MP2615
2A, 1- or 2- Cell Li-ion Battery Charger
In 3mm x 3mm Package
The Future of Analog IC Technology
DESCRIPTION
FEATURES
The MP2615 is a high efficiency switch mode
battery charger suitable for 1- or 2- cell lithiumion or lithium-Polymer applications. The
MP2615 is capable of delivering 2A of charge
current programmable via an accurate sense
resistor over the entire input range.
The MP2615 regulates the charge current and
full battery voltage using two control loops to
achieve high accuracy constant current (CC)
charge and constant voltage (CV) charge.
Constant-off-time (COT) mode control allows
operation up to 99% duty cycle when the
battery voltage is close to the input voltage and
in order to keep charge current always at a
relative high level.
Battery temperature and charging status are
always monitored during each charging cycle.
Two status monitor output pins are provided to
indicate the battery charging status and input
power status. The MP2615 also features
internal reverse blocking protection.
The MP2615 is available in a 3mm × 3mm 16pin QFN package.
4.75V to 18V Operating Input Voltage
Up to 99% Duty Cycle Operation
Up to 2A Programmable Charging Current
±0.75% Full Battery Voltage Accuracy
4.1V/Cell and 4.2V/Cell Selection for Full
Battery Voltage
Full Integrated Power Switches
Internal Loop Compensation
No External Reverse Blocking Diode
Required
Preconditioning for Fully Depleted Battery
Charging Operation Indicator
Programmable Safety Timer
Thermal Shutdown Protection
Cycle-by-Cycle Over Current Protection
Battery Temperature Monitor and Protection
APPLICATIONS
Smart Phones
Portable Hand-held Solutions
Portable Media Players
All MPS parts are lead-free and adhere to the RoHS directive. For MPS green
status, please visit MPS website under Products, Quality Assurance page.
“MPS” and “The Future of Analog IC Technology” are registered trademarks of
Monolithic Power Systems, Inc.
ADAM (Analog Digital Adaptive Modulation) and AAM (Advanced Asynchronous
Mode) are trademarks of Monolithic Power Systems, Inc.
TYPICAL APPLICATION
100
95
90
85
80
75
70
65
60
0
MP2615 Rev. 1.02
7/9/2019
0.5
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1
1.5
2
2.5
1
MP2615 – 2A, 1- CELL OR 2- CELL LI-ION BATTERY CHARGER
ORDERING INFORMATION
Part Number*
MP2615GQ
Package
QFN-16 (3mm×3mm)
Top Marking
See Below
* For Tape & Reel, add suffix –Z (e.g. MP2615GQ–Z);
TOP MARKING
AEG: product code of MP2615GQ
Y: year code
LLL: lot number
PACKAGE REFERENCE
TOP VIEW
QFN-16 (3mm×3mm)
MP2615 Rev. 1.02
7/9/2019
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2
MP2615 – 2A, 1- CELL OR 2- CELL LI-ION BATTERY CHARGER
ABSOLUTE MAXIMUM RATINGS (1)
Thermal Resistance (4)
VSW ................................................. –0.3V to 23V
VIN, VACOK, VCHGOK............................................ –0.3V to 23V
VBATT,VCSP…………………………...–0.3V to 12V
VBST........................................................VSW + 6V
All Other Pins ................................... –0.3V to 6V
Junction Temperature ............................... 150°C
Lead Temperature .................................... 260°C
Continuous Power Dissipation (TA = +25°C) (2)
............................................................... 2.5W
Operating Temperature ............. –40°C to +85°C
QFN-16 (3mmx3mm) .............. 50 ....... 12 ... °C/W
Recommended Operating Conditions (3)
VIN ................................................... 4.75V to 18V
VBATT ................................................... 2V to 8.4V
Operating Junction Temp. (TJ). –40°C to +125°C
MP2615 Rev. 1.02
7/9/2019
θJA
θJC
Notes:
1) Exceeding these ratings may damage the device.
2) The maximum allowable power dissipation is a function of the
maximum junction temperature TJ (MAX), the junction-toambient thermal resistance θJA, and the ambient temperature
TA. The maximum allowable continuous power dissipation at
any ambient temperature is calculated by PD (MAX) = (TJ
(MAX)-TA)/θJA. Exceeding the maximum allowable power
dissipation will cause excessive die temperature, and the
regulator will go into thermal shutdown. Internal thermal
shutdown circuitry protects the device from permanent
damage.
3) The device is not guaranteed to function outside of its
operating conditions.
4) Measured on JESD51-7, 4-layer PCB.
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3
MP2615 – 2A, 1- CELL OR 2- CELL LI-ION BATTERY CHARGER
ELECTRICAL CHARACTERISTICS
VIN = 12V, VCELL = 0V, VSEL = 0V, C1 = 22µF, C2=22µF, TA = 25°C, unless otherwise noted.
Parameter
Symbol Condition
Min
Typ
Max
Units
VCELL = 4V
VCELL = 0V
4.5
8.75
5
12
18
18
V
3.55
3.75
3.95
V
Input Voltage and Current
Input Voltage
VIN
Under
Voltage
Lockout
Threshold Rising
Under
Voltage
Lockout
Threshold Hysteresis
Supply Current
Power MOS
High-side
Switch
Resistance
Low-side
Switch
Resistance
On
On
VUVLO
225
ISHDN
EN = 4V, Shutdown Current
0.27
IQ
EN = 0V, Quiescent Current
1.1
110
mΩ
RL_DS(ON)
110
mΩ
EN = 4V, VSW = 0V
Frequency and Time Parameter
Switching Frequency
FSW
Fold-back Frequency
Minimum Off Time (5)
TOFF
Charging Parameter
VBATT = 7.5V
VBATT = 0V
VBATT = 9V
Battery
Over
Threshold
Voltage
Recharge Threshold at VBATT
VBATT_FULL
VBOVP
VRECH
VSEL = 0V
VSEL = 4V
VCELL = 0V, VSEL=0V
VCELL = 0V, VSEL=4V
VCELL = 4V, VSEL=0V
VCELL = 4V, VSEL=4V
VSEL = 0V
VSEL = 4V
0
Voltage
VTC
4.168
4.069
8.34
8.14
4.17
4.07
VSEL = 0V
VSEL = 4V
Trickle Charge Hysteresis
Peak Current Limit
CC Current
Trickle Charge Current
Termination
Current
Threshold
VIN minimum Head-room
(reverse blocking)
MP2615 Rev. 1.02
7/9/2019
ICC
ITC
CC
Trickle
RS1 = 50mΩ
IBF
VIN − VBATT
1
760
160
200
Recharge Hysteresis
Trickle
Charge
Threshold
mA
RH_DS(ON) Measured from VIN to SW
Switch Leakage
Terminal Battery Voltage
mV
4.2
4.1
8.71
8.51
4.36
4.26
4.0
3.9
150
3
2.91
225
μA
kHz
kHz
ns
4.231
4.131
9.08
8.88
4.54
4.44
V/Cell
mV/Cell
V/Cell
mV/Cell
3.2
A
1.8
5%
2.2
2
10%
2.2
15%
A
ICC
5%
10%
15%
ICC
300
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mV
4
MP2615 – 2A, 1- CELL OR 2- CELL LI-ION BATTERY CHARGER
ELECTRICAL CHARACTERISTICS (continued)
VIN = 12V, VCELL = 0V, VSEL = 0V, C1 = 22µF, C2=22µF, TA = 25°C, unless otherwise noted.
Parameter
Symbol Condition
Maximum Current Sense
Voltage
VSENSE
(CSP to BATT)
CSP, BATT Current
ICSP, IBATT Charging disabled
ACOK/CHGOK Open-drain
VDRAIN = 0.3V
Sink Current
VCC Regulator Output
VCC Output Voltage
VCC
VCC Load Regulation
∆VCC
ILOAD=0 to 10mA
EN Control
Min
Typ
Max
Units
90
100
110
mV
3
µA
5
4.35
mA
4.5
EN Input Low Voltage
IEN
Logic
CELL Input Low Voltage
VL
CELL Input High Voltage
VH
SEL Input Low Voltage
VL
SEL Input High Voltage
VH
Timer Protection
Trickle Charge Time
tTrickle_tmr
CC/CV Charge Time
tTotal_tmr
NTC Protection
NTC Low Temp Rising
Threshold
NTC Low Temp Rising
Threshold Hysteresis
NTC High Temp Falling
Threshold
NTC Low Temp Falling
Threshold Hysteresis
Thermal Protection
Thermal Shutdown(5)
Thermal
Shutdown
Hysteresis(5)
V
mV
0.4
V
1.8
EN Input High Voltage
EN Input Current
4.65
10
V
EN = 4V
4
EN = 0V
0.2
μA
0.4
1.8
0.4
1.8
CTMR = 0.47μF
CTMR = 0.47μF
30
165
72
73.3
V
V
V
V
Mins
74.6
RNTC=NCP18X103, 0°C
2
28
29.3
%VCC
30.6
RNTC=NCP18X103, 50°C
2
TSHDN
150
°C
20
°C
Reverse Leakage Blocking
Battery Reverse
Current
Leakage
ILEAKAGE
VCELL = 0V
VCELL = 4V
3
0.5
uA
µA
Notes:
5) Guaranteed by design.
MP2615 Rev. 1.02
7/9/2019
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MP2615 – 2A, 1- CELL OR 2- CELL LI-ION BATTERY CHARGER
PIN FUNCTIONS
Package
Pin #
Name
1
2
SW
VIN
3
VCC
4
CELL
5
SEL
6
EN
7
8
9
10
N/C
AGND
BATT
CSP
11
12
13
14
15
16
Description
Switch Output
Power Supply Voltage.
Coarse Regulator Output. Internally generated 4.5V. Bypass with a 1µF capacitor to AGND.
Used to be low-side switch driver and pull-up bias voltage NTC resistive divider. Do not
connect any external load at this pin.
Command Input for the Number of Li-Ion Cells. Connect this pin to VCC for 1-cell
application and short it to AGND or keep it floating for 2- Cell application.
Input Pin for Setting Terminal Battery Voltage:
SEL = Low-level or Float: VBATT = 4.2V/Cell.
SEL = High-level: VBATT =4.1V/Cell.
On/ Off Control Input. This pin is pulled to GND with a 1Meg internal resistor. suggest to
connect a 100kΩ resistor in series with EN pin.
NO CONNECT. Please leave this pin floating.
Analog Ground.
Positive Battery Terminal.
Battery Current Sense Positive Input. Connect a resistor RS1 between CSP and BATT.
Charging Completion Indicator. A logic Low indicates charging operation. The pin will
CHGOK become an open drain once the charge is completed or suspended.
Valid Input Supply Indicator. A logic Low on this pin indicates the presence of a valid input
ACOK power supply.
Thermistor Input. Connect a resistor from this pin to the pin VCC and the thermistor from
NTC
this pin to ground.
Internal Safety Timer Control. Connect a capacitor from this node to AGND to set the timer.
TMR
And the timer can be disabled by connecting this pin to AGND directly.
Bootstrap pin. A capacitor is needed to drive the power switch’s gate above the supply
BST
voltage. It is connected between SW and BST pins to form a floating supply across the
power switch driver.
PGND Power Ground.
MP2615 Rev. 1.02
7/9/2019
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MP2615 – 2A, 1- CELL OR 2- CELL LI-ION BATTERY CHARGER
TYPICAL PERFORMANCE CHARACTERISTICS
VIN = 5V/9V, C1=C2=22µF, SEL=Float/High, CELL=Float/High, L=6.8µH, RS1=50mΩ, Battery
Simulator, TA = 25°C, unless otherwise noted.
2.5
2.5
2
2
1.5
1.5
1
1
0.5
0.5
4.22
4.2
4.18
4.16
4.14
4.12
0
0
0
0
1
2
3
4
4.1
2
4
6
8
10
4.08
-50
8.45
2.09
230
8.4
2.07
220
2.05
210
2.03
200
2.01
190
1.99
180
1.97
170
8.35
8.3
8.25
8.2
8.15
-50
0
50
1.95
-50
100
100
150
4.52
190
4.51
180
4.49
170
4.48
0
50
100
150
50
100
0
50
100
150
3.92
3.9
4.47
4.46
4.45
-50
0
150
3.94
4.5
160
100
3.96
4.53
200
160
-50
50
3.98
4.54
210
MP2615 Rev. 1.02
7/9/2019
50
4.55
220
150
-50
0
0
3.88
0
50
100
150
3.86
-50
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150
7
MP2615 – 2A, 1- CELL OR 2- CELL LI-ION BATTERY CHARGER
TYPICAL PERFORMANCE CHARACTERISTICS (continued)
VIN = 5V/9V, C1=C2=22µF, SEL=Float/High, CELL=Float/High, L=6.8µH, RS1=50mΩ, Battery
Simulator, TA = 25°C, unless otherwise noted.
VIN
5V/div.
VCHGOK
5V/div.
VIN
5V/div.
VCHGOK
5V/div.
VIN
5V/div.
VCHGOK
5V/div.
VBATT
2V/div.
VBATT
2V/div.
IBATT
1A/div.
VBATT
2V/div.
IBATT
1A/div.
VIN
10V/div.
VBATT
2V/div.
VCHGOK
10V/div.
VIN
2V/div.
VSW
2V/div.
VIN
10V/div.
VSW
10V/div.
IBATT
1A/div.
VBATT
2V/div.
IBATT
200mA/div.
VBATT
2V/div.
IBATT
200mA/div.
VIN
5V/div.
VSW
5V/div.
VIN
2V/div.
VSW
2V/div.
VIN
10V/div.
VSW
10V/div.
IBATT
1A/div.
VBATT
2V/div.
IBATT
1A/div.
VBATT
2V/div.
VBATT
5V/div.
IBATT
200mA/div.
MP2615 Rev. 1.02
7/9/2019
IBATT
1A/div.
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MP2615 – 2A, 1- CELL OR 2- CELL LI-ION BATTERY CHARGER
TYPICAL PERFORMANCE CHARACTERISTICS (continued)
VIN = 5V/9V, C1=C2=22µF, SEL=Float/High, CELL=Float/High, L=6.8µH, RS1=50mΩ, Battery
Simulator, TA = 25°C, unless otherwise noted.
VIN
5V/div.
VSW
5V/div.
VBATT
2V/div.
IBATT
2A/div.
VIN
5V/div.
VSW
5V/div.
VBATT
2V/div.
IBATT
2A/div.
VIN
5V/div.
VSW
5V/div.
VBATT
2V/div.
IBATT
1A/div.
MP2615 Rev. 1.02
7/9/2019
VIN
10V/div.
VSW
10V/div.
VBATT
2V/div.
VIN
2V/div.
VSW
2V/div.
IBATT
1A/div.
VBATT
2V/div.
IBATT
2A/div.
VIN
2V/div.
VSW
2V/div.
VIN
10V/div.
VSW
10V/div.
IBATT
1A/div.
VBATT
2V/div.
IBATT
500mA/div.
VBATT
2V/div.
VIN
5V/div.
VSW
5V/div.
VIN
5V/div.
VSW
5V/div.
VBATT
2V/div.
IBATT
1A/div.
VBATT
2V/div.
IBATT
1A/div.
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MP2615 – 2A, 1- CELL OR 2- CELL LI-ION BATTERY CHARGER
TYPICAL PERFORMANCE CHARACTERISTICS (continued)
VIN = 5V/9V, C1=C2=22µF, SEL=Float/High, CELL=Float/High, L=6.8µH, RS1=50mΩ, Battery
Simulator, TA = 25°C, unless otherwise noted.
VIN
5V/div.
VSW
5V/div.
IBATT
1A/div.
VBATT
2V/div.
VIN
10V/div.
VSW
10V/div.
VBATT
2V/div.
IBATT
1A/div.
VIN
10V/div.
VSW
10V/div.
IBATT
500mA/div.
VBATT
2V/div.
VIN
5V/div.
VSW
10V/div.
VIN
5V/div.
VSW
10V/div.
VIN
5V/div.
VSW
10V/div.
VBATT
5V/div.
IBATT
2A/div.
VBATT
5V/div.
IBATT
2A/div.
VBATT
5V/div.
IBATT
1A/div.
VIN
10V/div.
VIN
10V/div.
VSW
10V/div.
VSW
10V/div.
VBATT
5V/div.
IBATT
1A/div.
VBATT
5V/div.
IBATT
1A/div.
VIN
5V/div.
VSW
10V/div.
VBATT
5V/div.
IBATT
1A/div.
MP2615 Rev. 1.02
7/9/2019
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MP2615 – 2A, 1- CELL OR 2- CELL LI-ION BATTERY CHARGER
TYPICAL PERFORMANCE CHARACTERISTICS (continued)
VIN = 5V/9V, C1=C2=22µF, SEL=Float/High, CELL=Float/High, L=6.8µH, RS1=50mΩ, Battery
Simulator, TA = 25°C, unless otherwise noted.
Power Off
En On
En Off
VIN = 18V, 2 Cell, VBATT = 8.4V
VIN = 5V, 1 Cell, VBATT = 3.6V
VIN = 5V, 1 Cell, VBATT = 3.6V
VIN
10V/div.
VSW
10V/div.
VBATT
10V/div.
IBATT
500mA/div.
VIN
5V/div.
VIN
5V/div.
VSW
5V/div.
VBATT
2V/div.
VSW
5V/div.
VBATT
2V/div.
IBATT
2A/div.
IBATT
2A/div.
En On
En On
En Off
VIN = 5V, 1 Cell, VBATT = 4.2V
VIN = 9V, 2 Cell, VBATT = 7.2V
VIN = 9V, 2 Cell, VBATT = 8.4V
VIN
5V/div.
VBATT
2V/div.
VSW
5V/div.
IBATT
2A/div.
VIN
5V/div.
VIN
5V/div.
VSW
10V/div.
VSW
10V/div.
VBATT
5V/div.
IBATT
1A/div.
VBATT
5V/div.
IBATT
1A/div.
NTC Fault Control
Timer Out
Charge Full Indication
VIN = 5V, 1 Cell, VBATT = 3.6V
VIN = 9V, 2 Cell,
VBATT = 8.4V, CTMR = 220pF
VIN = 5V, 1 Cell, VBATT = 4.2V
VTMR
2V/div.
VNTC
2V/div.
VSW
5V/div.
VSW
10V/div.
VBATT
2V/div.
IBATT
1A/div.
VBATT
2V/div.
IBATT
1A/div.
MP2615 Rev. 1.02
7/9/2019
VACOK
2V/div.
VBATT
2V/div.
VCHGOK
2V/div.
IBATT
500mA/div.
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11
MP2615 – 2A, 1- CELL OR 2- CELL LI-ION BATTERY CHARGER
FUNCTIONAL BLOCK DIAGRAM
Figure 1: Functional Block Diagram
MP2615 Rev. 1.02
7/9/2019
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12
MP2615 – 2A, 1- CELL OR 2- CELL LI-ION BATTERY CHARGER
OPERATION
The MP2615 is a peak current mode controlled
switching charger for 1- or 2- cell lithium-ion and
lithium-polymer battery. The MP2615 integrates
both the high-side and low-side switches of the
synchronous BUCK converter to provide high
efficiency and save on PCB area.
Charge Cycle (Mode change: TC CC CV)
The MP2615 regulates the charge current (ICHG)
and battery voltage (VBATT) using two control
loops to achieve highly-accurate constant current
(CC) charge and constant voltage (CV) charge.
As shown in Figure 2, when the VBATT < VTC, the
MP2615 stays in trickle-charge mode and the
output of charge current loop COMPI dominates
the control. The battery is charged by a tricklecharge current ITC until the battery voltage
reaches VTC. If the charger stays in the tricklecharge mode till the trickle-charge timer is
triggered, charging will be terminated.
The MP2615 will enter constant-current charge
mode once the battery voltage rises higher than
VTC. In this mode the charge current will increase
from ITC to ICC to fast charge the battery.
When the battery voltage rises over full battery
voltage VBATT_FULL, the charger enters into
constant-voltage mode. In constant voltage mode,
the battery voltage is regulated at VBATT_FULL
precisely and the charge current will fall naturally
due to the existing equivalent internal resistance
of the battery. For the operation flow chart,
please also refer to Figure 4.
Figure 2: Li-ion Battery Charge Profile
MP2615 Rev. 1.02
7/9/2019
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13
MP2615 – 2A, 1- CELL OR 2- CELL LI-ION BATTERY CHARGER
Charge Full Termination and Auto-Recharge
When the charge current drops below the
termination threshold (IBF) during the CV charge
phase, the charger will stop charging and the
CHGOK pin becomes open drain. The timer will
also be reset and turned off. Once the battery
voltage decreases below the recharge threshold
VRECH (4.0V/Cell while connect SEL-pin to AGND),
recharging will automatically kick in and the timer
restarts a new charge cycle.
COT Charge Mode
The MP2615 uses the floating ground method to
drive the high-side MOSFET of the buck
converter. During the off-time of the high-side
MOSFET, the BST capacitor is recharged and
the voltage across it is used as the HS-MOS gate
drive. Thus a minimum off-time 200ns is required
to maintain sufficient voltage at BST capacitor.
When200ns minimum off-time is achieved due to
large duty cycle, the MP2615 will enter COT
(constant off-time) charge mode. In this mode of
operation, switching frequency is slightly
decreased in order to achieve 99% duty cycle.
Charge Status Indication
The MP2615 has two open-drain status outputs,
CHGOK pin and ACOK pin. The ACOK pin
goes low when the input voltage is 300mV larger
than battery voltage and over the under voltage
lockout threshold. Pin CHGOK is used to indicate
the status of the charge cycle. Table 1
summarized the operation of both CHGOK and
ACOK according to the status of charge.
Table 1: Charging Status Indication
Charger Status
ACOK
CHGOK
Low
Low
High
impedance
MP2615 Rev. 1.02
7/9/2019
Low
High
impedance
High
impedance
In charging
End of charge;
NTC fault;
Timer out:
EN disable;
Thermal shutdown;
VIN absent;
VIN − VBATT < 0.3V
Safety Timer Operation
The MP2615 has an internal safety timer to
terminate charging during time out. The capacitor
CTMR connected between the TMR pin and GND
is used to set the internal oscillator period,
TP (seconds) 0.46 CTMR (uF)
(1)
This timer limits the max trickle charge time to
8192 internal oscillating periods. If the charger
stays in trickle charge mode for longer than the
max oscillating periods, it will be terminated and
the CHGOK becomes open drain to indicate the
timer-out fault. If charge cycle successfully goes
through trickle charge within the allowed time
limit, it enters into the CC charge mode and the
timer continues to count the oscillating periods.
When the battery is charged full, the timer turns
off and clears the counter, waiting for the autorecharge to restart.
If the charge time during CC/CV mode exceeds
49152 oscillating periods and the battery full has
not been qualified, the charger will be terminated
and a timer-out fault is also indicated by floating
the CHGOK . The charger can exit the timer-out
fault state and the on-chip safety timer restarts
counting when one of the following conditions
occurs:
The battery voltage falls below the autorecharge threshold VRECH.
A power-on-reset (POR) event occurs;
EN pin is toggled.
The timer can be disabled by pulling TMR-pin to
AGND.
Thus, the trickle mode charge time is:
t Trickle_tmr (minutes) 62.8 CTMR (uF)
(2)
If connect a CTMR of 0.47uF, the trickle charge
time is about 30 minutes.
The CC/CV mode charge time is:
t Total_tmr (hours) 6.28 CTMR (uF)
(3)
If connect a CTMR of 0.47uF, the CC/CV charge
time is 2.95 hours.
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14
MP2615 – 2A, 1- CELL OR 2- CELL LI-ION BATTERY CHARGER
Negative
Thermal
Coefficient
(NTC)
Thermistor
The NTC pin allows the MP2615 to sense the
battery temperature using the Negative Thermal
Coefficient (NTC) resistor available in the battery
pack to ensure safe operating environment of the
battery. . A resistor with appropriate value should
be connected from VCC to NTC pin and the
thermistor is connected from NTC pin to AGND.
The voltage on the NTC-pin is determined by the
resistor divider whose divide-ratio depends on
the battery temperature. When the voltage at the
NTC pin falls out of the NTC window range, the
charging will pause until the battery temperature
goes back to normal operating conditions.
As a result the MP2615 will stop charging and
report this condition to the status pins. Charging
will automatically resume after the temperature
falls back within safe range.
Short Circuit Protection
The MP2615 has an internal comparator to check
for battery short circuit. Once VBATT falls below 2V,
the device detects a battery-short status and the
cycle-by-cycle peak current limit falls to about
2.2A to limit the current spike during the batteryshort transition. Furthermore, the switching
frequency also folds back to minimize the power
loss.
Thermal Shutdown Protection
To prevent the chip from overheating during
charging, the MP2615 monitors the junction
temperature, TJ, of the die. Once TJ reaches the
thermal shutdown threshold (TSHTDWN) of 150°C,
the charger converter turns off. Once the TJ falls
below 130°C the charging will restart.
MP2615 Rev. 1.02
7/9/2019
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15
MP2615 – 2A, 1- CELL OR 2- CELL LI-ION BATTERY CHARGER
INPUT POWER UP START UP TIMING FLOW
Figure 3: Input Power Start-up Timing Diagram
MP2615 Rev. 1.02
7/9/2019
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MP2615 – 2A, 1- CELL OR 2- CELL LI-ION BATTERY CHARGER
OPERATION FLOW CHART
Figure 4: Operation Flow Chart
MP2615 Rev. 1.02
7/9/2019
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17
MP2615 – 2A, 1- CELL OR 2- CELL LI-ION BATTERY CHARGER
some tolerance. To optimize efficiency, chose an
inductor with a DC resistance less than 50mΩ.
APPLICATION INFORMATION
COMPONENT SELECTION
Charge Current Setting
The constant charge current (ICC) of the MP2615
can be set by the sense resistor RS1 (see
Typical Application). The equation to determine
the programmable CC-charge current is
expressed as following,
ICC
100mV
(A)
RS1(m )
NTC Resistor Divider Selection
Figure shows that an internal resistor divider is
used to set the low temperature threshold and
high temperature threshold at 73.3%·VCC and
29.3%·VCC, respectively. For a given NTC,
thermistor, select appropriate RT1 and RT2 to set
the NTC window.
VCC
(4)
To get 2A ICC, a RS1 of 50mΩ should be selected.
ITC 10%ICC
10mV
(A)
RS1(m )
L
VIN - VBATT VBATT
∆IL_MAX VIN fS
(6)
Where VIN, VBATT, and fS are the typical input
voltage, the CC charge threshold, and the
switching frequency, respectively. And ∆IL_MAX is
the maximum inductor ripple current, which is
usually 30% of the CC charge current.
∆IL_MAX 30%ICC
(7)
Based on the condition where ICC = 2A, VIN = 12V,
VBATT = 6V and fs = 760kHz the calculated
inductance is 6.6µH. The inductor saturation
current must exceed 2.6A at least and have
MP2615 Rev. 1.02
7/9/2019
V TH_Low
NTC
(5)
Inductor Selection
To select the right inductor, a trade off should be
made between cost, size, and efficiency. An
inductor of lower inductance value corresponds
with smaller size, but it results in higher ripple
currents, higher magnetic hysteretic losses, and
higher output capacitances. Conversely, higher
inductance value is beneficial to getting a lower
ripple current and smaller output filter capacitors,
but resulting in higher inductor DC resistance
(DCR) loss. Based on practical experience, the
inductor ripple current should not exceed 30% of
the maximum charge current under worst cases.
For the MP2615 with a typical 12V input voltage
to charge a 2-cell battery, the maximum inductor
current ripple occurs at the corner point between
trickle charge and CC charge (VBATT = 6V).
Inductance estimations are as follow:
Low Temp Threshold
RT1
Accordingly, the trickle charge current (ITC) can
be obtained by the following equation,
RT2
RNTC
High Temp Threshold
VTH_High
Figure 5: NTC Function Block
The thermistor (NCP18XH103) noted above has
the following electrical characteristic:
At 0°C, RNTC_Cold = 27.445kΩ;
At 50°C, RNTC_Hot = 4.1601kΩ.
The following equations are derived assuming
that the NTC window is between 0°C and 50°C:
RT2 //RNTC_Cold
VTH_Low
(8)
=
= 73.3%
RT1 + RT2 //RNTC_Cold VREF33
RT2//RNTC_Hot
RT1 + RT2//RNTC_Hot
=
VTH_High
VREF33
= 29.3%
(9)
According to Equation (8) (9), and the required
battery temperature range to calculate RT1 and
RT2.
Input Capacitor Selection
The input capacitors C1 from the typical
application circuit absorbs the maximum ripple
current from the buck converter, which is given
by:
IRMS_MAX ICC
VTC (VIN_MAX VTC )
VIN_MAX
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(10)
18
MP2615 – 2A, 1- CELL OR 2- CELL LI-ION BATTERY CHARGER
For a given ICC = 2A, VTC = 6V, VIN_MAX = 18V,
the maximum ripple current is 1A. Select the
input capacitors so that the temperature rise
due to the ripple current does not exceed 10°C.
Use ceramic capacitors with X5R or X7R
dielectrics because of their low ESR and small
temperature coefficients. For most applications,
use a 22µF capacitor.
1CO
8fs 2LrO_MAX
21.3F
(12)
We can then approximate this value and
choose a 22µF ceramic capacitor.
PCB Layout Guide
PCB layout is important to meet specified noise,
efficiency and stability requirements. The
following design considerations can improve
circuit performance,
1) Route the power stage adjacent to the
grounds. Aim to minimize the high-side
switching node (SW, inductor), trace
lengths in the high-current paths and the
current-sense resistor trace. Keep the
switching node short and away from the
feedback network.
2) Connect the charge current sense
resistor to CSP (pin 10), BATT (pin 9).
Minimize the length and area of this
circuit loop.
3) Place the input capacitor as close as
possible to the VIN and PGND pins.
Place the output inductor close to the IC
as and connect the output capacitor
between the inductor and PGND of the
IC. This minimizes the current path loop
area from the SW pin through the LC
filter and back to the PGND pin.
4) Connect AGND and PGND at a single
point.
5) Figure 6 is a PCB layout reference
design.
Output Capacitor Selection
The output capacitor C2 (see the typical
application circuit) is in parallel with the battery.
C2 absorbs the high-frequency switching ripple
current and smoothes the output voltage. Its
impedance must be much less than that of the
battery to ensure it absorbs the ripple current.
Use a ceramic capacitor because it has lower
ESR and smaller size.. The output voltage
ripple is given by,
VO
VO
VIN
∆rO
2
VO
8CO fS L
VTC
VIN_MAX
1-
(11)
In order to guarantee ± 0.5% full battery
voltage accuracy, the maximum output voltage
ripple must not exceed 0.5% (e.g., 0.1%). The
maximum output voltage ripple occurs at the
minimum battery voltage of the CC charge and
the maximum input voltage.
For VIN_MAX = 18V, VCC_MIN = VTC =6V, L = 6.8µH,
fS = 760kHz, ∆rO_MAX = 0.1%, the output
capacitor can be calculated as,
VIN
GND
SW
VIN
VCC
CHGOK
CSP
BATT
CELL
SEL
EN
NC
AGND
GND
PGND
BST
TMR
NTC
ACOK
BATT
Figure 6: MP2615 PCB Guild Design
MP2615 Rev. 1.02
7/9/2019
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19
MP2615 – 2A, 1- CELL OR 2- CELL LI-ION BATTERY CHARGER
TYPICAL APPLICATION CIRCUITS
Figure 7: Typical Application Circuit to Charge a 2 Cell Battery with 12VIN.
MP2615 Rev. 1.02
7/9/2019
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MP2615 – 2A, 1- CELL OR 2- CELL LI-ION BATTERY CHARGER
PACKAGE INFORMATION
QFN-16 (3mmX3mm)
PIN 1 ID
MARKING
PIN 1 ID
0.10x45° TYP.
PIN 1 ID
INDEX AREA
BOTTOM VIEW
TOP VIEW
SIDE VIEW
NOTE:
0.10x45°
1) ALL DIMENSIONS ARE IN MILLIMETERS.
2) EXPOSED PADDLE SIZE DOES NOT INCLUDE
MOLD FLASH.
3) LEAD COPLANARITY SHALL BE 0.10
MILLIMETERS MAX.
4) JEDEC REFERENCE IS MO-220.
5) DRAWING IS NOT TO SCALE.
RECOMMENDED LAND PATTERN
NOTICE: The information in this document is subject to change without notice. Please contact MPS for current specifications.
Users should warrant and guarantee that third party Intellectual Property rights are not infringed upon when integrating MPS
products into any application. MPS will not assume any legal responsibility for any said applications.
MP2615 Rev. 1.02
7/9/2019
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