MICROCHIP MCP73838B6IMF

MCP73837/8
Advanced Stand-Alone Li-Ion / Li-Polymer Battery Charge
Management Controller with Autonomous AC-Adapter or
USB-Port Source Selection
Features
Applications
• High Accuracy Preset Voltage Regulation: + 0.5%
• Available Voltage Regulation Options:
- 4.20V, 4.35V, 4.4V, or 4.5V
• Complete Linear Charge Management Controller:
- Autonomous Power Source Selection
- Integrated Pass Transistors
- Integrated Current Sense
- Integrated Reverse Discharge Protection
• Constant Current (CC) / Constant Voltage (CV)
Operation with Thermal Regulation
• Selectable USB-Port Charge Current:
- Low: 1 Unit Load / High: 5 Unit Loads
• Programmable AC-Adapter Charge Current:
- 15 mA - 1000 mA
• Two Charge Status Outputs
• Power-Good Monitor: MCP73837
• Timer Enable: MCP73838
• Automatic Recharge:
- Selectable Voltage Threshold
• Automatic End-of-Charge Control:
- Selectable Charge Termination Current Ratio
- Selectable Safety Timer Period
• Preconditioning of Deeply Depleted Cells - can be
disabled
• Battery Cell Temperature Monitor
• UVLO (Undervoltage Lockout)
• Automatic Power-Down when Input Power is
Removed
• Low-Dropout (LDO) Linear Regulator Mode
• Numerous Selectable Options Available for a
Variety of Applications:
- Refer to Section 1.0 “Electrical
Characteristics” for Selectable Options”
- Refer to the “Product Identification
System” for Standard Options
• Temperature Range: -40°C to 85°C
• Packaging:
- 10-Lead 3 mm x 3 mm DFN
- 10-Lead MSOP*
* Consult Factory for MSOP Package
Availability.
• Smart Phones and Personal Data Assistants
(PDA)
• Portable Media Players(PMP)
• Ultra Mobile Devices(UMD)
• Digital Cameras
• MP3 Players
• Bluetooth Headsets
• Handheld Medical Devices
• AC/USB Dual Source Li-Ion Battery Chargers
© 2007 Microchip Technology Inc.
Description
The MCP73837 and MCP73838 devices are fully
integrated linear Li-Ion / Li-Polymer battery chargers
with autonomous power source selection. Along with its
small physical size, the low number of external
components required makes the MCP73837/8 ideally
suitable for portable applications.
The MCP73837/8 automatically selects the USB-Port
or AC-Adapter as the power source for the system. For
the USB-Port powered systems, the MCP73837/8
specifically adheres to the current limits governed by
the USB specification. The host microcontroller can
select from two preset maximum charge current rates
of 100 mA (low power USB-port) or 500 mA (high
power USB-port). With an AC-Adapter providing power
to the system, an external resistor sets the magnitude
of the system or charge current up to a maximum of 1A.
The MCP73837/8 employs a constant current /
constant voltage charge algorithm with selectable
preconditioning and charge termination. The constant
voltage regulation is fixed with four available options:
4.20V, 4.35V, 4.40V, or 4.50V, to accommodated the
new emerging battery charging requirements. The
MCP73837/8 limits the charge current based on die
temperature during high power or high ambient
conditions. This thermal regulation optimizes the
charge cycle time while maintaining the device
reliability.
The MCP73837/8 are fully specified over the ambient
temperature range of -40°C to +85°C.
The MCP73837/8 devices are available in a 10-Lead,
3 mm x 3 mm, DFN package or in a 10-Lead MSOP
package.
DS22071A-page 1
MCP73837/8
Package Types
MCP73837/8
10-Lead DFN 3 mm x 3 mm
MCP73837/8
10-Lead MSOP
10 VBAT
VAC
1
10 VBAT
VAC
VUSB
2
9 THERM
VUSB 2
9 THERM
STAT1
3
8 PG (TE)
STAT1 3
8 PG (TE)
STAT2
4
7 PROG2
STAT2 4
7 PROG2
VSS
5
6 PROG1
VSS
1
5
6 PROG1
Typical Applications
MCP73837 Typical Application
1
Ac-dc Adapter
4.7 µF
2
USB Port
4.7 µF
1 kΩ
1 kΩ
1 kΩ
3
4
8
VAC
VBAT
VUSB
THERM
STAT1
VSS
STAT2
PROG2
PG
PROG1
10
Thermsitor
9
4.7 µF
Single
Li-Ion
Cell
5
7
Low Hi
6
RPROG
MCP73838 Typical Application
1
Ac-dc Adapter
4.7 µF
2
USB Port
4.7 µF
1 KΩ
1 KΩ
3
4
5
VAC
VBAT
VUSB
THERM
STAT1
TE
STAT2
PROG2
VSS
PROG1
10
Thermsitor
9
4.7 µF
Cell
8
Low
7
Low
Hi
Hi
6
RPROG
DS22071A-page 2
© 2007 Microchip Technology Inc.
MCP73837/8
Functional Block Diagram (MCP73837/8)
VOREG
DIRECTION
CONTROL
6 µA
VUSB
VBAT
SENSEFET
G=0.001
100 mA/500 mA
10k
2k
SENSEFET
G=0.001
VOREG
DIRECTION
CONTROL
VAC
AC/USB
+
SENSEFET
G=0.001
1k VREF
CURRENT
LIMIT
-
SENSEFET
G=0.001
PROG1
AC/USB
REFERENCE,
BIAS, UVLO,
AND SHDN
VOREG
+
VREF (1.21V)
CA
310k
111k
10k
+
UVLO
-
72.7k
-
PRECONDITION
470.6k
+
TERM
48k
-
PROG2
+
STAT1
STAT2
CHARGE
CONTROL,
TIMER,
AND
STATUS
LOGIC
CHARGE
6k
+
VA
-
157.3k
VOREG
+
-
LDO
175k
PG (TE)
50 µA
+
-
HTVT
470.6k
THERM
+
© 2007 Microchip Technology Inc.
-
LTVT
175k
121k
1M
VSS
DS22071A-page 3
MCP73837/8
1.0
ELECTRICAL
CHARACTERISTICS
† 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.
Absolute Maximum Ratings†
VDDN ................................................................................7.0V
All Inputs and Outputs w.r.t. VSS ............... -0.3 to (VDD+0.3)V
Maximum Junction Temperature, TJ ............Internally Limited
Storage temperature .....................................-65°C to +150°C
ESD protection on all pins
Human Body Model (1.5 kW in Series with 100 pF) ......≥ 4 kV
Machine Model (200 pF, No Series Resistance) .............300V
DC CHARACTERISTICS
Electrical Specifications: Unless otherwise indicated, all limits apply for VDD= [VREG(typical) + 0.3V] to 6V,
TA = -40°C to +85°C. Typical values are at +25°C, VDD = [VREG (typical) + 1.0V]
Parameters
Sym
Min
Typ
Max
Units
Conditions
Supply Voltage
VDD
VREG(Typ)
+0.3V
—
6
V
Note 1
Supply Current
ISS
—
1900
3000
µA
Charging
110
300
µA
Charge Complete, No Battery
—
75
100
µA
Standby (PROG Floating)
—
0.6
5
µA
Shutdown (VDD < VBAT 100 mV or VDD < VSTOP)
V
VDD= Low to High (USB-Port)
Supply Input
UVLO Start Threshold
VSTART
3.35
3.45
3.55
UVLO Stop Threshold
VSTOP
3.25
3.35
3.45
V
UVLO Hysteresis
VHYS
—
75
—
mV
UVLO Start Threshold
VSTART
4.1
4.15
4.3
V
(AC-Adapter)
UVLO Stop Threshold
VSTOP
4.0
4.1
4.2
V
(AC-Adapter)
UVLO Hysteresis
VHYS
—
55
—
mV
(AC-Adapter)
VDD= High to Low (USB-Port)
(USB-Port)
Voltage Regulation (Constant Voltage Mode)
Regulated Charge Voltage
VREG
4.179
4.20
4.221
V
VDD=[VREG(typical)+1V]
4.328
4.35
4.372
V
IOUT=30 mA
TA=-5°C to +55°C
4.378
4.40
4.422
V
4.477
4.50
4.523
V
VRTOL
-0.5
—
+0.5
%
Line Regulation
|(ΔVBAT/
VBAT)/ΔVDD|
—
0.075
0.2
%/V
Load Regulation
|ΔVBAT/VBAT|
—
0.150
0.3
%
IOUT=10 mA to 100 mA
VDD=[VREG(typical)+1V]
PSRR
—
60
—
dB
IOUT=10 mA, 10Hz to 1 kHz
—
52
—
dB
IOUT=10 mA, 10Hz to 10 kHz
—
23
—
dB
IOUT=10 mA, 10Hz to 1 MHz
Regulated Charge Voltage Tolerance
Supply Ripple Attenuation
TA=-5°C to +55°C
VDD=[VREG(typical)+1V] to 6V
IOUT=30 mA
Current Regulation (Fast Charge Constant-Current Mode)
AC-Adapter Fast Charge Current
Note 1:
2:
3:
4:
IREG
95
105
115
mA
PROG1 = 10 kΩ
900
1000
1100
mA
PROG1 = 1 kΩ, Note 2
TA=-5°C to +55°C
The supply voltage (VDD) = VAC when input power source is from Ac-Adapter and the supply voltage (VDD) = VUSB
when input power source is from USB-Port.
The value is guaranteed by design and not production tested.
The current is based on the ratio of selected current regulation (IREG).
The maximum charge impedance has to be less than shutdown impedance for normal operation.
DS22071A-page 4
© 2007 Microchip Technology Inc.
MCP73837/8
DC CHARACTERISTICS (Continued)
Electrical Specifications: Unless otherwise indicated, all limits apply for VDD= [VREG(typical) + 0.3V] to 6V,
TA = -40°C to +85°C. Typical values are at +25°C, VDD = [VREG (typical) + 1.0V]
Parameters
USB-Port Fast Charge Current
Maximum Output Current Limit
Sym
IREG
IMAX
Min
Typ
Max
Units
Conditions
80
90
100
mA
PROG2 = Low
400
450
500
mA
PROG2 = High
TA=-5°C to +55°C
—
1200
—
mA
PROG1 < 833Ω
12.5
%
Note 3
TA=-5°C to +55°C
Precondition Current Regulation (Trickle Charge Constant-Current Mode)
Precondition Current Ratio
IPREG / IREG
7.5
10
15
20
25
%
30
40
50
%
64
66.5
69
%
100
Precondition Current Threshold Ratio
Precondition Hysteresis
VPTH / VREG
%
VBAT Low to High
69
71.5
74
%
VPHYS
—
120
—
mV
ITERM / IREG
3.75
5
6.25
%
PROG1 = 1 kΩ to 10 kΩ
VBAT High to Low
Charge Termination
Charge Termination Current Ratio
5.6
7.5
9.4
%
TA=-5°C to +55°C
7.5
10
12.5
%
Note 3
15
20
25
%
92
94.0
96
%
VBAT High to Low
95
97
99
%
TA=-5°C to +55°C
RDSON
—
350
—
mΩ
VDD = 4.5V, TJ = 105°C
IDISCHARGE
—
0.1
2
µA
Standby (PROG1 or PROG2
Floating)
—
0.55
2
µA
Shutdown (VDD < VBAT 100 mV or VDD < VSTOP)
—
-6
-15
µA
Charge Complete
mA
Automatic Recharge
Recharge Voltage Threshold Ratio
VRTH / VREG
Pass Transistor ON-Resistance
ON-Resistance
Battery Discharge Current
Output Reverse Leakage Current
Status Indicators - STAT1, STAT2, PG (MCP73837)
Sink Current
ISINK
—
16
35
Low Output Voltage
VOL
—
0.3
1
V
ISINK = 4 mA
Input Leakage Current
ILK
—
0.03
1
µA
High Impedance, VDD on pin
PROG1 Input (PROG1)
Charge Impedance Range
RPROG
1
—
—
kΩ
Note 4
Shutdown Impedance
RPROG
70
—
200
kΩ
Minimum Impedance for
Shutdown
PROG2 Inputs (PROG2)
Input High Voltage Level
VIH
0.8VDD
—
—
%
Input Low Voltage Level
VIL
—
—
0.2VDD
%
Shutdown Voltage Level
VSD
0.2VDD
—
0.8VDD
%
Input Leakage Current
ILK
—
7
15
µA
Note 1:
2:
3:
4:
VPROG2 = VDD
The supply voltage (VDD) = VAC when input power source is from Ac-Adapter and the supply voltage (VDD) = VUSB
when input power source is from USB-Port.
The value is guaranteed by design and not production tested.
The current is based on the ratio of selected current regulation (IREG).
The maximum charge impedance has to be less than shutdown impedance for normal operation.
© 2007 Microchip Technology Inc.
DS22071A-page 5
MCP73837/8
DC CHARACTERISTICS (Continued)
Electrical Specifications: Unless otherwise indicated, all limits apply for VDD= [VREG(typical) + 0.3V] to 6V,
TA = -40°C to +85°C. Typical values are at +25°C, VDD = [VREG (typical) + 1.0V]
Parameters
Sym
Min
Typ
Max
Units
Conditions
Timer Enable (TE)
Input High Voltage Level
VIH
2
—
—
V
Input Low Voltage Level
VIL
—
—
0.8
V
Input Leakage Current
ILK
—
0.01
1
µA
VTE = VDD
ITHERM
47
50
53
µA
2 kΩ < RTHERM < 50 kΩ
VT1 Low to High
Thermistor Bias
Thermistor Current Source
Thermistor Comparator
Upper Trip Threshold
Upper Trip Point Hysteresis
Lower Trip Threshold
Lower Trip Point Hysteresis
VT1
1.20
1.23
1.26
V
VT1HYS
—
-40
—
mV
VT2
0.235
0.250
0.265
V
VT2HYS
—
40
—
mV
VT2 High to Low
System Test (LDO) Mode
VIH
—
—
VDD - 0.1
V
THERM Input Sink Current
ISINK
3
5.5
20
µA
Stand-by Or System Test
Mode
Bypass Capacitance
CBAT
1
4.7
—
—
µF
µF
IOUT < 250 mA
IOUT > 250 mA
Input High Voltage Level
Automatic Power Down (SLEEP Comparator, Direction Control)
Automatic Power Down Entry
Threshold
Automatic Power Down Exit Threshold
VPD
VBAT +
10 mV
VBAT +
100 mV
—
V
2.3V < VBAT < VREG
VDD Falling
VPDEXIT
-
VBAT +
150 mV
VBAT +
250 mV
V
2.3V < VBAT < VREG
VDD Rising
TSD
—
150
—
°C
TSDHYS
—
10
—
°C
Thermal Shutdown
Die Temperature
Die Temperature Hysteresis
Note 1:
2:
3:
4:
The supply voltage (VDD) = VAC when input power source is from Ac-Adapter and the supply voltage (VDD) = VUSB
when input power source is from USB-Port.
The value is guaranteed by design and not production tested.
The current is based on the ratio of selected current regulation (IREG).
The maximum charge impedance has to be less than shutdown impedance for normal operation.
DS22071A-page 6
© 2007 Microchip Technology Inc.
MCP73837/8
AC CHARACTERISTICS
Electrical Specifications: Unless otherwise indicated, all limits apply for VDD = [VREG (typical) + 0.3V] to 6V.
Typical values are at +25°C, VDD = [VREG (typical) + 1.0V]
Parameters
Sym
Min
Typ
Max
Units
tSTART
—
—
5
ms
VDD Low to High
tDELAY
—
—
10
ms
VBAT < VPTH to VBAT > VPTH
tRISE
—
—
10
ms
IOUT Rising to 90% of IREG
Precondition Comparator Filter Time
tPRECON
0.4
1.3
3.2
ms
Average VBAT Rise/Fall
Termination Comparator Filter Time
tTERM
0.4
1.3
3.2
ms
Average IOUT Falling
Charge Comparator Filter Time
tCHARGE
0.4
1.3
3.2
ms
Average VBAT Falling
Thermistor Comparator Filter Time
tTHERM
0.4
1.3
3.2
ms
Average THERM Rise/Fall
UVLO Start Delay
Conditions
Current Regulation
Transition Time Out of Precondition
Current Rise Time Out of Precondition
Elapsed Timer
Elapsed Timer Period
tELAPSED
0
0
0
Hours
3.6
4.0
4.4
Hours
5.4
6.0
6.6
Hours
7.2
8.0
8.8
Hours
Timer Disabled
Status Indicators
Status Output Turn-off
tOFF
—
—
500
µs
ISINK = 1 mA to 0 mA
Status Output Turn-on
tON
—
—
500
µs
ISINK = 0 mA to 1 mA
TEMPERATURE SPECIFICATIONS
Electrical Specifications: Unless otherwise indicated, all limits apply for VDD = [VREG (typ.) + 0.3V] to 6V.
Typical values are at +25°C, VDD = [VREG (typ.) + 1.0V]
Parameters
Sym
Min
Typ
Max
Units
Conditions
TA
-40
—
+85
°C
Operating Temperature Range
TJ
-40
—
+125
°C
Storage Temperature Range
TA
-65
—
+150
°C
Thermal Resistance, 10-Lead MSOP
θJA
—
113
—
°C/W
4-Layer JC51-7 Standard Board,
Natural Convection. Note 1
Thermal Resistance, 10-Lead 3 mm x
3 mm DFN
θJA
—
41
—
°C/W
4-Layer JC51-7 Standard Board,
Natural Convection
Temperature Ranges
Specified Temperature Range
Thermal Package Resistances
Note 1:
This represents the minimum copper condition on the PCB ( Printed Circuit Board).
© 2007 Microchip Technology Inc.
DS22071A-page 7
MCP73837/8
2.0
TYPICAL PERFORMANCE CURVES
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.
TEMP = 25°C
IOUT = 50 mA
IOUT = 10 mA
IOUT = 100 mA
IOUT = 500 mA
IOUT = 1000 mA
4.5
4.8
5.0
5.3
5.5
Supply Voltage (V)
5.8
Battery Regulation Voltage (V)
4.205
IOUT = 10 mA
VDD = 5.2V
IOUT = 50 mA
4.200
4.195
IOUT = 100 mA
4.190
IOUT = 500 mA
4.185
4.180
IOUT = 1000 mA
4.175
4.170
Battery Voltage (V)
FIGURE 2-3:
Output Leakage Current
(IDISCHARGE) vs. Battery Regulation Voltage
(VBAT).
DS22071A-page 8
0.8
0.4
0.0
10 20 30 40 50 60 70 80
Temperature (°C)
2.0
1.8
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0.0
VDD = Floating
TEMP = +25°C
Battery Voltage (V)
FIGURE 2-5:
Output Leakage Current
(IDISCHARGE) vs. Battery Voltage (VBAT).
VDD = VBAT
TEMP = 25 °C
3.0 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9 4.0 4.1 4.2
1.2
3.0 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9 4.0 4.1 4.2
IREG (mA)
Output Leakage Current (µA)
0.50
0.45
0.40
0.35
0.30
0.25
0.20
0.15
0.10
0.05
0.00
VDD = Floating
VBAT = 4.2V
1.6
FIGURE 2-4:
Output Leakage Current
(IDISCHARGE) vs. Ambient Temperature (TA).
-40 -30 -20 -10 0 10 20 30 40 50 60 70 80
Ambient Temperature (°C)
FIGURE 2-2:
Battery Regulation Voltage
(VBAT) vs. Ambient Temperature (TA).
2.0
-40 -30 -20 -10 0
6.0
FIGURE 2-1:
Battery Regulation Voltage
(VBAT) vs. Supply Voltage (VDD).
4.210
Output Leakage Current (µA)
4.210
4.205
4.200
4.195
4.190
4.185
4.180
4.175
4.170
4.165
4.160
Output Leakage Current (µA)
Battery Regulation Voltage (V)
Note: Unless otherwise indicated, VDD = [VREG(typical) + 1V], IOUT = 30 mA, and TA= +25°C, Constant-voltage mode.
1000
900
800
700
600
500
400
300
200
100
0
VDD = 5.2V
Temp = 25°C
1
6 11 16 21 26 31 36 41 46 51 56 61
RPROG (kΩ)
FIGURE 2-6:
Charge Current (IOUT) vs.
Programming Resistor (RPROG).
© 2007 Microchip Technology Inc.
MCP73837/8
90
5.0
5.3
5.5
Supply Voltage (V)
5.8
FIGURE 2-8:
Charge Current (IOUT) vs.
Supply Voltage (VDD).
1100
RPROG = 1 kΩ
VDD = 5.2V
Charge Current (mA)
1050
1000
950
900
850
800
750
700
-40 -30 -20 -10 0 10 20 30 40 50 60 70 80
Ambient Temperature (°C)
FIGURE 2-9:
Charge Current (IOUT) vs.
Ambient Temperature (TA).
© 2007 Microchip Technology Inc.
-40 -30 -20 -10 0 10 20 30 40 50 60 70 80
Ambient Temperature (°C)
6.0
FIGURE 2-11:
Charge Current (IOUT) vs.
Ambient Temperature (TA).
1200
1100
1000
900
800
700
600
500
400
300
200
100
0
RPROG = 1 kΩ
25
4.8
Charge Current (mA)
4.5
155
92
145
94
135
96
125
98
115
100
RPROG = 20 kΩ
VDD = 5.2V
95
102
55
54
53
52
51
50
49
48
47
46
45
105
Charge Current (mA)
RPROG = 10 kΩ
Temp = +25°C
FIGURE 2-10:
Charge Current (IOUT) vs.
Ambient Temperature (TA).
85
FIGURE 2-7:
Charge Current (IOUT) vs.
Supply Voltage (VDD).
104
-40 -30 -20 -10 0 10 20 30 40 50 60 70 80
Ambient Temperature (°C)
6.0
75
5.8
65
5.0
5.3
5.5
Supply Voltage (V)
55
4.8
RPROG = 10 kΩ
VDD = 5.2V
45
4.5
110
108
106
104
102
100
98
96
94
92
90
35
RPROG = 1 kΩ
Temp = +25°C
Charge Current (mA)
1200
1150
1100
1050
1000
950
900
850
800
750
700
Charge Current (mA)
Charge Current (mA)
Note: Unless otherwise indicated, VDD = [VREG(typical) + 1V], IOUT = 30 mA and TA= +25°C, Constant-voltage mode.
Junction Temperature (°C)
FIGURE 2-12:
Charge Current (IOUT) vs.
Junction Temperature (TJ).
DS22071A-page 9
MCP73837/8
52.0
51.5
51.0
50.5
50.0
49.5
49.0
48.5
48.0
47.5
47.0
90
80
70
60
50
40
30
20
0
FIGURE 2-16:
Thermistor Current (ITHERM)
vs. Ambient Temperature (TA).
0
RPROG = 10 kΩ
Attenuation (dB)
-10
IOUT = 10 mA
COUT = 4.7 µF
-20
-30
-40
-50
-70
0.01
155
145
135
125
115
105
95
85
75
65
55
45
35
25
-60
0.1
FIGURE 2-14:
Charge Current (IOUT) vs.
Junction Temperature (TJ).
52.0
51.5
51.0
50.5
50.0
49.5
49.0
48.5
48.0
47.5
47.0
1
10
100
1000
Frequency (kHz)
Junction Temperature (°C)
FIGURE 2-17:
Power Supply Ripple
Rejection (PSRR).
0
Temp = +25°C
-10
Attenuation (dB)
Thermistor Current (mA)
10
-10
Ambient Temperature (°C)
FIGURE 2-13:
Charge Current (IOUT) vs.
Junction Temperature (TJ).
Charge Current (mA)
-20
Junction Temperature (°C)
120
110
100
90
80
70
60
50
40
30
20
10
0
VDD = 5.2V
-30
Thermistor Current (mA)
155
145
135
125
115
95
105
85
75
65
55
45
35
RPROG = 2 kΩ
-40
600
550
500
450
400
350
300
250
200
150
100
50
0
25
Charge Current (mA)
Note: Unless otherwise indicated, VDD = [VREG(typical) + 1V], IOUT = 30 mA and TA= +25°C, Constant-voltage mode.
IOUT = 100 mA
COUT = 4.7 µF
-20
-30
-40
-50
-60
4.5
4.8
5.0
5.3
5.5
Supply Voltage (V)
5.8
6.0
FIGURE 2-15:
Thermistor Current (ITHERM)
vs. Supply Voltage (VDD).
DS22071A-page 10
-70
0.01
0.1
1
10
100
1000
Frequency (kHz)
FIGURE 2-18:
Power Supply Ripple
Rejection (PSRR).
© 2007 Microchip Technology Inc.
MCP73837/8
1.6E-03
700
600
500
400
300
200
100
0
-100
-200
Line Transient Response.
FIGURE 2-22:
Load Transient Response.
FIGURE 2-23:
(IOUT = 1A).
VAC UVLO Start Delay
FIGURE 2-24:
(USB = Low).
VUSB UVLO Start Delay
14
0
12
-0.1
10
-0.2
8
6
-0.3
4
-0.4
2
Output Ripple (V)
0.1
16
Input Source (V)
0.1
0.05
0
-0.05
-0.1
-0.15
-0.2
-0.25
-0.3
Time (Minutes)
Time (µs)
FIGURE 2-19:
1.4E-03
-0.5
1.2E-03
0
1.0E-03
IOUT = 100 mA
-4.0E-04
-0.4
2
8.0E-04
-0.3
4
6.0E-04
-0.2
6
4.0E-04
8
IOUT = 100 mA
2.0E-04
-0.1
10
1
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
-0.1
0.0E+00
Output Ripple (V)
Input Source (V)
0
12
Output Current (A)
0.1
14
-2.0E-04
16
Output Ripple (V)
Note: Unless otherwise indicated, VDD = [VREG(typical) + 1V], IOUT = 30 mA and TA= +25°C, Constant-voltage mode.
IOUT = 10 mA
0
-0.5
800
700
600
500
400
300
200
100
0
-100
-200
Time (µs)
Line Transient Response.
0.35
0.3
0.25
0.2
0.15
0.1
0.05
0
-0.05
0.04
0.02
0
-0.02
-0.04
-0.06
-0.08
-0.1
-0.12
IOUT = 10 mA
Output Ripple (V)
Output Current (A)
FIGURE 2-20:
1.6E-03
1.4E-03
1.2E-03
1.0E-03
8.0E-04
6.0E-04
4.0E-04
2.0E-04
0.0E+00
-2.0E-04
-4.0E-04
Time (Minutes)
FIGURE 2-21:
Load Transient Response.
© 2007 Microchip Technology Inc.
DS22071A-page 11
MCP73837/8
Note: Unless otherwise indicated, VDD = [VREG(typical) + 1V], IOUT = 30 mA and TA= +25°C, Constant-voltage mode.
5.0
0.12
4.0
0.1
0.08
3.0
0.06
2.0
0.04
VDD = 5.2V
RPROG = USB_Low
180 mAh Li-Ion Battery
1.0
0.02
0.0
Charge Current (A)
Battery Voltage (V)
UVLOVAC
0
0
20 40 60 80 100 120 140 160 180
Time (Minutes)
1.2
0.8
3.0
0.6
2.0
0.4
VDD = 5.2V
RPROG = 1 kΩ
1200 mAh Li-Ion Battery
1.0
0.1
4.0
0.08
3.0
0.06
C.V. Begins
2.0
0.04
VDD = 5.2V
RPROG = USB_Low
180 mAh Li-Ion Battery
1.0
Preconditioning
0
0.02
0.0
0
10
20
30
40
50
60
70
80
90
100
110
120
130
140
150
0.0
0.2
0.12
C.C. Begins
Battery Voltage (V)
1
4.0
5.0
Charge Current (A)
5.0
Battery Voltage (V)
FIGURE 2-28:
Complete Charge Cycle
(180 mAh Li-Ion Battery).
VUSB UVLO Start Delay
Charge Current (A)
FIGURE 2-25:
(USB = High)
0
0
1
2
3
4
5
6
7
8
9
10
Time (Minutes)
Time (Minutes)
FIGURE 2-29:
Typical Charge Profile in
Preconditioning and CC-CV (180 mAh Li-Ion
Battery).
FIGURE 2-26:
Complete Charge Cycle
(1200 mAh Li-Ion Battery).
1.2
4.5
3.5
0.9
3.0
2.5
0.6
2.0
1.5
VDD = 5.2V
RPROG = 1 kΩ
1200 mAh Li-Ion Battery
1.0
0.5
0.3
0.0
Charge Current (A)
Battery Voltage (V)
4.0
0
0
1
2
3
4
5
6
7
8
9
10
Time (Minutes)
FIGURE 2-27:
Typical Charge Profile in
Thermal Regulation (1200 mAh Li-Ion Battery).
DS22071A-page 12
© 2007 Microchip Technology Inc.
MCP73837/8
3.0
PIN DESCRIPTION
The descriptions of the pins are listed in Table 3-1.
TABLE 3-1:
PIN FUNCTION TABLES
Pin Number
MSOP-10
3.1
DFN-10
Symbol
I/O
Function
1
1
VAC
I
2
2
VUSB
I
AC-Adapter Supply Input
USB-Port Supply Input
3
3
STAT1
O
Charge Status Output 1 (Open-Drain)
4
4
STAT2
O
Charge Status Output 2 (Open-Drain)
5
5
VSS
—
Battery Management 0V Reference
6
6
PROG1
I/O
Current Regulation Setting With AC-Adapter; Device Charge
Control Enable; Precondition Set Point for AC control
7
7
PROG2
I
Current Regulation Setting With USB-Port; Precondition Set Point
for USB control.
8
8
PG
O
Available on MCP73837: Power-Good Status Output (Open-Drain)
8
8
TE
I
Available on MCP73838: Timer Enable; Enables Safety Timer
(Active Low)
9
9
THERM
I/O
Thermistor Monitoring Input and Bias current; System Test (LDO)
Mode Input
10
10
VBAT
I/O
Battery Positive Input and Output Connection
—
EP
VSS
—
EP (Exposed Thermal Pad); There is an internal electrical
connection between the exposed thermal pad and VSS. The EP
must be connected to the same potential as the VSS pin on the
Printed Circuit Board (PCB).
AC-Adapter Supply Input (VAC)
A supply voltage of VREG + 0.3V to 6V from ac-dc walladapter is recommended. When both the AC-Adapter
and the USB-Port supply voltages are present at same
time, the AC-Adapter dominates the regulated charge
current with the maximum value of 1A. Bypass to VSS
with a minimum of 4.7 µF is recommended.
3.2
USB-Port Supply Input (VUSB)
A supply voltage of VREG + 0.3V to 6V from USB-Port is
recommended. When no supply voltage from VAC pin is
available, the Li-Ion battery is charged directly from
USB-Port. Bypass to VSS with a minimum of 1 µF is
recommended.
3.3
Charge Status Output 1 (STAT1)
STAT1 is an open-drain logic output for connection to a
LED for charge status indication. Alternatively, a pull-up
resistor can be applied for interfacing to a host microcontroller.
3.4
Charge Status Output 2 (STAT2)
STAT2 is an open-drain logic output for connection to a
LED for charge status indication. Alternatively, a pull-up
resistor can be applied for interfacing to a host
microcontroller.
© 2007 Microchip Technology Inc.
3.5
Battery Management 0V Reference
(VSS)
Connect to negative terminal of battery and input
supply.
3.6
Battery Charge Control Output
(VBAT)
Connect to the positive terminal of Li-Ion / Li-Polymer
batteries. Bypass to VSS with a minimum of 1 µF to
ensure loop stability when the battery is disconnected.
3.7
AC-Adapter Current Regulation
Set (PROG1)
The AC-Adapter constant charge current is set by
placing a resistor from PROG1 to VSS. PROG1 is the
set point of precondition and termination when the ACAdapter is present.
PROG1 also functions as device charge control
enable. The MCP73837/8 is shut down when an
impedance value greater than 70 kΩ is applied to
PROG1. When PROG1 is floating, the MCP73837/8
enters stand-by mode.
DS22071A-page 13
MCP73837/8
3.8
USB-Port Current Regulation Set
(PROG2)
The MCP73837/8 USB-Port current regulation set
input (PROG2) is a digital input selection. A logic Low
selects a 1 unit load charge current; a logic High selects
a 5 unit loads charge current.
PROG2 also functions as the set point of precondition
and termination when USB-Port is present. When
PROG2 is floating, the MCP73837/8 enters in stand-by
mode.
3.9
Power Good (PG)
Power Good (PG) is available only on MCP73837. PG
is an open-drain logic output for connection to a LED
for input power supply indication. Alternatively, a pullup resistor can be applied for interfacing to a host
microcontroller.
DS22071A-page 14
3.10
Timer Enable (TE)
Timer Enable (TE) is available only on MCP73838.
(TE) enables the built-in safety timer when pull low and
disables the built-in safety timer when pull high.
Note:
3.11
The built-in safety timer is available for both
MCP73837 and MCP73838 in the following
options: Disable, 4 HR, 6 HR, and 8 HR.
Battery Temperature Monitor
(THERM)
MCP73837/8 continuously monitors the battery
temperature during a charge cycle by measuring the
voltage between the THERM and VSS pins. An internal
50 µA current source provides the bias for the most
common 10 kΩ negative-temperature coefficient
thermistors (NTC).
© 2007 Microchip Technology Inc.
MCP73837/8
4.0
DEVICE OVERVIEW
The MCP73837/8 devices are simple, yet fully integrated linear charge management controllers. Figure 4-1 depicts the
operational flow algorithm.
SHUTDOWN MODE*
V <V
DD
BAT -100 mV
VDD < VSTOP
* Continuously Monitored
STAT1 = Hi-Z
STAT2 = Hi-Z
PG = Hi-Z
SYSTEM TEST (LDO) MODE
V
> (V -100 mV)
THERM
DD
STAT1 = LOW
STAT2 = LOW
PG = LOW
Timer Suspended
STANDBY MODE *
V
BAT
> (V
REG
+100 mV)
PROG > 200kΩ
STAT1 = Hi-Z
STAT2 = Hi-Z
PG = LOW
VBAT < VPTH
PRECONDITIONING MODE
Charge Current = IPREG
STAT1 = LOW
STAT2 = Hi-Z
PG = LOW
Timer Reset
V
BAT
TEMPERATURE FAULT
No Charge Current
STAT1 = Hi-Z
STAT2 = Hi-Z
PG = LOW
Timer Suspended
>V
PTH
FAST CHARGE MODE
Charge Current = IREG
STAT1 = LOW
STAT2 = Hi-Z
PG = LOW
Timer Enabled
VBAT > VPTH
Timer Expired
VBAT < VRTH
TIMER FAULT
No Charge Current
STAT1 = Hi-Z
STAT2 = Hi-Z
PG = LOW
Timer Suspended
VBAT = VREG
CONSTANT VOLTAGE MODE
Charge Voltage = VREG
STAT1 = LOW
STAT2 = Hi-Z
PG = LOW
IBAT < I TERM
Timer Expired
CHARGE COMPLETE MODE
No Charge Current
STAT1 = Hi-Z
STAT2 = LOW
PG = LOW
FIGURE 4-1:
Flow Chart.
© 2007 Microchip Technology Inc.
DS22071A-page 15
MCP73837/8
4.1
Undervoltage Lockout (UVLO)
An internal undervoltage lockout (UVLO) circuit
monitors the input voltage and keeps the charger in
shutdown mode until the input supply rises above the
UVLO threshold. The UVLO circuitry has a built-in
hysteresis of 75 mV for the USB-Port and 55 mV for the
AC-Adapter.
In the event a battery is present when the input power
is applied, the input supply must rise 100 mV above the
battery voltage before MCP73837/8 becomes
operational.
The UVLO circuit places the device in shutdown mode
if the input supply falls to within +100 mV of the battery
voltage.
The UVLO circuit is always active. At any time the input
supply is below the UVLO threshold or within +100 mV
of the voltage at the VBAT pin, the MCP73837/8 is
placed in a shutdown mode.
During any UVLO condition, the battery reverse
discharge current shall be less than 2 µA.
4.2
4.3
When the voltage at the VBAT pin rises above the
preconditioning threshold, the MCP73837/8 enters the
constant current or fast charge mode.
4.5
If the input power is switched during a
charge cycle, the power path switch-over
shall be a break-before-make connection.
As a result, the charge current can
momentarily go to zero. The charge cycle
timer shall remain continuous.
Charge Qualification
For AC-Adapter, the charge current is established
using a single resistor from PROG to VSS. The
program resistor and the charge current are calculated
using the following equation:
EQUATION 4-1:
1000VI REG = ---------------R PROG
where RPROG is in kilo-ohms (kΩ) and IREG is in
milliampers (mA).
When charging from a USB-Port, the host
microcontroller has the option of selecting either a one
unit load or a five unit loads charge rate based on the
PROG2 input. A logic LOW selects a one unit load
charge rate, a HIGH selects a five unit loads charge
rate, and high impedance input suspends or disables
charging.
Note:
For a charge cycle to begin, all UVLO conditions must
be met and a battery or output load must be present.
A charge current programming resistor must be connected from PROG1 to VSS. If the PROG1 or PROG2
pin are open or floating, the MCP73837/8 is disabled
and the battery reverse discharge current is less than
2 µA. In this manner, the PROG1 pin acts as a charge
enable and can be used as a manual shutdown.
4.4
Preconditioning
If the voltage at the VBAT pin is less than the
preconditioning threshold, the MCP73837/8 enters a
preconditioning mode. The preconditioning threshold is
factory set. Refer to Section 1.0 “Electrical
Characteristics” for preconditioning threshold
options.
DS22071A-page 16
Constant Current MODE - Fast
Charge
During the constant current mode, the programmed
(AC-Adapter) or selected (USB-Port) charge current is
supplied to the battery or load.
AUTONOMOUS POWER SOURCE
SELECTION
The MCP73837/8 devices are designed to select the
USB-port or the AC-Adapter as the power source
automatically. If the AC-Adapter input is not present,
the USB-Port is selected. If both inputs are available,
the AC-Adapter has first priority.
Note:
In this mode, the MCP73837/8 supplies a percentage
of the charge current (established with the value of the
resistor connected to the PROG pin) to the battery. The
percentage or ratio of the current is factory set. Refer to
Section 1.0
“Electrical
Characteristics”
for
preconditioning current options.
USB Specification Rev. 2.0 defines the
maximum absolute current for one unit
load is 100 mA. This value is not an average over time and shall not be exceed.
Constant current mode is maintained until the voltage
at the VBAT pin reaches the regulation voltage, VREG.,
when constant current mode is invoked, the internal
timer is reset.
4.5.1
TIMER EXPIRED DURING
CONSTANT CURRENT - FAST
CHARGE MODE
If the internal timer expires before the recharge voltage
threshold is reached, a timer fault is indicated and the
charge cycle terminates. The MCP73837/8 remains in
this condition until the battery is removed, the input
battery is removed or the PROG1/2 pin is opened. If the
battery is removed or the PROG1/2 pin is opened, the
MCP73837/8 enters the Stand-by mode where it
remains until a battery is reinserted or the PROG1/2 pin
© 2007 Microchip Technology Inc.
MCP73837/8
is reconnected. If the input power is removed, the
MCP73837/8 is in Shutdown. When the input power is
reapplied, a normal start-up sequence ensues.
4.6
Constant Voltage Mode
When the voltage at the VBAT pin reaches the
regulation voltage, VREG, constant voltage regulation
begins. The regulation voltage is factory set to 4.20V,
4.35V, 4.40V, or 4.5V with a tolerance of ± 0.5%.
4.9
Thermal Regulation
The MCP73837/8 limits the charge current based on
the die temperature. The thermal regulation optimizes
the charge cycle time while maintaining device
reliability. Figure 4-2 depicts the thermal regulation for
the MCP73837/8. Refer to Section 1.0 “Electrical
Characteristics” for thermal package resistances and
Section 6.1.1.2 “Thermal Considerations” for
calculating power dissipation.
.
4.7
Charge Termination
1200
RPROG = 1 kΩ
1100
The charge cycle is terminated when, during constant
voltage mode, the average charge current diminishes
below a percentage of the programmed charge current
(established with the value of the resistor connected to
the PROG pin) or the internal timer has expired. A 1 ms
filter time on the termination comparator ensures that
transient load conditions do not result in premature
charge cycle termination. The percentage or ratio of the
current is factory set. The timer period is factory set and
can be disabled. Refer to Section 1.0 “Electrical
Characteristics” for charge termination current ratio
and timer period options.
FIGURE 4-2:
The charge current is latched off and the MCP73837/8
enters a charge complete mode.
4.10
4.8
Automatic Recharge
The MCP73837/8 continuously monitors the voltage at
the VBAT pin in the charge complete mode. If the
voltage drops below the recharge threshold, another
charge cycle begins and current is once again supplied
to the battery or load. The recharge threshold is factory
set. Refer to Section 1.0 “Electrical Characteristics”
for recharge threshold options.
Note:
Charge Current (mA)
1000
900
800
700
600
500
400
300
200
100
0
25
35
45
55
65 75 85 95 105 115 125 135 145 155
Junction Temperature (°C)
Thermal Regulation.
Thermal Shutdown
The MCP73837/8 suspends charge if the die
temperature exceeds 150°C. Charging will resume
when the die temperature has cooled by
approximately 10°C. The thermal shutdown is a
secondary safety feature in the event that there is a
failure within the thermal regulation circuitry.
Charge termination and automatic
recharge features avoid constant charging
Li-Ion batteries to prolong the life of Li-Ion
batteries while keeping their capacity at
healthy level.
© 2007 Microchip Technology Inc.
DS22071A-page 17
MCP73837/8
5.0
DETAILED DESCRIPTION
5.1
Analog Circuitry
5.1.1
BATTERY MANAGEMENT INPUT
SUPPLY (VDD)
The VDD input is the input supply to the MCP73837/8.
The MCP73837/8 can be supplied by either ACAdapter (VAC) or USB-Port (VUSB) with autonomous
source selection. The MCP73837/8 automatically
enters a Power-down mode if the voltage on the VDD
input falls to within +100 mV of the battery voltage or
below the UVLO voltage (VSTOP). This feature prevents
draining the battery pack when both the VAC and VUSB
supplies are not present.
5.1.2
AC-ADAPTER CURRENT
REGULATION SET (PROG1)
For the MCP73837/8, the charge current regulation
can be scaled by placing a programming resistor
(RPROG) from the PROG input to VSS. The program
resistor and the charge current are calculated using
the following equation:
EQUATION 5-1:
1000VI REG = ---------------R PROG
Where:
RPROG
=
kilo-ohms (kΩ)
IREG
=
milli-ampere (mA)
at the THERM pin to factory set thresholds of 1.20V
and 0.25V, typically. Once a voltage outside the
thresholds is detected during a charge cycle, the
MCP73837/8 immediately suspends the charge cycle.
The MCP73837/8 suspends charge by turning off the
pass transistor and holding the timer value. The charge
cycle resumes when the voltage at the THERM pin
returns to the normal range.
If temperature monitoring is not required, place a
standard 10 kΩ resistor from THERM to VSS.
5.1.5
The MCP73837/8 can be placed in a system test mode.
In this mode, the MCP73837/8 operates as a low dropout linear regulator (LDO). The output voltage is
regulated to the factory set voltage regulation option.
The available output current is limited to the programmed fast charge current. For stability, the VBAT
output must be bypassed to VSS with a minimum
capacitance of 1 µF for output currents up to 250 mA.
A minimum capacitance of 4.7 µF is required for output
currents above 250 mA.
The system test mode is entered by driving the THERM
input greater than (VDD - 100 mV) with no battery
connected to the output. In this mode, the MCP73837/
8 can be used to power the system without a battery
being present.
Note 1: ITHERM is disabled during shutdown,
stand-by, and system test modes.
2: A pull-down current source on the
THERM input is active only in stand-by
and system test modes.
The preconditioning current and the charge
termination current are ratiometric to the fast charge
current based on the selected device options.
5.1.3
5.1.4
3: During system test mode, the PROG
input sets the available output current
limit.
BATTERY CHARGE CONTROL
OUTPUT (VBAT)
The battery charge control output is the drain terminal
of an internal P-channel MOSFET. The MCP73837/8
provides constant current and voltage regulation to the
battery pack by controlling this MOSFET in the linear
region. The battery charge control output should be
connected to the positive terminal of the battery pack.
TEMPERATURE QUALIFICATION
(THERM)
The MCP73837/8 continuously monitors battery
temperature during a charge cycle by measuring the
voltage between the THERM and the VSS pins. An
internal 50 µA current source provides the bias for the
most common 10 kΩ negative-temperature coefficient
(NTC) or positive-temperature coefficient (PTC)
thermistors. The current source is controlled, avoiding
measurement sensitivity to fluctuations in the supply
voltage (VDD). The MCP73837/8 compares the voltage
DS22071A-page 18
SYSTEM TEST (LDO) MODE
4: System test mode shall be exited by
releasing the THERM input or cycling
input power.
5.2
5.2.1
Digital Circuitry
STATUS INDICATORS AND POWER
GOOD (PG) OPTION
The charge status outputs have two different states:
Low (L), and High Impedance (Hi-Z). The charge status
outputs can be used to illuminate LEDs. Optionally, the
charge status outputs can be used as an interface to a
host microcontroller. Table 5-1 summarizes the state of
the status outputs during a charge cycle.
© 2007 Microchip Technology Inc.
MCP73837/8
5.2.2
USB-PORT CURRENT
REGULATION SELECT (PROG2)
For the MCP73837/8, driving the PROG2 input to a
logic Low selects the low charge current setting
(maximum 100 mA). Driving the PROG2 input to a logic
High selects the high charge current setting (maximum
500 mA).
TABLE 5-1:
STATUS OUTPUTS
CHARGE CYCLE STATE
STAT1
STAT2
PG
Shutdown
Hi-Z
Hi-Z
Hi-Z
Standby
Hi-Z
Hi-Z
L
Preconditioning
L
Hi-Z
L
Constant Current
L
Hi-Z
L
Constant Voltage
L
Hi-Z
L
Charge Complete - Standby
Hi-Z
L
L
Temperature Fault
Hi-Z
Hi-Z
L
Timer Fault
Hi-Z
Hi-Z
L
L
L
L
System Test Mode
5.2.3
5.2.4
TIMER ENABLE (TE) OPTION
The timer enable (TE) input option is used to enable or
disable the internal timer. A low signal on this pin
enables the internal timer and a high signal disables
the internal timer. The TE input can be used to disable
the timer when the charger is supplying current to
charge the battery and power the system load. The TE
input is compatible with 1.8V logic. The TE option is
available only on MCP73838.
5.2.5
DEVICE DISABLE (PROG1/2)
The current regulation set input pin (PROG1/2) can be
used to terminate a charge at any time during the
charge cycle, as well as to initiate a charge cycle or to
initiate a recharge cycle. Placing a programming
resistor from the PROG1/2 input to VSS enables the
device. Allowing the PROG1/2 input to float or applying
a logic-high input signal, disables the device and
terminates a charge cycle. When disabled, the device’s
supply current is reduced to 75 µA, typically.
POWER GOOD (PG) OPTION
The power good (PG) option is a pseudo open-drain
output. The PG output can sink current, but not source
current. However, there is a diode path back to the
input, and as such, the output should be pulled up only
to the input. The PG output is low whenever the input
to the MCP73837 is above the UVLO threshold and
greater than the battery voltage. If the supply voltage is
above the UVLO, but below VREG(typical)+0.3V, the
MCP73837 will pulse the PG output as the device
determines if a battery is present. The PG option is
available only on MCP73837.
© 2007 Microchip Technology Inc.
DS22071A-page 19
MCP73837/8
6.0
APPLICATIONS
Lithium-Polymer cells Constant-current followed by
Constant-voltage. Figure 6-1 depicts a typical standalone MCP73837 application circuit, while Figure 6-2
and Figure 6-3 depict the accompanying charge
profile.
The MCP73837/8 devices are designed to operate in
conjunction with a host microcontroller or in standalone applications. The MCP73837/8 devices provide
the preferred charge algorithm for Lithium-Ion and
1
2
USB Port
CIN1
REGULATED
WALL CUBE
1 ΚΩ
CIN2
1 ΚΩ
1 ΚΩ
3
4
8
VAC
VBAT
VUSB
THERM
STAT1
V
STAT2
PROG2
/PG
SS
PROG1
MCP73837
FIGURE 6-1:
4.0
1
0.8
3.0
0.6
2.0
0.4
VDD = 5.2V
RPROG = 1 kΩ
1200 mAh Li-Ion Battery
0.2
Charge Current (A)
Battery Voltage (V)
6.1
1.2
0
0
10
20
30
40
50
60
70
80
90
100
110
120
130
140
150
0.0
Time (Minutes)
4.5
1.2
0.9
3.0
2.5
0.6
2.0
VDD = 5.2V
RPROG = 1 kΩ
1200 mAh Li-Ion Battery
0.3
0.0
Charge Current (A)
Battery Voltage (V)
3.5
0.5
0
0
1
Single
Li-Ion
Cell
5
7
Low
Hi
6
RPROG
2
3
4
5
6
7
8
9
10
Time (Minutes)
FIGURE 6-3:
Typical Charge Profile in
Thermal Regulation (1200 mAh Li-Ion Battery).
DS22071A-page 20
Application Circuit Design
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.
4.0
1.0
COUT
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 battery charger
and the ambient cooling air. The worst-case situation is
when the device has transitioned from the
Preconditioning mode to the Constant Current mode. In
this situation, the battery charger 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
FIGURE 6-2:
Typical Charge Profile
(1200 mAh Li-Ion Battery).
1.5
Thermsitor
9
MCP73837 Typical Stand-Alone Application Circuit.
5.0
1.0
10
6.1.1.1
Charge Current
The preferred fast charge current for Lithium-Ion cells
should always follow references and guidance from
battery manufacturers. For example, programming
700 mA fast charge current for a 1000 mAh Li-Ion
battery pack if its preferred fast charge rate is 0.7C.
This will result the shortest charge cycle time without
degradation a battery's life and performance.
6.1.1.2
Thermal Considerations
The worst-case power dissipation in the battery
charger occurs when the input voltage is at the
maximum and the device has transitioned from the
Preconditioning mode to the Constant-current mode. In
this case, the power dissipation is:
© 2007 Microchip Technology Inc.
MCP73837/8
EQUATION 6-1:
PowerDissipation = ( V
DDMAX
–V
PTHMIN
)×I
REGMAX
Where:
VDDMAX
=
the maximum input voltage
IREGMAX
=
the maximum fast charge current
VPTHMIN
=
the minimum transition threshold
voltage
For example, power dissipation with a 5V, ±10% input
voltage source and 500 mA, ±10% fast charge current
is:
EXAMPLE 6-1:
Placing a programming resistor from the PROG1 input
to VSS or driving PROG2 to logic High or Low enables
the device. Allowing either the PROG1 or PROG2 input
float disables the device and terminates a charge cycle.
When disabled, the device’s supply current is reduced
to 75 µA, typically.
6.1.1.6
Temperature Monitoring
The charge temperature window can be set by placing
fixed value resistors in series-parallel with a thermistor.
The resistance values of RT1 and RT2 can be calculated
with the following equations in order to set the
temperature window of interest.
For NTC thermistors:
EQUATION 6-2:
PowerDissipation = ( 5.5V – 2.7V ) × 550 mA = 1.54W
This power dissipation with the battery charger in the
MSOP-10 package will cause thermal regulation to be
entered as depicted in Figure 6-3. Alternatively, the
3 mm x 3 mm DFN package could be utilized to reduce
the charge cycle times.
6.1.1.3
R T2 × R COLD
24k Ω = R T1 + -------------------------------R T2 + R COLD
R T2 × R HOT
5k Ω = R T1 + ---------------------------R T2 + R HOT
Where:
External Capacitors
The MCP73837/8 is stable with or without a battery
load. In order to maintain good AC stability in the
Constant Voltage mode, a minimum capacitance of
1 µF is recommended to bypass the VBAT pin to VSS.
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.
RT1
=
the fixed series resistance
RT2
=
the fixed parallel resistance
the thermistor resistance at the
lower temperature of interest
RCOLD
RHOT
=
the thermistor resistance at the
upper temperature of interest
For example, by utilizing a 10 kΩ at 25°C NTC
thermistor with a sensitivity index, β, of 3892, the
charge temperature range can be set to 0°C - 50°C by
placing a 1.54 kΩ resistor in series (RT1), and a
69.8 kΩ resistor in parallel (RT2) with the thermistor.
Virtually any good quality output filter capacitor can be
used, independent of the capacitor’s minimum
Effective Series Resistance (ESR) value. The actual
value of the capacitor (and its associated ESR)
depends on the output load current. A 1 µF ceramic,
tantalum, or aluminum electrolytic capacitor at the
output is usually sufficient to ensure stability for output
currents up to 500 mA.
6.1.1.7
6.1.1.4
For optimum voltage regulation, place the battery pack
as close as possible to the device’s VBAT and VSS pins,
recommended to minimize voltage drops along the
high current-carrying PCB traces.
Reverse-Blocking Protection
The MCP73837/8 provides protection from a faulted or
shorted input. Without the protection, a faulted or
shorted input would discharge the battery pack through
the body diode of the internal pass transistor.
6.1.1.5
Charge Inhibit
The current regulation set input pin (PROG1/2) can be
used to terminate a charge at any time during the
charge cycle, as well as to initiate a charge cycle or
initiate a recharge cycle.
© 2007 Microchip Technology Inc.
Charge Status Interface
A status output provides information on the state of
charge. The output can be used to illuminate external
LEDs or interface to a host microcontroller. Refer to
Figure 5-1 for a summary of the state of the status
output during a charge cycle.
6.2
PCB Layout Issues
If the PCB layout is used as a heatsink, adding many
vias in the heatsink pad can help conduct more heat to
the backplane of the PCB, thus reducing the maximum
junction temperature.
DS22071A-page 21
MCP73837/8
7.0
PACKAGING INFORMATION
7.1
Package Marking Information
10-Lead DFN
1
2
3
4
Part Number *
10
XXXX
XYWW
NNN
5
9
8
7
6
Marking
Code
Part Number *
Marking
Code
MCP73837-FCI/MF
BABA
MCP73837T-FCI/MF
MCP73837-FJI/MF
BABB
MCP73837T-FJI/MF
MCP73837-NVI/MF
BABC
MCP73837T-NVI/MF
MCP73838-FCI/MF
BACA
MCP73838T-FCI/MF
MCP73838-FJI/MF
BACB
MCP73838T-FJI/MF
MCP73838-NVI/MF
BACC
MCP73838T-NVI/MF
* Consult Factory for Alternative Device Options.
BABA
BABB
BABC
BACA
BACB
BACC
Marking
Code
Marking
Code
Part Number *
e3
*
DS22071A-page 22
Part Number *
MCP73837-FCI/UN
837FCI MCP73837T-FCI/UN
MCP73837-FJI/UN
837FJI
MCP73837T-FJI/UN
MCP73837-NVI/UN
837NVI MCP73837T-NVI/UN
MCP73838-FCI/UN
838FCI MCP73838T-FCI/UN
MCP73838-FJI/UN
838FJI
MCP73838T-FJII/UN
MCP73838-NVI/UN
838NVI MCP73838T-NVI/UN
* Consult Factory for Alternative Device Options.
* * Consult Factory for MSOP Package Availability.
Legend: XX...X
Y
YY
WW
NNN
Note:
1
2
3
4
10
BABA
0748
256
5
9
8
7
6
Example:
10-Lead MSOP * *
XXXXXX
YWWNNN
Example:
837FCI
837FJI
837NVI
838FCI
838FJI
838NVI
837FCI
748256
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.
MCP73837/8
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© 2007 Microchip Technology Inc.
DS22071A-page 23
MCP73837/8
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DS22071A-page 24
© 2007 Microchip Technology Inc.
MCP73837/8
APPENDIX A:
REVISION HISTORY
Revision A (November 2007)
• Original Release of this Document.
© 2007 Microchip Technology Inc.
DS22071A-page 25
MCP73837/8
NOTES:
DS22071A-page 26
© 2007 Microchip Technology Inc.
MCP73837/8
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.
Device
XX
Examples: * *
XX
X/
Output Temp. Package
Options*
Device:
MCP73837: 1A Fully Integrated Charger,
PG function on pin 8
MCP73837T: 1A Fully Integrated Charger,
PG function on pin 8
(Tape and Reel)
MCP73838: 1A Fully Integrated Charger,
TE function on pin 8
MCP73838T: 1A Fully Integrated Charger,
TE function on pin 8
(Tape and Reel)
Output Options * *
* Refer to table below for different operational options.
a)
b)
c)
d)
e)
f)
MCP73837-FCI/UN:
MCP73837-FJI/UN:
MCP73837-NVI/UN:
MCP73837-FCI/MF:
MCP73837-FJI/MF:
MCP73837-NVI/MF:
10-lead MSOP pkg.
10-lead MSOP pkg.
10-lead MSOP pkg.
10-lead DFN pkg.
10-lead DFN pkg.
10-lead DFN pkg.
a)
b)
c)
d)
e)
f)
MCP73838-FCI/UN:
MCP73838-FJI/UN:
MCP73838-NVI/UN:
MCP73838-FCI/MF:
MCP73838-FJI/MF:
MCP73838-NVI/MF:
10-lead MSOP pkg.
10-lead MSOP pkg.
10-lead MSOP pkg.
10-lead DFN pkg.
10-lead DFN pkg.
10-lead DFN pkg.
* * Consult Factory for Alternative Device Options
* * Consult Factory for Alternative Device Options.
Temperature:
I
= -40°C to +85°C
Package Type:
MF = Plastic Dual Flat No Lead (DFN)
(3x3x0.9 mm Body), 10-lead
UN = Plastic Micro Small Outline Package (MSOP***),
10-lead
* Operational Output Options
Output Options
VREG
IPREG/IREG
VPTH/VREG
ITERM/IREG
VRTH/VREG
Timer Period
AM
BZ
4.20V
10%
71.5%
7.5%
96.5%
0 hours
4.20V
100%
N/A
7.5%
96.5%
0 hours
FC
4.20V
10%
71.5%
7.5%
96.5%
6 hours
GP
4.20V
100%
N/A
7.5%
96.5%
6 hours
G8
4.20V
10%
71.5%
7.5%
96.5%
8 hours
NV
4.35V
10%
71.5%
7.5%
96.5%
6 hours
YA
4.40V
10%
71.5%
7.5%
96.5%
6 hours
6S
4.50V
10%
71.5%
7.5%
96.5%
6 hours
B6
4.20V
10%
66.5%
5.0%
96.5%
4 hours
CN
4.20V
10%
71.5%
20%
94%
4 hours
* * Consult Factory for Alternative Device Options.
* * * Consult Factory for MSOP Package Availability
© 2007 Microchip Technology Inc.
DS22071A-page 27
MCP73837/8
NOTES:
DS22071A-page 28
© 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, KEELOQ logo, microID, MPLAB, PIC,
PICmicro, PICSTART, PRO MATE, rfPIC and SmartShunt are
registered trademarks of Microchip Technology Incorporated
in the U.S.A. and other countries.
AmpLab, FilterLab, Linear Active Thermistor, 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, dsSPEAK, ECAN,
ECONOMONITOR, FanSense, FlexROM, fuzzyLAB,
In-Circuit Serial Programming, ICSP, ICEPIC, Mindi, MiWi,
MPASM, MPLAB Certified logo, MPLIB, MPLINK, PICkit,
PICDEM, PICDEM.net, PICLAB, PICtail, PowerCal,
PowerInfo, PowerMate, PowerTool, REAL ICE, rfLAB, 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 design centers in California
and India. 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.
DS22071A-page 29
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Technical Support:
http://support.microchip.com
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www.microchip.com
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Fax: 63-2-634-9069
China - Shanghai
Tel: 86-21-5407-5533
Fax: 86-21-5407-5066
Singapore
Tel: 65-6334-8870
Fax: 65-6334-8850
China - Shenyang
Tel: 86-24-2334-2829
Fax: 86-24-2334-2393
Taiwan - Hsin Chu
Tel: 886-3-572-9526
Fax: 886-3-572-6459
China - Shenzhen
Tel: 86-755-8203-2660
Fax: 86-755-8203-1760
Taiwan - Kaohsiung
Tel: 886-7-536-4818
Fax: 886-7-536-4803
China - Shunde
Tel: 86-757-2839-5507
Fax: 86-757-2839-5571
Taiwan - Taipei
Tel: 886-2-2500-6610
Fax: 886-2-2508-0102
China - Wuhan
Tel: 86-27-5980-5300
Fax: 86-27-5980-5118
Thailand - Bangkok
Tel: 66-2-694-1351
Fax: 66-2-694-1350
Italy - Milan
Tel: 39-0331-742611
Fax: 39-0331-466781
Netherlands - Drunen
Tel: 31-416-690399
Fax: 31-416-690340
Spain - Madrid
Tel: 34-91-708-08-90
Fax: 34-91-708-08-91
UK - Wokingham
Tel: 44-118-921-5869
Fax: 44-118-921-5820
China - Xian
Tel: 86-29-8833-7252
Fax: 86-29-8833-7256
10/05/07
DS22071A-page 30
© 2007 Microchip Technology Inc.