827
6 VDRV
5 VBAT
DS21704B-page 1
SHDN
VSNS
VIN
VIN
0.3V CLAMP
CHARGE CURRENT
FOLDBACK AMPLIFIER
–
+
12 kΩ
VREF (1.2V)
CHARGE
CURRENT
AMPLIFIER
SHUTDOWN,
REFERENCE
GENERATOR
+
–
Value = 352.5KΩ for MCP73827-4.2
NOTE 1: Value = 340.5KΩ for MCP73827-4.1
37.5 kΩ
112.5 kΩ
VREF
1.1 kΩ
500 kΩ
CHARGE CURRENT
CONTROL AMPLIFIER
–
+
VIN
VOLTAGE CONTROL
AMPLIFIER
VREF
MODE
COMPARATOR
-
+
138 kΩ
CHARGE CURRENT
MONITOR AMPLIFIER
–
DS21704B-page 2
+
100 kΩ
–
+
75 kΩ
75 kΩ
352.5 kΩ
(NOTE 1)
GND
VBAT
VDRV
MODE
IMON
MCP73827
Functional Block Diagram
© 2007 Microchip Technology Inc.
MCP73827
1.0
ELECTRICAL
CHARACTERISTICS
1.1
Maximum Ratings*
PIN FUNCTION TABLE
Pin
Name
1
SHDN
2
GND
Battery Management
0V Reference
Current at MODE Pin .............................................. +/-30 mA
3
MODE
Charge Status Output
IMON
Charge Current Monitor
VIN ...................................................................... -0.3V to 6.0V
All inputs and outputs w.r.t. GND ................-0.3 to (VIN+0.3)V
Description
Logic Shutdown
Current at VDRV .......................................................... +/-1 mA
4
Maximum Junction Temperature, TJ.............................. 150°C
5
VBAT
Cell Voltage Monitor Input
Storage temperature .....................................-65°C to +150°C
6
VDRV
Drive Output
7
VSNS
Charge Current Sense Input
8
VIN
ESD protection on all pins ..................................................≥ 4 kV
*Notice: Stresses above those listed under “Maximum
Ratings” may cause permanent damage to the device.
This is a stress rating only and functional operation of
the device at those or any other conditions above those
indicated in the operational listings of this specification
is not implied. Exposure to maximum rating conditions
for extended periods may affect device reliability.
Battery Management
Input Supply
DC CHARACTERISTICS: MCP73827-4.1, MCP73827-4.2
Unless otherwise specified, all limits apply for VIN = [VREG(typ)+1V], RSENSE = 500 mΩ, TA = -20°C to +85°C.
Typical values are at +25°C. Refer to Figure 1-1 for test circuit.
Sym
Min
Typ
Max
Units
Supply Voltage
Parameter
VIN
4.5
—
5.5
V
Conditions
Supply Current
IIN
—
—
0.5
250
15
560
µA
Shutdown, VSHDN = 0V
Constant Voltage Mode
Regulated Output Voltage
VREG
4.059
4.158
4.1
4.2
4.141
4.242
V
V
MCP73827-4.1 only
MCP73827-4.2 only
Line Regulation
ΔVBAT
-10
—
10
mV
VIN = 4.5V to 5.5V,
IOUT = 75 mA
Load Regulation
ΔVBAT
-1
+0.1
1
mV
IOUT=10 mA to 75 mA
ILK
—
8
—
µA
VIN=Floating, VBAT=VREG
Gate Drive Current
IDRV
—
0.08
—
—
1
—
mA
mA
Sink, CV Mode
Source, CV Mode
Gate Drive Minimum Voltage
VDRV
—
1.6
—
V
Voltage Regulation (Constant Voltage Mode)
Output Reverse Leakage Current
External MOSFET Gate Drive
Current Regulation (Controlled Current Mode)
Current Sense Gain
ACS
—
100
—
dB
Δ(VSNS-VDRV) / ΔVBAT
Current Limit Threshold
VCS
40
53
75
mV
(VIN-VSNS) at IOUT
K
—
0.43
—
A/A
Foldback Current Scale Factor
Charge Status Indicator - MODE
Threshold Voltage
VTH
—
VREG
—
V
Low Output Voltage
VOL
—
—
400
mV
ISINK = 10 mA
Leakage Current
ILK
—
—
1
µA
ISINK=0 mA, VMODE=5.5V
Input High Voltage Level
VIH
40
—
—
%VIN
Input Low Voltage Level
VIL
—
—
25
%VIN
Input Leakage Current
ILK
—
—
1
µA
VSHDN=0V to 5.5V
AIMON
—
26
—
V/V
ΔVIMON / Δ(VIN-VSNS)
Shutdown Input - SHDN
Charge Current Monitor - IMON
Charge Current Monitor Gain
© 2007 Microchip Technology Inc.
DS21704B-page 3
MCP73827
TEMPERATURE SPECIFICATIONS
Unless otherwise specified, all limits apply for VIN = 4.5V-5.5V
Parameters
Symbol
Min
Typ
Max
Units
Conditions
Temperature Ranges
Specified Temperature Range
TA
-20
—
+85
°C
Operating Temperature Range
TA
-40
—
+125
°C
Storage Temperature Range
TA
-65
—
+150
°C
θJA
—
206
—
°C/W
Package Thermal Resistance
Thermal Resistance, 8L-MSOP
VIN = 5.1V
(MCP73827-4.1)
VIN = 5.2V
(MCP73827-4.2)
NDS8434
RSENSE
Single Layer SEMI G42-88
Standard Board, Natural
Convection
IOUT
22 µF
8
100 kΩ
100 kΩ
1
3
VOUT
7
6
VSNS
VDRV
VBAT
VIN
SHDN
GND
MODE
IMON
5
2
22 µF
4
MCP73827
FIGURE 1-1:
MCP73827 Test Circuit.
DS21704B-page 4
© 2007 Microchip Technology Inc.
MCP73827
2.0
TYPICAL PERFORMANCE CHARACTERISTICS
Note:
The graphs and tables provided following this note are a statistical summary based on a limited number of
samples and are provided for informational purposes only. The performance characteristics listed herein
are not tested or guaranteed. In some graphs or tables, the data presented may be outside the specified
operating range (e.g., outside specified power supply range) and therefore outside the warranted range.
Note: Unless otherwise indicated, IOUT = 10 mA, Constant Voltage Mode, TA = 25°C. Refer to Figure 1-1 for test circuit.
4.205
300
4.204
Supply Current (μA)
Output Voltage (V)
4.203
4.202
4.201
4.200
4.199
4.198
4.197
280
260
240
220
4.196
4.195
200
0
200
400
600
800
1000
0
200
Output Current (mA)
FIGURE 2-1: Output Voltage vs. Output Current
(MCP73827-4.2).
FIGURE 2-4:
4.205
600
800
1000
Supply Current vs. Output Current.
300
IOUT = 1000 mA
IOUT = 1000 mA
4.204
Supply Current (μA)
4.203
Output Voltage (V)
400
Output Current (mA)
4.202
4.201
4.200
4.199
4.198
4.197
280
260
240
220
4.196
4.195
200
4.5
4.6
4.7
4.8
4.9
5.0
5.1
5.2
5.3
5.4
5.5
4.5
4.6
4.7
4.8
Input Voltage (V)
4.9
5.0
5.1
5.2
FIGURE 2-2: Output Voltage vs. Input Voltage
(MCP73827-4.2)
4.205
FIGURE 2-5:
5.4
5.5
Supply Current vs. Input Voltage.
300
IOUT = 10 mA
IOUT = 10 mA
4.204
Supply Current (μA)
4.203
Output Voltage (V)
5.3
Input Voltage (V)
4.202
4.201
4.200
4.199
4.198
280
260
240
220
4.197
4.196
4.195
200
4.5
4.6
4.7
4.8
4.9
5.0
5.1
5.2
5.3
5.4
5.5
4.5
4.6
Input Voltage (V)
FIGURE 2-3: Output Voltage vs. Input Voltage
(MCP73827-4.2)
© 2007 Microchip Technology Inc.
4.7
4.8
4.9
5.0
5.1
5.2
5.3
5.4
5.5
Input Voltage (V)
FIGURE 2-6:
Supply Current vs. Input Voltage.
DS21704B-page 5
MCP73827
12
300
VIN = Floating
VSHDN = VOUT
10
275
o
85 C
o
8
25 C
o
-20 C
6
4
Supply Current (μA)
Output Reverse Leakage Current (μA)
Note: Unless otherwise indicated, IOUT = 10 mA, Constant Voltage Mode, TA = 25°C. Refer to Figure 1-1 for test circuit.
250
225
200
175
2
150
0
2.0
2.5
3.0
3.5
4.0
-20
4.5
-10
0
10
20
50
60
70
80
FIGURE 2-10: Supply Current vs. Temperature.
1.6
4.206
VIN = Floating
VSHDN = GND
1.4
4.204
o
85 C
1.2
o
25 C
o
1.0
-20 C
0.8
0.6
0.4
Output Voltage (V)
Output Reverse Leakage Current (μA)
40
o
FIGURE 2-7: Output Reverse Leakage Current vs.
Output Voltage.
4.202
4.200
4.198
4.196
4.194
4.192
0.2
4.190
0.0
2.0
2.5
3.0
3.5
4.0
-20
4.5
-10
0
10
20
30
40
50
60
70
80
o
Temperature ( C)
Output Voltage (V)
FIGURE 2-8: Output Reverse Leakage Current vs.
Output Voltage.
FIGURE 2-11: Output
(MCP73827-4.2).
4.500
4.5
4.000
4.0
3.500
3.5
Output Voltage (V)
Output Voltage (V)
30
Temperature ( C)
Output Voltage (V)
3.000
2.500
2.000
1.500
1.000
Voltage
vs.
Temperature
3.0
2.5
2.0
1.5
1.0
0.500
Power Down
Power Up
0.5
0.000
0
20
40
60
80
100
120
0.0
0
Output Current (mA)
FIGURE 2-9:
Current Limit Foldback.
DS21704B-page 6
1
2
3
4
5
64
73
8
2
9
1
10
0
Input Voltage (V)
FIGURE 2-12: Power-Up / Power-Down.
© 2007 Microchip Technology Inc.
MCP73827
Note: Unless otherwise indicated, IOUT = 10 mA, Constant Voltage Mode, TA = 25°C. Refer to Figure 1-1 for test circuit.
FIGURE 2-13: Line Transient Response.
FIGURE 2-15: Load Transient Response.
FIGURE 2-14: Line Transient Response.
FIGURE 2-16: Load Transient Response.
© 2007 Microchip Technology Inc.
DS21704B-page 7
MCP73827
3.0
PIN DESCRIPTION
The descriptions of the pins are listed in Table 3-1.
Pin
Name
1
SHDN
2
GND
Description
Logic Shutdown
Battery Management
0V Reference
Cell Voltage Monitor Input (VBAT)
Voltage sense input. Connect to positive terminal of
battery. Bypass to GND with a minimum of 10 µF to
ensure loop stability when the battery is disconnected.
A precision internal resistor divider regulates the final
voltage on this pin to VREG.
3.6
Drive Output (VDRV)
3
MODE
4
IMON
Charge Current Monitor
Direct output drive of an external P-channel MOSFET
pass transistor for current and voltage regulation.
5
VBAT
Cell Voltage Monitor Input
3.7
6
VDRV
Drive Output
7
VSNS
Charge Current Sense Input
8
VIN
TABLE 3-1:
3.1
Charge Status Output
3.5
Battery Management
Input Supply
Pin Function Table.
Logic Shutdown (SHDN)
Input to force charge termination, initiate charge, or initiate recharge.
3.2
Battery Management 0V Reference
(GND)
Charge Current Sense Input (VSNS)
Charge current is sensed via the voltage developed
across an external precision sense resistor. The sense
resistor must be placed between the supply voltage
(VIN) and the source of the external pass transistor. A
50 mΩ sense resistor produces a fast charge current of
1 A, typically.
3.8
Battery Management Input Supply
(VIN)
A supply voltage of 4.5V to 5.5V is recommended.
Bypass to GND with a minimum of 10 µF.
Connect to negative terminal of battery.
3.3
Charge Status Output (MODE)
Open-drain drive for connection to an LED for charge
status indication. Alternatively, a pull-up resistor can be
applied for interfacing to a microcontroller. A low
impedance state indicates foldback current limit or controlled current phase. A high impedance indicates constant voltage phase or battery cell disconnected.
3.4
Charge Current Monitor (IMON)
Amplified output of the voltage difference between VIN
and VSNS. A host microcontroller can monitor this output with an A/D converter.
DS21704B-page 8
© 2007 Microchip Technology Inc.
MCP73827
4.0
DEVICE OVERVIEW
The MCP73827 is a linear charge management controller. Refer to the functional block diagram on page 2
and the typical application circuit, Figure 6-1.
4.1
Charge Qualification and
Preconditioning
Upon insertion of a battery or application of an external
supply, the MCP73827 verifies the state of the SHDN
pin. The SHDN pin must be above the logic High level.
If the SHDN pin is above the logic High level, the
MCP73827 initiates a charge cycle. The charge status
output, MODE, is pulled low throughout throughout the
preconditioning and controlled current phases (see
Table 5-1 for charge status outputs). If the cell is below
the preconditioning threshold, 2.4V typically, the
MCP73827 preconditions the cell with a scaled back
current. The preconditioning current is set to approximately 43% of the fast charge peak current. The preconditioning safely replenishes deeply depleted cells
and minimizes heat dissipation in the external pass
transistor during the initial charge cycle.
4.2
4.3
Constant Voltage Regulation
When the cell voltage reaches the regulation voltage,
VREG, constant voltage regulation begins. The
MCP73827 monitors the cell voltage at the VBAT pin.
This input is tied directly to the positive terminal of the
battery. The MCP73827 is offered in two fixed-voltage
versions for battery packs with either coke or graphite
anodes:
4.1V
(MCP73827-4.1)
and
4.2V
(MCP73827-4.2).
4.4
Charge Cycle Completion
The charge cycle can be terminated by a host microcontroller when the output of the charge current monitor, IMON, has diminished below approximately 10% of
the peak output voltage level. Alternatively, the transition of the charge status output, MODE, can be used to
initialize a timer to terminate the charge. The charge is
terminated by pulling the shutdown pin, SHDN, to a
logic Low Level.
Controlled Current Regulation - Fast
Charge
Preconditioning ends and fast charging begins when
the cell voltage exceeds the preconditioning threshold.
Fast charge utilizes a foldback current scheme based
on the voltage at the VSNS input developed by the drop
across an external sense resistor, RSENSE, and the output voltage, VBAT. Fast charge continues until the cell
voltage reaches the regulation voltage, VREG.
© 2007 Microchip Technology Inc.
DS21704B-page 9
MCP73827
5.0
DETAILED DESCRIPTION
5.2
Digital Circuitry
Refer to the typical application circuit, Figure 6-1.
5.2.1
SHUTDOWN INPUT (SHDN)
5.1
Analog Circuitry
5.1.1
CHARGE CURRENT MONITOR (IMON)
The shutdown input pin, SHDN, can be used to terminate a charge anytime during the charge cycle, initiate
a charge cycle, or initiate a recharge cycle.
The IMON pin provides an output voltage that is proportional to the battery charging current. It is an amplified
version of the sense resistor voltage drop that the current loop uses to control the external P-channel pass
transistor. This voltage signal can be applied to the
input of an A/D Converter and used by a host microcontroller to display information about the state of the battery or charge current profile.
5.1.2
CELL VOLTAGE MONITORED INPUT
(VBAT)
The MCP73827 monitors the cell voltage at the VBAT
pin. This input is tied directly to the positive terminal of
the battery. The MCP73827 is offered in two fixed-voltage versions for single cells with either coke or graphite
anodes:
4.1V
(MCP73827-4.1)
and
4.2V
(MCP73827-4.2).
5.1.3
GATE DRIVE OUTPUT (VDRV)
The MCP73827 controls the gate drive to an external
P-channel MOSFET, Q1. The P-channel MOSFET is
controlled in the linear region, regulating current and
voltage supplied to the cell. The drive output is automatically turned off when the input supply falls below
the voltage sensed on the VBAT input.
5.1.4
Applying a logic High input signal to the SHDN pin, or
tying it to the input source, enables the device. Applying a logic Low input signal disables the device and terminates a charge cycle. In shutdown mode, the
device’s supply current is reduced to 0.5 µA, typically.
5.2.2
CHARGE STATUS OUTPUT (MODE)
A charge status output, MODE, provides information on
the state of charge. The open drain output can be used
to illuminate an external LED. Optionally, a pull-up
resistor can be used on the output for communication
with a microcontroller. Table 5-1 summarizes the state
of the charge status output during a charge cycle.
Charge Cycle State
Mode
Qualification
OFF
Preconditioning
ON
Controlled Current Fast Charge
ON
Constant Voltage
OFF
Disabled - Sleep mode
OFF
Battery Disconnected
OFF
TABLE 5-1:
Charge Status Output.
CURRENT SENSE INPUT (VSNS)
Fast charge current regulation is maintained by the
voltage drop developed across an external sense resistor, RSENSE, applied to the VSNS input pin. The following formula calculates the value for RSENSE:
V CS
RSENSE = -----------I OUT
Where:
VCS is the current limit threshold
IOUT is the desired peak fast charge current in
amps. The preconditioning current is scaled to
approximately 43% of IPEAK.
5.1.5
SUPPLY VOLTAGE (VIN)
The VIN input is the input supply to the MCP73827. The
MCP73827 automatically enters a power-down mode if
the voltage on the VIN input falls below the voltage on
the VBAT pin. This feature prevents draining the battery
pack when the VIN supply is not present.
DS21704B-page 10
© 2007 Microchip Technology Inc.
MCP73827
6.0
APPLICATIONS
The MCP73827 is designed to operate in conjunction
with a host microcontroller or in stand-alone applications. The MCP73827 provides the preferred charge
algorithm for Lithium-Ion cells, controlled current fol-
lowed by constant voltage. Figure 6-1 depicts a typical
stand-alone application circuit and Figure 6-2 depicts
the accompanying charge profile.
VOLTAGE
REGULATED
WALL CUBE
MA2Q705
RSENSE
Q1
NDS8434
IOUT
PACK+
332 Ω
10 µF
100 mΩ
10 µF
22 kΩ
SHDN
8
1
GND
7
2
MODE
100 kΩ
IMON
MCP73827
3
6
4
5
VIN
VSNS
+
VDRV
-
VBAT
PACKSINGLE CELL
LITHIUM-ION
BATTERY PACK
FIGURE 6-1:
Typical Application Circuit.
PRECONDITIONING
PHASE
REGULATION
VOLTAGE
(VREG)
CONTROLLED CURRENT
PHASE
CONSTANT VOLTAGE
PHASE
CHARGE
VOLTAGE
REGULATION
CURRENT
(IOUT(PEAK))
TRANSITION
THRESHOLD
PRECONDITION
CURRENT
CHARGE
CURRENT
5V
MODE - CHARGE
STATUS OUTPUT
0V
1.5V
IMON - CHARGE
CURRENT MONITOR
0V
FIGURE 6-2:
Typical Charge Profile.
© 2007 Microchip Technology Inc.
DS21704B-page 11
MCP73827
6.1
Application Circuit Design
Due to the low efficiency of linear charging, the most
important factors are thermal design and cost, which
are a direct function of the input voltage, output current
and thermal impedance between the external P-channel pass transistor, Q1, and the ambient cooling air.
The worst-case situation is when the output is shorted.
In this situation, the P-channel pass transistor has to
dissipate the maximum power. A trade-off must be
made between the charge current, cost and thermal
requirements of the charger.
6.1.1
EXTERNAL PASS TRANSISTOR
The external P-channel MOSFET is determined by the
gate to source threshold voltage, input voltage, output
voltage, and peak fast charge current. The selected Pchannel MOSFET must satisfy the thermal and electrical design requirements.
Thermal Considerations
The worst case power dissipation in the external pass
transistor occurs when the input voltage is at the maximum and the output is shorted. In this case, the power
dissipation is:
COMPONENT SELECTION
Selection of the external components in Figure 6-1 is
crucial to the integrity and reliability of the charging system. The following discussion is intended as a guide for
the component selection process.
6.1.1.1
6.1.1.2
PowerDissipation = V INMAX × I OUT × K
Where:
VINMAX is the maximum input voltage
SENSE RESISTOR
IOUT is the maximum peak fast charge current
The preferred fast charge current for Lithium-Ion cells
is at the 1C rate with an absolute maximum current at
the 2C rate. For example, a 500 mAH battery pack has
a preferred fast charge current of 500 mA. Charging at
this rate provides the shortest charge cycle times without degradation to the battery pack performance or life.
The current sense resistor, RSENSE, is calculated by:
V CS
RSENSE = -----------I OUT
Where:
VCS is the current limit threshold voltage
IOUT is the desired fast charge current
For the 500 mAH battery pack example, a standard
value 100 mΩ, 1% resistor provides a typical peak fast
charge current of 530 mA and a maximum peak fast
charge current of 758 mA. Worst case power dissipation in the sense resistor is:
2
PowerDissipation = 100mΩ × 758mA = 57.5mW
A Panasonic ERJ-L1WKF100U 100 mΩ, 1%, 1 W
resistor is more than sufficient for this application.
A larger value sense resistor will decrease the peak
fast charge current and power dissipation in both the
sense resistor and external pass transistor, but will
increase charge cycle times. Design trade-offs must be
considered to minimize space while maintaining the
desired performance.
K is the foldback current scale factor.
Power dissipation with a 5V, +/-10% input voltage
source, 100 mΩ, 1% sense resistor, and a scale factor
of 0.43 is:
PowerDissipation = 5.5V × 758mA × 0.43 = 1.8W
Utilizing a Fairchild NDS8434 or an International Rectifier IRF7404 mounted on a 1in2 pad of 2 oz. copper, the
junction temperature rise is 90°C, approximately. This
would allow for a maximum operating ambient temperature of 60°C.
By increasing the size of the copper pad, a higher ambient temperature can be realized or a lower value sense
resistor could be utilized.
Alternatively, different package options can be utilized
for more or less power dissipation. Again, design tradeoffs should be considered to minimize size while maintaining the desired performance.
Electrical Considerations
The gate to source threshold voltage and RDSON of the
external P-channel MOSFET must be considered in the
design phase.
The worst case, VGS provided by the controller occurs
when the input voltage is at the minimum and the
charge current is at the maximum. The worst case, VGS
is:
VGS = V DRVMAX – ( V INMIN – IOUT × R SENSE )
Where:
VDRVMAX is the maximum sink voltage at the VDRV
output
DS21704B-page 12
© 2007 Microchip Technology Inc.
MCP73827
VINMIN is the minimum input voltage source
IOUT is the maximum peak fast charge current
RSENSE is the sense resistor
Worst case, VGS with a 5V, +/-10% input voltage
source, 100 mΩ, 1% sense resistor, and a maximum
sink voltage of 1.6V is:
V GS = 1.6V – ( 4.5V – 758mA × 99mΩ ) = – 2.8 V
At this worst case VGS, the RDSON of the MOSFET
must be low enough as to not impede the performance
of the charging system. The maximum allowable
RDSON at the worst case VGS is:
VINMIN – I PEAK × R SENSE – V BATMAX
RDSON = ---------------------------------------------------------------------------------------------I OUT
If a reverse protection diode is incorporated in the
design, it should be chosen to handle the peak fast
charge current continuously at the maximum ambient
temperature. In addition, the reverse leakage current of
the diode should be kept as small as possible.
6.1.1.5
In the stand-alone configuration, the shutdown pin is
generally tied to the input voltage. The MCP73827 will
automatically enter a low power mode when the input
voltage is less than the output voltage reducing the battery drain current to 8 µA, typically.
By connecting the shutdown pin as depicted in
Figure 6-1, the battery drain current may be further
reduced. In this application, the battery drain current
becomes a function of the reverse leakage current of
the reverse protection diode.
6.1.1.6
R DSON
4.5V – 758mA × 99mΩ – 4.242V
= -------------------------------------------------------------------------------- = 242mΩ
758mA
The Fairchild NDS8434 and International Rectifier
IRF7404 both satisfy these requirements.
6.1.1.3
EXTERNAL CAPACITORS
The MCP73827 is stable with or without a battery load.
In order to maintain good AC stability in the constant
voltage mode, a minimum capacitance of 10 µF is recommended to bypass the VBAT pin to GND. This capacitance provides compensation when there is no battery
load. In addition, the battery and interconnections
appear inductive at high frequencies. These elements
are in the control feedback loop during constant voltage
mode. Therefore, the bypass capacitance may be necessary to compensate for the inductive nature of the
battery pack.
Virtually any good quality output filter capacitor can be
used, independent of the capacitor’s minimum ESR
(Effective Series Resistance) value. The actual value of
the capacitor and its associated ESR depends on the
forward trans conductance, gm, and capacitance of the
external pass transistor. A 10 µF tantalum or aluminum
electrolytic capacitor at the output is usually sufficient
to ensure stability for up to a 1 A output current.
6.1.1.4
SHUTDOWN INTERFACE
CHARGE STATUS INTERFACE
The charge status indicator, MODE, can be utilized to
illuminate an LED when the MCP73827 is in the controlled current phase. When the MCP73827 transitions
to constant voltage mode, the MODE pin will transition
to a high impedance state. A current limit resistor
should be used in series with the LED to establish a
nominal LED bias current of 10 mA. The maximum
allowable sink current of the MODE pin is 30 mA.
6.2
PCB Layout Issues
For optimum voltage regulation, place the battery pack
as close as possible to the device’s VBAT and GND
pins. It is recommended to minimize voltage drops
along the high current carrying PCB traces.
If the PCB layout is used as a heatsink, adding many
vias around the external pass transistor can help conduct more heat to the back-plane of the PCB, thus
reducing the maximum junction temperature.
REVERSE BLOCKING PROTECTION
The optional reverse blocking protection diode
depicted in Figure 6-1 provides protection from a
faulted or shorted input or from a reversed polarity input
source. Without the protection diode, a faulted or
shorted input would discharge the battery pack through
the body diode of the external pass transistor.
© 2007 Microchip Technology Inc.
DS21704B-page 13
MCP73827
7.0
PACKAGING INFORMATION
7.1
Package Marking Information
Example:
8-Lead MSOP
738271 e3
XXXXXX
YWWNNN
Legend: XX...X
Y
YY
WW
NNN
e3
*
Note:
DS21704B-page 14
712NNN
Part Number
Code
MCP73827-4.1VUA
738271
MCP73827-4.2VUA
738272
Customer-specific information
Year code (last digit of calendar year)
Year code (last 2 digits of calendar year)
Week code (week of January 1 is week ‘01’)
Alphanumeric traceability code
Pb-free JEDEC designator for Matte Tin (Sn)
This package is Pb-free. The Pb-free JEDEC designator ( e3 )
can be found on the outer packaging for this package.
In the event the full Microchip part number cannot be marked on one line, it will
be carried over to the next line, thus limiting the number of available
characters for customer-specific information.
© 2007 Microchip Technology Inc.
MCP73827
8-Lead Plastic Micro Small Outline Package (MS or UA) [MSOP]
Note:
For the most current package drawings, please see the Microchip Packaging Specification located at
http://www.microchip.com/packaging
D
N
E
E1
NOTE 1
1
2
e
b
A2
A
c
φ
L
L1
A1
Units
Dimension Limits
Number of Pins
MILLIMETERS
MIN
N
NOM
MAX
8
Pitch
e
Overall Height
A
–
0.65 BSC
–
Molded Package Thickness
A2
0.75
0.85
0.95
Standoff
A1
0.00
–
0.15
Overall Width
E
Molded Package Width
E1
3.00 BSC
Overall Length
D
3.00 BSC
Foot Length
L
Footprint
L1
1.10
4.90 BSC
0.40
0.60
0.80
0.95 REF
Foot Angle
φ
0°
–
8°
Lead Thickness
c
0.08
–
0.23
Lead Width
b
0.22
–
0.40
Notes:
1. Pin 1 visual index feature may vary, but must be located within the hatched area.
2. Dimensions D and E1 do not include mold flash or protrusions. Mold flash or protrusions shall not exceed 0.15 mm per side.
3. Dimensioning and tolerancing per ASME Y14.5M.
BSC: Basic Dimension. Theoretically exact value shown without tolerances.
REF: Reference Dimension, usually without tolerance, for information purposes only.
Microchip Technology Drawing C04-111B
© 2007 Microchip Technology Inc.
DS21704B-page 15
MCP73827
NOTES:
DS21704B-page 16
© 2007 Microchip Technology Inc.
MCP73827
APPENDIX A:
REVISION HISTORY
Revision B (February 2007)
This revision includes updates to the packaging
diagrams.
© 2007 Microchip Technology Inc.
DS21704B-page 17
MCP73827
PRODUCT IDENTIFICATION SYSTEM
To order or obtain information, e.g., on pricing or delivery, refer to the factory or the listed sales office.
PART NO.
-X.X
X
XX
Device
Output
Voltage
Temperature
Range
Package
Examples:
a)
MCP73827-4.1VUA: Linear Charge Man-
b)
MCP73827-4.2VUA: Linear Charge Man-
agement Controller, 4.1V
agement Controller, 4.2V
Device:
MCP73827: Linear Charge Management Controller
Output Voltage:
MCP73827-4.2VUATR: Linear Charge Management Controller, 4.2V, in tape and reel
4.1 = 4.1V
4.2 = 4.2V
Temperature Range:
V
Package:
UA = Plastic Micro Small Outline (MSOP), 8-lead
DS21704B-page 18
c)
= -20°C to +85°C
© 2007 Microchip Technology Inc.
Note the following details of the code protection feature on Microchip devices:
•
Microchip products meet the specification contained in their particular Microchip Data Sheet.
•
Microchip believes that its family of products is one of the most secure families of its kind on the market today, when used in the
intended manner and under normal conditions.
•
There are dishonest and possibly illegal methods used to breach the code protection feature. All of these methods, to our
knowledge, require using the Microchip products in a manner outside the operating specifications contained in Microchip’s Data
Sheets. Most likely, the person doing so is engaged in theft of intellectual property.
•
Microchip is willing to work with the customer who is concerned about the integrity of their code.
•
Neither Microchip nor any other semiconductor manufacturer can guarantee the security of their code. Code protection does not
mean that we are guaranteeing the product as “unbreakable.”
Code protection is constantly evolving. We at Microchip are committed to continuously improving the code protection features of our
products. Attempts to break Microchip’s code protection feature may be a violation of the Digital Millennium Copyright Act. If such acts
allow unauthorized access to your software or other copyrighted work, you may have a right to sue for relief under that Act.
Information contained in this publication regarding device
applications and the like is provided only for your convenience
and may be superseded by updates. It is your responsibility to
ensure that your application meets with your specifications.
MICROCHIP MAKES NO REPRESENTATIONS OR
WARRANTIES OF ANY KIND WHETHER EXPRESS OR
IMPLIED, WRITTEN OR ORAL, STATUTORY OR
OTHERWISE, RELATED TO THE INFORMATION,
INCLUDING BUT NOT LIMITED TO ITS CONDITION,
QUALITY, PERFORMANCE, MERCHANTABILITY OR
FITNESS FOR PURPOSE. Microchip disclaims all liability
arising from this information and its use. Use of Microchip
devices in life support and/or safety applications is entirely at
the buyer’s risk, and the buyer agrees to defend, indemnify and
hold harmless Microchip from any and all damages, claims,
suits, or expenses resulting from such use. No licenses are
conveyed, implicitly or otherwise, under any Microchip
intellectual property rights.
Trademarks
The Microchip name and logo, the Microchip logo, Accuron,
dsPIC, KEELOQ, microID, MPLAB, PIC, PICmicro, PICSTART,
PRO MATE, PowerSmart, rfPIC, and SmartShunt are
registered trademarks of Microchip Technology Incorporated
in the U.S.A. and other countries.
AmpLab, FilterLab, Migratable Memory, MXDEV, MXLAB,
SEEVAL, SmartSensor and The Embedded Control Solutions
Company are registered trademarks of Microchip Technology
Incorporated in the U.S.A.
Analog-for-the-Digital Age, Application Maestro, CodeGuard,
dsPICDEM, dsPICDEM.net, dsPICworks, ECAN,
ECONOMONITOR, FanSense, FlexROM, fuzzyLAB,
In-Circuit Serial Programming, ICSP, ICEPIC, Linear Active
Thermistor, Mindi, MiWi, MPASM, MPLIB, MPLINK, PICkit,
PICDEM, PICDEM.net, PICLAB, PICtail, PowerCal,
PowerInfo, PowerMate, PowerTool, REAL ICE, rfLAB,
rfPICDEM, Select Mode, Smart Serial, SmartTel, Total
Endurance, UNI/O, WiperLock and ZENA are trademarks of
Microchip Technology Incorporated in the U.S.A. and other
countries.
SQTP is a service mark of Microchip Technology Incorporated
in the U.S.A.
All other trademarks mentioned herein are property of their
respective companies.
© 2007, Microchip Technology Incorporated, Printed in the
U.S.A., All Rights Reserved.
Printed on recycled paper.
Microchip received ISO/TS-16949:2002 certification for its worldwide
headquarters, design and wafer fabrication facilities in Chandler and
Tempe, Arizona, Gresham, Oregon and Mountain View, California. The
Company’s quality system processes and procedures are for its PIC®
MCUs and dsPIC DSCs, KEELOQ® code hopping devices, Serial
EEPROMs, microperipherals, nonvolatile memory and analog
products. In addition, Microchip’s quality system for the design and
manufacture of development systems is ISO 9001:2000 certified.
© 2007 Microchip Technology Inc.
DS21704B-page 19
WORLDWIDE SALES AND SERVICE
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12/08/06
DS21704B-page 20
© 2007 Microchip Technology Inc.