MP2147
The Future of Analog IC Technology
5.5V, 4A, 1.2MHz, High-Efficiency, 40μA IQ
Constant On-Time
Synchronous, Step-Down Switcher
DESCRIPTION
FEATURES
The MP2147 is a monolithic, step-down, switchmode converter with internal power MOSFETs. It
can achieve up to 4A continuous output current
from a 2.8V-to-5.5V input voltage with excellent
load and line regulation. The output voltage can
be regulated to as low as 0.6V.
•
•
•
•
•
•
•
•
•
•
•
•
•
Constant-on-time control provides a fast transient
response and eases loop stabilization. Fault
condition protections include cycle-by-cycle
current limiting and thermal shutdown.
The MP2147 is available in a small QFN2×3mm
package and requires only a minimal number of
readily-available, standard, external components.
The MP2147 is ideal for a wide range of
applications, including storage (SSD, HDD), highperformance DSPs, FPGAs, and distributed
power systems.
•
•
•
Up to 4A Output Current
Wide 2.8V-to-5.5V Operating Input Range
22mΩ and 14mΩ Internal Power MOSFETs
40µA Quiescent Current
1.2MHz Fixed Switching Frequency
1% Feedback Accuracy
External Mode Control
External VCON Control
Adjustable Output from 0.6V
1.5ms Internal SS Time with Pre-Bias Startup
Cycle-by-Cycle Over Current Protection
Short Circuit Protection with Hiccup Mode
Stable with Low-ESR Output Ceramic
Capacitors
Thermal Shutdown
Available in a 2mm×3mm QFN Package
Output Discharge Function
APPLICATIONS
•
•
•
Storage (SSD, HDD)
Portable Instruments
Battery-Powered Devices
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.
TYPICAL APPLICATION
100
90
80
70
60
50
40
30
20
10
0
0.01
MP2147 Rev. 1.0
9/16/2014
0.1
1
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10
1
MP2147 – 5.5V, 4A, 1.2MHz, COT, BUCK SWITCHER
ORDERING INFORMATION
Part Number*
MP2147GD
Package
QFN-12 (2mmx3mm)
Top Marking
ALH
* For Tape & Reel, add suffix –Z (e.g. MP2147GD–Z).
PACKAGE REFERENCE
TOP VIEW
GND GND GND
12 11 10
SW 1
OUT 2
FB
VIN
3
9
SW
8
VIN
7
PG
5
4
6
RAMP EN MODE/VCON
QFN12 (2×3mm)
ABSOLUTE MAXIMUM RATINGS (1)
Thermal Resistance
Supply Voltage VIN ......................................... 6V
VSW ......................................................................
–0.3V (-3V for <10ns) to 6V (8V for <10ns)
All Other Pins ................................–0.3V to +6 V
Junction Temperature ...............................150°C
Lead Temperature ....................................260°C
(2)
Continuous Power Dissipation (TA = +25°C)
................................................................. 1.78W
QFN-12 (2mmx3mm)..…………70.….15.…°C/W
Recommended Operating Conditions
(3)
Supply Voltage VIN ..........................2.8V to 5.5V
Output Voltage VOUT ........................0.6V to 5.5V
Operating Junction Temp. ....... -40°C to +125°C
MP2147 Rev. 1.0
9/16/2014
(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
MP2147 – 5.5V, 4A, 1.2MHz, COT, BUCK SWITCHER
ELECTRICAL CHARACTERISTICS
VIN = 3.6V, TA = 25°C, unless otherwise noted.
Parameters
Symbol
Supply Current (Quiescent)
Shutdown Current
IN Under-Voltage Lockout Threshold
IN Under-Voltage Lockout Hysteresis
Regulated FB Voltage
FB Input Current
EN High Threshold
EN Low Threshold
IQ
VFB
2.8V<VIN<5.5V
VFB = 0.65V
0.594
Typ
Max
Units
40
60
μA
0.1
2.55
300
0.600
50
1
2.7
μA
V
mV
V
nA
V
V
0.606
1.6
0.4
VEN = 2V
VEN = 0V
2
0
1.5
22
14
0
τSS
RDSON_P
RDSON_N
Sourcing
Sinking, PWM Mode
Sinking, PFM Mode
Low-Side Switch Current Limit (6)
Oscillator Frequency
Minimum On Time
Minimum Off Time
PG Rising Threshold
PG Falling Threshold
PG Delay
PG Sink Current Capability
PG INTERNEL Pull Up Resistor
Discharge Resistor
Thermal Shutdown Threshold (6)
Thermal Shutdown Hysteresis (6)
MODE Forced PWM Threshold
MODE PFM Threshold
Min
2.4
EN Input Current
Internal Soft-Start Time (5)
High-Side Switch On-Resistance
Low-Side Switch On-Resistance
SW Leakage Current
High-Side Switch Current Limit
Condition
VIN=3.6V, VEN=2V,
VFB = 0.65V
VEN = 0V
μA
1
6
0.96
τON_MIN
τOFF_MIN
PGTH_H
PGTH_L
PGTD
4
0
1.2
50
60
0.9
0.85
140
Sink 1mA
A
1.44
0.4
500
150
150
20
VIN=3.6V, VEN=2V
VIN=3.6V, VEN=2V
ms
mΩ
mΩ
μA
A
1.2
0.4
MHz
ns
ns
VFB
VFB
μs
V
kΩ
Ω
°C
°C
V
V
Notes:
5) Guaranteed by characterization
6) Guaranteed by design.
MP2147 Rev. 1.0
9/16/2014
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3
MP2147 – 5.5V, 4A, 1.2MHz, COT, BUCK SWITCHER
TYPICAL PERFORMANCE CHARACTERISTICS
VIN = 5V, VOUT = 1.2V, L = 0.47µH, COUT = 44µF, TA = 25°C, unless otherwise noted.
100
100
100
90
90
90
80
80
80
70
70
70
60
60
60
50
50
50
40
40
40
30
30
30
20
20
20
10
10
10
0
0.01
0
0.01
0.1
1
10
0.1
1
10
0
0.01
0.50
0.50
0.50
0.40
0.40
0.40
0.30
0.30
0.30
0.20
0.20
0.20
0.10
0.10
0.10
0.00
0.00
0.00
-0.10
-0.10
-0.10
-0.20
-0.20
-0.20
-0.30
-0.30
-0.30
-0.40
-0.40
-0.40
-0.50
0 0.5
-0.50
0 0.5
1 1.5
2 2.5
3 3.5
4
0.50
1 1.5
2 2.5
3 3.5
4
3 3.5
4 4.5
5 5.5
6
-0.50
0 0.5
0.1
1 1.5
1
2 2.5
10
3 3.5
4
1.0
0.40
0.30
0.5
0.20
0.10
0.00
0.0
-0.10
-0.20
-0.5
-0.30
-0.40
-0.50
0 0.5
MP2147 Rev. 1.0
9/16/2014
1 1.5
2 2.5
3 3.5
4
-1.0
2 2.5
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4
MP2147 – 5.5V, 4A, 1.2MHz, COT, BUCK SWITCHER
TYPICAL PERFORMANCE CHARACTERISTICS (continued)
VIN = 5V, VOUT = 1.2V, L = 0.47µH, COUT = 44µF, TA = 25°C, unless otherwise noted.
Quiescent Current
vs. Temperature
VIN UVLO Rising Threshold
vs. Temperature
100
100
4
90
90
80
3.5
80
70
70
60
60
50
50
2
40
40
1.5
30
30
20
20
10
10
0
0
-60 -40 -20 0
2
2.5
3
3.5
4
4.5
5
5.5
6
EN Rising Threshold
vs. Temperature
1
2
1.8
0.8
1.6
0.7
1.4
0.6
1.2
0.5
1
0.4
0.8
0.3
0.6
0.2
0.4
0.1
0.2
-60 -40 -20 0
20 40 60 80 100
2.5
1
0.5
20 40 60 80 100
0
-60 -40 -20 0
20 40 60 80 100
Switch Frequency
vs. Temperature
0.9
0
3
0.605
0.603
0.601
0.599
0.597
0
-60 -40 -20 0
25
30
20
25
20 40 60 80 100
0.595
-60 -40 -20 0
20 40 60 80 100
20
15
15
10
10
5
0
5
0 0.5
MP2147 Rev. 1.0
9/16/2014
1 1.5
2 2.5
3 3.5 4
0
0 0.5
1 1.5
2 2.5
3
3.5 4
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5
MP2147 – 5.5V, 4A, 1.2MHz, COT, BUCK SWITCHER
TYPICAL PERFORMANCE CHARACTERISTICS (continued)
VIN = 5V, VOUT = 1.2V, L = 0.47µH, COUT = 44µF, TA = 25°C, unless otherwise noted.
VOUT
1V/div.
VOUT
1V/div.
VOUT
1V/div.
VIN
2V/div.
VIN
5V/div.
VIN
2V/div.
VSW
2V/div.
IL
2A/div.
VSW
5V/div.
VSW
2V/div.
IL
5A/div.
IL
2A/div.
VOUT
1V/div.
VOUT
1V/div.
VOUT
1V/div.
VIN
5V/div.
VIN
2V/div.
VIN
5V/div.
VSW
5V/div.
VSW
2V/div.
VSW
5V/div.
IL
5A/div.
IL
500mA/div.
IL
5A/div.
VOUT
1V/div.
VOUT
1V/div.
VOUT
1V/div.
VIN
2V/div.
VIN
5V/div.
VEN
5V/div.
VSW
2V/div.
VSW
5V/div.
VSW
5V/div.
IL
5A/div.
IL
1A/div.
IL
2A/div.
MP2147 Rev. 1.0
9/16/2014
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6
MP2147 – 5.5V, 4A, 1.2MHz, COT, BUCK SWITCHER
TYPICAL PERFORMANCE CHARACTERISTICS (continued)
VIN = 5V, VOUT = 1.2V, L = 0.47µH, COUT = 44µF, TA = 25°C, unless otherwise noted.
VOUT
1V/div.
VOUT
1V/div.
VOUT
1V/div.
VEN
5V/div.
VIN
5V/div.
VEN
5V/div.
VSW
5V/div.
VSW
5V/div.
IL
2A/div.
VSW
5V/div.
IL
5A/div.
IL
5A/div.
VOUT
1V/div.
VOUT
1V/div.
VOUT
1V/div.
VEN
5V/div.
VEN
5V/div.
VEN
5V/div.
VSW
2V/div.
VSW
5V/div.
IL
1A/div.
IL
5A/div.
VSW
5V/div.
IL
2A/div.
VOUT/AC
10mV/div.
VOUT/AC
10mV/div.
VEN
5V/div.
VIN
5V/div.
VIN
5V/div.
VSW
5V/div.
VSW
5V/div.
IL
2A/div.
VSW
5V/div.
VOUT
1V/div.
IL
5A/div.
MP2147 Rev. 1.0
9/16/2014
IL
2A/div.
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MP2147 – 5.5V, 4A, 1.2MHz, COT, BUCK SWITCHER
TYPICAL PERFORMANCE CHARACTERISTICS (continued)
VIN = 5V, VOUT = 1.2V, L = 0.47µH, COUT=44µF, TA = 25°C, unless otherwise noted.
VOUT/AC
10mV/div.
VIN
5V/div.
VSW
5V/div.
IL
5A/div.
VOUT/AC
50mV/div.
VOUT/AC
50mV/div.
VOUT
1V/div.
VIN
5V/div.
VSW
2V/div.
VEN
5V/div.
IL
2A/div.
IL
2A/div.
VOUT/AC
50mV/div.
VSW
5V/div.
VOUT/AC
20mV/div.
VIN
5V/div.
VIN
5V/div.
VSW
5V/div.
VSW
5V/div.
IOUT
5A/div.
IOUT
5A/div.
IOUT
2A/div.
VOUT
1V/div.
VOUT
1V/div.
VIN
5V/div.
VSW
5V/div.
VIN
5V/div.
VSW
5V/div.
VIN
5V/div.
VSW
5V/div.
IOUT
2A/div.
IL
5A/div.
IL
5A/div.
VOUT/AC
50mV/div.
MP2147 Rev. 1.0
9/16/2014
VIN
5V/div.
VSW
5V/div.
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MP2147 – 5.5V, 4A, 1.2MHz, COT, BUCK SWITCHER
TYPICAL PERFORMANCE CHARACTERISTICS (continued)
VIN = 5V, VOUT = 1.2V, L = 0.47µH, COUT = 44µF, TA = 25°C, unless otherwise noted.
MP2147 Rev. 1.0
9/16/2014
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9
MP2147 – 5.5V, 4A, 1.2MHz, COT, BUCK SWITCHER
PIN FUNCTIONS
Package
Pin #
1, 9
2
3
4
5
6
7
Name
Description
Switch Node. Connect to the inductor. This pin connects to the internal high-side and lowside power MOSFET switches.
OUT Output Voltage Sensing pin.
Feedback. Input to the error amplifier. Connect to an external resistor divider between the
FB
output and GND. Comparing the FB voltage to the internal 0.6V reference sets the
regulation voltage.
RAMP External Ramp. Sets the ramp to optimize the transient performance.
Enable. EN is high voltage level to enable. For automatic start-up, connect EN pin to VIN
EN
pin with a pull-up resistor.
Multi-Use Pin. 1. PWM and PFM Selection. When MODE is more than 1.2V, MP2147
MODE enters PWM mode. When MODE is lower than 0.4V or floating, MP2147 enters PFM
/VCON mode. 2. Analog Voltage Dynamic Regulation. Analog voltage input pin which control
output voltage by PWM mode.
Power Good. This pin is an open drain that goes HIGH if the output voltage exceeds 90%
PG
of the nominal voltage. There is a 140µs delay between when VFB>90% to when the PG
pin goes HIGH.
SW
8,
Exposed
Pad
VIN
Input Supply. Requires a decoupling capacitor to ground to reduce switching spikes.
10, 11,12
GND
IC Ground. Connect these pins to larger copper areas to the negative terminals of the input
and output capacitors.
MP2147 Rev. 1.0
9/16/2014
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MP2147 – 5.5V, 4A, 1.2MHz, COT, BUCK SWITCHER
BLOCK DIAGRAM
VIN
Bias
&
Voltage
Reference
EN
Soft start
+
COMP
VTH
Lo-Iq
0.6V
RST
+
+ E.A.
-
Constant
On - Time
Pulse
Main
Switch
(PCH)
PDRV
PWM
PWM
+
Lo-Iq
+
FB
SW
EN
FBCOMP
Driver
VOUT
Lo-Iq
RAMP
Ramp
generator
Synchronous
Rectifier
( NCH)
ZCX
SW
Lo-Iq
Hi-Z
NDRV
OUT
+
IN
GND
COMP
-
FB for
fixed output
Lo-Iq
+
COMP
0. 54V
-
MODE/
VCON
PG
Figure 1: Functional Block Diagram
MP2147 Rev. 1.0
9/16/2014
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11
MP2147 – 5.5V, 4A, 1.2MHz, COT, BUCK SWITCHER
The MP2147 uses constant on-time control with
input voltage feed-forward to stabilize the
switching frequency over its full input Voltage
range. During light loads, the MP2147 employs
a proprietary control over the low-side MOSFET
(LS-FET) and inductor current to improve
efficiency.
Constant-On-Time Control
When compared to fixed-frequency PWM
control, constant-on-time control offers a
simpler control loop and faster transient
response. The MP2147’s input-voltage feedforward maintains a nearly constant switching
frequency across the entire input and output
voltage range. The on-time of the switching
pulse can be estimated as:
t ON =
VOUT
⋅ 0.83μs
VIN
To prevent inductor current runaway during the
load transient, the MP2147 has a fixed
minimum off time of 60ns. However, this
minimum off time limit does not affect the
operation of the MP2147 in steady state in any
way.
Light-Load Operation
During light loads, the MP2147 uses a
proprietary control scheme to save power and
improve efficiency: There is a zero current
cross circuit to detect if the inductor current
starts to reverse. LS-FET turns off immediately
when the inductor current starts to reverse and
trigger the ZCD in discontinuous conduction
mode (DCM) operation.
Considering the internal circuit propagation time,
the typical delay is 50ns. It means the inductor
current still fall after the ZCD is trigger in this
delay. If the inductor current falling slew rate is
fast (Vo voltage is high or close to Vin), the low
side MOSFET is turned off and inductor current
may be negative. This phenomena will cause
MP2147 can not enter DCM operation. If the
DCM mode is required, the off time of low side
MOSFET in CCM should be longer than 100ns.
For example, Vin is 3.6V and Vo is 3.3V, the off
MP2147 Rev. 1.0
9/16/2014
time in CCM is 70ns. It is difficult to enter DCM
at light load. And using smaller inductor can
improve it and make it enter DCM easily.
Enable
When the input voltage exceeds the undervoltage lockout (UVLO) threshold—typically
2.55V—the MP2147 can be enabled by pulling
the EN pin above 1.6V. Leaving EN pin floating
or grounded will disable the MP2147. There is
an internal 1MΩ resistor from the EN pin to
ground.
Mode Selection and Analog Voltage
Dynamic Regulation
MP2147 has programmable PWM and PFM
work mode. When MODE/VCON is more than
1.2V, MP2147 enters PWM mode. When
MODE/VCON is lower than 0.4V or floating,
MP2147 enters PFM mode. PFM mode can
achieve high efficiency by light-load operation.
PWM mode can keep constant switch
frequency and smaller Vo ripple, but it has low
efficiency at light load.
0.7
REFERENCE VOLTAGE (V)
OPERATION
0.6
0.5
0.4
0.3
0.2
0.1
0
0.5 0.6 0.7 0.8 0.9 1
VCON (V)
1.1 1.2
Figure 2: Reference Voltage change with VCON
MP2147 can dynamic regulate output voltage
by MODE/VCON pin to meet some situation
need change output voltage directly. When
MOED/VCON pin get an appropriate voltage
value (from 0.6V to 1.1V), MP2147 will work
with PWM mode and internal reference voltage
changes smoothly to achieve a new output
voltage without changing external resistor
divider. When VCON function is enabled, set
Ref voltage from 0.35V to 0.6V, the accuracy is
3% typically. When set Ref voltage from 0.1V to
0.35V, the accuracy is 10% typically. Detail Ref
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12
MP2147 – 5.5V, 4A, 1.2MHz, COT, BUCK SWITCHER
voltage calculation formula such as below:
Ref(V)=0.985 × VCON(V)-0.486
Soft-Start
The MP2147 has a built-in soft-start that ramps
up the output voltage at a constant slew rate
that avoids overshooting at startup. The softstart time is typically about 1.5ms.
Pre-Bias Startup
The MP2147 can start up with a pre-bias output
voltage. If the internal SS voltage is lower than
the FB voltage, the HS-FET and LS-FET
remain off until the SS voltage crosses the FB
voltage.
Power-Good Indicator
The MP2147 has an open drain with a 500kΩ
pull-up resistor as a power-good (PG) indication.
When the FB voltage exceeds 90% of the
regulation voltage (0.6V), the PG pin is pulled
up to VIN by the internal resistor. Otherwise the
PG pin is pulled to ground by an internal
MP2147 Rev. 1.0
9/16/2014
MOSFET. The MOSFET has a maximum Rdson
of less than 100Ω.
Current Limit
The MP2147 has a 6A min current limit for the
HS-FET. When the HS-FET hits its current limit,
the MP2147 enters hiccup mode until the
current drops to prevent the inductor current
from rising and possibly damaging the
components.
Short Circuit and Recovery
The MP2147 enters short-circuit protection
(SCP) mode when it hits the current limit, and
tries to recover from the short circuit by entering
hiccup mode. In SCP, the MP2147 disables the
output power stage, discharges a soft-start
capacitor, and then enacts a soft-start
procedure. If the short-circuit condition still
holds after soft-start ends, the MP2147 repeats
this operation until the short circuit ceases and
output rises back to regulation level.
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13
MP2147 – 5.5V, 4A, 1.2MHz, COT, BUCK SWITCHER
APPLICATION INFORMATION
COMPONENT SELECTION
Setting the Output Voltage
The external resistor divider sets the output
voltage (see the Typical Application schematic).
The feedback resistor (R1) must balance
between stability and dynamic response, and
thus cannot be too large or too small. Choose
an R1 value between 120kΩ and 200kΩ. R2 is
then given by:
R2 =
R1
Vout
−1
0.6
The feedback circuit is shown as Figure 3:
Vout
MP2147
R1
FB
R2
Figure 3: Feedback Network
Table 1 lists the recommended resistors values
for common output voltages.
Table 1: Resistor Values for Common Output
Voltages
VOUT (V)
R1 (kΩ)
R2 (kΩ)
1.0
200(1%)
300(1%)
1.2
200(1%)
200(1%)
1.8
200(1%)
100(1%)
2.5
200(1%)
63.2(1%)
3.3
200(1%)
44.2(1%)
Selecting the Inductor
In order to achieve high efficiency at light load,
a low value inductor such as 0.47 µH is
recommended for most applications. For
highest efficiency, chose an inductor with a DC
resistance less than 15mΩ. For most designs,
the inductance value can be derived from the
following equation.
L1 =
VOUT × (VIN − VOUT )
VIN × ΔIL × fOSC
Choose an inductor current to be approximately
30% of the maximum load current. The
maximum inductor peak current is:
IL(MAX) = ILOAD +
ΔIL
2
Selecting the Input Capacitor
The input current to the step-down converter is
discontinuous, and requires a capacitor to
supply the AC current to the step-down
converter while maintaining the DC input
voltage. Use low-ESR capacitors for the best
performance. Ceramic capacitors with X5R or
X7R dielectrics are highly recommended
because of their low ESR values and small
temperature coefficients. For most applications,
a 22µF capacitor is sufficient. For higher output
voltage, 47uF may be needed to improve
system stability.
Since the input capacitor absorbs the input
switching current it requires an adequate ripple
current rating. The RMS current in the input
capacitor can be estimated by:
IC1 = ILOAD ×
VOUT ⎛⎜ VOUT ⎞⎟
× 1−
VIN ⎜⎜⎝ VIN ⎟⎟⎠
The worse case condition occurs at VIN =
2VOUT, where:
IC1 =
ILOAD
2
For simplification, choose an input capacitor
whose RMS current rating greater than half of
the maximum load current.
The input capacitor can be electrolytic, tantalum
or ceramic. When using electrolytic or tantalum
capacitors, use a small high-quality ceramic
capacitor (0.1μF), placed as close to the IC as
possible. When using ceramic capacitors, make
sure that they have enough capacitance to
prevent excessive voltage ripple at input. The
input voltage ripple caused by capacitance can
be estimated by:
Where ΔIL is the inductor ripple current.
MP2147 Rev. 1.0
9/16/2014
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14
MP2147 – 5.5V, 4A, 1.2MHz, COT, BUCK SWITCHER
⎛
ILOAD
V
V ⎞
× OUT × ⎜ 1 − OUT ⎟
fS × C1 VIN ⎝
VIN ⎠
ΔVIN =
Power Dissipation
IC power dissipation plays an important role in
circuit design—not only because of efficiency
concerns, but also because of the chip’s
thermal requirements. Several parameters
influence power dissipation, such as:
Conduction Loss (Cond)
Dead time (DT)
Switching Loss (SW)
MOSFET Driver Current (DR)
Supply Current (S)
Based on these parameters, we can estimate
the power loss to equal:
PLOSS = PCond + PDT + PSW + PDR + PS
Thermal Regulation
As previously discussed, changes in IC
temperature
change
the
electrical
characteristics,
especially
when
the
temperature exceeds the IC’s recommended
operating
range.
Managing
the
IC’s
temperature requires additional considerations
to ensure that the IC runs within the maximum
allowable temperature junction. While operating
the IC within recommended electrical limits is a
major component to maintaining proper thermal
regulation, specific layout designs can improve
the thermal profile while limiting costs to either
efficiency or operating range.
For the MP2147, connect the ground pin on the
package to a GND plane on top of the PCB to
use this plane as a heat sink. Connect this GND
plane to GND planes beneath the IC using vias
to further improve heat dissipation. However,
given that these GND planes can introduce
unwanted EMI noise and occupy valuable PCB
space requires designing the size and shape of
these planes to match the thermal resistance
requirement:
MP2147 Rev. 1.0
9/16/2014
θSA = θJA − θJC
However, connecting the GND pin to a heat
sink cannot guarantee that the IC will not
exceed its recommended temperature limits; for
instance, if the ambient temperature exceeds
the IC’s temperature limits. If the ambient air
temperature approaches the IC’s temperature
limit, options such as derating the IC so it
operates using less power can help prevent
thermal damage and unwanted electrical
characteristics
PCB Layout Recommendation
Proper layout of the switching power supplies is
very important, and sometimes critical to make
it work properly. Especially, for the high
switching converter, if the layout is not carefully
done, the regulator could show poor line or load
regulation, stability issues.
For MP2147, the high speed step-down
regulator, the input capacitor should be placed
as close as possible to the IC pins. As shown in
Figure 4, the 0805 size ceramic capacitor is
used, please make sure the two ends of the
ceramic capacitor be directly connected to PIN
8 (the Power Input Pin) and PIN 10/11/12 (the
Power GND Pin).
Figure 4: Two ends of Input decoupling
Capacitor close to Pin 8 and Pin 10/11/12
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15
MP2147 – 5.5V, 4A, 1.2MHz, COT, BUCK SWITCHER
TYPICAL APPLICATION CIRCUITS
Figure 5: VIN=5V, IOUT=4A
MP2147 Rev. 1.0
9/16/2014
www.MonolithicPower.com
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MP2147 – 5.5V, 4A, 1.2MHz, COT, BUCK SWITCHER
PACKAGE INFORMATION
QFN-12 (2mmx3mm)
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.
MP2147 Rev.1.0
9/16/2014
www.MonolithicPower.com
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2014 MPS. All Rights Reserved.
17
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