MP2147 Datasheet by Monolithic Power Systems Inc.

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MP2147
5.5V, 4A, 1.2MHz, High-Efficiency, 40μA IQ
Constant On-Time
Synchronous, Step-Down Switcher
MP2147 Rev. 1.1 www.MonolithicPower.com 1
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© 2016 MPS. All Rights Reserved.
The Future of Analog IC Technology
DESCRIPTION
The MP2147 is a monolithic, step-down, switch-
mode 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), high-
performance DSPs, FPGAs, and distributed
power systems.
FEATURES
Up to 4A Output Current
Wide 2.8V-to-5.5V Operating Input Range
22m and 14m 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, halogen free, and adhere to the RoHS
directive. For MPS green status, please visit MPS website under Quality
Assurance.
“MPS” and “The Future of Analog IC Technology” are Registered
Trademarks of Monolithic Power Systems, Inc.
TYPICAL APPLICATION
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0.01 0.1 1 10
MP2147 — 5.5V, 4A, 1.2MHz, COT, BUCK SWITCHER l'l'lP5' LLI. ALHY r1 rfi L4 L4 L_______, rw I 0-! r u.. \III
MP2147 – 5.5V, 4A, 1.2MHz, COT, BUCK SWITCHER
MP2147 Rev. 1.1 www.MonolithicPower.com 2
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ORDERING INFORMATION
Part Number* Package Top Marking
MP2147GD QFN-12 (2mmx3mm)
See Below
* For Tape & Reel, add suffix –Z (e.g. MP2147GD–Z).
TOP MARKING
ALH: product code of MP2147GD;
Y: year code;
LLL: lot number;
PACKAGE REFERENCE
TOP VIEW
1
4
10
9
37
6
12
SW
OUT
RAMP
FB
VIN
SW
VIN
PG
EN MODE/VCON
GND GND GND
5
28
11
QFN-12 (2mm×3mm)
"IE MP2147 — 5.5V, 4A, 1.2MHz, COT, BUCK SWITCHER TJ r
MP2147 – 5.5V, 4A, 1.2MHz, COT, BUCK SWITCHER
MP2147 Rev. 1.1 www.MonolithicPower.com 3
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ABSOLUTE MAXIMUM RATINGS (1)
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
Continuous Power Dissipation (TA = +25°C)(2)
................................................................. 1.78W
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
Thermal Resistance (4) θJA θJC
QFN-12 (2mmx3mm)..…………70.….15.…°C/W
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 JA, and the ambient temperature
TA. The maximum allowable continuous power dissipation at
any ambient temperature is calculated by PD (MAX) = (TJ
(MAX)-TA)/JA. Exceeding the maximum allowable powe
r
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.
ij MP2147 — 5.5V, 4A, 1.2MHz, COT, BUCK SWITCHER
MP2147 – 5.5V, 4A, 1.2MHz, COT, BUCK SWITCHER
MP2147 Rev. 1.1 www.MonolithicPower.com 4
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© 2016 MPS. All Rights Reserved.
ELECTRICAL CHARACTERISTICS
VIN = 3.6V, TA = 25°C, unless otherwise noted.
Parameters Symbol Condition Min Typ Max Units
Supply Current (Quiescent) IQ VIN=3.6V, VEN=2V,
VFB = 0.65V 40 60 A
Shutdown Current VEN = 0V 0.1 1 A
IN Under-Voltage Lockout
Threshold 2.4 2.55 2.7 V
IN Under-Voltage Lockout
Hysteresis 300 mV
Regulated FB Voltage VFB 2.8V<VIN<5.5V 0.594 0.600 0.606 V
FB Input Current VFB = 0.65V 50 nA
EN High Threshold 1.6 V
EN Low Threshold 0.4 V
VEN = 2V 2
EN Input Current
VEN = 0V 0
A
Internal Soft-Start Time (5) SS 1.5 ms
High-Side Switch On-Resistance RDSON_P 22 m
Low-Side Switch On-Resistance RDSON_N 14 m
SW Leakage Current 0 1 A
High-Side Switch Current Limit Sourcing 6 A
Sinking, PWM Mode 4
Low-Side Switch Current Limit (6) Sinking, PFM Mode 0 A
Oscillator Frequency 0.96 1.2 1.44 MHz
Minimum On Time ON_MIN 50 ns
Minimum Off Time OFF_MIN 60 ns
PG UV Threshold Rising PGTH_Hi 0.9 VFB
PG UV Threshold Falling PGTH_Lo 0.85 VFB
PG OV Threshold Rising PGTH_Hi 1.15 VFB
PG OV Threshold Falling PGTH_Lo 1.1 VFB
PG Delay PGTD 140 s
PG Sink Current Capability Sink 1mA 0.4 V
PG INTERNEL Pull Up Resistor 500 k
Discharge Resistor 150
Thermal Shutdown Threshold (6) 150 °C
Thermal Shutdown Hysteresis (6) 20 °C
MODE Forced PWM Threshold VIN=3.6V, VEN=2V 1.2 V
MODE PFM Threshold VIN=3.6V, VEN=2V 0.4 V
Notes:
5) Guaranteed by characterization
6) Guaranteed by design.
mp5 MP2147 — 5 5v 4A 1 ZMHz, COT BUCK SWITCHER Efficiency Efficiency Efficiency v(N 5v vw=3 3v Myles 3v °; ; ; _WLVLW % 3 g —WLM y y y —pw,v.m 2v 9 9 9 —PwM,v::: 2v LL LL LL LL LL AMA/0:3 3v LL —pw,vm 5V W Lu “J PwMiva: 3V mung 5v OUTPUT CURRENT (A) OUTPUT CURRENT (A) OUTPUT CURRENT (A) Load Regulation Load Regulation Load Regulation vw=3 3v 2 PPM Vo:lV z z 9 Q 9 5 P M7Vo:l 2v 5 5 <><1 (="" 3="" 3="" 3="" 8="" vo:z.5v="" $="" 8="" :1="" t="" m="" m="" n="" a="" a=""><>< (="" o="" o="" o="" u="" 4="" u="" output="" current="" (a)="" output="" current="" (a)="" output="" current="" (a)="" load="" regulation="" line="" regulation="" v(n:3.3v="" 2="" z="" :="" g="" 9="" pwmjo="" 0a="" 5="" e="" r="">< 3="" 3="" d="" l="" 0="" pwm7va="12V" u="" pwmju:="" a="" lu="" lu="" ‘="" l="" 1="" m="" ‘="" 53="" g="" pwmilo="4A" 3="" j="" output="" current="" (a)="" lnput="" voltage="" (v)="">
MP2147 – 5.5V, 4A, 1.2MHz, COT, BUCK SWITCHER
MP2147 Rev. 1.1 www.MonolithicPower.com 5
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© 2016 MPS. All Rights Reserved.
TYPICAL PERFORMANCE CHARACTERISTICS
VIN = 5V, VOUT = 1.2V, L = 0.47µH, COUT = 44µF, TA = 25°C, unless otherwise noted.
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0.01 0.1 1 10 0.01 0.1 1 10 0.01 0.1 1 10
-1.0
-0.5
0.0
0.5
1.0
2 2.5 3 3.5 4 4.5 5 5.5 6
0 0.5 1 1.5 2 2.5 3 3.5 4 0 0.5 1 1.5 2 2.5 3 3.5 4 0 0.5 1 1.5 2 2.5 3 3.5 4
0 0.5 1 1.5 2 2.5 3 3.5 4
-0.50
-0.40
-0.30
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-0.10
0.00
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-0.50
-0.40
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-0.10
0.00
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-0.10
0.00
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-0.50
-0.40
-0.30
-0.20
-0.10
0.00
0.10
0.20
0.30
0.40
0.50
mp5 MP2147 — 5 5v 4A 1 ZMHz, COT BUCK SWITCHER Quiescent Current vs. Input Voltage ENZZV, FBZO GSV‘SWZGND i i r: V 2 E E g A § m g o 3 g E z = z 8 8 S y m 3 y C 3 \NPUT VOLTAGE (V) TEMPERATURE (°C) TEMPERATURE (Dc; Reference Voltage vs Temperature VTN* .sv A A S 5 £ m 3 E, g g a , I a ,/ E m g ’ o m m z “L 5 m E E b 2 cc m TEMFERATURE (“(2) TEMPERATURE (”C) TEMPERATURE ('C) Tcase Rise Tease Rise vs. Output Current vs. Output Current VW:3.3V 9‘ Q E ’ a M E W Lu § VOUT=1 2 E“; > 5 L“ LU % ///< %="" vou1:1="" 2v,="" e="" vomiuv="" e="" ’/="" w="" 0="" g="" output="" current="" (a)="" outputcurrent(a)="">
MP2147 – 5.5V, 4A, 1.2MHz, COT, BUCK SWITCHER
MP2147 Rev. 1.1 www.MonolithicPower.com 6
6/8/2016 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2016 MPS. All Rights Reserved.
TYPICAL PERFORMANCE CHARACTERISTICS (continued)
VIN = 5V, VOUT = 1.2V, L = 0.47µH, COUT = 44µF, TA = 25°C, unless otherwise noted.
0
0.2
0.4
0.6
0.8
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1.6
1.8
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0.9
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1.5
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3
3.5
4
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100
-60 -40 -20 0 20 40 60 80 100
Quiescent Current
vs. Temperature
V
IN
UVLO Rising Threshold
vs. Temperature
EN Rising Threshold
vs. Temperature
Switch Frequency
vs. Temperature
-60 -40 -20 0 20 40 60 80 100 -60 -40 -20 0 20 40 60 80 100 -60 -40 -20 0 20 40 60 80 100
-60 -40 -20 0 20 40 60 80 100
0.595
0.597
0.599
0.601
0.603
0.605
0
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30
40
50
60
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100
2 2.5 3 3.5 4 4.5 5 5.5 6
0
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25
0 0.5 1 1.5 2 2.5 3 3.5 4
0
5
10
15
20
25
30
0 0.5 1 1.5 2 2.5 3 3.5 4
MP2147 — 5.5V, 4A 1.2MHz, COT, BUCK SWITCHER Power Up low: 4A, PFM Power Up low: 0A, PWM st/div. Ams/aiv stldiv Power Up Power Off Power Off wot”: 4A, PWM wow: DA, PFM low: M. PFM i 1 H‘ F‘ n a '1 Ams/div films/div «yous/div Power Off Power Off Enable On ‘OUT: DA, PWM wow: 4A, PWM new: 0A. PFM i E.—_\ w , A‘ Ex.“ limb—— W1 films/div ways/div. stldlv
MP2147 – 5.5V, 4A, 1.2MHz, COT, BUCK SWITCHER
MP2147 Rev. 1.1 www.MonolithicPower.com 7
6/8/2016 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2016 MPS. All Rights Reserved.
TYPICAL PERFORMANCE CHARACTERISTICS (continued)
VIN = 5V, VOUT = 1.2V, L = 0.47µH, COUT = 44µF, TA = 25°C, unless otherwise noted.
V
OUT
1V/div.
V
IN
2V/div.
V
SW
2V/div.
I
L
2A/div.
V
OUT
1V/div.
V
IN
2V/div.
V
SW
2V/div.
I
L
2A/div.
V
OUT
1V/div.
V
IN
2V/div.
V
SW
2V/div.
I
L
2A/div.
V
OUT
1V/div.
V
IN
2V/div.
V
SW
2V/div.
I
L
500mA/div.
V
OUT
1V/div.
V
IN
5V/div.
V
SW
5V/div.
I
L
5A/div.
V
OUT
1V/div.
V
IN
5V/div.
V
SW
5V/div.
I
L
5A/div.
V
OUT
1V/div.
V
EN
5V/div.
V
SW
5V/div.
I
L
1A/div.
V
OUT
1V/div.
V
IN
5V/div.
V
SW
5V/div.
I
L
5A/div.
V
OUT
1V/div.
V
IN
5V/div.
V
SW
5V/div.
I
L
5A/div.
I'I'IPS' MP2147 — 5.5V, 4A, 1.2MHz, COT, BUCK SWITCHER Enable On Enable On Enable On low: 4A, FFM no“: DA‘ PWM low: 4A, PWM , I , I F [1‘ E‘ n E 1ms/dw 2ms/div lms/div Enable Shutdown Enable Shutdown Enable Shutdown IOUT= OA‘ PFM low: 4A PFM low: OA‘ FWM i E) V) F Ex) 2ms/dlv lms/div Enable Shutdown Steady State Steady State IOUT: 4A pWM No Load. PWM Half Load 2A FWM fi 1ms/dw
MP2147 – 5.5V, 4A, 1.2MHz, COT, BUCK SWITCHER
MP2147 Rev. 1.1 www.MonolithicPower.com 8
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© 2016 MPS. All Rights Reserved.
TYPICAL PERFORMANCE CHARACTERISTICS (continued)
VIN = 5V, VOUT = 1.2V, L = 0.47µH, COUT = 44µF, TA = 25°C, unless otherwise noted.
V
OUT
1V/div.
V
IN
5V/div.
V
SW
5V/div.
I
L
2A/div.
V
OUT
1V/div.
V
EN
5V/div.
V
SW
2V/div.
I
L
1A/div.
V
OUT
1V/div.
V
EN
5V/div.
V
SW
5V/div.
I
L
5A/div.
V
OUT
1V/div.
V
EN
5V/div.
V
SW
5V/div.
I
L
5A/div.
V
OUT
1V/div.
V
EN
5V/div.
V
SW
5V/div.
I
L
2A/div.
V
OUT
1V/div.
V
EN
5V/div.
V
SW
5V/div.
I
L
5A/div.
V
OUT
1V/div.
V
EN
5V/div.
V
SW
5V/div.
I
L
5A/div.
V
OUT
/AC
10mV/div.
V
IN
5V/div.
V
SW
5V/div.
I
L
2A/div.
V
OUT
/AC
10mV/div.
V
IN
5V/div.
V
SW
5V/div.
I
L
2A/div.
I'I'IPS' Steady State Fuli Load 4A, PWM MP2147 — 5.5V, 4A, 1.2MHz, COT, BUCK SWITCHER Steady State No Load, PFM VoUT Prebias Start Up vaE=o 5v, wow: 0A, PFM ”WWW FNN /——-~—.— “L'MJLM. LU; aM—W—vl—«— w iiHii H ms/div. Load Transient Response iom=0A4A, PFM Atoms/div. Load Transient Response iom=0A4A, PWM l Ins/div. Load Transient Response iom=2A4A, PFM W 6 WW FW’M‘L FFMMI ”Fm—'1... mowaiv Load Transient Response iOUT=2A-4A, PWM mowaiv Hiccup With Output Short Nu Load. PFM. Entry 100us/div Hiccup With Output Short Nu Load. PFM.Slsady 6 W Zr H r”? ans m s q . .JLJL/LJ a, “ WITTIT WW 100us/div 1 ms/dw 1 ms/div
MP2147 – 5.5V, 4A, 1.2MHz, COT, BUCK SWITCHER
MP2147 Rev. 1.1 www.MonolithicPower.com 9
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TYPICAL PERFORMANCE CHARACTERISTICS (continued)
VIN = 5V, VOUT = 1.2V, L = 0.47µH, COUT=44µF, TA = 25°C, unless otherwise noted.
V
OUT
/AC
50mV/div.
V
IN
5V/div.
V
SW
5V/div.
I
OUT
5A/div.
V
OUT
/AC
50mV/div.
V
IN
5V/div.
V
SW
5V/div.
I
OUT
5A/div.
V
OUT
/AC
20mV/div.
V
IN
5V/div.
V
SW
5V/div.
I
OUT
2A/div.
V
OUT
/AC
50mV/div.
V
IN
5V/div.
V
SW
5V/div.
I
OUT
2A/div.
V
OUT
1V/div.
V
EN
5V/div.
V
SW
5V/div.
I
L
2A/div.
V
OUT
1V/div.
V
IN
5V/div.
V
SW
5V/div.
I
L
5A/div.
V
OUT
1V/div.
V
IN
5V/div.
V
SW
5V/div.
I
L
5A/div.
V
OUT
/AC
10mV/div.
V
IN
5V/div.
V
SW
5V/div.
I
L
5A/div.
V
OUT
/AC
50mV/div.
V
IN
5V/div.
V
SW
2V/div.
I
L
2A/div.
mp5 MP2147 — 5.5V, 4A, 1.2MHz, COT, BUCK SWITCHER Hiccup With Output Short Hiccup With Output Short Hiccup With Output Short No Load, PPM, Recovery No Load, PWM, Entry No Load, PWM,Steady fl ‘1 i M Maw W/dlv E W/dlv H ‘ M /Vw /Vw VIN ‘ 4 5V div 5V dlv 5V/dlv | HI il Ii WW— vw_ ll i Mil i W 5V/dw SVMIV SVMIV : SNG‘LEM—LM W“ Km; 5th ‘L . W w w w Mus/div. 1msldw. Hus/div Hiccup With Output Short No Load, PWM, Recovery
MP2147 – 5.5V, 4A, 1.2MHz, COT, BUCK SWITCHER
MP2147 Rev. 1.1 www.MonolithicPower.com 10
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© 2016 MPS. All Rights Reserved.
TYPICAL PERFORMANCE CHARACTERISTICS (continued)
VIN = 5V, VOUT = 1.2V, L = 0.47µH, COUT = 44µF, TA = 25°C, unless otherwise noted.
"IE MP2147 — 5.5V, 4A, 1.2MHz, COT, BUCK SWITCHER MP2147 PFM | he
MP2147 – 5.5V, 4A, 1.2MHz, COT, BUCK SWITCHER
MP2147 Rev. 1.1 www.MonolithicPower.com 11
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PIN FUNCTIONS
Package
Pin # Name Description
1, 9 SW Switch Node. Connect to the inductor. This pin connects to the internal high-side and low-
side power MOSFET switches.
2 OUT
Output Voltage Sensing pin.
3 FB
Feedback. Input to the error amplifier. Connect to an external resistor divider between the
output and GND. Comparing the FB voltage to the internal 0.6V reference sets the
regulation voltage.
4 RAMP External Ramp. Sets the ramp to optimize the transient performance.
5 EN
Enable. EN is high voltage level to enable. For automatic start-up, connect EN pin to VIN
pin with a pull-up resistor.
6 MODE
/VCON
Multi-Use Pin. 1. PWM and PFM Selection. When MODE is more than 1.2V, MP2147
enters PWM mode. When MODE is lower than 0.4V or floating, MP2147 enters PFM
mode. 2. Analog Voltage Dynamic Regulation. Analog voltage input pin which control
output voltage by PWM mode.
7 PG
Power Good. The output of this pin is an open drain with internal pull up resistor to VIN.
PG is pulled up to VIN when the FB voltage is within 10% of the regulation level, otherwise
it is LOW. There is a 140µs delay between when VFB reach PG threshold to when the PG
pin goes HIGH.
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.
"IE MP2147 — 5.5V, 4A, 1.2MHz, COT, BUCK SWITCHER fl ENE u Wu RS‘ Puwv swam PwM , a.» mm. “W m. .mw E” D """" '4U 5"" FE 1 , a , ma RAMP 4» mm W T vanerala: ] GND 1 w ma ~ cow FE mr , fixed mm 7; cow use/4b , T MODE! VCON we
MP2147 – 5.5V, 4A, 1.2MHz, COT, BUCK SWITCHER
MP2147 Rev. 1.1 www.MonolithicPower.com 12
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BLOCK DIAGRAM
Figure 1: Functional Block Diagram
"IE MP2147 — 5.5V, 4A, 1.2MHz, COT, BUCK SWITCHER Av-ug- rs: REF
MP2147 – 5.5V, 4A, 1.2MHz, COT, BUCK SWITCHER
MP2147 Rev. 1.1 www.MonolithicPower.com 13
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OPERATION
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 feed-
forward 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:
OUT
ON
IN
V
t0.83s
V

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.
Sleep Mode Operation
MP2147 features sleep mode to get high
efficiency at extreme light load. In sleep-mode,
most of the circuit blocks are turned off, except
the error amplifier and PWM comparator, thus
the operation current is reduced to a minimal
value, as Figure 2.
When the loading gets lighter, the ripple of the
output voltage is bigger and it drives the error
amplifier output (EAO) lower. When EAO hits
an internal low threshold, it will be clamped at
that level, MP2147 enters sleep mode. During
sleep mode, the valley of the FB pin voltage is
regulated to the internal reference voltage, thus,
the average output voltage is slightly higher
than the output voltage at DCM or CCM mode.
The on-time pulse at sleep mode is around 40%
larger than that on DCM or CCM mode. Figure
3 shows the average FB pin voltage
relationship with the internal reference at sleep
mode.
Figure 2: Operation Blocks at Sleep Mode
Figure 3: FB Average Voltage at Sleep Mode
When MP2147 is in sleep mode, the average
output voltage is higher than the internal
reference voltage. The EAO is kept low and
clamped in sleep mode. When the loading
increases, the PWM switching period
decreases in order to keep the output voltage
regulated and the output voltage ripple is
decrease relatively. Once EAO is more than
internal low threshold, MP2147 will be out of
sleep mode and enter DCM or CCM mode
depending on the loading. In DCM or CCM
mode, the EA regulates the average output
voltage to the internal reference which is shown
in Figure 4.
Figure 4: DCM Mode Control
There is always a loading hysteresis of entering
sleep mode and leaving sleep mode due to the
error amplifier clamping response time.
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.
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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
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 under-
voltage 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 1M 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.
REFERENCE VOLTAGE (V)
VCON (V)
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.5 0.6 0.7 0.8 0.9 1 1.1 1.2
Figure 5: 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
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 soft-
start 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 500k
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
MOSFET. The MOSFET has a maximum Rdson
of less than 100.
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
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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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APPLICATION INFORMATION
COMPONENT SELECTION
Setting the Output Voltage
The external resistor divider sets the output
voltage (see the Typical Application schematic).
Select the feedback resistor R1 which
considers reducing VOUT leakage current,
typically between 40k to 200k. There is not
strict requirement on feedback resistor.
R1>10k is reasoned for some application. R2
can be gotten below then:
out
R1
R2 V1
0.6
The feedback circuit is shown as Figure 6:
R1
R2
Vout
FB
MP2147
Figure 6: Feedback Network
Table 1 lists the recommended resistors values
for common output voltages.
Table 1: Resistor Values for Common Output
Voltages
VOUT (V) R1 (k) R2 (k)
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 30m. For most designs,
the inductance value can be derived from the
following equation.
OUT IN OUT
1
IN L OSC
V(VV)
LVIf

 
Where IL is the inductor ripple current.
Choose an inductor current to be approximately
30% of the maximum load current. The
maximum inductor peak current is:
L
L(MAX) LOAD
I
II2

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:
OUT OUT
C1 LOAD
IN IN
VV
II 1
VV






The worse case condition occurs at VIN =
2VOUT, where:
LOAD
C1
I
I2
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 (0.1F), 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:
LOAD OUT OUT
IN IN
SIN
IV V
V1
fC1V V

  


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Selecting the Output Capacitor
The output capacitor stabilizes the DC output
voltage. Ceramic capacitors are recommended.
Low ESR capacitors are preferred to limit the
output voltage ripple. Estimate the output
voltage ripple as:
OUT OUT
OUT ESR
S1 IN S
VV 1
V1R
fL V 8fC2


  





Where L1 is the inductor value and RESR is the
equivalent series resistance (ESR) value of the
output capacitor.
When using ceramic capacitors, the
capacitance dominates the impedance at the
switching frequency, and causes most of the
output voltage ripple. For simplification, the
output voltage ripple can be estimated as:
OUT OUT
OUT 2
S1 IN
VV
V1
8f L C2 V




For tantalum or electrolytic capacitors, the ESR
dominates the impedance at the switching
frequency. For simplification, the output ripple
can be approximated as:
OUT OUT
OUT ESR
IN
S1
VV
V1R
fL V




The characteristics of the output capacitor also
affect the stability of the regulation system. For
MP2147, 2pcs 22uF Co can satisfy the most
application. Add Co can reduce DCM and CCM
output ripple effectively. However, a very large
Co may cause light group pulse in sleep mode.
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 7, 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 7: Two ends of Input decoupling
Capacitor close to Pin 8 and Pin 10/11/12
"IE MP2147 — 5.5V, 4A, 1.2MHz, COT, BUCK SWITCHER L1 vw 74417324un47 vour ZflVto 5.5V 0.47m 1_2V/4A c . . . vm sw rym . . . . . o C1JEZ_LCS_L R5 06 c7 05 c9 C10 100k our 22u 22uF NS NS NS F R1 I I III ””147 20m%: : = = = FB || R2 200k ODE/ Ramp II 05 GND NS
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TYPICAL APPLICATION CIRCUITS
Figure 8: Typical Application Circuit for VIN=5V, IOUT=4A
Note: VIN<3.6V may need more input capacitor.
MP5” PHI 1 ID WI MARKING \ E PIN 1 In if i 7 *7 INDEX AREA TOP VIEW y, CLELD SIDE VIEW 0.1 on??? :UIL; 7‘ /I {mafia i E— EEI RECOMMENDED LAND PATTERN MP2147 — 5.5V, 4A, 1.2MHz, COT, BUCK SWITCHER I I_ fl“ ‘ 7:211:12?" 3+ I_IH_I } g; ‘ / J W TEE; 1 1E 744— E4 w NOTE: 1) ALL DIMENSIONS ARE IN MILLIMETERS. Z) EXPOSED PADDLE SIZE DOES NOT INCLUDE MOLD FLASH. 3) LEAD COPLANARITY SHALL SE 0.10 MILLIMETERS MAX. 4) JEDEC REFERENCE IS MID-220. 5) DRAWING IS NOT TO SCALE.
MP2147 – 5.5V, 4A, 1.2MHz, COT, BUCK SWITCHER
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.
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PACKAGE INFORMATION
QFN-12 (2mmx3mm)

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