MICROCHIP MCP73812

MCP73811/2
Simple, Miniature Single-Cell, Fully Integrated
Li-Ion / Li-Polymer Charge Management Controllers
Features
Description
• Complete Linear Charge Management Controller
- Integrated Pass Transistor
- Integrated Current Sense
- Integrated Reverse Discharge Protection
• Constant Current / Constant Voltage Operation
with Thermal Regulation
• High Accuracy Preset Voltage Regulation: + 1%
• Voltage Regulation: 4.20V
• Selectable Charge Current:
- MCP73811: 85 mA / 450 mA
• Programmable Charge Current:
- MCP73812: 50 mA - 500 mA
• Minimum External Components Required:
- MCP73811: 2 Ceramic Capacitors
- MCP73812: 2 Ceramic Capacitors and
1 Resistor
• No Preconditioning
• No End-of-Charge Control
• No Undervoltage Lockout (UVLO)
• Automatic Power-Down when Input Power
Removed
• Active High Charge Enable
• Temperature Range:
- -40°C to +85°C
• Packaging:
- 5-Lead SOT-23
The MCP73811/2 devices are linear charge management controllers that are designed for use in space
limited and cost sensitive applications. The
MCP73811/2 provide specific charge algorithms for
single cell Li-Ion or Li-Polymer battery to achieve
optimal capacity in the shortest charging time possible.
Along with its small physical size, the low number of
external components required make the MCP73811/2
ideally suited for portable applications. For applications
charging from a USB port, the MCP73811 adheres to
all the specifications governing the USB power bus.
The MCP73811/2 employ a constant current/constant
voltage charge algorithm. The constant voltage regulation is fixed at 4.20V, with a tight regulation tolerance of
1%. For the MCP73811, the constant current value is
selected as 85 mA (low power USB port) or 450 mA
(high power USB port) with a digital input signal on the
PROG input. For the MCP73812, the constant current
value is set with one external resistor. The
MCP73811/2 limit the charge current based on die
temperature during high power or high ambient
conditions. This thermal regulation optimizes the
charge cycle time while maintaining device reliability.
The MCP73811/2 are fully specified over the ambient
temperature range of -40°C to +85°C. The
MCP73811/2 are available in a 5-Lead, SOT-23
package.
Package Types
5-Pin SOT-23
Applications
• Low-Cost Lithium-Ion/Lithium-Polymer Battery
Chargers
• Rechargeable Toys
• Electronic Cigarettes
• Bluetooth Headsets
• USB Chargers
© 2007 Microchip Technology Inc.
CE
1
VSS
2
VBAT
3
5
PROG
4
VDD
DS22036A-page 1
MCP73811/2
Typical Applications
450 mA Li-Ion Battery Charger
VIN
1 µF
4
5
1
VBAT 3
1 µF
VDD
500 mA Li-Ion Battery Charger
4 V
DD
VIN
1 µF
+ Single
Li-Ion
- Cell
PROG
PROG
VSS 2
CE
VBAT 3
1 µF
1 CE
MCP73811
+ Single
Li-Ion
- Cell
5
VSS 2
2 kΩ
MCP73812
Functional Block Diagram
Direction
Control
VDD
VBAT
6µA
G=0.001
MCP73812
MCP73811
+
CA
-
2.7 kΩ
PROG
12 kΩ
388.7 kΩ
+
Reference
Generator
VA
111 kΩ
Direction
Control
VREF (1.21V)
157.3 kΩ
+
VBAT
CE
VSS
DS22036A-page 2
-
528.6 kΩ
Charge
Enable
+
-
© 2007 Microchip Technology Inc.
MCP73811/2
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 (200pF, No Series Resistance) ..............400V
DC CHARACTERISTICS
Electrical Specifications: Unless otherwise indicated, all limits apply for VDD= [VREG(typ.) + 0.3V] to 6V,
TA = -40°C to +85°C. Typical values are at +25°C, VDD = [VREG (typ.) + 1.0V]
Parameters
Sym
Min
Typ
Max
Units
Conditions
Supply Voltage
VDD
3.75
—
6
V
Supply Current
ISS
—
1000
1500
µA
Charging
—
50
100
µA
Standby (CE = VSS)
—
1.2
5
µA
Shutdown
(VDD < VBAT - 100 mV)
—
4.20
—
V
VDD=[VREG(Typ)+1V]
IOUT=10 mA
TA=-5°C to +55°C
Supply Input
Voltage Regulation (Constant Voltage Mode)
Regulated Output Voltage
VREG
VRTOL
-1
—
+1
%
Line Regulation
|(ΔVBAT/VBAT)
/ΔVDD|
—
0.09
0.30
%/V
Load Regulation
|ΔVBAT/VBAT|
—
0.09
0.30
%
IOUT=10 mA to 50 mA
VDD=[VREG(Typ)+1V]
PSRR
—
52
—
dB
IOUT=10 mA, 10 Hz to 1 kHz
—
47
—
dB
IOUT=10 mA, 10 Hz to 10 kHz
—
22
—
dB
IOUT=10 mA, 10 Hz to 1 MHz
Output Voltage Tolerance
Supply Ripple Attenuation
VDD=[VREG(Typ)+1V] to 6V
IOUT=10 mA
Current Regulation (Fast Charge Constant-Current Mode)
—
85
—
mA
MCP73811 - PROG = Low
—
450
—
mA
MCP73811 - PROG = High
—
50
—
mA
MCP73812 - PROG = 20 kΩ
—
100
—
mA
MCP73812 - PROG = 10 kΩ
—
500
—
mA
IRTOL
-10
—
+10
%
RDSON
—
400
—
mΩ
VDD = 3.75V, TJ = 105°C
—
0.5
2
µA
Shutdown
(VDD < VBAT - 100 mV)
Fast Charge Current
IREG
Regulation
Charge Current Tolerance
MCP73812 - PROG = 2 kΩ
TA=-5°C to +55°C
Pass Transistor ON-Resistance
ON-Resistance
Battery Discharge Current
Output Reverse Leakage
IDISCHARGE
Current
© 2007 Microchip Technology Inc.
DS22036A-page 3
MCP73811/2
DC CHARACTERISTICS (Continued)
Electrical Specifications: Unless otherwise indicated, all limits apply for VDD= [VREG(typ.) + 0.3V] to 6V,
TA = -40°C to +85°C. Typical values are at +25°C, VDD = [VREG (typ.) + 1.0V]
Parameters
Sym
Min
Typ
Max
Units
Conditions
Charge Enable (CE), PROG Input - MCP73811
Input High Voltage Level
VIH
2
—
—
V
Input Low Voltage Level
VIL
—
—
0.8
V
Input Leakage Current
ILK
—
0.01
1
µA
VCE = VDD, VPROG = VDD
RPROG
2
—
20
kΩ
MCP73812
PROG Input - MCP73812
Charge Impedance Range
Automatic Power Down (Direction Control)
Automatic Power Down
Entry Threshold
VPD
VBAT +
10 mV
VBAT +
50 mV
—
V
2.3V < VBAT < VREG
VDD Falling
Automatic Power Down
Exit Threshold
VPDEXIT
—
VBAT +
150 mV
VBAT +
250 mV
V
2.3V < VBAT < VREG
VDD Rising
Die Temperature
TSD
—
150
—
°C
Die Temperature
TSDHYS
—
10
—
°C
Thermal Shutdown
Hysteresis
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
Specified Temperature Range
TA
-40
—
+85
°C
Operating Temperature Range
TJ
-40
—
+125
°C
Storage Temperature Range
TA
-65
—
+150
°C
θJA
—
230
—
°C/W
Conditions
Temperature Ranges
Thermal Package Resistances
Thermal Resistance, 5-Lead, SOT-23
DS22036A-page 4
4-Layer JC51-7 Standard Board,
Natural Convection
© 2007 Microchip Technology Inc.
MCP73811/2
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.
4.210
4.205
Charge Current (mA)
Battery Regulation Voltage
(V)
Note: Unless otherwise indicated, VDD = [VREG(typ.) + 1V], IOUT = 10 mA and TA= +25°C, Constant-voltage mode.
IOUT = 10 mA
4.200
4.195
4.190
IOUT = 100 mA
4.185
IOUT = 450 mA
4.180
4.175
4.170
4.50
4.75
5.00
5.25
5.50
5.75
6.00
90
89
88
87
86
85
84
83
82
81
80
PROG = Low
Temp = +25°C
4.5
4.75
455
Charge Current (mA)
460
4.205
IOUT = 10 mA
4.195
4.190
IOUT = 100 mA
4.180
4.175
IOUT = 450 mA
445
440
435
430
4.5
Charge Current (mA)
Output Leakage Current (µA)
4.00
4.20
Battery Regulation Voltage (V)
FIGURE 2-3:
Output Leakage Current
(IDISCHARGE) vs. Battery Regulation Voltage
(VBAT).
© 2007 Microchip Technology Inc.
4.75
5
5.25
5.5
5.75
6
FIGURE 2-5:
Charge Current (IOUT) vs.
Supply Voltage (VDD) - MCP73811.
100
3.80
PROG = High
Temp = 25°C
Supply Voltage (V)
FIGURE 2-2:
Battery Regulation Voltage
(VBAT) vs. Ambient Temperature (TA).
3.60
6
450
Ambient Temperature (°C)
3.40
5.75
425
80
70
60
50
40
30
20
0
10
-10
-20
-30
4.170
0.40
0.35 +85°C
0.30
-40°C
0.25
0.20
+25°C
0.15
0.10
0.05
0.00
3.00
3.20
5.5
FIGURE 2-4:
Charge Current (IOUT) vs.
Supply Voltage (VDD) - MCP73811.
4.210
-40
Battery Regulation Voltage (V)
FIGURE 2-1:
Battery Regulation Voltage
(VBAT) vs. Supply Voltage (VDD).
4.185
5.25
Supply Voltage (V)
Supply Voltage (V)
4.200
5
95
PROG = Low
VDD = 5V
90
85
80
75
70
65
-40 -30 -20 -10 0 10 20 30 40 50 60 70 80
Ambient Temperature (°C)
FIGURE 2-6:
Charge Current (IOUT) vs.
Ambient Temperature (TA) - MCP73811.
DS22036A-page 5
MCP73811/2
Typical Performance Curves (Continued)
Note: Unless otherwise indicated, VDD = [VREG(typ.) + 1V], IOUT = 10 mA and TA= +25°C, Constant-voltage mode.
516
PROG = High
VDD = 5V
470
Charge Current (mA)
460
450
440
430
420
410
RPROG = 2 kΩ
514
512
510
508
506
504
502
500
4.50
400
-40 -30 -20 -10 0 10 20 30 40 50 60 70 80
4.75
5.00
5.50
5.75
6.00
550
500
450
400
350
300
250
200
150
100
50
0
FIGURE 2-10:
Charge Current (IOUT) vs.
Supply Voltage (VDD) - MCP73812.
104
Charge Current (mA)
RPROG = 10 kΩ
103
102
101
100
99
98
97
Programming Resistor (kΩ)
516
Charge Current (mA)
102
101
100
99
98
97
80
RPROG = 2 kΩ
514
512
510
508
506
504
502
Supply Voltage (V)
FIGURE 2-9:
Charge Current (IOUT) vs.
Supply Voltage (VDD) - MCP73812.
DS22036A-page 6
80
70
60
50
40
30
6.00
20
5.75
10
5.50
-10
5.25
-20
5.00
-30
500
4.75
-40
96
4.50
FIGURE 2-11:
Charge Current (IOUT) vs.
Ambient Temperature (TA) - MCP73812.
RPROG = 10 kΩ
103
70
Ambient Temperature (°C)
FIGURE 2-8:
Charge Current (IOUT) vs.
Programming Resistor (RPROG) - MCP73812.
104
60
20
50
18
40
16
30
14
20
12
0
10
10
8
-10
6
-20
4
-30
96
2
-40
Charge Current (mA)
FIGURE 2-7:
Charge Current (IOUT) vs.
Ambient Temperature (TA) - MCP73811.
Charge Current (mA)
5.25
Supply Voltage (V)
Ambient Temperature (°C)
0
Charge Current (mA)
480
Ambient Temperature (°C)
FIGURE 2-12:
Charge Current (IOUT) vs.
Ambient Temperature (TA) - MCP73812.
© 2007 Microchip Technology Inc.
MCP73811/2
Typical Performance Curves (Continued)
Note: Unless otherwise indicated, VDD = [VREG(typ.) + 1V], IOUT = 10 mA and TA= +25°C, Constant-voltage mode.
0
RPROG = 10 kΩ
-10
90
75
60
45
30
15
-30
-40
-50
-60
0.01
155
145
135
0.1
-0.05
6
-0.10
4
-0.15
2
0
-50
80
0.10
12
0.05
10
0.00
8
-0.05
6
-0.10
4
-0.15
2
0
© 2007 Microchip Technology Inc.
100
-0.25
-0.30
Time (µs)
Frequency (kHz)
FIGURE 2-15:
Power Supply Ripple
Rejection (PSRR).
80
1000
60
100
40
0
10
20
-2
1
-0.20
IOUT = 100 mA
COUT = 4.7 µF, X7R
Ceramic
Output Ripple (V)
-40
14
200
-30
0.1
-0.30
Line Transient Response.
180
Source Voltage (V)
Attenuation (dB)
VAC = 100 mVp-p
IOUT = 10 mA
COUT = 4.7 μF, X7R
Ceramic
FIGURE 2-17:
160
FIGURE 2-14:
Charge Current (IOUT) vs.
Junction Temperature (TJ) - MCP73812.
-60
0.01
-0.25
Time (µs)
Junction Temperature (°C)
-20
100
60
40
0
20
-2
155
145
135
125
115
105
95
85
75
65
55
45
35
25
0
-0.20
IOUT = 10 mA
COUT = 4.7 µF, X7R
Ceramic
Output Ripple (V)
75
0.00
8
200
150
0.05
10
180
225
0.10
12
160
300
-10
1000
14
140
Source Voltage (V)
Charge Current (mA)
RPROG = 2 kΩ
375
0
100
FIGURE 2-16:
Power Supply Ripple
Rejection (PSRR).
120
FIGURE 2-13:
Charge Current (IOUT) vs.
Junction Temperature (TJ) - MCP73812.
450
10
Frequency (kHz)
Junction Temperature (°C)
525
1
140
125
115
95
105
85
75
65
55
45
35
25
0
-20
VAC = 100 mVp-p
IOUT = 100 mA
COUT = 4.7 µF, X7R
Ceramic
120
105
Attenuation (dB)
Charge Current (mA)
120
FIGURE 2-18:
Line Transient Response.
DS22036A-page 7
MCP73811/2
Typical Performance Curves (Continued)
-0.10
20
0
0
200
180
160
140
Time (µs)
0.60
-0.10
0.40
-0.15
0.20
-0.20
COUT = 4.7 µF, X7R
Ceramic
0.00
-0.25
200
180
160
140
120
100
80
60
40
20
-0.30
0
-0.20
Time (µs)
FIGURE 2-20:
DS22036A-page 8
Load Transient Response.
400
3.0
300
2.0
200
MCP738312
VDD = 5.2V
RPROG = 2 kΩ
1.0
100
0.0
Charge Current (mA)
-0.05
500
4.0
0
240
0.80
5.0
210
0.00
600
90
1.00
6.0
60
0.05
30
0.10
1.20
0
1.40
FIGURE 2-21:
Complete Charge Cycle
(180 mAh Li-Ion Battery).
Battery Voltage (V)
Load Transient Response.
Output Ripple (V)
Output Current (A)
FIGURE 2-19:
Time (s)
180
120
80
100
60
40
0
1.0
0.0
-0.12
20
40
MCP73812/IOT
VDD = 5.2V
RPROG = 10 kΩ
150
0.00
-0.05
2.0
Charge Current (mA)
-0.08
COUT = 4.7 µF, X7R
Ceramic
60
120
0.05
3.0
180
-0.06
160
-0.04
0.10
140
0.15
80
120
-0.02
100
4.0
80
0.20
5.0
100
0.00
120
60
0.25
6.0
40
0.02
20
0.04
0.30
Battery Voltage (V)
0.35
Output Ripple (V)
Output Current (A)
Note: Unless otherwise indicated, VDD = [VREG(typ.) + 1V], IOUT = 10 mA and TA= +25°C, Constant-voltage mode.
Time (s)
FIGURE 2-22:
Complete Charge Cycle
(1000 mAh Li-Ion Battery).
© 2007 Microchip Technology Inc.
MCP73811/2
3.0
PIN DESCRIPTION
The descriptions of the pins are listed in Table 3-1.
TABLE 3-1:
Pin Number
SOT-23-5
1
3.1
PIN FUNCTION TABLES
Symbol
Function
CE
Active High Charge Enable
2
VSS
Battery Management 0V Reference
3
VBAT
Battery Charge Control Output
4
VDD
Battery Management Input Supply
5
PROG
Current Regulation Set and Charge Control Enable
Charge Enable Input (CE)
3.4
Battery Management Input Supply
(VDD)
A logic High enables battery charging. A logic Low
disables battery charging. The charge enable input is
compatible with 1.8V logic.
A supply voltage of [VREG (typ.) + 0.3V] to 6V is
recommended. Bypass to VSS with a minimum of 1 µF.
3.2
3.5
Battery Management 0V Reference
(VSS)
Connect to negative terminal of battery and input
supply.
3.3
Battery Charge Control Output
(VBAT)
Current Regulation Set (PROG)
For the MCP73811, the current regulation set input
(PROG) functions as a digital input selection. A logic
Low selects a 85 mA charge current; a logic High
selects a 450 mA charge current.
For the MCP73812, the charge current is set by placing
a resistor from PROG to VSS.
Connect to positive terminal of battery. Drain terminal
of internal P-channel MOSFET pass transistor. Bypass
to VSS with a minimum of 1 µF to ensure loop stability
when the battery is disconnected.
© 2007 Microchip Technology Inc.
DS22036A-page 9
MCP73811/2
4.0
DEVICE OVERVIEW
The MCP73811/2 are simple, but fully integrated linear
charge management controllers. Figure 4-1 depicts the
operational flow algorithm.
4.3
PRECONDITIONING
The MCP73811/2 does not support preconditioning of
deeply depleted cells.
4.4
SHUTDOWN MODE*
VDD < VPD
Constant Current MODE - Fast
Charge
During the constant current mode, the selected
(MCP73811) or programmed (MCP73812) charge
current is supplied to the battery or load.
For the MCP73812, 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:
STANDBY MODE*
CE = Low
EQUATION 4-1:
CONSTANT CURRENT
MODE
Charge Current = IREG
VBAT < VREG
* Continuously
Monitored
4.1
Flow Chart.
Undervoltage Lockout (UVLO)
The MCP73811/2 does not have an internal under
voltage lockout (UVLO) circuit.
4.2
Where:
VBAT = VREG
CONSTANT VOLTAGE
MODE
Charge Voltage = VREG
FIGURE 4-1:
1000V
I REG = ----------------R PROG
Charge Qualification
When the input power is applied, the input supply must
rise 150 mV above the battery voltage before the
MCP73811/2 becomes operational.
The automatic power down circuit places the device in
a shutdown mode if the input supply falls to within
+50 mV of the battery voltage.
The automatic circuit is always active. Whenever the
input supply is within +50 mV of the voltage at the VBAT
pin, the MCP73811/2 is placed in a shutdown mode.
RPROG
=
kilo-ohms
IREG
=
milliamperes
Constant current mode is maintained until the voltage
at the VBAT pin reaches the regulation voltage, VREG.
4.5
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
with a tolerance of ±1.0%.
4.6
Charge Termination
The charge cycle is terminated by removing the battery
from the charger, removing input power, or driving the
charge enable input (CE) to a logic Low. An automatic
charge termination method is not implemented.
4.7
Automatic Recharge
The MCP73811/2 does not support automatic recharge
cycles since automatic charge termination has not
been implemented. In essence, the MCP73811/2 is
always in a charge cycle whenever the qualification
parameters have been met.
During power down condition, the battery reverse discharge current is less than 2 µA.
For a charge cycle to begin, the automatic power down
conditions must be met and the charge enable input
must be above the input high threshold.
DS22036A-page 10
© 2007 Microchip Technology Inc.
MCP73811/2
4.8
Thermal Regulation
4.9
The MCP73811/2 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 MCP73811/2.
.
Charge Current (mA)
525
Thermal Shutdown
The MCP73811/2 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.
RPROG = 2 kΩ
450
375
300
225
150
75
155
145
135
125
115
95
105
85
75
65
55
45
35
25
0
Junction Temperature (°C)
FIGURE 4-2:
Thermal Regulation.
© 2007 Microchip Technology Inc.
DS22036A-page 11
MCP73811/2
5.0
DETAILED DESCRIPTION
5.2
5.1
Analog Circuitry
5.2.1
5.1.1
BATTERY MANAGEMENT INPUT
SUPPLY (VDD)
The VDD input is the input supply to the MCP73811/2.
The MCP73811/2 automatically enters a Power-down
mode if the voltage on the VDD input falls to within
+50 mV of the battery voltage. This feature prevents
draining the battery pack when the VDD supply is not
present.
5.1.2
MCP73812 CURRENT REGULATION
SET (PROG)
For the MCP73812, 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:
Digital Circuitry
CHARGE ENABLE (CE)
The charge enable input pin (CE) 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.
Driving the input to a logic High enables the device.
Driving the input to a logic Low disables the device and
terminates a charge cycle. When disabled, the device’s
supply current is reduced to 50 µA, typically.
5.2.2
MCP73811 CURRENT REGULATION
SELECT (PROG)
For the MCP73811, driving the PROG input to a logic
Low selects the low charge current setting (85 mA).
Driving the PROG input to a logic High selects the high
charge current setting (450 mA).
EQUATION 5-1:
1000VI REG = ---------------R PROG
Where:
5.1.3
RPROG
=
kilo-ohms
IREG
=
milliamperes
BATTERY CHARGE CONTROL
OUTPUT (VBAT)
The battery charge control output is the drain terminal
of an internal P-channel MOSFET. The MCP73811/2
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.
DS22036A-page 12
© 2007 Microchip Technology Inc.
MCP73811/2
6.0
APPLICATIONS
charge algorithm for Lithium-Ion and Lithium-Polymer
cells Constant-current followed by Constant-voltage.
Figure 6-1 depicts a typical stand-alone application
circuit, while Figures 6-2 and 6-3 depict the
accompanying charge profile.
The MCP73811/2 is designed to operate in conjunction
with a host microcontroller or in stand-alone
applications. The MCP73811/2 provides the preferred
Li-Ion Battery Charger
4 V
DD
CIN
VBAT
3
PROG
5
VSS
2
COUT
REGULATED
WALL CUBE
1 CE
+ Single
Li-Ion
- Cell
RPROG
MCP73812
FIGURE 6-1:
Typical Application Circuit.
120
5.0
100
4.0
80
3.0
60
2.0
40
MCP73812/IOT
VDD = 5.2V
RPROG = 10 kΩ
1.0
20
180
160
140
120
100
80
60
40
20
0
0
0.0
Charge Current (mA)
Battery Voltage (V)
6.1
6.0
Time (s)
600
5.0
500
4.0
400
3.0
300
2.0
200
MCP738312
VDD = 5.2V
RPROG = 2 kΩ
1.0
100
240
210
180
150
120
90
60
30
0
0
0.0
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.
Charge Current (mA)
Battery Voltage (V)
6.0
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
(180 mAh Battery).
Application Circuit Design
6.1.1.1
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.
Time (s)
FIGURE 6-3:
Typical Charge Profile in
Thermal Regulation (1000 mAh Battery).
© 2007 Microchip Technology Inc.
DS22036A-page 13
MCP73811/2
6.1.1.2
Thermal Considerations
6.1.1.5
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:
EQUATION 6-1:
PowerDissipation = ( V
DDMAX
–V
PTHMIN
)×I
REGMAX
Where:
The charge enable input pin (CE) 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.
Driving the input to a logic High enables the device.
Driving the input to a logic Low disables the device and
terminates a charge cycle. When disabled, the device’s
supply current is reduced to 50 µA, typically.
6.2
VDDMAX
=
the maximum input voltage
IREGMAX
=
the maximum fast charge current
VPTHMIN
=
the minimum transition threshold
voltage
Power dissipation with a 5V, ±10% input voltage source
is:
EQUATION 6-2:
Charge Inhibit
PCB Layout Issues
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.
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. Figures 6-4 and 6-5 depict a
typical layout with PCB heatsinking.
PowerDissipation = ( 5.5V – 2.7V ) × 500 mA = 1.4 W
RPROG
VSS
This power dissipation with the battery charger in the
SOT-23-5 package will cause thermal regulation to be
entered as depicted in Figure 6-3.
6.1.1.3
COUT
CIN
VDD
External Capacitors
The MCP73811/2 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.
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 a 500 mA.
6.1.1.4
VBAT
MCP73812
FIGURE 6-4:
Typical Layout (Top).
VSS
VBAT
FIGURE 6-5:
VDD
Typical Layout (Bottom).
Reverse-Blocking Protection
The MCP73811/2 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.
DS22036A-page 14
© 2007 Microchip Technology Inc.
MCP73811/2
7.0
PACKAGE INFORMATION
7.1
Package Marking Information
5-Pin SOT-23
Example:
Standard *
XXNN
Part Number
MCP73811T-420I/OT
MCP73812T-420I/OT
1
KSNN
Code
KSNN
KWNN
1
* Custom output voltages available upon request.
Contact your local Microchip sales office for more information.
Legend: XX...X
Y
YY
WW
NNN
e3
*
Note:
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.
DS22036A-page 15
MCP73811/2
5-Lead Plastic Small Outline Transistor (OT or CT) [SOT-23]
Note:
For the most current package drawings, please see the Microchip Packaging Specification located at
http://www.microchip.com/packaging
b
N
E
E1
3
2
1
e
e1
D
A2
A
c
φ
A1
L
L1
Units
Dimension Limits
Number of Pins
MILLIMETERS
MIN
NOM
MAX
N
5
Lead Pitch
e
0.95 BSC
Outside Lead Pitch
e1
Overall Height
A
0.90
–
Molded Package Thickness
A2
0.89
–
1.30
Standoff
A1
0.00
–
0.15
Overall Width
E
2.20
–
3.20
Molded Package Width
E1
1.30
–
1.80
Overall Length
D
2.70
–
3.10
Foot Length
L
0.10
–
0.60
Footprint
L1
0.35
–
0.80
Foot Angle
φ
0°
–
30°
Lead Thickness
c
0.08
–
0.26
1.90 BSC
1.45
Lead Width
b
0.20
–
0.51
Notes:
1. Dimensions D and E1 do not include mold flash or protrusions. Mold flash or protrusions shall not exceed 0.127 mm per side.
2. Dimensioning and tolerancing per ASME Y14.5M.
BSC: Basic Dimension. Theoretically exact value shown without tolerances.
Microchip Technology Drawing C04-091B
DS22036A-page 16
© 2007 Microchip Technology Inc.
MCP73811/2
APPENDIX A:
REVISION HISTORY
Revision A (March 2007)
• Original Release of this Document.
© 2007 Microchip Technology Inc.
DS22036A-page 17
MCP73811/2
NOTES:
DS22036A-page 18
© 2007 Microchip Technology Inc.
MCP73811/2
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.
— XXX
Device
Device:
Voltage Options *:
X
/XX
Voltage Temperature Package
Options
MCP73811T: Li-Ion Charger w/Selectable Charge Current,
Tape and Reel
MCP73812T: Li-Ion Charger w/Selectable Charge Current,
Tape and Reel
Examples:
a)
MCP73811T-420I/OT:
4.2V Charger
SOT-23-5 pkg.
a)
MCP73812T-420I/OT:
4.2V Charger
SOT-23-5 pkg.
420 = 4.2V “Standard”
*Contact factory for other output voltage options.
Temperature:
I
= -40°C to +85°C
Package Type:
OT = Small Outline Transistor (SOT-23), 5-lead
© 2007 Microchip Technology Inc.
DS22036A-page 19
MCP73811/2
NOTES:
DS22036A-page 20
© 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
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The Microchip name and logo, the Microchip logo, Accuron,
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All other trademarks mentioned herein are property of their
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© 2007, Microchip Technology Incorporated, Printed in the
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Printed on recycled paper.
Microchip received ISO/TS-16949:2002 certification for its worldwide
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Company’s quality system processes and procedures are for its PIC®
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EEPROMs, microperipherals, nonvolatile memory and analog
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© 2007 Microchip Technology Inc.
DS22036A-page 21
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DS22036A-page 22
© 2007 Microchip Technology Inc.