MCP73853/55
USB Compatible Li-Ion/Li-Polymer
Charge Management Controllers
Features
Description
• Linear Charge Management Controllers
- Integrated Pass Transistor
- Integrated Current Sense
- Reverse Blocking Protection
• High-Accuracy Preset Voltage Regulation: + 0.5%
• Two Selectable Voltage Regulation Options:
- 4.1V, 4.2V
• Programmable Charge Current
• USB Compatible Charge Current Settings
• Programmable Safety Charge Timers
• Preconditioning of Deeply Depleted Cells
• Automatic End-of-Charge Control
• Optional Continuous Cell Temperature Monitoring
The MCP7385X devices are highly-advanced, linear
charge management controllers, for use in spacelimited, cost-sensitive applications. The MCP73853
combines high-accuracy constant-voltage, constantcurrent regulation, cell preconditioning, cell temperature
monitoring, advanced safety timers, automatic charge
termination, internal current sensing, reverse blocking
protection and charge status and fault indication in a
space-saving 16-lead, 4x4 QFN package.
MCP73853
The MCP73855 employs all the features of the
MCP73853, with the exception of the cell temperature
monitor and one status output. The MCP73855 is
offered in a space-saving 10-lead, 3x3 DFN package.
The MCP73853 and MCP73855 are designed
specifically for USB applications, adhering to all the
specifications governing the USB power bus.
• Charge Status Output for Direct LED Drive
• Fault Output for Direct LED Drive
The MCP7385X devices provide two selectable
voltage regulation options (4.1V or 4.2V) for use with
either coke or graphite anodes.
MCP73853
These devices have complete and fully-functional,
charge management solutions, operating with an input
voltage range of 4.5V to 5.5V. These are fully specified
over the ambient temperature range of -40°C to +85°C.
VSS2
EN
16 15 14 13
12 VBAT3
VSET 1
VDD1 2
11 VBAT2
EP
17
VDD2 3
10 VBAT1
9 VSS3
VSS1 4
6
7
STAT1 1
VSET 2
VDD1 3
VSS1 4
PROG 5
8
TIMER
MCP73855
3x3 DFN*
5
THERM
Lithium-Ion/Lithium-Polymer Battery Chargers
Personal Data Assistants (PDAs)
Cellular Telephones
Hand-Held Instruments
Cradle Chargers
Digital Cameras
MP3 Players
Bluetooth Headsets
USB Chargers
STAT2
MCP73853
4x4 QFN*
Applications
•
•
•
•
•
•
•
•
•
STAT1
Package Types
PROG
• Packaging:
- 16-Lead, 4x4 mm QFN (MCP73853)
- 10-Lead, 3x3 mm DFN (MCP73855)
THREF
• Automatic Power-Down
• Thermal Regulation
• Temperature Range: -40°C to +85°C
10 EN
EP
11
9 VBAT2
8 VBAT1
7 VSS2
6 TIMER
*Exposed Pad (EP) is at VSS potential.
2004-2013 Microchip Technology Inc.
DS21915C-page 1
MCP73853/55
Typical Application
400 mA Lithium-Ion Battery Charger
3
5V
4.7 µF
2
10
1
5
VDD1
VSET
VBAT1 8
9
V
4.7 µF
BAT2
EN
STAT1
PROG
+ Single
– Lithium-Ion
Cell
6
TIMER
0.1 µF
4, 7
VSS
MCP73855
Functional Block Diagram
Direction
Control
VDD1
VBAT1
VDD2
VBAT2
VDD
G = 0.001
4 k
PROG
90
k
Charge Current
Control Amplifier
Voltage Control
Amplifier
+
–
110 k
Charge
10 k
Termination
Comparator
+
IREG/12
–
10 k
+
–
VREF
+
11 k
VREF
Precondition
Control
Charge_OK
Precon.
UVLO
COMPARATOR
–
VBAT3
Precondition
Comp.
Constant-voltage/
Recharge Comp.
VUVLO
149 k
+
–
EN
600 k
–
+
VREF
3 k
Power-On
Delay
1.58 k
VREF
300 k
Bias and
Reference
Generator
VUVLO
VREF(1.2V)
VSET
10.3 k
THREF
100 k
+
-
THERM
Temperature
Comparators
50 k
+
-
50 k
TIMER
MCP73853 ONLY
VSS1
VSS2
VSS3
STAT1
IREG/12
Oscillator
Drv Stat 1
Charge Control,
Charge Timers,
and
Drv Stat 2
Status Logic
STAT2
MCP73853 ONLY
Charge_OK
DS21915C-page 2
2004-2013 Microchip Technology Inc.
MCP73853/55
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*
VDD1,2 .............................................................................6.5V
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 (1.5k in Series with 100pF) 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 5.5V,
TA = -40°C to 85°C. Typical values are at +25°C, VDD = [VREG (Typ) + 1.0V]
Parameters
Sym
Min
Typ
Max
Supply Voltage
VDD
Supply Current
ISS
—
UVLO Start Threshold
VSTART
4.25
UVLO Stop Threshold
VSTOP
4.20
Units
Conditions
4.5
—
5.5
V
—
0.28
4
µA
0.83
4
mA
4.45
4.65
V
VDD Low-to-High
4.40
4.55
V
VDD High-to-Low
4.079
4.1
4.121
V
VSET = VSS
4.179
4.2
4.221
V
VSET = VDD
Supply Input
Disabled
Operating
Voltage Regulation (Constant-Voltage Mode)
Regulated Output Voltage
VREG
VDD = [VREG(Typ) + 1V],
IOUT = 10 mA, TA = -5°C to +55°C
Line Regulation
VBAT/
VBAT)| /VDD
—
0.020
0.25
Load Regulation
VBAT/VBAT|
—
0.022
0.25
%
IOUT = 10 mA to 150 mA
VDD = [VREG(Typ) + 1V]
PSRR
—
50
—
dB
IOUT = 10 mA, 10 Hz to 1 kHz
—
26
—
dB
IOUT = 10 mA, 10 Hz to 10 kHz
—
24
—
dB
IOUT = 10 mA, 10 Hz to 1 MHz
—
0.24
1
µA
VDD < VBAT = VREG(Typ)
Supply Ripple Attenuation
Output Reverse-Leakage
Current
IDISCHARGE
%/V VDD = [VREG(Typ) + 1V] to 5.5V
IOUT = 10 mA
Current Regulation (Fast Charge Constant-Current Mode)
Fast Charge Current
Regulation
IREG
70
85
100
mA
PROG = OPEN
325
400
475
mA
PROG = VSS
TA = -5°C to +55°C
Preconditioning Current Regulation (Trickle Charge Constant-Current Mode)
Precondition Current
Regulation
IPREG
Precondition Threshold
Voltage
VPTH
5
9
15
mA
PROG = OPEN
25
40
75
mA
PROG = VSS
2.70
2.80
2.90
V
VSET = VSS
2.75
2.85
2.95
V
VSET = VDD
TA = -5°C to +55°C
VBAT Low-to-High
2004-2013 Microchip Technology Inc.
DS21915C-page 3
MCP73853/55
DC CHARACTERISTICS (Continued)
Electrical Specifications: Unless otherwise indicated, all limits apply for VDD = [VREG(Typ) + 0.3V] to 5.5V,
TA = -40°C to 85°C. Typical values are at +25°C, VDD = [VREG (Typ) + 1.0V]
Parameters
Sym
Min
Typ
Max
Units
Conditions
ITERM
3.7
6.5
9.3
mA
PROG = OPEN
18
32
46
mA
PROG = VSS
Charge Termination
Charge Termination Current
TA = -5°C to +55°C
Automatic Recharge
Recharge Threshold Voltage
VRTH
VREG – VREG – VREG –
300mV 200mV 100mV
V
VBAT High-to-Low
TA = 25°C, VDD = VREG(Typ) + 1V,
ITHREF = 0 mA
Thermistor Reference - MCP73853
Thermistor Reference
Output Voltage
VTHREF
2.475
2.55
2.625
V
Thermistor Reference
Source Current
ITHREF
200
—
—
µA
VTHREF/
—
0.05
0.25
0.02
0.10
Thermistor Reference Line
Regulation
VTHREF)|/VDD
Thermistor Reference Load
Regulation
VTHREF/
VTHREF|
%/V VDD = [VREG (Typ) + 1V] to 5.5V
%
ITHREF = 0 mA to 0.20 mA
Thermistor Comparator - MCP73853
Upper Trip Threshold
Upper Trip Point Hysteresis
VT1
1.18
1.25
1.32
V
VT1HYS
—
-50
—
mV
Lower Trip Threshold
Lower Trip Point Hysteresis
VT2
0.59
0.62
0.66
V
VT2HYS
—
80
—
mV
IBIAS
—
—
2
A
Input Bias Current
Status Indicator – STAT1, STAT2
Sink Current
ISINK
4
8
12
mA
Low Output Voltage
VOL
—
200
400
mV
ISINK = 1 mA
Input Leakage Current
ILK
—
0.01
1
A
ISINK = 0 mA, VSTAT1,2 = 5.5V
Input High Voltage Level
VIH
1.4
—
—
V
Input Low Voltage Level
VIL
—
—
0.8
V
Input Leakage Current
ILK
—
0.01
1
A
TSD
—
155
—
°C
TSDHYS
—
10
—
°C
Enable Input
VENABLE = 5.5V
Thermal Shutdown
Die Temperature
Die Temperature Hysteresis
DS21915C-page 4
2004-2013 Microchip Technology Inc.
MCP73853/55
AC CHARACTERISTICS
Electrical Specifications: Unless otherwise indicated, all limits apply for VDD = [VREG (Typ) + 0.3V] to 5.5V,
TA = -40°C to 85°C. Typical values are at +25°C, VDD = [VREG (Typ) + 1.0V]
Parameters
Sym
Min
Typ
Max
Units
tSTART
—
—
5
ms
VDD Low-to-High
tDELAY
—
—
1
ms
VBAT < VPTH to VBAT > VPTH
Current Rise Time Out of
Preconditioning
tRISE
—
—
1
ms
IOUT Rising to 90% of IREG
Fast Charge Safety Timer
Period
tFAST
1.1
1.5
1.9
Hours
tPRECON
45
60
75
tTERM
2.2
3
3.8
Hours
Status Output Turn-off
tOFF
—
—
200
µs
ISINK = 1 mA to 0 mA
Status Output Turn-on
tON
—
—
200
µs
ISINK = 0 mA to 1 mA
UVLO Start Delay
Conditions
Current Regulation
Transition Time Out of
Preconditioning
CTIMER = 0.1 µF
Preconditioning Current Regulation
Preconditioning Charge
Safety Timer Period
Minutes CTIMER = 0.1 µF
Charge Termination
Elapsed Time Termination
Period
CTIMER = 0.1 µF
Status Indicators
TEMPERATURE SPECIFICATIONS
Electrical Specifications: Unless otherwise indicated, all limits apply for VDD = [VREG (Typ) + 0.3V] to 5.5.
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, 16-L, 4mm x 4mm QFN
JA
—
37
—
°C/W
4-Layer JC51-7
Standard Board,
Natural Convection
Thermal Resistance, 10-L, 3mm x 3mm DFN
JA
—
51
—
°C/W
4-Layer JC51-7
Standard Board,
Natural Convection
Temperature Ranges
Specified Temperature Range
Thermal Package Resistances
2004-2013 Microchip Technology Inc.
DS21915C-page 5
MCP73853/55
NOTES:
DS21915C-page 6
2004-2013 Microchip Technology Inc.
MCP73853/55
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.
NOTE: Unless otherwise indicated, VDD = [VREG(Typ) + 1V], IOUT = 10 mA and TA= +25°C.
4.250
4.230
VSET = VDD
VDD = 5.2 V
0.90
0.80
ISS (mA)
VBAT (V)
1.00
VSET = VDD
VDD = 5.2 V
4.210
4.190
0.70
0.60
0.50
0.40
4.170
0.30
0.20
4.150
0
50
100
150
200
250
300
350
0
400
50
100
FIGURE 2-1:
Battery Regulation Voltage
(VBAT) vs. Charge Current (IOUT).
300
350
400
VSET = VDD
IOUT = 375 mA
0.90
0.80
4.210
ISS (mA)
VBAT (V)
1.00
4.190
0.70
0.60
0.50
0.40
4.170
0.30
4.150
0.20
4.5
4.7
4.9
5.1
5.3
5.5
4.5
4.7
4.9
VDD (V)
4.250
5.3
5.5
FIGURE 2-5:
Supply Current (ISS) vs.
Supply Voltage (VDD).
1.00
VSET = VDD
IOUT = 10 mA
4.230
5.1
VDD (V)
FIGURE 2-2:
Battery Regulation Voltage
(VBAT) vs. Supply Voltage (VDD).
VSET = VDD
IOUT = 10 mA
0.90
0.80
ISS (mA)
VBAT (V)
250
FIGURE 2-4:
Supply Current (ISS) vs.
Charge Current (IOUT).
VSET = VDD
IOUT = 375 mA
4.230
200
IOUT (mA)
IOUT (mA)
4.250
150
4.210
4.190
0.70
0.60
0.50
0.40
4.170
0.30
4.150
0.20
4.5
4.7
4.9
5.1
5.3
5.5
4.5
4.7
4.9
VDD (V)
FIGURE 2-3:
Battery Regulation Voltage
(VBAT) vs. Supply Voltage (VDD).
5.1
5.3
5.5
VDD (V)
FIGURE 2-6:
Supply Current (ISS) vs.
Supply Voltage (VDD).
NOTE: Unless otherwise indicated, VDD = [VREG(Typ) + 1V], IOUT = 10 mA and TA= +25°C.
2004-2013 Microchip Technology Inc.
DS21915C-page 7
0.45
0.40
0.35
0.30
0.25
0.20
0.15
0.10
0.05
0.00
1.00
VSET = VDD
VDD = VSS
VSET = VDD
IOUT = 10 mA
0.90
0.80
+85°C
+25°C
ISS (mA)
0.70
0.60
0.50
0.40
-40°C
0.30
VBAT (V)
80
70
60
VSET = VDD
IOUT = 10 mA
4.230
2.555
2.545
4.210
4.190
4.170
2.535
VDD (V)
80
70
60
50
40
FIGURE 2-11:
Battery Regulation Voltage
(VBAT) vs. Ambient Temperature (TA).
2.575
MCP73853
VSET = VDD
2.555
2.545
2.535
MCP73853
VSET = VDD
ITHREF = 100 µA
2.565
VTHREF (V)
2.565
30
TA (°C)
FIGURE 2-8:
Thermistor Reference
Voltage (VTHREF) vs. Supply Voltage (VDD).
2.575
20
5.5
10
5.3
0
5.1
-10
4.9
-20
4.7
-40
4.5
-30
4.150
2.525
2.555
2.545
2.535
2.525
ITHREF (µA)
FIGURE 2-9:
Thermistor Reference
Voltage (VTHREF) vs. Thermistor Bias Current
(ITHREF).
80
70
60
50
40
30
20
10
100 125 150 175 200
0
75
-10
50
-20
25
-30
2.525
0
-40
VTHREF (V)
50
4.250
VBAT (V)
VTHREF (V)
FIGURE 2-10:
Supply Current (ISS) vs.
Ambient Temperature (TA).
MCP73853
VSET = VDD
ITHREF = 100 µA
2.565
40
TA (°C)
FIGURE 2-7:
Output Leakage Current
(IDISCHARGE) vs. Battery Voltage (VBAT).
2.575
30
4.4
20
4.0
0
3.6
10
3.2
-10
2.8
-20
2.4
-30
0.20
2.0
-40
IDISCHARGE (mA)
MCP73853/55
TA (°C)
FIGURE 2-12:
Thermistor Reference
Voltage (VTHREF) vs. Ambient Temperature (TA).
NOTE: Unless otherwise indicated, VDD = [VREG(Typ) + 1V], IOUT = 10 mA and TA= +25°C.
DS21915C-page 8
2004-2013 Microchip Technology Inc.
MCP73853/55
FIGURE 2-13:
Line Transient Response.
FIGURE 2-16:
Line Transient Response.
FIGURE 2-14:
Load Transient Response.
FIGURE 2-17:
Load Transient Response.
Attenuation (dB)
-10
-20
-30
0
MCP73853
VDD = 5.2 V
VAC = 100 mVp-p
IOUT = 10 mA
COUT = 10 F, Ceramic
-10
Attenuation (dB)
0
-40
-50
-60
-70
0.01
-20
-30
-40
-60
-70
0.1
1
10
100
1000
-80
0.01
Power Supply Ripple
0.1
1
10
100
1000
Frequency (kHz)
Frequency (kHz)
FIGURE 2-15:
Rejection.
MCP73853
VDD = 5.2 V
VAC = 100 mVp-p
IOUT = 100 mA
COUT = 10 F, X7R, Ceramic
-50
FIGURE 2-18:
Rejection.
Power Supply Ripple
NOTE: Unless otherwise indicated, VDD = [VREG(Typ) + 1V], IOUT = 10 mA, and TA= +25°C.
2004-2013 Microchip Technology Inc.
DS21915C-page 9
MCP73853/55
FIGURE 2-19:
Charge Current (IOUT) vs.
Programming Resistor (RPROG).
DS21915C-page 10
80
70
60
0
50
536
40
1.6K
RPROG ()
30
4.8K
20
0
OPEN
0
100
10
200
-10
300
VSET = VDD
RPROG = 1.6 k
-40
IOUT (mA)
IOUT (mA)
400
300
295
290
285
280
275
270
265
260
255
250
-20
VSET = VDD
-30
500
TA (°C)
FIGURE 2-20:
Charge Current (IOUT) vs.
Ambient Temperature (TA).
2004-2013 Microchip Technology Inc.
MCP73853/55
3.0
PIN DESCRIPTION
The descriptions of the pins are listed in Table 3-1.
TABLE 3-1:
PIN FUNCTION TABLE
MCP73853
MCP73855
Sym
Description
1
2
VSET
Voltage Regulation Selection
2
3
VDD1
Battery Management Input Supply
3
—
VDD2
Battery Management Input Supply
4
4
VSS1
5
5
PROG
Current Regulation Set
6
—
THREF
Cell Temperature Sensor Bias
7
—
THERM
Cell Temperature Sensor Input
8
6
TIMER
Timer Set
3.1
Battery Management 0V Reference
9
—
VSS3
Battery Management 0V Reference
10
8
VBAT1
Battery Charge Control Output
11
9
VBAT2
Battery Charge Control Output
12
—
VBAT3
Battery Voltage Sense
13
7
VSS2
14
10
EN
15
—
STAT2
Fault Status Output
16
1
STAT1
Charge Status Output
17
11
EP
Voltage Regulation Selection
(VSET)
Battery Management 0V Reference
Logic Enable
Exposed Pad, VSS Potential
3.7
Timer Set (TIMER)
All safety timers are scaled by CTIMER/0.1 µF.
Connect to VSS for 4.1V regulation voltage. Connect to
VDD for 4.2V regulation voltage.
3.8
3.2
Connect to positive terminal of battery. Drain terminal
of internal P-channel MOSFET pass transistor. Bypass
to VSS with a minimum of 4.7 µF to ensure loop stability
when the battery is disconnected.
Battery Management Input Supply
(VDD1, VDD2)
A supply voltage of [VREG(Typ) + 0.3V] to 5.5V is
recommended. Bypass to VSS with a minimum of
4.7 µF.
3.3
Battery Management 0V Reference
(VSS1, VSS2, VSS3)
3.9
Battery Charge Control Output
(VBAT1, VBAT2)
Battery Voltage Sense (VBAT3)
Connect to negative terminal of battery.
Voltage sense input. Connect to positive terminal of
battery. A precision internal resistor divider regulates
the final voltage on this pin to VREG.
3.4
3.10
Current Regulation Set (PROG)
Logic Enable (EN)
Preconditioning, fast and termination currents are
scaled by placing a resistor from PROG to VSS.
Input to force charge termination, initiate charge, clear
faults or disable automatic recharge.
3.5
3.11
Cell Temperature Sensor Bias
(THREF)
THREF is a voltage reference to bias external
thermistor for continuous cell temperature monitoring
and pre-qualification.
3.6
Cell Temperature Sensor Input
(THERM)
Input for an external thermistor for continuous celltemperature monitoring and prequalification. Connect
to THREF/3 to disable temperature sensing.
2004-2013 Microchip Technology Inc.
Fault Status Output (STAT2)
Current-limited, open-drain drive for direct connection
to an LED for charge status indication. Alternatively, a
pull-up resistor can be applied for interfacing to a host
microcontroller.
3.12
Charge Status Output (STAT1)
Current-limited, open-drain drive for direct connection
to a LED for charge status indication. Alternatively, a
pull-up resistor can be applied for interfacing to a host
microcontroller.
DS21915C-page 11
MCP73853/55
NOTES:
DS21915C-page 12
2004-2013 Microchip Technology Inc.
MCP73853/55
4.0
DEVICE OVERVIEW
The MCP7385X devices are highly-advanced, linear
charge management controllers. For more information,
refer to the “Functional Block Diagram” on page 2.
Figure 4-2 depicts the operational flow algorithm from
charge initiation to completion and automatic recharge.
4.1
Charge Qualification and
Preconditioning
Upon insertion of a battery or application of an external
supply, the MCP7385X devices automatically perform a
series of safety checks to qualify the charge. The input
source voltage must be above the Undervoltage Lockout (UVLO) threshold, the enable pin must be above the
logic high level, and the cell temperature monitor must
be within the upper and lower thresholds (MCP73853
only). The qualification parameters are continuously
monitored, with any deviation beyond the limits automatically suspending or terminating the charge cycle. The
input voltage must deviate below the UVLO stop
threshold for at least one clock period to be considered
valid.
Once the qualification parameters have been met, the
MCP7385X devices initiate a charge cycle. The charge
status output is pulled low throughout the charge cycle
(see Table 5-1 and Table 5-2 for charge status outputs). If the battery voltage is below the preconditioning
threshold (VPTH), the MCP7385X devices precondition
the battery with a trickle charge. The preconditioning
current is set to approximately 10% of the fast charge
regulation current. The preconditioning trickle charge
safely replenishes deeply depleted cells and minimizes
heat dissipation during the initial charge cycle. If the
battery voltage has not exceeded the preconditioning
threshold before the preconditioning timer has expired,
a fault is indicated and the charge cycle is terminated.
4.2
4.4
Charge Cycle Completion and
Automatic Recharge
The MCP7385X devices monitor the charging current
during the Constant-voltage Regulation mode. The
charge cycle is considered complete when either the
charge current has diminished below approximately
7% of the regulation current (IREG) or the elapsed timer
has expired.
Assuming all the qualification parameters are met, the
MCP7385X devices automatically begin a new charge
cycle when the battery voltage falls below the recharge
threshold (VRTH).
4.5
Thermal Regulation
The MCP7385X devices limit the charge current based
on the die temperature. Thermal regulation optimizes
the charge cycle time while maintaining device reliability. If thermal regulation is entered, the timer is automatically slowed down to ensure that a charge cycle does
not terminate prematurely. Figure 4-1 depicts the
thermal regulation.
Constant Current Regulation –
Fast Charge
Preconditioning ends and fast charging begins when
the battery voltage exceeds the preconditioning threshold. Fast charge regulates to a constant current (IREG),
which is set via an external resistor connected to the
PROG pin. Fast charge continues until either the
battery voltage reaches the regulation voltage (VREG)
or the fast charge timer expires; in which case, a fault
is indicated and the charge cycle is terminated.
4.3
With VSET tied to VSS, the MCP7385X devices regulate
to 4.1V or with VSET tied to VDD, the MCP7385X
devices regulate to 4.2V.
Constant Voltage Regulation
FIGURE 4-1:
Typical Maximum Charge
Current vs. Junction Temperature.
4.6
Thermal Shutdown
The MCP7385X devices suspend charge if the die
temperature exceeds 155°C. Charging resumes 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.
When the battery voltage reaches the regulation voltage (VREG), constant voltage regulation begins. The
MCP7385X devices monitor the battery voltage at the
VBAT pin. This input is tied directly to the positive terminal of the battery. The MCP7385X devices select the
voltage regulation value based on the state of VSET.
2004-2013 Microchip Technology Inc.
DS21915C-page 13
FIGURE 4-2:
DS21915C-page 14
Yes
Yes
Yes
VDD < VUVLO
or EN Low
Yes
VBAT > VPTH
Yes
Temperature OK
Yes
VDD > VUVLO
EN High
Initialize
Yes
Yes
Yes
Yes
STAT1 = On
STAT2 = Off
Yes
No
STAT1 = Flashing
Safety Timer Suspended
Charge Current = 0
Temperature OK
No
IOUT < ITERM
Elapsed Timer
Expired
Constant-voltage Mode
Output Voltage = VREG
No
STAT1 = Off
STAT2 = Flashing
Charge Current = 0
No
STAT1 = Off
STAT2 = Off
No
STAT1 = Off
STAT2 = Flashing
Safety Timer Suspended
Charge Current = 0
Temperature OK
No
Safety Timer
Expired
No
VBAT = VREG
Constant-current
NOTE 2 Mode
Charge Current = IREG
Reset Safety Timer
NOTE 1
NOTE 1
No
STAT1 = Off
STAT2 = On
Fault
Charge Current = 0
Reset Safety Timer
No
Yes
STAT1 = Off
STAT2 = Flashing
Safety Timer Suspended
Charge Current = 0
Temperature OK
No
Safety Timer
Expired
No
VBAT > VPTH
No
The charge current will be scaled based on the
die temperature during thermal regulation. For
more details, refer to Section 4.5 “Thermal
Regulation”.
Note 2:
Preconditioning Mode
Charge Current = IPREG
Reset Safety Timer
The qualification parameters are continuously
monitored throughout the charge cycle. For more
details on this, refer to Section 4.1 “Charge
Qualification and Preconditioning”.
Note 1:
Yes
VDD < VUVLO
VBAT < VRTH
or EN Low
No
STAT1 = Flashing
STAT2 = Off
Charge Termination
Charge Current = 0
Reset Safety Timer
MCP73853/55
Operational Flow Algorithm.
2004-2013 Microchip Technology Inc.
MCP73853/55
5.0
DETAILED DESCRIPTION
5.1
Analog Circuitry
5.1.1
BATTERY MANAGEMENT INPUT
SUPPLY (VDD1, VDD2)
The VDD pin is the input supply pin for the MCP7385X
devices. The MCP7385X devices automatically enter a
power-down mode if the voltage on the VDD input falls
below the UVLO voltage (VSTOP). This feature prevents
draining the battery pack when the VDD supply is not
present.
5.1.2
Figure 6-1 depicts a typical application circuit with
connection of the THERM input. The resistor values of
RT1 and RT2 are calculated with the following
equations:
For NTC thermistors:
2 R COLD R HOT
R T1 = ---------------------------------------------R COLD – R HOT
2 R COLD R HOT
R T2 = ---------------------------------------------R COLD – 3 R HOT
For PTC thermistors:
2 R COLD R HOT
R T1 = ---------------------------------------------R HOT – R COLD
PROG INPUT
Fast charge current regulation can be scaled by placing
a programming resistor (RPROG) from the PROG input
to VSS. Connecting the PROG input to VSS allows a
maximum fast charge current of 400 mA, typically. The
minimum fast charge current is 85 mA (Typ) and is set
by letting the PROG input float. Equation 5-1 calculates
the value for RPROG.
2 R COLD R HOT
R T2 = ---------------------------------------------R HOT – 3 R COLD
Where:
RCOLD and RHOT are the thermistor
resistance values at the temperature window
of interest.
EQUATION 5-1:
13.32 – 33.3 I REG
R PROG = -----------------------------------------------14.1 I REG – 1.2
Where:
5.1.5
IREG is the desired fast charge current in
amps
RPROG is in kilohms.
The preconditioning trickle charge current and the
charge termination current are scaled to approximately
10% and 7% of IREG, respectively.
5.1.3
CELL TEMPERATURE SENSOR
BIAS (THREF)
A 2.55V voltage reference is provided to bias an
external thermistor for continuous cell temperature
monitoring and prequalification. A ratiometric window
comparison is performed at threshold levels of
VTHREF/2 and VTHREF/4.
5.1.4
Applying a voltage equal to VTHREF/3 to the THERM
input disables temperature monitoring.
CELL TEMPERATURE SENSOR
INPUT (THERM)
The MCP73853 continuously monitors temperature by
comparing the voltage between the THERM input and
VSS with the upper and lower temperature thresholds.
A negative or positive temperature coefficient, NTC or
PTC thermistor, and an external voltage divider
typically develop this voltage. The temperaturesensing circuit has its own reference, to which it
performs a ratiometric comparison. Therefore, it is
immune to fluctuations in the supply input (VDD). The
temperature-sensing circuit is removed from the
system when VDD is not applied, eliminating additional
discharge of the battery pack.
2004-2013 Microchip Technology Inc.
TIMER SET INPUT (TIMER)
The TIMER input programs the period of the safety timers by placing a timing capacitor (CTIMER) between the
TIMER input pin and VSS. Three safety timers are
programmed via the timing capacitor:
The preconditioning safety timer period:
C TIMER
t PRECON = ------------------- 1.0Hour s
0.1 F
The fast charge safety timer period:
C TIMER
t FAST = ------------------- 1.5Hours
0.1 F
And, the elapsed time termination period:
C TIMER
t TERM = ------------------- 3.0Hours
0.1 F
The preconditioning timer starts after qualification and
resets when the charge cycle transitions to the
constant-current, fast charge phase. The fast charge
timer and the elapsed timer start after the MCP7385X
devices transition from preconditioning. The fast
charge timer resets when the charge cycle transitions
to the Constant-voltage mode. The elapsed timer
expires and terminates the charge if the sensed current
does not diminish below the termination threshold.
During thermal regulation, the timer is slowed down
proportional to the charge current.
DS21915C-page 15
MCP73853/55
5.1.6
BATTERY VOLTAGE SENSE (VBAT3)
TABLE 5-2:
The MCP73853 monitors the battery voltage at the
VBAT3 pin. This input is tied directly to the positive
terminal of the battery pack.
Qualification
OFF
5.1.7
Preconditioning
ON
Constant Current Fast Charge
ON
BATTERY CHARGE CONTROL
OUTPUT (VBAT1, VBAT2)
The battery charge control output is the drain terminal of
an internal P-channel MOSFET. The MCP7385X
devices provide constant-current and constant-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.
5.2
Digital Circuitry
5.2.1
CHARGE CYCLE STATE
ON
Charge Complete
OFF
Fault
Flashing (1Hz,
50% duty cycle)
THERM Invalid
Flashing (1Hz,
50% duty cycle)
Disabled - Sleep mode
OFF
Input Voltage Disconnected
OFF
CHARGE STATUS OUTPUTS
(STAT1, STAT2)
TABLE 5-1:
STATUS OUTPUTS – MCP73853
CHARGE
CYCLE STATE
STAT1
Constant Voltage
Note:
Two status outputs provide information on the state of
charge for the MCP73853. One status output provides
information on the state of charge for the MCP73855.
The current-limited, open-drain outputs can be used to
illuminate external LEDs. Optionally, a pull-up resistor
can be used on the output for communication with a
host microcontroller. Table 5-1 and Table 5-2 summarize the state of the status outputs during a charge
cycle for the MCP73853 and MCP73855, respectively.
STATUS OUTPUT – MCP73855
OFF state: open-drain is high impedance;
ON state: open-drain can sink current, typically 7 mA; FLASHING: toggles between
OFF state and ON state.
The flashing rate (1 Hz) is based on a timer capacitor
(CTIMER) of 0.1 µF. The rate varies based on the value
of the timer capacitor.
5.2.1.1
MCP73853 Only
STAT1 is on whenever the input voltage is above the
under voltage lockout, the device is enabled, and all
conditions are normal.
During a fault condition, the STAT1 status output is off
and the STAT2 status output flashes. To recover from a
fault condition, the input voltage must be removed and
then reapplied, or the enable input, EN, must be deasserted to a logic low, then asserted to a logic high.
STAT1
STAT2
Qualification
OFF
OFF
Preconditioning
ON
OFF
Constantcurrent Fast
Charge
ON
OFF
Constantvoltage
ON
OFF
When the voltage on the THERM input is outside the
preset window, the charge cycle will either not start or
be suspended. However, the charge cycle is not terminated, with recovery being automatic. The charge cycle
resumes (or starts) once the THERM input is valid and
all other qualification parameters are met.
Charge
Complete
Flashing (1 Hz,
50% duty cycle)
OFF
5.2.2
Fault
OFF
ON
THERM Invalid
OFF
Flashing (1 Hz,
50% duty cycle)
Disabled Sleep mode
OFF
OFF
Input Voltage
Disconnected
OFF
OFF
Note:
OFF state: open-drain is high-impedance;
ON state: open-drain can sink current,
typically 7 mA; FLASHING: toggles
between OFF and ON states.
DS21915C-page 16
VSET INPUT
The VSET input selects the regulated output voltage of
the MCP7385X devices. With VSET tied to VSS, the
MCP7385X devices regulate to 4.1V. With VSET tied to
VDD, the MCP7385X devices regulate to 4.2V.
5.2.3
LOGIC ENABLE (EN)
The logic enable input pin (EN) can be used to terminate a charge anytime during the charge cycle, initiate
a charge cycle or initiate a recharge cycle.
Applying a logic high input signal to the EN 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. When disabled, the device’s
supply current is reduced to 0.28 µA, typically.
2004-2013 Microchip Technology Inc.
MCP73853/55
6.0
APPLICATIONS
cells. The algorithm uses a constant current followed
by a constant voltage charging method. Figure 6-1
depicts a typical stand-alone application circuit, while
Figure 6-2 and Figure 6-3 depict the accompanying
charge profile.
STAT1
16
VSET
VDD1
VDD2
VSS1
15
EN VSS2
14 13
1
12
2
11
MCP73853
3
10
4
9
RPROG
6
THREF
5
PROG
7
VBAT3
VBAT2
+ Single
- Lithium-Ion
Cell
VBAT1
VSS3
8
TIMER
CTIMER
THERM
Regulated Wall Cube
or
USB Power Bus
STAT2
The MCP7385X devices are designed to operate in
conjunction with a host microcontroller or in standalone applications. The MCP7385X devices provide
the preferred charge algorithm for Li-Ion/Li-Polymer
RT1
RT2
FIGURE 6-1:
Typical Application Circuit.
Preconditioning
Mode
Constant-current
Mode
Constant-voltage
Mode
Regulation
Voltage
(VREG)
Regulation
Current
(IREG)
Charge
Voltage
Transition
Threshold
(VPTH)
Precondition
Current
(IPREG)
Charge
Current
Termination
Current
(ITERM)
Precondition
Safety Timer
Fast Charge
Safety Timer
Elapsed Time
Termination Timer
FIGURE 6-2:
Typical Charge Profile.
2004-2013 Microchip Technology Inc.
DS21915C-page 17
MCP73853/55
Preconditioning
Mode
Constant-current
Mode
Constant-voltage
Mode
Regulation
Voltage
(VREG)
Regulation
Current
(IREG)
Charge
Voltage
Transition
Threshold
(VPTH)
Precondition
Current
(IPREG)
Termination
Current
(ITERM)
Charge
Current
Precondition
Safety Timer
Fast Charge
Safety Timer
Elapsed Time
Termination Timer
FIGURE 6-3:
DS21915C-page 18
Typical Charge Profile in Thermal Regulation.
2004-2013 Microchip Technology Inc.
MCP73853/55
6.1
Application Circuit Design
Due to the low efficiency of linear charging, the most
important factors are thermal design and cost. These
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
exists 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
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 to be a
guide for the component selection process.
6.1.1.1
CURRENT PROGRAMMING RESISTOR
(RPROG)
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.
400 mA is the typical maximum charge current
obtainable from the MCP7385X devices. For this situation, the PROG input should be connected directly to
VSS.
6.1.1.2
THERMAL CONSIDERATIONS
The worst-case power dissipation in the battery charger occurs when the input voltage is at its maximum
and the device has transitioned from the
Preconditioning mode to the Constant-current mode. In
this case, the power dissipation is:
PowerDissipation = V DDMAX – V PTHMIN I REGMAX
Where VDDMAX is the maximum input voltage, IREGMAX
is the maximum fast charge current, and VPTHMIN is the
minimum transition threshold voltage. Power
dissipation with a 5V, +/-10% input voltage source is:
PowerDissipation = 5.5V – 2.7V 475mA = 1.33W
With the battery charger mounted on a 1 in2 pad of
1 oz. copper, the junction temperature rise is approximately 50°C. This allows for a maximum operating
ambient temperature of 35°C before thermal regulation
is entered.
2004-2013 Microchip Technology Inc.
6.1.1.3
EXTERNAL CAPACITORS
The MCP7385X devices are stable with or without a
battery load. To maintain good AC stability in the
Constant-voltage mode, a minimum capacitance of
4.7 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 4.7 µF ceramic,
tantalum or aluminum electrolytic capacitor at the
output is usually sufficient to ensure stability for up to
the maximum output current.
6.1.1.4
REVERSE BLOCKING PROTECTION
The MCP7385X devices provide protection from a
faulted or shorted input or from a reversed-polarity
input source. 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
ENABLE INTERFACE
In the stand-alone configuration, the enable pin is generally tied to the input voltage. The MCP7385X devices
automatically enter a low power mode when voltage on
the VDD input falls below the UVLO voltage (VSTOP),
reducing the battery drain current to 0.28 µA, typically.
6.1.1.6
CHARGE STATUS INTERFACE
Two status outputs provide information on the state of
charge. The current-limited, open-drain outputs can be
used to illuminate external LEDs. Refer to Table 5-1
and Table 5-2 for a summary of the state of the status
output during a charge cycle.
6.2
PCB Layout Issues
For optimum voltage regulation, place the battery pack
as close as possible to the device’s VBAT and VSS pins.
It is recommended that the designer minimizes voltage
drops along the high-current-carrying PCB traces.
If the PCB layout is used as a heat sink, adding many
vias in the heat sink pad helps to conduct more heat to
the PCB backplane, thus reducing the maximum junction temperature.
DS21915C-page 19
MCP73853/55
NOTES:
DS21915C-page 20
2004-2013 Microchip Technology Inc.
MCP73853/55
7.0
PACKAGING INFORMATION
7.1
Package Marking Information
10-Lead DFN (MCP73855) (3x3x0.9 mm)
Example
XXXX
YYWW
NNN
3855
I139
256
PIN 1
PIN 1
16-Lead QFN (MCP73853)
PIN 1
PIN 1
Legend:
Note:
*
Example
XX...X
YY
WW
NNN
73853
I/ML
1139
256
Customer specific information*
Year code (last 2 digits of calendar year)
Week code (week of January 1 is week ‘01’)
Alphanumeric traceability code
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.
Standard OTP marking consists of Microchip part number, year code, week code, and traceability code.
2004-2013 Microchip Technology Inc.
DS21915C-page 21
MCP73853/55
Note:
For the most current package drawings, please see the Microchip Packaging Specification located at
http://www.microchip.com/packaging
DS21915C-page 22
2004-2013 Microchip Technology Inc.
MCP73853/55
Note:
For the most current package drawings, please see the Microchip Packaging Specification located at
http://www.microchip.com/packaging
2004-2013 Microchip Technology Inc.
DS21915C-page 23
MCP73853/55
Note:
For the most current package drawings, please see the Microchip Packaging Specification located at
http://www.microchip.com/packaging
DS21915C-page 24
2004-2013 Microchip Technology Inc.
MCP73853/55
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