MP2615GQ [MPS]
2A, 1- or 2- Cell Li-ion Battery Charger In 3mm x 3mm Package;
| 型号： | MP2615GQ |
| 厂家： | 
MONOLITHIC POWER SYSTEMS |
| 描述： | 2A, 1- or 2- Cell Li-ion Battery Charger In 3mm x 3mm Package 电池 |
| 文件： | 总21页 (文件大小：1466K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
MP2615
2A, 1- or 2- Cell Li-ion Battery Charger
In 3mm x 3mm Package
DESCRIPTION
FEATURES
The MP2615 is a high efficiency switch mode
battery charger suitable for 1- or 2- cell lithium-
ion 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.
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
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.
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
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.
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.
The MP2615 is available in a 3mm × 3mm 16-
pin QFN package.
“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
L
RS1
5V to 18V Input
SW
VIN
C4
R2
R1
BST
CHGOK
CSP
ACOK
VCC
NTC
1- or2-
MP2615
Cell
C2
C1
BATT
TMR
SEL
Battery
RNTC
R3
C3
EN
ON
OFF
CTMR
AGND
CELL
PGND
MP2615 Rev. 1.0
1/16/2014
www.MonolithicPower.com
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© 2014 MPS. All Rights Reserved.
1
MP2615 – 2A, 1- CELL OR 2- CELL LI-ION BATTERY CHARGER
ORDERING INFORMATION
Part Number*
Package
Top Marking
MP2615GQ
QFN16 (3×3mm)
AEG
* For Tape & Reel, add suffix –Z (e.g. MP2615GQ–Z);
PACKAGE REFERENCE
16
15
14
13
12
1
2
3
11
SW
VIN
CHGOK
CSP
10
9
BATT
VCC
4
5
6
7
8
ABSOLUTE MAXIMUM RATINGS (1)
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
Thermal Resistance (4)
QFN16 (3x3mm) .................... 50...... 12... °C/W
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-to-
ambient 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.
(2)
Continuous Power Dissipation (TA = +25°C)
............................................................2.5W
Operating Temperature............. –40°C to +85°C
Recommended Operating Conditions (3)
VIN................................................. 4.75V to 18V
VBATT ................................................. 2V to 8.4V
Operating Junction Temp. (TJ).–40°C to +125°C
3) The device is not guaranteed to function outside of its
operating conditions.
4) Measured on JESD51-7, 4-layer PCB.
MP2615 Rev. 1.0
1/16/2014
www.MonolithicPower.com
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© 2014 MPS. All Rights Reserved.
2
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
Input Voltage and Current
VCELL = 4V
VIN
4.5
5
18
18
Input Voltage
V
VCELL = 0V
8.75
12
Under
Threshold Rising
Under Voltage
Threshold Hysteresis
Supply Current
Power MOS
Voltage
Lockout
Lockout
VUVLO
3.55
3.75
225
3.95
V
mV
ISHDN
IQ
0.27
1.1
= 4V, Shutdown Current
= 0V, Quiescent Current
EN
EN
mA
High-side
Resistance
Switch
On
On
RH_DS(ON) Measured from VIN to SW
RL_DS(ON)
110
mΩ
Low-side
Resistance
Switch
110
0
mΩ
Switch Leakage
Frequency and Time Parameter
1
μA
= 4V, VSW = 0V
EN
Switching Frequency
Fold-back Frequency
Minimum Off Time (5)
Charging Parameter
FSW
VBATT = 7.5V
VBATT = 0V
VBATT = 9V
760
160
200
kHz
kHz
ns
TOFF
VSEL = 0V
4.168
4.069
8.34
8.14
4.17
4.07
4.2
4.1
4.231
4.131
9.08
8.88
4.54
4.44
Terminal Battery Voltage
VBATT_FULL
VSEL = 4V
VCELL = 0V, VSEL=0V
VCELL = 0V, VSEL=4V
VCELL = 4V, VSEL=0V
VCELL = 4V, VSEL=4V
VSEL = 0V
8.71
8.51
4.36
4.26
4.0
Battery
Over
Voltage
VBOVP
V/Cell
Threshold
Recharge Threshold at VBATT VRECH
Recharge Hysteresis
VSEL = 4V
3.9
150
3
mV/Cell
V/Cell
mV/Cell
A
VSEL = 0V
VSEL = 4V
Trickle
Charge
Voltage
VTC
Threshold
2.91
225
Trickle Charge Hysteresis
CC
3.2
Peak Current Limit
Trickle
2.2
2
CC Current
ICC
ITC
RS1 = 50mΩ
1.8
5%
2.2
A
Trickle Charge Current
10%
15%
ICC
MP2615 Rev. 1.0
1/16/2014
www.MonolithicPower.com
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© 2014 MPS. All Rights Reserved.
3
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
Min
Typ
Max
Units
Termination
Threshold
Current
IBF
5%
10%
15%
ICC
VIN minimum Head-room
(reverse blocking)
VIN − VBATT
300
100
mV
mV
Maximum Current Sense
Voltage
(CSP to BATT)
VSENSE
90
110
3
CSP, BATT Current
ICSP, IBATT Charging disabled
VDRAIN = 0.3V
µA
ACOK/CHGOK Open-drain
Sink Current
5
mA
VCC Regulator Output
VCC Output Voltage
VCC Load Regulation
EN Control
VCC
4.35
4.5
4.65
10
V
∆VCC
ILOAD=0 to 10mA
mV
0.4
V
V
EN Input Low Voltage
EN Input High Voltage
1.8
4
= 4V
= 0V
EN
EN
IEN
μA
Input Current
EN
0.2
Timer Protection
Trickle Charge Time
CC/CV Charge Time
NTC Protection
tTrickle_tmr CTMR = 0.47μF
tTotal_tmr CTMR = 0.47μF
30
Mins
165
NTC Low Temp Rising
Threshold
72
28
73.3
2
74.6
30.6
RNTC=NCP18X103, 0°C
NTC Low Temp Rising
Threshold Hysteresis
%VCC
NTC High Temp Falling
Threshold
29.3
2
RNTC=NCP18X103, 50°C
NTC Low Temp Falling
Threshold Hysteresis
Thermal Protection
Thermal Shutdown(5)
TSHDN
150
20
°C
°C
Thermal
Shutdown
Hysteresis(5)
Reverse Leakage Blocking
VCELL = 0V
VCELL = 4V
3
uA
µA
Battery Reverse Leakage
Current
ILEAKAGE
0.5
Notes:
5) Guaranteed by design.
MP2615 Rev. 1.0
1/16/2014
www.MonolithicPower.com
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4
MP2615 – 2A, 1- CELL OR 2- CELL LI-ION BATTERY CHARGER
PIN FUNCTIONS
Package
Pin #
Name Description
1
2
SW
VIN
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.
3
4
5
VCC
CELL
SEL
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.
6
7
On/ Off Control Input. This pin is pulled to GND with a 1Meg internal resistor.
EN
N/C
NO CONNECT. Please leave this pin floating.
8
AGND Analog Ground.
9
BATT Positive Battery Terminal.
10
CSP
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
become an open drain once the charge is completed or suspended.
11
12
13
14
CHGOK
Valid Input Supply Indicator. A logic Low on this pin indicates the presence of a valid input
power supply.
ACOK
NTC
Thermistor Input. Connect a resistor from this pin to the pin VCC and the thermistor from
this pin to ground.
Internal Safety Timer Control. Connect a capacitor from this node to AGND to set the timer.
And the timer can be disabled by connecting this pin to AGND directly.
TMR
Bootstrap pin. A capacitor is needed to drive the power switch’s gate above the supply
voltage. It is connected between SW and BST pins to form a floating supply across the
power switch driver.
15
16
BST
PGND Power Ground.
MP2615 Rev. 1.0
1/16/2014
www.MonolithicPower.com
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5
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.
MP2615 Rev. 1.0
1/16/2014
www.MonolithicPower.com
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© 2014 MPS. All Rights Reserved.
6
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.
MP2615 Rev. 1.0
1/16/2014
www.MonolithicPower.com
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© 2014 MPS. All Rights Reserved.
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.
MP2615 Rev. 1.0
1/16/2014
www.MonolithicPower.com
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© 2014 MPS. All Rights Reserved.
8
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.
MP2615 Rev. 1.0
1/16/2014
www.MonolithicPower.com
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© 2014 MPS. All Rights Reserved.
9
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.
MP2615 Rev. 1.0
1/16/2014
www.MonolithicPower.com
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© 2014 MPS. All Rights Reserved.
10
MP2615 – 2A, 1- CELL OR 2- CELL LI-ION BATTERY CHARGER
FUNCTIONAL BLOCK DIAGRAM
VIN
Current Sense
A1
IHS
BST
PRE_REGS
VREF
OSC
EN
Regulator
CTRL
Drive
M1
M2
5 bit trim
Current Limit
Comparator
S
Q
R
R
SW
LDO
COMP
VCC
NTC
PWM
Comparator
L
M3
BATT
Charge
Current Sense
CSP
FB
COMPV
GMV
A2
0.123V
or 1.23V
RS1
GMI
BATT
cells
OVP
COMPI
1.23V
1- or 2-
cell
battery
CTRL
ICHG
TMR
SEL
Timer
CELLS
TC/CC
Charge
OVP
Comparator
Comparator
FB
OVP
1.23V
0.879V
Charge Control
Logic
Recharge
Comparator
ACOK
Comparator
FB
VIN
1.171V
BF
VBATT+0.2V
Comparator
ICHG
ACOK
0.123V
CHGOK
AGND
PGND
Figure 1: Functional Block Diagram
MP2615 Rev. 1.0
1/16/2014
www.MonolithicPower.com
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11
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.
reaches VTC. If the charger stays in the trickle-
charge 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.
Charge Cycle (Mode change: TC CC CV)
The MP2615 regulates the charge current (ICHG
)
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.
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 trickle-
charge current ITC until the battery voltage
CV Charge
Threshold
Auto-recharge
Threshold
CC Charge
Current
ICHG
VBATT
CC Charge
Threshold
IBF
TC Charge
Current
CC
Charge
CV
Charge
Charge
Full
Auto-
recharge
Trickle
Charge
Figure 2: Li-ion Battery Charge Profile
MP2615 Rev. 1.0
1/16/2014
www.MonolithicPower.com
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12
MP2615 – 2A, 1- CELL OR 2- CELL LI-ION BATTERY CHARGER
Charge Full Termination and Auto-Recharge
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,
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.
T (seconds) 0.46CTMR(uF)
(1)
P
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 auto-
recharge to restart.
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.
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:
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
The battery voltage falls below the auto-
recharge threshold VRECH
.
lockout threshold. Pin CHGOK is used to indicate
the status of the charge cycle. Table 1
A power-on-reset (POR) event occurs;
EN pin is toggled.
summarized the operation of both CHGOK and
ACOK according to the status of charge.
The timer can be disabled by pulling TMR-pin to
AGND.
Table 1: Charging Status Indication
Thus, the trickle mode charge time is:
Charger Status
ACOK
Low
CHGOK
Low
tTrickle_tmr (minutes) 62.8CTMR(uF)
(2)
In charging
End of charge;
NTC fault;
If connect a CTMR of 0.47uF, the trickle charge
time is about 30 minutes.
High
impedance
Timer out:
Low
The CC/CV mode charge time is:
EN disable;
Thermal shutdown;
tTotal_tmr (hours) 6.28CTMR(uF)
(3)
High
High
VIN absent;
If connect a CTMR of 0.47uF, the CC/CV charge
time is 2.95 hours.
impedance impedance VIN − VBATT < 0.3V
MP2615 Rev. 1.0
1/16/2014
www.MonolithicPower.com
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© 2014 MPS. All Rights Reserved.
13
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 battery-
short 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. 1.0
1/16/2014
www.MonolithicPower.com
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© 2014 MPS. All Rights Reserved.
14
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. 1.0
1/16/2014
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15
MP2615 – 2A, 1- CELL OR 2- CELL LI-ION BATTERY CHARGER
OPERATION FLOW CHART
Figure 4: Operation Flow Chart
MP2615 Rev. 1.0
1/16/2014
www.MonolithicPower.com
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16
MP2615 – 2A, 1- CELL OR 2- CELL LI-ION BATTERY CHARGER
APPLICATION INFORMATION
some tolerance. To optimize efficiency, chose an
inductor with a DC resistance less than 50mΩ.
COMPONENT SELECTION
Charge Current Setting
NTC Resistor Divider Selection
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,
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.
100mV
(4)
ICC
(A)
RS1(m)
VCC
To get 2A ICC, a RS1 of 50mΩ should be selected.
Accordingly, the trickle charge current (ITC) can
be obtained by the following equation,
10mV
Low Temp Threshold
RT1
VTH_Low
NTC
(5)
ITC 10%ICC
(A)
RS1(m)
Inductor Selection
RNTC
RT2
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:
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
RT1 +RT2//RNTC_Cold VREF33
RT2//RNTC_Hot
VTH_High
RT1 +RT2//RNTC_Hot VREF33
VTH_Low
(8)
=
= 73.3%
(9)
V - VBATT VBATT
=
= 29.3%
IN
(6)
L
ΔIL_MAX V fS
IN
According to Equation (8) (9), and the required
battery temperature range to calculate RT1 and
RT2.
Where VIN, VBATT, and fS are the typical input
voltage, the CC charge threshold, and the
switching frequency, respectively. And ΔIL_MAX is
the maximum inductor ripple current, which is
usually 30% of the CC charge current.
ΔI L_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. 1.0
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MP2615 – 2A, 1- CELL OR 2- CELL LI-ION BATTERY CHARGER
For VIN_MAX = 18V, VCC_MIN = VTC =6V, L = 6.8µH,
fS = 760kHz, ∆rO_MAX = 0.1%, the output capacitor
can be calculated as,
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:
VTC
1-
V
IN_MAX
(12)
CO
21.3F
8fs2LrO_MAX
VTC(V
VTC )
IN_MAX
IRMS_MAX ICC
(10)
V
IN_MAX
We can then approximate this value and choose
a 22µF ceramic capacitor.
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.
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.
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,
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.
VO
1-
VO
VO
V
IN
(11)
ΔrO
2
8COfS L
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.
4) Connect AGND and PGND at a single
point.
5) Figure 6 is a PCB layout reference design.
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MP2615 – 2A, 1- CELL OR 2- CELL LI-ION BATTERY CHARGER
BATT
GND
GND
VIN
SW
VIN
VCC
CHGOK
CSP
BATT
Figure 6: MP2615 PCB Guild Design
MP2615 Rev. 1.0
1/16/2014
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MP2615 – 2A, 1- CELL OR 2- CELL LI-ION BATTERY CHARGER
TYPICAL APPLICATION CIRCUITS
L
RS1
50m
VIN
SW
6.8uH
VIN
1k
1k
C4
R2
R1
100nF
BST
CHGOK
CSP
ACOK
VCC
NTC
MP2615
C2
22uF
2 Cell
Battery
C1
22uF
BATT
TMR
SEL
10k
R3
RNTC
10k
C3
1uF
EN
ON
OFF
CTMR
1uF
AGND
CELL
PGND
Figure 7: Typical Application Circuit to Charge a 2 Cell Battery with 12VIN.
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MP2615 – 2A, 1- CELL OR 2- CELL LI-ION BATTERY CHARGER
PACKAGE INFORMATION
QFN16 3X3
PACKAGE OUTLINE DRAWING FOR 16L FCQFN (3X3MM)
MF-PO-D-0157 revision 0.0
PIN 1 ID
MARKING
PIN 1 ID
0.10x45° TYP.
PIN 1 ID
INDEX AREA
TOP VIEW
BOTTOM 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. 1.0
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21
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