MPS MP2148GQD-18 1a synchronous step-down converter with 11ua iq in ultra-small 1x1.5mm qfn Datasheet

MP2148
1A Synchronous Step-down Converter
with 11µA Iq in Ultra-small 1x1.5mm QFN
The Future of Analog IC Technology
DESCRIPTION
FEATURES
The MP2148 is a monolithic, step-down, switchmode converter with built-in internal power
MOSFETs. It achieves 1A continuous output
current from a 2.3V-to-5.5V input voltage with
excellent load and line regulation. The output
voltage can be regulated to as low as 0.6V.
•
•
•
•
•
•
•
•
The
Constant-On-Time
control
scheme
provides fast transient response and eases loop
stabilization. Fault protections include cycle-bycycle current limiting and thermal shutdown.
•
•
•
•
The MP2148 is available in an ultra-small QFN6 (1.0mmx1.5mm) package and requires a
minimal number of readily available standard
external components.
•
The MP2148 is ideal for a wide range of
applications including high performance DSPs,
wireless power, portable and mobile devices,
and other low-power systems.
Low IQ: 11μA
2.2MHz Switching Frequency
EN for Power Sequencing
Power Good Only for Fixed Output Version
Wide 2.3V-to-5.5V Operating Input Range
Output Adjustable from 0.6V
Up to 1A Output Current
120mΩ and 80mΩ Internal Power MOSFET
Switches
Output Discharge
100% Duty Cycle
Short-Circuit Protection with Hiccup Mode
Stable with Low ESR Output Ceramic
Capacitors
Available in a QFN-6 (1.0mmx1.5mm)
Package
APPLICATIONS
•
•
•
•
Wireless/Networking Cards
Portable and Mobile Devices
Battery Powered /Wearable Devices
Low Voltage I/O System Power
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
L1
1μH
VIN
5V
SW
VIN
OUT
C1
10μF
R1
200kΩ
MP2148
EN
EN
C2
10μF
FB
GND
MP2148 Rev. 1.11
5/25/2015
VOUT
1.2V/1A
R2
200kΩ
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1
MP2148 –1A SYNCHRONOUS STEP-DOWN CONVERTER WITH 11µA IQ IN ULTRA-SMALL 1X1.5mm QFN
ORDERING INFORMATION
Part Number*
MP2148GQD
MP2148GQD-12
MP2148GQD-15
MP2148GQD-18
MP2148GQD-25
MP2148GQD-33
Package
QFN-6 (1.0mmx1.5mm)
Top Marking
See Below
See Below
See Below
See Below
See Below
See Below
VOUT Range
Adjustable
Fixed 1.2V
Fixed 1.5V
Fixed 1.8V
Fixed 2.5V
Fixed 3.3V
* For Tape & Reel, add suffix –Z (e.g. MP2148GQD–Z);
TOP MARKING
CF: product code of MP2148GQD;
LL: lot number;
TOP MARKING
DH: product code of MP2148GQD-12;
LL: lot number;
TOP MARKING
DQ: product code of MP2148GQD-15;
LL: lot number;
MP2148 Rev. 1.11
5/25/2015
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2
MP2148 –1A SYNCHRONOUS STEP-DOWN CONVERTER WITH 11µA IQ IN ULTRA-SMALL 1X1.5mm QFN
TOP MARKING
DJ: product code of MP2148GQD-18;
LL: lot number;
TOP MARKING
DZ: product code of MP2148GQD-25;
LL: lot number;
TOP MARKING
DN: product code of MP2148GQD-33;
LL: lot number;
MP2148 Rev. 1.11
5/25/2015
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MP2148 –1A SYNCHRONOUS STEP-DOWN CONVERTER WITH 11µA IQ IN ULTRA-SMALL 1X1.5mm QFN
PACKAGE REFERENCE
TOP VIEW
MP2148GQD
TOP VIEW
MP2148GQD-12 MP2148GQD-15
MP2148GQD-18 MP2148GQD-25
MP2148GQD-33
QFN-6 (1.0mmx1.5mm)
ABSOLUTE MAXIMUM RATINGS (1)
Thermal Resistance
Supply Voltage VIN ........................................6 V
VSW ....................................................................
-0.3V (-5V for <10ns) to
6V (8V for <10ns or 10V for <3ns)
All Other Pins ................................... -0.3V to 6V
Junction Temperature .............................. 150°C
Lead Temperature ................................... 260°C
(2)
Continuous Power Dissipation (TA = +25°C)
……….….. .................................................0.6W
Storage Temperature ............... -65°C to +150°C
QFN-6 (1mm x1.5mm)………… 220
Recommended Operating Conditions
(3)
Supply Voltage VIN ......................... 2.3V to 5.5V
Operating Junction Temp. (TJ). -40°C to +125°C
MP2148 Rev. 1.11
5/25/2015
(4)
θJA
θJC
110 °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-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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MP2148 –1A SYNCHRONOUS STEP-DOWN CONVERTER WITH 11µA IQ IN ULTRA-SMALL 1X1.5mm QFN
ELECTRICAL CHARACTERISTICS
VIN = 3.6V, TJ = -40°C to +125°C, Typical value is tested at TJ = +25°C. The limit over temperature
is guaranteed by characterization, unless otherwise noted.
Parameter
Symbol
Feedback Voltage
(MP2148GQD Only)
VFB
(7)
Fixed Output Voltage
Feedback Current
(MP2148GQD only)
PFET Switch On Resistance
NFET Switch On Resistance
IFB
RDSON
RDSON
Condition
Min
Typ
Max
2.3V ≤ VIN ≤ 5.5V, TJ=25°C
594
600
606
TJ=-40°C to +125°C
588
1.188
1.2
1.212
V
Only for MP2148GQD12, IOUT=10mA,
TJ=-40°C to +125°C
1.176
1.2
1.224
V
Only for MP2148GQD15, IOUT=10mA, TJ=+25°C
1.485
1.5
1.515
V
Only for MP2148GQD15, IOUT=10mA,
TJ=-40°C to +125°C
1.470
1.5
1.530
V
Only for MP2148GQD18, IOUT=10mA, TJ=+25°C
1.782
1.8
1.818
V
Only for MP2148GQD18, IOUT=10mA,
TJ=-40°C to +125°C
1.764
1.8
1.836
V
Only for MP2148GQD25, IOUT=10mA, TJ=+25°C
2.475
2.5
2.525
V
Only for MP2148GQD25, IOUT=10mA,
TJ=-40°C to +125°C
2.450
2.5
2.550
V
Only for MP2148GQD33, IOUT=10mA, TJ=+25°C
3.267
3.3
3.333
V
Only for MP2148GQD33, IOUT=10mA,
TJ=-40°C to +125°C
3.234
3.3
3.366
V
50
100
nA
VFB = 0.63V
120
80
P
N
VEN = 0V, TJ=25°C
PFET Peak Current Limit
Sourcing
NFET Valley Current Limit
Sourcing, valley current
limit
ZCD
MP2148 Rev. 1.11
5/25/2015
TON
mV
Only for MP2148GQD12, IOUT=10mA, TJ=+25°C
Switch Leakage Current
On Time
(MP2148GQD only)
612
Units
VIN=5V, VOUT=1.2V
VIN=3.6V, VOUT=1.2V
0
1.8
mΩ
mΩ
1
μA
2.4
A
1.5
A
0
mA
110
150
ns
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5
MP2148 –1A SYNCHRONOUS STEP-DOWN CONVERTER WITH 11µA IQ IN ULTRA-SMALL 1X1.5mm QFN
ELECTRICAL CHARACTERISTICS
VIN = 3.6V, TJ = -40°C to +125°C, Typical value is tested at TJ = +25°C. The limit over temperature
is guaranteed by characterization, unless otherwise noted.
Parameter
Symbol
Switching Frequency
Minimum Off Time
fs
Condition
VIN=5V, VOUT=1.2V,
(5)
IOUT=500mA, TJ=25°C
VIN=5V, VOUT=1.2V,
IOUT=500mA ,TJ=-40°C to
(5)
+125°C
Min
Typ
Max
Units
1760
2200
2640
kHz
1650
2200
2750
kHz
TMIN-OFF
60
ns
Minimum On Time
TMIN-ON
60
ns
Soft-Start Time
TSS-ON
0.5
ms
(5)
VOUT rise from 10% to 90%
Under Voltage Lockout
Threshold Rising
2
Under Voltage Lockout
Threshold Hysteresis
150
EN Input Logic Low Voltage
1.2
RDIS
EN Input Current
Supply Current (Shutdown)
Supply Current (Quiescent)
Power Good Leakage
Current
(MP2148GQD-XX only)
Power Good Upper Trip
Threshold
(MP2148GQD-XX only)
Power Good Lower Trip
Threshold
(MP2148GQD-XX only)
Power Good Delay
(MP2148GQD-XX only)
Power Good Sink Current
Capability
(MP2148GQD-XX only)
Thermal Shutdown
(6)
Thermal Hysteresis
(6)
VEN=0V, VOUT=1.2V
VEN=2V
V
mV
0.4
EN Input Logic High Voltage
Output Discharge Resistor
2.25
V
V
1
1.2
kΩ
μA
VEN=0V
0
μA
VEN=0V, TJ=25°C
VEN=2V, VFB=0.63V,
VIN=3.6V,5V, TJ=25°C
0
1
μA
11
13
μA
50
100
nA
IPG
Vo with Respect to the
Regulation
90
%
85
%
70
μs
Sink 1mA
400
mV
160
°C
30
°C
Notes:
5) Guaranteed by characterization.
6) Guaranteed by design.
7) Without Sleep Mode.
MP2148 Rev. 1.11
5/25/2015
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MP2148 –1A SYNCHRONOUS STEP-DOWN CONVERTER WITH 11µA IQ IN ULTRA-SMALL 1X1.5mm QFN
TYPICAL PERFORMANCE CHARACTERISTICS
VIN = 5V, VOUT = 1.2V, L =1.0µH, TA = +25ºC, unless otherwise noted.
MP2148 Rev. 1.11
5/25/2015
www.MonolithicPower.com
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MP2148 –1A SYNCHRONOUS STEP-DOWN CONVERTER WITH 11µA IQ IN ULTRA-SMALL 1X1.5mm QFN
TYPICAL PERFORMANCE CHARACTERISTICS (continued)
VIN = 5V, VOUT = 1.2V, L =1.0µH, TA = +25ºC, unless otherwise noted.
MP2148 Rev. 1.11
5/25/2015
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MP2148 –1A SYNCHRONOUS STEP-DOWN CONVERTER WITH 11µA IQ IN ULTRA-SMALL 1X1.5mm QFN
TYPICAL PERFORMANCE CHARACTERISTICS (continued)
VIN = 5V, VOUT = 1.2V, L =1.0µH, TA = +25ºC, unless otherwise noted.
Steady State
Steady State
Steady State
without Load
with 1A Load
VIN=3.6V, VOUT=3.3V, IOUT=0A,AAM
VOUT/AC
10mV/div.
VOUT/AC
50mV/div.
VOUT/AC
100mV/div.
VIN
5V/div.
VIN
5V/div.
VIN
5V/div.
VSW
2V/div.
VSW
2V/div.
IL
500mA/div.
VSW
5V/div.
IL
0.2A/div.
IL
1A/div.
Steady State
VIN=3.6V, VOUT=3.3V, IOUT=0.05A, AAM
Steady State
Steady State
VIN=3.6V, VOUT=3.3V, IOUT=0.25A, AAM
VIN=3.6V, VOUT=3.3V, IOUT=1A
VOUT/AC
20mV/div.
VOUT/AC
50mV/div.
VIN
5V/div.
VIN
5V/div.
VIN
5V/div.
VSW
2V/div.
VSW
2V/div.
VOUT/AC
100mV/div.
VSW
2V/div.
IL
0.2A/div.
IL
0.2A/div.
VIN Power Up
IL
1A/div.
VIN Power Up
without Load
VIN Shut Down
with 1A Load
without Load
VOUT
1V/div.
VIN
5V/div.
VOUT
1V/div.
VIN
5V/div.
VOUT
1V/div.
VIN
5V/div.
VSW
5V/div.
VSW
5V/div.
VSW
5V/div.
IL
1A/div.
IL
1A/div.
IL
1A/div.
MP2148 Rev. 1.11
5/25/2015
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MP2148 –1A SYNCHRONOUS STEP-DOWN CONVERTER WITH 11µA IQ IN ULTRA-SMALL 1X1.5mm QFN
TYPICAL PERFORMANCE CHARACTERISTICS (continued)
VIN = 5V, VOUT = 1.2V, L =1.0µH, TA = +25ºC, unless otherwise noted.
MP2148 Rev. 1.11
5/25/2015
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MP2148 –1A SYNCHRONOUS STEP-DOWN CONVERTER WITH 11µA IQ IN ULTRA-SMALL 1X1.5mm QFN
TYPICAL PERFORMANCE CHARACTERISTICS (continued)
VIN = 5V, VOUT = 1.2V, L =1.0µH, TA = +25ºC, unless otherwise noted.
MP2148 Rev. 1.11
5/25/2015
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MP2148 –1A SYNCHRONOUS STEP-DOWN CONVERTER WITH 11µA IQ IN ULTRA-SMALL 1X1.5mm QFN
PIN FUNCTIONS
Pin
#
1
Name
Description
MP2148GQD: Feedback Pin. An external resistor divider from the output to GND, tapped to the
FB pin, sets the output voltage.
FB/PG
MP2148GQD-XX: Power Good Indicator. The output of this pin is an open drain output. Keep PG
pulls up voltage is lower than Vin.
2
GND
3
VIN
4
SW
5
EN
6
OUT
MP2148 Rev. 1.11
5/25/2015
Power Ground.
Supply Voltage. The MP2148 operates from a +2.3V to +5.5V unregulated input. Decouple
capacitor is needed to prevent large voltage spikes from appearing at the input.
Output Switching Node. SW is the drain of the internal high-side P-Channel MOSFET. Connect
the inductor to SW to complete the converter.
On/Off Control.
Output Voltage Power Rail and Input Sense Pin for Output Voltage. Connect load to this pin.
Output capacitor is needed to decrease the output voltage ripple.
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MP2148 –1A SYNCHRONOUS STEP-DOWN CONVERTER WITH 11µA IQ IN ULTRA-SMALL 1X1.5mm QFN
BLOCK DIAGRAM
Figure 1: Functional Block Diagram
Note: Optional 1: FB pin is only for MP2148GQD
Optional 2: PG pin is only for MP2148GQD-XX
MP2148 Rev. 1.11
5/25/2015
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13
MP2148 –1A SYNCHRONOUS STEP-DOWN CONVERTER WITH 11µA IQ IN ULTRA-SMALL 1X1.5mm QFN
OPERATION
The MP2148 uses constant on-time control with
input voltage feed forward to stabilize the
switching frequency over the full input range. It
achieves 1A continuous output current from a
2.3V-to-5.5V input voltage with excellent load
and line regulation. The output voltage can be
regulated to as low as 0.6V.
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.
Constant On-Time Control
Compare to fixed frequency PWM control,
constant on-time control offers a simpler control
loop and a faster transient response. By using
input-voltage feed forward, the MP2148
maintains a nearly constant switching frequency
across the input and output voltage ranges. The
switching pulse on time can be estimated as:
TON =
VOUT
⋅ 0.454μs
VIN
To prevent inductor current runaway during
load transient, MP2148 has fixed minimum off
time of 60ns.
Sleep Mode Operation
MP2148 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.
Figure 3: FB Average Voltage at Sleep Mode
When MP2148 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, MP2148 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.
AAM Operation at Light-Load Operation
The
MP2148
has
AAM
(Advanced
Asynchronous Modulation) power-save mode
together with ZCD (Zero Current Cross
Detection) circuit for light load.
Figure 2: Operation Blocks at Sleep Mode
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, MP2148 enters sleep mode. During
sleep mode, the valley of the FB pin voltage is
MP2148 Rev. 1.11
5/25/2015
The MP2148 has AAM power-save mode for
light load. Simplified AAM control theory is as
Figure 5. AAM current IAAM is set internally. The
SW on pulse time is decided by on-timer
generator and AAM comparator. At light load
condition, the SW on pulse time is the longer
one. If the AAM comparator pulse is longer than
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MP2148 –1A SYNCHRONOUS STEP-DOWN CONVERTER WITH 11µA IQ IN ULTRA-SMALL 1X1.5mm QFN
on-timer generator, the operation mode is
below in Figure 6.
VFB
EN
COT
Generator
VREF
FBCOMP
S
Q
HS_ driver
Figure 8: AAM Blank Time in Sleep Mode
R
IL_ sense
IAAM
AAMCOMP
Figure 5: Simplified AAM Control Logic
Figure9 shows AAM threshold decreases with
Ton increasing gradually. For the CCM state, Io
needs more than half of AAM threshold at least.
Figure 6: AAM Comparator Control Ton
If the AAM comparator pulse is shorter than ontimer generator, the operation mode is below in
Figure 7. Generally, using very small
inductance may bring this case.
AAM
Io
IL
a. Light load in on-timer
AAM
Io
Figure 9: AAM Threshold decreases with Ton
Increases.
MP2148 have a zero current cross detect circuit
(ZCD) to judge if the inductor current starts to
reverse. When the inductor current reaches
ZCD threshold, the low side switch will be
turned off.
AAM mode together with ZCD circuit make
MP2148 always work on DCM mode at light
load, even if Vo is closed to Vin.
Enable
IL
b. Increase load in on-timer
Figure 7: On-Timer Control Ton
Except upper on-timer method, AAM circuit has
another 150ns AAM blank time in sleep mode.
That means if on-timer is less than 150ns, the
high side MOSFET may turn off after on-timer
generator pulse without AAM control. Just a
remind, the on-time pulse at sleep mode is
around 40% larger than that on DCM or CCM
mode. At this condition, IL may not reach AAM
threshold as Figure 8.
When input voltage is greater than the undervoltage lockout threshold (UVLO), typically 2V,
MP2148 can be enabled by pulling EN pin to
higher than 1.2V. Leaving EN pin float or pull
down to ground will disable MP2148. There is
an internal 1Meg Ohm resistor from EN pin to
ground.
When the device is disabled, the part goes into
output discharge mode automatically and its
internal discharge MOSFET provides a resistive
discharge path for the output capacitor.
Soft Start
The MP2148 has a built-in soft start that ramps
up the output voltage at a controlled slew rate
to avoid overshoot at startup. The soft start time
is about 0.5ms typically.
MP2148 Rev. 1.11
5/25/2015
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15
MP2148 –1A SYNCHRONOUS STEP-DOWN CONVERTER WITH 11µA IQ IN ULTRA-SMALL 1X1.5mm QFN
Power Good Indictor (only for MP2148GQDXX)
The MP2148 has an open drain and need a
external pull-up resistor (100kΩ~500kΩ) for the
power good indicator (Note: Keep PG pull up
voltage is lower than Vin). When VFB is within 10% of regulation voltage, VPG is pulled up to
Vo/Vin by the external resistor. If VFB exceeds
the -10% window, the internal MOSFET pulls
the PG to ground. The MOSFET has a
maximum RDSON of less than 400Ω.
Current limit
The MP2148 typically has a 2.4A high-side
switch current limit. When the high side switch
hits its current limit, the MP2148 will remain in
hiccup mode until the current drops. This
prevents the inductor current from continuing to
rise and damage components.
Short Circuit and Recovery
The MP2148 will also enter short-circuit
protection mode when it hits the current limit,
and tries to recover with hiccup mode: The
MP2148 will disable the output power stage,
discharge the soft-start capacitor and then
automatically try soft-start again. If the short
circuit condition remains after soft-start ends,
the MP2148 repeats this cycle until the short
circuit disappears and output rises back to
regulation level.
MP2148 Rev. 1.11
5/25/2015
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MP2148 –1A SYNCHRONOUS STEP-DOWN CONVERTER WITH 11µA IQ IN ULTRA-SMALL 1X1.5mm QFN
APPLICATION INFORMATION
COMPONENT SELECTION
metal alloy or multiplayer chip power are best
candidates for application, can decrease the
Setting the Output Voltage(Only for
MP2148GQD)
influence effectively. Table2 is some suggested
inductors.
The external resistor divider sets the output
voltage (see the Typical Application on
Figure13). Select the feedback resistor R1 that
consider reducing VOUT leakage current,
typically between 100kΩ to 200kΩ. There is not
strict requirement on feedback resistor. Select
R1>10kΩ is reasoned for application.
R2 =
R1
Vout
−1
0.6
Table 2: Suggested Inductor List
Manufacturer P/N
Inductance( μH )
Manufacturer
PIFE25201B-1R0MS
1.0
CYNTEC CO.
LTD.
1239AS-H-1R0M
1.0
Tokyo
74438322010
1.0
Wurth
For most designs, estimate the inductance
value from the following equation.
L1 =
Figure 10 shows the feedback circuit.
VOUT × (VIN − VOUT )
VIN × ΔIL × fOSC
Where ΔIL is the inductor ripple current.
Choose an inductor current to be approximately
30% of the maximum load current. The
maximum inductor peak current is:
IL(MAX ) = ILOAD +
Figure 10: Feedback Network
Table 1 lists the recommended resistors value
for common output voltages.
Table 1: Resistor Values for Common Output
Voltages
VOUT (V)
R1 (kΩ)
R2 (kΩ)
1.0
1.2
1.8
2.5
200(1%)
200(1%)
200(1%)
200(1%)
300(1%)
200(1%)
100(1%)
63.2(1%)
3.3
200(1%)
44.2(1%)
Selecting the Inductor
Most applications work best with a 0.47µH to
1.5µH inductor. Select an inductor with a DC
resistance less than 15mΩ to optimize
efficiency.
High frequency switch mode power supply with
magnetic device has strong electronic magnetic
inference for system. Any un-shield power
inductor should be avoided applying as poor
magnetic shielding. Shield inductor, such as
MP2148 Rev. 1.11
5/25/2015
Δ IL
2
Selecting the Input Capacitor
The input current to the step-down converter is
discontinuous, and therefore requires a
capacitor to supply the AC current to the stepdown 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 and small
temperature coefficients. For most applications,
a 10µF capacitor is sufficient. Higher output
voltages may require a 22μF capacitor to
increase system stability.
The input capacitor requires an adequate ripple
current rating because it absorbs the input
switching current. Estimate the RMS current in
the input capacitor with:
⎛
V
V ⎞
IC1 = ILOAD × OUT ×⎜⎜1− OUT ⎟⎟
⎜
VIN ⎝ VIN ⎟⎠
The worst case occurs at VIN = 2VOUT, where:
IC1 =
ILOAD
2
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MP2148 –1A SYNCHRONOUS STEP-DOWN CONVERTER WITH 11µA IQ IN ULTRA-SMALL 1X1.5mm QFN
For simplification, choose an input capacitor
with an 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, add a small and high quality
ceramic 0.1μF capacitor as close to the IC as
possible. When using ceramic capacitors, make
sure that they have enough capacitance to
provide sufficient charge to prevent excessive
voltage ripple at the input. The input voltage
ripple caused by capacitance can be estimated
as:
⎛
I
V
V ⎞
ΔVIN = LOAD × OUT × ⎜ 1 − OUT ⎟
fS × C1 VIN ⎝
VIN ⎠
Selecting the Output Capacitor
The output capacitor (C2) 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:
ΔVOUT =
⎞
VOUT ⎛ VOUT ⎞ ⎛
1
× ⎜1−
⎟ × ⎜ RESR +
⎟
fS × L1 ⎝
VIN ⎠ ⎝
8 × fS × C2 ⎠
ΔVOUT =
VOUT ⎛
V
× ⎜ 1 − OUT
fS × L1 ⎝
VIN
⎞
⎟ × RESR
⎠
The characteristics of the output capacitor also
affect the stability of the regulation system.
PCB Layout
Proper layout of the switching power supplies is
very important, and sometimes critical for
proper function. For the high-frequency
switching converter, poor layout design can
result in poor line or load regulation and stability
issues.
Place the high-current paths (GND, IN and SW)
very close to the device with short, direct and
wide traces. The input capacitor needs to be as
close as possible to the IN and GND pins.
Place the external feedback resistors next to
the FB pin. Keep the switching node SW short
and away from the feedback network. Vout
sense line need as short as possible or keeps
away from power inductor, especial forbids
surrounding inductor. Figure11 is advised PCB
layout.
Where L1 is the inductor value and RESR is the
equivalent series resistance (ESR) value of the
output capacitor.
When
using
ceramic
capacitors,
capacitance dominates the impedance at
switching frequency, and causes most of
output voltage ripple. For simplification,
output voltage ripple can be estimated as:
ΔVOUT =
the
the
the
the
⎛ V ⎞
VOUT
× ⎜ 1 − OUT ⎟
8 × fS × L1 × C2 ⎝
VIN ⎠
For tantalum or electrolytic capacitors, the ESR
dominates the impedance at the switching
frequency. For simplification, the output ripple
can be approximated as:
MP2148 Rev. 1.11
5/25/2015
Figure 11: Two Ends of Input Decoupling
Capacitor Close to Pin 2 and Pin3.
2
.
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MP2148 –1A SYNCHRONOUS STEP-DOWN CONVERTER WITH 11µA IQ IN ULTRA-SMALL 1X1.5mm QFN
TYPICAL APPLICATION CIRCUITS
VIN
2.3V to 5.5V
L1
1µH
U1
SW
VIN
R3
100kΩ
EN
C1A
NS
VOUT
1.2V/1A
OUT
C1
10 µF
MP2148GQD
EN
R1
200k Ω
C2
10µF
C2A
NS
FB
R2
200kΩ
GND
Figure 12: Typical Application Circuit for MP2148GQD
Note: VIN<3.3V may need more input capacitor.
Figure 13: Typical Application Circuit for MP2148GQD-XX
Note: 1. VIN<3.3V may need more input capacitor;
2. VIN>VOUT for application.
MP2148 Rev. 1.11
5/25/2015
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MP2148 –1A SYNCHRONOUS STEP-DOWN CONVERTER WITH 11µA IQ IN ULTRA-SMALL 1X1.5mm QFN
PACKAGE INFORMATION
QFN-6 (1.0mmx1.5mm)
PIN 1 ID
PIN 1 ID
MARKING
PIN 1 ID
INDEX AREA
BOTTOM VIEW
TOP VIEW
SIDE VIEW
NOTE:
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.
0
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.
MP2148 Rev. 1.11
5/25/2015
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