MP2110
3A Synchronous Step-Down Converter
with Programmable Input Current Limit
The Future of Analog IC Technology
DESCRIPTION
FEATURES
•
•
The MP2110 is a monolithic step-down switch
mode converter with integrated input current limit
switch. The step-down converter integrates a
main switch and a synchronous rectifier for high
efficiency without an external Schottky diode.
The input average current limit can be externally
programmed. It is ideal for powering portable
equipment that is powered by an USB port. The
MP2110 can supply 3A of load current from a
3.3V to 5.4V continuous input voltage with
excellent load and line regulation. The MP2110
input can support up to 12V transient and clamp
the current limit switch output at 5.65V (Typical).
•
The Constant-On-time (COT) control scheme
provides fast transient response high light-load
efficiency and easy loop stabilization. Fault
condition protection includes cycle-by-cycle
current limit and thermal shutdown.
•
•
•
•
The MP2110 is available in a space-saving
14-pin 3mmx3mm QFN package.
High Efficiency: Up to 95%
High Current Step-Down Converter
♦ 1.5MHz Switching Frequency
♦ 70mΩ/50mΩ Internal Power MOSFET
♦ 3A Available Load Current
♦ 100% Low Dropout Operation
♦ Output Voltage as Low as 0.6V
Input Current Limit Switch
♦ Programmable Current Limit: 0.3-3A
♦ ± 10% Current Limit Accuracy when
Current Limit > 1A
♦ Wide Input Voltage Range: 3.3V to 5.4V
♦ 12V Input Transient Tolerance
♦ 70mΩ Internal MOSFET
♦ OVP Clamp Protection
Independent Enable Pins
External Temperature Sense & Protection
Internal Thermal Fault Protection
Space Saving 3mm x 3mm QFN14 Package
APPLICATIONS
•
•
•
•
Wireless Modem Data Cards
USB Powered Devices
Cellular and Smart Phones
Portable Instruments
All MPS parts are lead-free and adhere to the RoHS directive.
“MPS” and “The Future of Analog IC Technology” are Registered Trademarks of
Monolithic Power Systems, Inc.
ADAM (Analog Digital Adaptive Modulation), AAM (….) are Trademarks of
Monolithic Power Systems, Inc.
TYPICAL APPLICATION
SYSIN
C1
10μF
R4
31.6kΩ
RNTC
100k
ENSYS
RSET
NTC
+
OFF ON
MP2110 Rev. 1.11
9/26/2014
C2
22μF
REGIN
FB
PGND, EXPOSED PAD
ENREG
OFF
OUT
SW
C2A
330μF
ON
RSET
1.2k
AGND
L1
1μH
R1
340kΩ
C3
22μF
R2
68kΩ
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1
MP2110 – 3A SYNCHRONOUS BUCK CONVERTER WITH INPUT CURRENT LIMIT
ORDERING INFORMATION
Part Number*
MP2110GQ
Package
QFN-14 (3mm x 3mm)
Top Marking
AFQ
* For Tape & Reel, add suffix –Z (e.g. MP2110GQ–Z).
PACKAGE REFERENCE
TOP VIEW
QFN14 (3x3mm)
ABSOLUTE MAXIMUM RATINGS (1)
Thermal Resistance
VSYSIN, VNTC to GND ..................... -0.3V to +13V
VREGIN to GND ............................. -0.3V to +6.5V
VSW to GND....................... -0.3V to VREGIN +0.3V
All other pins to GND .................. -0.3V to +6.5V
(2)
Continuous Power Dissipation (TA = +25°C)
............................................................2.5W
Junction Temperature ............................ +150°C
Lead Temperature ................................. +260°C
Storage Temperature .............. -65°C to +150°C
QFN-14 (3mmx3mm) ............. 50 ...... 12 ... °C/W
Recommended Operating Conditions
(3)
Continuous Supply Voltage VSYSIN .. 3.3V to 5.4V
Transient Supply Voltage VSYSIN ...................12V
Output Voltage VOUT.......................... 0.6V to 5V
Operating Junction Temp. (TJ). -40°C to +125°C
MP2110 Rev. 1.11
9/26/2014
(4)
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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2
MP2110 – 3A SYNCHRONOUS BUCK CONVERTER WITH INPUT CURRENT LIMIT
ELECTRICAL CHARACTERISTICS
VSYSIN = VENREG = 5.0V, VENSYS = GND, L=1μH, TA = +25°C, unless otherwise noted.
Parameter
Symbol Condition
Supply
Current
(No
IQ
Switching)
Shutdown Current
ISTD
SYSIN Under Voltage
VSYSIN_R
Lockout Threshold
SYSIN Under Voltage
VSYSIN_HYS
Lockout Hysteresis
REGIN Under Voltage
VREGIN_R
Lockout Threshold
REGIN Under Voltage
VREGIN_HYS
Lockout Hysteresis
Regulator
Input
VDISCH_F
Discharge Threshold
Discharge Hysteresis
Typ
Max
Units
VFB = 0.63V
190
230
μA
VENSYS = 5V
3
5
μA
2.4
2.6
V
Rising Edge
Min
2.2
140
Rising Edge
2.5
SYSIN Falling
2.7
2.9
RNTC=NCP18WF104
(80°C), R4=31.6kΩ
V
mV
3.1
100
Discharge MOSEFT On
RON_DISCH VSYSIN = 2.6V
Resistance
RNTC=NCP18WF104
External Thermal Sense
VNCT_R
Trip Voltage
(100°C), R4=31.6kΩ
VNCT_F
3.1
340
VDISCH_HYS
External Thermal Sense
Recovery Voltage
2.8
mV
V
mV
8.5
15
Ω
12.5
14.5
16.5
%VSYSIN
25
27
29
%VSYSIN
70
85
mΩ
390
810
1.15
490
910
1.25
mA
mA
A
0.4
V
System Input Current Limit Switch
Current Limit Switch On
Resistance
Current Limit
EN Input Logic
Voltage
En Input Logic
Voltage
EN Input Current
Low
High
RON_SW
ISWITCH=100mA
ILIMIT1
ILIMIT2
ILIMIT3
RSET = 13.3kΩ
RSET = 5.1kΩ
RSET = 3.48kΩ
VSYSEN_L
VSYSEN_H
ISYSEN
Output Clamping Voltage
Output Soft-start Time
290
710
1.05
1.5
tSS
VEN = 5V
Over
Voltage
Protection
Output from 10% to
90%
VFB
IFB
2.7V ≤ VREGIN ≤ 6V
VFB=0.6V
VOVP
5.45
V
3.5
7
μA
5.65
5.85
V
2.5
ms
Step-Down Regulator
Feedback Voltage
Feedback Current
PFET
Switch
Resistance
NFET Switch On
Resistance
MP2110 Rev. 1.11
9/26/2014
On
0.588
0.600
10
0.612
50
V
nA
RDSON_P VREGIN =5V
70
mΩ
RDSON_N VREGIN =5V
50
mΩ
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© 2014 MPS. All Rights Reserved.
3
MP2110 – 3A SYNCHRONOUS BUCK CONVERTER WITH INPUT CURRENT LIMIT
ELECTRICAL CHARACTERISTICS
VSYSIN = VENREG = 5.0V, VENSYS = GND, L=1μH, TA = +25°C, unless otherwise noted.
Parameter
Symbol
PFET Current Limit
(5)
On Time
ILIMIT REG
TON
Minimum Off Time
(5)
Min
Typ
3.9
5
520
A
ns
60
ns
1.5
ms
VOUT=3.6V
TOFF
Soft-Start Time
tSS
EN Input Logic Low Voltage
En Input Logic High Voltage
EN Input Current
VENREG L
VENREG H
IENREG
Thermal Shutdown Trip Threshold
Thermal Shutdown Hysteresis
Condition
(5)
(5)
Output from 10% to
90%
Max
0.4
VEN = 0V to 6V
1.5
-1
1
Units
V
V
μA
TOTP
160
°C
TOTP_HYS
20
°C
Note:
5) Guaranteed by characterization test.
MP2110 Rev. 1.11
9/26/2014
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4
MP2110 – 3A SYNCHRONOUS BUCK CONVERTER WITH INPUT CURRENT LIMIT
PIN FUNCTIONS
Pin #
Name
1, 2
PGND
3, 4
REGIN
5
ENREG
6
RSET
7
AGND
8
ENSYS
9
FB
10
OUT
11
NTC
12
SYSIN
13, 14
SW
Exposed
Pad
MP2110 Rev. 1.11
9/26/2014
Description
Power Ground. PGND is internally connected to the source of the low-side N-channel
MOSFET.
Current limit switch output and buck regulator input. Usually this pin connects to a
large tantalum capacitor as energy reservoir.
On/Off Control Input of Step-Down Regulator. Active high. Can not be floated.
Input Current Limit setting pin. A resistor from this pin to ground sets the input current
limit.
Analog Ground. Internally connects to the analog ground of control circuitry.
Current Limit Switch Enable Input. Active low. It has internal pull down resister.
Feedback Input. Connect FB to the center point of the external resistor divider. The
feedback threshold voltage is 0.6V.
Sense pin for output voltage.
Thermistor Input. Connect a resistor from this pin to SYSIN pin and the thermistor
from this pin to ground. Connect to SYSIN to disable the thermal sense function.
Supply Voltage. SYSIN supplies power for internal current limit switch. MP2110
operates from a 3.3V to 5.4V continuous input voltage and 12V transient input
voltage.C1 is needed to prevent large voltage spikes at the input. Put C1as close to
the IC as possible.
Power Switch Output. Inductor connection to drains of the internal PFET and NFET
switches.
The exposed pad and PGND pin must be connected to the same ground plane.
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5
MP2110 – 3A SYNCHRONOUS BUCK CONVERTER WITH INPUT CURRENT LIMIT
TYPICAL PERFORMANCE CHARACTERISTICS
VSYSIN=VENREG=5.0V, VENSYS=GND, L=1μH, TA=25°C, unless otherwise noted.
MP2110 Rev. 1.11
9/26/2014
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© 2014 MPS. All Rights Reserved.
6
MP2110 – 3A SYNCHRONOUS BUCK CONVERTER WITH INPUT CURRENT LIMIT
TYPICAL PERFORMANCE CHARACTERISTICS (continued)
VSYSIN=VENREG=5.0V, VENSYS=GND, L=1μH, TA=25°C, unless otherwise noted.
MP2110 Rev. 1.11
9/26/2014
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7
MP2110 – 3A SYNCHRONOUS BUCK CONVERTER WITH INPUT CURRENT LIMIT
TYPICAL PERFORMANCE CHARACTERISTICS (continued)
VSYSIN=VENREG=5.0V, VENSYS=GND, L=1μH, TA=25°C, unless otherwise noted.
MP2110 Rev. 1.11
9/26/2014
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8
MP2110 – 3A SYNCHRONOUS BUCK CONVERTER WITH INPUT CURRENT LIMIT
FUNCTIONAL BLOCK DIAGRAM
SYSIN
Vref1
Regulator
ENSYS
ENUSB
ENIC
Comp
Charge
Pump
Current Limit
1.31MΩ
219KΩ Comp
NTC
Soft Start
EA
575KΩ
Isense
RSET
NTC
REGIN
150KΩ
219KΩ
Vref2
Comp
Bias&Voltage
Reference
ENREG
0.6V
Soft Start
500KΩ
2.9V
SYSIN
Discharge
Comp
Discharge OK
Comp
0.6V
EA
PDRV
Comp
COT
Pulse
PWM
Driver
SW
NDRV
FB
AGND
Hi-z
Ramp
Generator
SW
Comp
OUT
PGND
Figure 1: Functional Block Diagram
MP2110 Rev. 1.11
9/26/2014
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© 2014 MPS. All Rights Reserved.
9
MP2110 – 3A SYNCHRONOUS BUCK CONVERTER WITH INPUT CURRENT LIMIT
OPERATION
The MP2110 is a high efficiency, 1.5MHz,
synchronous step-down converter with input
current limit switch. The MP2110 is optimized for
low voltage, USB port and Li-Ion battery powered
applications where high efficiency and small size
are critical. The MP2110 can achieve 100% duty
cycle.
MP2110 uses constant on-time control with input
voltage feed forward to stabilize the switching
frequency over full input range. At light load,
MP2110 employs a proprietary control of low side
switch and inductor current to eliminate ringing
on switching node and improve efficiency.
Constant On-time Control
Compare to fixed frequency PWM control,
constant on-time control offers the advantage of
simpler control loop and faster transient response.
By using input voltage feed forward, MP2110
maintains a nearly constant switching frequency
across input and output voltage range. The ontime of the switching pulse can be estimated as:
TON
V
= OUT ⋅ 0.722μs
VIN
To prevent inductor current run away during load
transient, MP2110 fixes the minimum off time to
be 60ns. However, this minimum off time limit will
not affect operation of MP2110 in steady state.
Light Load Operation
In light load condition, MP2110 uses a
proprietary control scheme to save power and
improve efficiency. Instead of turning off the low
side switch immediately when inductor current
start to reverse, MP2110 gradually ramp down
and regulates the low side switch current to a
minimal level, thus avoids the ringing at switching
node that always occurs in discontinuous
conduction mode (DCM) operation.
Current Limit
MP2110 has a typical 5A current limit for the high
side switch. When the high side switch hits
current limit, the high side switch will turn off, and
low side switch will turn on until the inductor
current decreases to the valley current limit. This
will prevent inductor current from continuing to
build up which will result in damage of the
components.
MP2110 Rev. 1.11
9/26/2014
Short Circuit Protection
MP2110 enters short circuit protection mode after
the inductor current hits the current limit and lasts
for 100μs, and tries to recover from short circuit
with hiccup mode. In short circuit protection,
MP2110 will disable output power stage,
discharge soft-start cap and then automatically
try to soft-start again. If the short circuit condition
still holds, MP2110 repeats this operation cycle
till short circuit disappears and output rises back
to regulation level.
Programmable Input Current Limit
The MP2110 has an input current limit protection
function. It will insure that the input current
doesn't exceed the maximum value, when the
input is supplied by the USB. Once the input
current triggers the set current limit level, the
output current will hold at the current limit until
thermal shutdown.
The current limit can be estimated as:
ILIM =
0.96x4
6
( A )( )
RSET ( kΩ )
The input current limit resistor value can be found
from Table 1.
Notes:
6) The formula is theoretic. Refer to table 1 for accurate current
limit setting.
Table 1—Resistor vs. Current Limit Setting
ILIMIT (A)
0.39
0.6
0.81
1.05
1.15
1.52
1.85
2.05
2.25
2.57
2.83
3.08
RSET (kΩ)
13.3
7.15
5.1
3.92
3.48
2.4
1.96
1.74
1.58
1.37
1.24
1.13
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10
MP2110 – 3A SYNCHRONOUS BUCK CONVERTER WITH INPUT CURRENT LIMIT
Output over Voltage Clamp
As the system input voltage rises up and the
current limit switch’s output exceeds its OVP
threshold 5.65V, the output voltage (REGIN) will
be clamped to 5.65V.
Current Limit Switch Output Discharge
When the current limit switch’s input SYSIN is
lower than 2.9V, MP2110 turns on the discharge
MOSFET to discharge the REGIN capacitor
storage. Discharge resistance is typical 8.5Ω and
the specific discharge time depends on the
capacitance between REGIN and GND.
Negative
Thermal
Thermistor
Coefficient
(NTC)
The MP2110 has a built-in NTC comparator that
allows it to sense the external device’s
temperature via the thermistor mounted near the
device. It ensures a safe operating environment
MP2110 Rev. 1.11
9/26/2014
and prevents any smoke and fire happen due to
over temperature. Connect an appropriatelyvalued resistor from SYSIN to the NTC-pin and
connect the thermistor from the NTC-pin to
AGND. The resistor divider with a dividing ratio
depends on device temperature determines the
voltage on the NTC-pin. Once the voltage at the
NTC-pin falls to 14.5% of VSYSIN, the MP2110
output is disabled. The MP2110 restarts if the
voltage rises to 27% of VSYSIN.
Thermal Shutdown
Thermal shutdown is implemented to prevent the
chip from operating at exceedingly high
temperatures. When the silicon die temperature
is higher than 160°C, it shuts down the whole
chip. When the temperature is lower than its
lower threshold, typically 140°C, the chip is
enabled again.
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11
MP2110 – 3A SYNCHRONOUS BUCK CONVERTER WITH INPUT CURRENT LIMIT
APPLICATION INFORMATION
Output Voltage Setting
The external resistor divider sets the output
voltage (see Typical Application Circuit on page
1).
Choose R1 around 200kΩ for optimal transient
response. R2 is then given by:
R2 =
R1
VOUT
−1
0 .6 V
Table 2—Resistor Selection vs. Output
Voltage Setting
VOUT
R1
R2
1V
1.2V
1.8V
180kΩ (1%)
180kΩ (1%)
180kΩ (1%)
267kΩ (1%)
180kΩ (1%)
88.7kΩ (1%)
2.5V
3.3V
3.6V
340kΩ (1%)
340kΩ (1%)
340kΩ (1%)
107kΩ (1%)
75kΩ (1%)
68kΩ (1%)
Inductor Selection
A 0.47μH to 4.7μH inductor with DC current
rating at least 25% higher than the maximum
load current is recommended for most
applications. For best efficiency, the inductor DC
resistance shall be
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