MP3424A
Configurable-Current, CC/CV, Synchronous
Step-Up Converter with Output Disconnect
and Minimized Inrush Current
DESCRIPTION
FEATURES
The MP3424A is a synchronous, highefficiency, current-mode, step-up (boost)
converter with output disconnect. The
MP3424A targets various load capability boosts
from a battery input with an accurate load
current limit.
The MP3424A starts up from an input voltage
(VIN) as low as 2V while providing inrush current
limiting, output short-circuit protection (SCP),
and a configurable load current limit. The
integrated P-channel synchronous rectifier
improves efficiency and eliminates the need for
an external Schottky diode. The P-channel
MOSFET disconnects the output from the input
during shutdown.
The 580kHz switching frequency allows for
small external components, while internal
compensation and soft start minimize the
external component count. The MP3424A
provides flexible current limit programming for
up to 5V/3.1A load from a supply voltage down
to 2.8V.
2V to 5.5V Operating Input Voltage Range
3V to 5.5V Output Range
Supports 5V/3.1A Output from a 2.8V Input
270mA Linear Charge Inrush Current
Switching Current Limit Configurable Up to
9.5A
Configurable Average Load Current Limit
580kHz Fixed Switching Frequency
Up to 97% Efficiency
Internal Soft Start and Compensation
True Output Load Disconnect from Input
Over-Current Protection (OCP), ShortCircuit Protection (SCP), and OverTemperature Protection (OTP)
Available in a QFN-14 (2mmx2mm)
Package
Optimized Performance with
MPS Inductor MPL-AL5030 Series
APPLICATIONS
The MP3424A is available in a QFN-14
(2mmx2mm) package.
Battery-Powered Products
Power Banks, Juice Packs, Battery Backup
Units
Optical Modules
USB Power Supplies
Consumer Electronic Accessories
All MPS parts are lead-free, halogen-free, and adhere to the RoHS
directive. For MPS green status, please visit the MPS website under
Quality Assurance. “MPS”, the MPS logo, and “Simple, Easy Solutions” are
trademarks of Monolithic Power Systems, Inc. or its subsidiaries.
TYPICAL APPLICATION
VIN
Efficiency
L1
100
MPL-AL5030-1R5
95
SW
IN
SENSE
SOUT
R5
EN
OUT
EN
MP3424A
R4
2kΩ
R1
1MΩ
ILIM
C3
10nF
FB
R3
100kΩ
VOUT
AGND
PGND
R2
191kΩ
5V
C2
22µF x 2
EFFICIENCY(%)
C1
22µF x 2
90
85
VIN=2.8V
80
VIN=3.3V
75
VIN=4.2V
70
0
0.5
1
1.5
2
2.5
3
3.5
LOAD CURRENT (A)
MP3424A Rev. 1.0
MonolithicPower.com
6/22/2021
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© 2021 MPS. All Rights Reserved.
1
MP3424A – CONFIGURABLE-CURRENT, OUTPUT DISCONNECT BOOST CONVERTER
ORDERING INFORMATION
Part Number*
Package
Top Marking
MSL Rating
MP3424AGG
QFN-14 (2mmx2mm)
See Below
1
* For Tape & Reel, add suffix -Z (e.g. MP3424AGG-Z).
TOP MARKING
LU: Product code of MP3424AGG
Y: Year code
LLLL: Lot number
PACKAGE REFERENCE
TOP VIEW
SENSE
1
PGND
2
SW
3
OUT
4
SOUT
FB
12
11
10
AGND
13 PGND
9
ILIM
14 SW
8
IN
7
EN
5
6
OUT
OUT
QFN-14 (2mmx2mm)
MP3424A Rev. 1.0
MonolithicPower.com
6/22/2021
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2
MP3424A – CONFIGURABLE-CURRENT, OUTPUT DISCONNECT BOOST CONVERTER
PIN FUNCTIONS
Pin #
1
2, 13
Name
Description
Load current sense. Connect a load-sense resistor signal between SENSE and SOUT to
SENSE determine the maximum load current. If average load current limiting is not required, connect
SENSE and SOUT directly to OUT.
PGND
3, 14
SW
4, 5, 6
OUT
7
EN
8
IN
9
ILIM
10
AGND
11
FB
12
SOUT
Power ground.
Power switch output. SW is the connection node of the internal N-channel MOSFET and
synchronous P-channel MOSFET. Connect the power inductor between SW and the input
power. Keep the PCB trace lengths as short and wide as possible to reduce EMI and voltage
spikes.
Output. OUT is the drain of the internal synchronous rectifier MOSFET. The bias is derived
from OUT when VOUT exceeds VIN. Keep the PCB trace length from OUT to the output filter
capacitor as short and wide as possible. OUT is completely disconnected from IN when EN is
low due to the output disconnect feature.
Chip enable control input.
Power supply input. The start-up bias is derived from IN. IN must be bypassed locally. Once
OUT exceeds IN, the bias is derived from OUT. Once started, operation is completely
independent from IN.
Switching current limit set. A resistor from ILIM to AGND programs the low-side MOSFET
(LS-FET) cycle-by-cycle peak current limit when the output constant load current limit is not
triggered. When the output current (IOUT) signal between SOUT and SENSE exceeds the
current limit threshold, ILIM is pulled low to regulate the average load current. RC
compensation is required in this condition. If average load current limiting is not required, RC
compensation can be removed, and only a resistor from ILIM to AGND is required.
Analog signal ground.
Feedback input to the error amplifier (EA). Connect a resistor divider tap to FB. The output
voltage (VOUT) can be adjusted from 3V to 5.5V.
Load current sense. Connect a load-sense resistor signal between SOUT and SENSE to
determine the maximum load current. If average load current limiting is not required, connect
SENSE and SOUT directly to OUT.
θJA
θJC
ABSOLUTE MAXIMUM RATINGS (1)
Thermal Resistance
SW pin ................. -0.3V to +6.5V (10V for VOUT
VOUT > VIN
500
OUTPUT BIAS CURRENT (μA)
INPUT BIAS CURRENT (μA)
500
400
300
200
100
400
300
200
100
0
0
2
2.5
3
3.5
4
4.5
INPUT VOLTAGE (V)
5
3
5.5
Input Leakage Current vs. Input
Voltage
3.5
4
4.5
5
OUTPUT VOLTAGE (V)
5.5
IN UVLO Threshold vs. Temperature
EN = low
2
IN UVLO THRESHOLD (V)
INPUT LEAKAGE (μA)
2
1.6
1.2
0.8
0.4
1.8
1.6
1.4
1.2
1
0.8
0.6
0.4
Rising Threshold
0.2
Falling Threshold
0
0
2
2.5
3
3.5
4
4.5
INPUT VOLTAGE (V)
5
-40 -20 0 20 40 60 80 100 120 140
JUNCTION TEMPERATURE (°C)
5.5
VOUT Rising Threshold for
Switching vs. Temperature
EN Threshold vs. Temperature
2.5
0.75
0.5
0.25
Rising Threshold
Falling Threshold
0
-40 -20
0 20 40 60 80 100 120 140
TEMPERATURE (°C)
VOUT RISING THRESHOLD FOR
SWITCHING (V)
EN THRESHOLD (V)
1
2.25
2
1.75
1.5
1.25
1
-40 -20
0
20 40 60 80 100 120 140
TEMPERATURE (°C)
MP3424A Rev. 1.0
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6/22/2021
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MP3424A – CONFIGURABLE-CURRENT, OUTPUT DISCONNECT BOOST CONVERTER
TYPICAL CHARACTERISTICS (continued)
VIN = 3.3V, VOUT = 5V, L = 1.5μH, TA = 25°C, unless otherwise noted.
Feedback Voltage vs. Temperature
Frequency vs. Temperature
700
815
650
810
FREQUENCY (kHz)
FEEDBACK VOLTAGE (mV)
820
805
800
795
790
600
550
500
450
785
780
400
-40 -20
0
-40 -20
20 40 60 80 100 120 140
TEMPERATURE (°C)
Linear Charge Current vs. Output
Voltage
0.4
0.3
0.2
Vin=4.2V
Vin=3.3V
Vin=2.8V
0.1
0
0
0.4
0.8
1.2
1.6
0.5
0.4
0.3
0.2
Vout=1.2V
0.1
-40 -20
2
OUTPUT VOLTAGE (V)
Switching Current Limit vs. Input
Voltage
0
20 40 60 80 100 120 140
TEMPERATURE (℃)
Switching Current Limit vs. ILIMIT
Resistor
RLIMIT = 100kΩ
16
12
SWITCHING CURRENT LIMIT (A)
SWITCHING CURRENT LIMIT (A)
20 40 60 80 100 120 140
TEMPERATURE (°C)
Linear Charge Current vs.
Temperature
LINEAR CHARGE CURRENT (A)
LINEAR CHARGE CURRENT (A)
0.5
0
14
12
10
8
6
4
2
0
2
2.5
3
3.5
4
INPUT VOLTAGE (V)
4.5
10
8
6
4
2
0
30
40
50
60
70
80
ILIMIT RESISTOR (kΩ)
MP3424A Rev. 1.0
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6/22/2021
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90
100
6
MP3424A – CONFIGURABLE-CURRENT, OUTPUT DISCONNECT BOOST CONVERTER
TYPICAL CHARACTERISTICS (continued)
VIN = 3.3V, VOUT = 5V, L = 1.5μH, TA = 25°C, unless otherwise noted.
Constant Output Current vs.
Ambient Temperature
4
3.5
3
R5=10mΩ
R5=15mΩ
R5=30mΩ
2.5
2
1.5
1
0.5
0
2.8
3.1
3.4
3.7
4
INPUT VOLTAGE (V)
4.3
R5 = 15mΩ
CONSTANT OUTPUT CURRENT
(A)
CONSTANT OUTPUT CURRENT
(A)
Constant Output Current vs. Input
Voltage
4.6
4
3.5
3
2.5
2
1.5
1
0.5
0
-40
-20
0
20
40
60
80
AMBIENT TEMPERATURE (°C)
MP3424A Rev. 1.0
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6/22/2021
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100
7
MP3424A – CONFIGURABLE-CURRENT, OUTPUT DISCONNECT BOOST CONVERTER
TYPICAL PERFORMANCE CHARACTERISTICS
VIN = 3.3V, VOUT = 5V, L = 1.5μH, TA = 25°C, unless otherwise noted.
Efficiency vs. Load Current
Line Regulation vs. Input Voltage
100
LINE REGULATION (%)
EFFICIENCY (%)
95
90
85
VIN=2.8V
80
VIN=3.3V
75
VIN=4.2V
70
0
0.5
1
1.5
2
2.5
3
1
0.8
0.6
0.4
0.2
0
-0.2
-0.4
-0.6
-0.8
-1
Io=0A
Io=1.5A
Io=3.1A
2
3.5
2.5
3
LOAD CURRENT (A)
4
4.5
5
5.5
INPUT VOLTAGE (V)
Load Regulation vs. Output
Current
Case Temperature Rise vs. Load
Current
45
1
0.8
0.6
0.4
0.2
0
-0.2
-0.4
-0.6
-0.8
-1
VIN=2.8V
VIN=3.3V
VIN=4.2V
0
0.5
1
1.5
2
2.5
OUTPUT CURRENT (A)
3
3.5
CASE TEMPERATURE RISE (°C)
LOAD REGULATION (%)
3.5
VIN=2.8V
VIN=4.2
40
35
30
25
20
15
10
5
0
0
1
2
3
LOAD CURRENT (A)
MP3424A Rev. 1.0
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6/22/2021
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8
MP3424A – CONFIGURABLE-CURRENT, OUTPUT DISCONNECT BOOST CONVERTER
TYPICAL PERFORMANCE CHARACTERISTICS (continued)
VIN = 3.3V, VOUT = 5V, L = 1.5μH, TA = 25°C, unless otherwise noted.
Output Voltage Ripple
Output Voltage Ripple
Load = 0A
Load = 0.1A
CH1:
VOUT/AC
10mV/div.
CH1:
VOUT/AC
10mV/div.
CH3: VSW
2V/div.
CH3: VSW
2V/div.
CH4: IL
200mA/div.
CH4: IL
500mA/div.
20μs/div.
1μs/div.
Output Voltage Ripple
Start-Up through VIN
Load = 3.1A
Load = 0A
CH1:
VOUT/AC
100mV/div.
CH1: VOUT
2V/div.
CH2: VIN
2V/div.
CH3: VSW
2V/div.
CH3: VSW
2V/div.
CH4: IL
5A/div.
CH4: IL
1A/div.
1μs/div.
2ms/div.
Start-Up through VIN
Shutdown through VIN
Load = 0.1A
Load = 0.1A
CH1: VOUT
2V/div.
CH2: VIN
2V/div.
CH1: VOUT
2V/div.
CH2: VIN
2V/div.
CH3: VSW
5V/div.
CH3: VSW
5V/div.
CH4: IL
1A/div.
CH4: IL
1A/div.
2ms/div.
10ms/div.
MP3424A Rev. 1.0
MonolithicPower.com
6/22/2021
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© 2021 MPS. All Rights Reserved.
9
MP3424A – CONFIGURABLE-CURRENT, OUTPUT DISCONNECT BOOST CONVERTER
TYPICAL PERFORMANCE CHARACTERISTICS (continued)
VIN = 3.3V, VOUT = 5V, L = 1.5μH, TA = 25°C, unless otherwise noted.
Shutdown through VIN
Start-Up through EN
Load = 3.1A
Load = 0A
CH1: VOUT
2V/div.
CH1: VOUT
2V/div.
CH2: VEN
5V/div.
CH2: VIN
2V/div.
CH3: VSW
5V/div.
CH3: VSW
5V/div.
CH4: IL
1A/div.
CH4: IL
5A/div.
10ms/div.
2ms/div.
Start-Up through EN
Shutdown through EN
Load = 0.1A
Load = 0.1A
CH1: VOUT
2V/div.
CH1: VOUT
2V/div.
CH2: VEN
5V/div.
CH2: VEN
5V/div.
CH3: VSW
5V/div.
CH3: VSW
5V/div.
CH4: IL
1A/div.
CH4: IL
1A/div.
2ms/div.
2ms/div.
Shutdown through EN
Load Transient
Load = 3.1A
ILOAD = 0A to 1.5A at 150mA/μs
CH1:
VOUT/AC
500mV/div.
CH1: VOUT
2V/div.
CH2: VEN
5V/div.
CH3: VSW
5V/div.
CH4: ILOAD
1A/div.
CH4: IL
5A/div.
200µs/div.
1ms/div.
MP3424A Rev. 1.0
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6/22/2021
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© 2021 MPS. All Rights Reserved.
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MP3424A – CONFIGURABLE-CURRENT, OUTPUT DISCONNECT BOOST CONVERTER
TYPICAL PERFORMANCE CHARACTERISTICS (continued)
VIN = 3.3V, VOUT = 5V, L = 1.5μH, TA = 25°C, unless otherwise noted.
Load Transient
Short-Circuit Entry
ILOAD = 1.5A to 3.1A at 150mA/μs
0A load to short
CH1:
VOUT/AC
500mV/div.
CH1: VOUT
2V/div.
CH4: IL
2A/div.
CH4: ILOAD
1A/div.
40μs/div.
1ms/div.
Short-Circuit Entry
Short-Circuit Recovery
3.1A load to short
Recover to 0A load
CH1: VOUT
2V/div.
CH1: VOUT
2V/div.
CH4: IL
5A/div.
CH4: IL
1A/div.
40µs/div.
2ms/div.
Short-Circuit Recovery
Recover to 0.1A load
CH1: VOUT
2V/div.
CH4: IL
1A/div.
2ms/div.
MP3424A Rev. 1.0
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MP3424A – CONFIGURABLE-CURRENT, OUTPUT DISCONNECT BOOST CONVERTER
FUNCTIONAL BLOCK DIAGRAM
L1
CIN
IN
SCP/OVP
SW
VOUT
UVLO 1.7V
Body VIN
Control
A
B
C
Start-Up
OUT
PWM Control
R5
COUT
SYNC Drive
Control
AGND
OSC
580kHz
Slope Comp
PGND
R1
RT
EA
PWM
Comparator
ILIM
VREF
FB
0.805V
REF
R2
VOCL
Current Limit
Current
Sense
C3
R3
Enable
Enable Control
R4
Load CurrentLimit Amplifier
SOUT
SENSE
Under-Voltage
Lockout (UVLO)
EN
Figure 1: Functional Block Diagram
MP3424A Rev. 1.0
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MP3424A – CONFIGURABLE-CURRENT, OUTPUT DISCONNECT BOOST CONVERTER
OPERATION
The MP3424A is a 580kHz, synchronous, stepup (boost) converter with true output disconnect
in a QFN-14 (2mmx2mm) package. The device
features fixed-frequency current mode pulsewidth modulation (PWM) control for excellent
line and load regulation. The special voltage
loop and current loop provide flexibility for
voltage regulation and overload protection. The
special voltage loop offers linear charging and
step-down mode to control the output start-up.
The current loop includes a configurable current
limit and a cycle-by-cycle current limit, which
help protect the IC. Internal soft start and loop
compensation simplify the design process and
minimize the external component count.
Internal low RDS(ON) MOSFETs enable the
device to maintain high efficiency across a wide
load current range.
Start-Up
When the IC is enabled and the IN voltage (VIN)
exceeds VUVLO_IN_R, the MP3424A starts up in
linear charge mode. During this linear charge
period, the rectifier P-channel MOSFET (PFET) turns on until the output capacitor is
charged to 1.7V. The P-FET current is limited to
0.27A to avoid inrush current. This circuit also
helps limit the output current (IOUT) under shortcircuit conditions.
Once the output is charged to 1.7V, the linear
charge period ends, and the MP3424A begins
switching in normal closed-loop operation. In
normal operation, if the output voltage (VOUT) is
below the input voltage (VIN) + 0.3V, then the
MP3424A operates in step-down mode. If VOUT
is above VIN + 0.3V, the MP3424A operates in
boost mode. The switching current limit in both
step-down mode and boost mode are
programmed by RILIM, which is located between
ILIM and GND. RILIM must always be below
100kΩ. Figure 2 and Table 1 show the
operation mode and current limit during the
start-up process.
Table 1: Operation Mode during Start-Up
VOUT < 1.7V
VOUT ≥ 1.7V, VOUT < VIN + 0.3V
VOUT ≥ 1.7V, VOUT ≥ VIN + 0.3V
Linear charge
mode
Step-down mode
Boost mode
Linear Charge
Mode
Down
Mode
VOUT
Boost Mode
VIN
VOUT = VIN + 0.3V
1.7V
1.2V
Configured Current Limit
0.27A
Figure 2: Current Limit and Operation Mode
during Start-Up
In step-down mode, the gate of the high-side
MOSFET (HS-FET) is pulled to VIN and
operates with a high impedance when the HSFET is on. During step-down mode, the power
loss is high. Step-down mode is designed to
work during start-up and short-circuit protection
(SCP). It is not recommended to operate the
MP3424A in step-down mode for normal
operation, unless the system performance will
not be affected by the rise in temperature.
When VOUT exceeds VIN, the MP3424A powers
the internal circuits from VOUT instead of VIN.
Soft Start (SS)
The MP3424A provides soft start (SS) by
charging an internal capacitor with a current
source. This soft-start voltage (VSS) rises in
proportion with the FB voltage (VFB) during a
linear charge period. Once the linear charge
period elapses, the voltage on this capacitor is
charged by a fixed internal current, and the
reference voltage (VREF) ramps up slowly. The
reference soft-start time (tSS) is typically 3ms
(0V to 0.805V).
In the event of a commanded shutdown,
thermal shutdown, or a short circuit at the
output, the soft-start capacitor (CSS) is
discharged completely.
MP3424A Rev. 1.0
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MP3424A – CONFIGURABLE-CURRENT, OUTPUT DISCONNECT BOOST CONVERTER
Device Enable (EN)
Pull the EN pin high to enable the MP3424A;
pull it low to shut down the MP3424A. When the
device is shut down, the regulator stops
switching, all internal control circuitry turns off,
and the load is isolated from the input.
By connecting ILIM to AGND through a resistor,
the MP3424A limits the low-side MOSFET (LSFET) current cycle by cycle. The switching peak
current can be configured by changing RILIM.
The load current capability is affected by VIN,
VOUT, and the inductance (L).
Error Amplifier (EA)
The error amplifier (EA) is an internally
compensated amplifier. The EA compares the
internal 0.805V reference voltage (VREF) against
VFB to generate an error signal. VOUT can be
adjusted by an external resistor divider.
By inserting a sense resistor between the
output capacitor and load terminal, the
MP3424A can sense and limit the load current
flowing through the current-sense resistor. The
limited load current is 30mV / RSENSE (R5 in
Figure 1 on page 12). When the load current
limit is triggered, the ILIM voltage (VILIM) is
pulled low internally, which controls IL,
regulating the average load current. When
using
an
output-sense
resistor,
RC
compensation is required on ILIM.
Output Disconnect
The MP3424A offers true output disconnect by
eliminating body diode conduction of the
internal P-FET rectifier. This allows VOUT to drop
to 0V during shutdown, or for VIN to be isolated
when maintaining an external bias on VOUT. This
limits the inrush current limit at start-up,
minimizing surge current seen by the input
supply. To maintain the advantages of output
disconnect, there must not be an external
Schottky diode connected between SW and
VOUT.
Overload and Short-Circuit Protection (SCP)
When overload occurs, the inductor current (IL)
is limited cycle by cycle, and VOUT drops. If VOUT
drops below VIN + 0.3V, then the MP3424A runs
back into step-down mode. When VOUT drops
below 1.7V, the MP3424A operates in linear
charge mode.
At the same time, if VOUT drops below 50% of
the nominal output voltage, the MP3424A treats
this as a short-circuit condition and shuts down
immediately. After 40µs, the MP3424A exits
short-circuit protection (SCP) and restarts with
a new start-up cycle. If VOUT exceeds 50% of
the setting voltage under overload conditions,
the MP3424A does not treat this as a shortcircuit condition. The current is only controlled
by cycle-by-cycle switching current limiting or
an output current-sense resistor. See the
Constant Output Current Limit section below for
details on accurate current limit setting.
Different load current limits can be achieved by
changing RILIM or the output-sense resistor
value. To set the average current limit, connect
a 100kΩ resistor from ILIM to AGND and
change the average current-sense resistor on
the output port.
If load current limiting is not required, connect
the SENSE and SOUT pins directly to OUT,
and remove the RC compensation on ILIM.
The switching current signal is blanked for 70ns
internally to enhance noise rejection. The
average load current limit does not respond to
the load change quickly due to the low-pass
filter.
Over-Voltage Protection (OVP)
If VOUT exceeds 6.5V, boost switching stops.
This prevents an over-voltage (OV) condition
from damaging the internal power MOSFET.
When VOUT drops below 6.5V, the device
resumes switching automatically.
Thermal Shutdown
The MP3424A contains an internal temperature
monitor. The switches turn off if the die
temperature exceeds 150°C. Once the die
temperature drops below 130°C, the device
resumes normal operation.
Constant Output Current Limit
The MP3424A integrates programmable current
limit functions, including cycle-by-cycle current
limiting and output load current limiting.
MP3424A Rev. 1.0
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14
MP3424A – CONFIGURABLE-CURRENT, OUTPUT DISCONNECT BOOST CONVERTER
APPLICATION INFORMATION
Setting the Output Voltage
VOUT is fed back to the EA through a resistor
divider. The feedback reference voltage (VREF)
is typically 0.805V. Calculate VOUT with
Equation (1):
VOUT VREF (1
R1
)
R2
(1)
Where R1 is the top feedback resistor, R2 is the
bottom feedback resistor, and VREF is the
reference voltage (typically 0.805V).
Set the values of R1 and R2 as high as
necessary to achieve a low quiescent current.
Note that setting the resistance too high can
lead to noise and a low loop bandwidth. R1
should be between 600kΩ and 1MΩ for good
leakage, stability, and transient balance.
Selecting the Current Limit Resistor
Peak Switching Current Limit
The MP3424A limits the LS-FET cycle-by-cycle
current with a current-limit resistor (RILIM). The
switching peak current can be configured by
changing RILIM.
Load Average Current Limit
The MP3424A senses and limits the load
current flowing through the current-sense
resistor. RSENSE is connected from the output
capacitor to the load terminal and sets the load
current limit (IOCL). Estimate RSENSE with
Equation (2):
IOCL VOCL / RSENSE
(2)
Where VOCL is typically 30mV, IOCL is the load
current limit (in A), and RSENSE is the sense
resistor (in Ω) (R5 in Figure 1 on page 12).
Use an RC compensation net on ILIM to
regulate the stable load current limit loop. It is
recommended to use a 2kΩ resistor and 10nF
capacitor.
Input Capacitor Selection
Low-ESR input capacitors reduce input
switching noise and the peak current drawn
from the battery. Ceramic capacitors are
recommended for input decoupling, and should
be placed as close to the device as possible.
Use a ceramic capacitor above 22μF to restrain
the input voltage ripple.
Selecting the Output Capacitor
The output capacitor requires a minimum 22μF
capacitance of at the configured VOUT to ensure
stability across the entire operating range. A
higher capacitance may be required to lower
the output ripple and transient ripple. Use lowESR capacitors such as X5R or X7R ceramic
capacitors. Assuming the ESR is 0, the
minimum output capacitance (COUT) to support
the ripple in PWM mode can be calculated
using Equation (3):
COUT
IOUT (VOUT(MAX) VIN(MIN) )
fSW VOUT(MAX) ΔV
(3)
Where VOUT(MAX) is the maximum output voltage,
VIN(MIN) is the minimum input voltage, IOUT is the
output current, fSW is the switching frequency,
and ∆VOUT is the acceptable output voltage
ripple.
It is recommended to place a 1μF ceramic
capacitor between OUT and PGND to reduce
spikes on the SW node and improve EMI
performance.
Selecting the Inductor
Optimized Performance with
MPS Inductor MPL-AL5030 Series
The MP3424A can utilize small surface-mount
chip inductors due to its 580kHz fSW. Inductor
values between 1μH and 2.2μH are suitable for
most applications. Larger inductances allow for
slightly greater IOUT capability; however,
reducing the inductor ripple current also
increases component size. Calculate the
minimum inductance (L) with Equation (4):
L
VIN(MIN) (VOUT(MAX) VIN(MIN) )
VOUT(MAX) ΔL fSW
(4)
Where ∆IL is the acceptable inductor current
ripple.
The inductor current ripple is typically set to be
between 30% and 40% of the average IL. The
inductor should have a low DCR to reduce
resistive power loss. The saturated current (ISAT)
should be large enough to support the peak
current.
MP3424A Rev. 1.0
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MP3424A – CONFIGURABLE-CURRENT, OUTPUT DISCONNECT BOOST CONVERTER
MPS inductors are optimized and tested for use
with our complete line of integrated circuits.
Table
2
lists
our
power
inductor
recommendations. Select a part number based
on your design requirements.
Table 2: Power Inductor Selection
Part Number
Inductor Value Manufacturer
MPL-AL
MPL-AL5030-1R5
MPL-AL5030-1R0
1µH to 2.2µH
1.5μH
1μH
MPS
MPS
MPS
MPL-AL5030-2R2
2.2μH
MPS
Visit MonolithicPower.com under Products >
Inductors for more information.
Design Example
Table 3 shows a design example following the
application guidelines for the described
specifications.
Table 3: Design Example
VIN
VOUT
IOUT
2.8V to 4.2V
5V
3.1A
Figure 4 on page 18 shows the detailed
application schematic. For the typical
performance and circuit waveforms, see the
Typical Performance Characteristics section on
page 8. For more device applications, refer to
the related evaluation board datasheet.
MP3424A Rev. 1.0
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MP3424A – CONFIGURABLE-CURRENT, OUTPUT DISCONNECT BOOST CONVERTER
2. Place a small decoupling capacitor in
parallel with the bulk output capacitor, and
as close to OUT as possible. This is very
important to reduce the spikes on SW and
improve EMI performance.
3. Place the input capacitor and inductor as
close to IN and SW as possible.
4. Keep the trace between the inductor and
SW as wide and short as possible.
5. Keep the feedback (FB) loop far away from
all noise sources, such as SW.
8. Place the ILIM set and compensation net
close to ILIM and AGND.
9. Tie the ground return of the input and output
capacitors as close to PGND as possible
with a large copper GND area.
10. Place vias around GND to lower the die
temperature.
Top Layer
L1
VIN
SW
Via
R6
C1A
C1B
C2A
C3
6
C2C
R5
5
7
R4 R3
C2B
U1
4
8
14
3
9
13
2
10
6. Place the feedback resistor dividers as
close to FB and AGND as possible.
Bottom Layer
11
1. Place the output capacitor as close to OUT
and PGND as possible.
7. Connect the current-sense traces (SOUT
and SENSE) from the sense resistor pad,
and route them in close parallel with a small
closed area, far away from noise sources
such as the SW trace.
12
PCB Layout Guidelines
Efficient PCB layout is critical for stable
operation. Poor layout can result in reduced
performance, excessive EMI, resistive loss, and
system instability. For the best results, refer to
Figure 3 and follow the guidelines below:
1
R2
R1
VOUT
Vias for heat sink
PGND
Figure 3: Recommended PCB Layout
MP3424A Rev. 1.0
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MP3424A – CONFIGURABLE-CURRENT, OUTPUT DISCONNECT BOOST CONVERTER
TYPICAL APPLICATION CIRCUITS
L1
VIN
C1A
22µF
C1B
22µF
MPL-AL5030-1R5
SW
IN
R6
100kΩ
SENSE
VOUT
5V
EN
OUT
EN
MP3424A
R1
1MΩ
ILIM
C3
10nF
R4
2kΩ
R5a
16mΩ
SOUT
R5b
18mΩ
FB
R3
100kΩ
AGND
R2
191kΩ
PGND
C2A C2B C2C
1µF 22µF 22µF
Figure 4: Typical Boost Circuit with Average Load Current Limit (VIN = 2V to 4.2V, VOUT = 5V)
L1
VIN
C1A
22µF
C1B
22µF
MPL-AL5030-1R5
SW
IN
R6
100kΩ
EN
SENSE
SOUT
VOUT
5V
OUT
EN
MP3424A
R1
1MΩ
ILIM
FB
R3
100kΩ
AGND
PGND
R2
191kΩ
C2A C2B C2C
1µF 22µF 22µF
Figure 5: Typical Boost Circuit without Average Load Current Limit (VIN = 2V to 4.2V, VOUT = 5V)
MP3424A Rev. 1.0
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18
MP3424A – CONFIGURABLE-CURRENT, OUTPUT DISCONNECT BOOST CONVERTER
PACKAGE INFORMATION
QFN-14 (2mmx2mm)
PIN 1 ID
0.125X45º TYP
PIN 1 ID
MARKING
PIN 1 ID
INDEX AREA
BOTTOM VIEW
TOP VIEW
SIDE VIEW
NOTE:
0.125X45º
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
MP3424A Rev. 1.0
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MP3424A – CONFIGURABLE-CURRENT, OUTPUT DISCONNECT BOOST CONVERTER
CARRIER INFORMATION
Part Number
Package
Description
Quantity/
Reel
Quantity/
Tube
Reel
Diameter
Carrier
Tape Width
Carrier
Tape Pitch
MP3424AGG-Z
QFN-14 (2mmx2mm)
5000
N/A
13in
12mm
8mm
MP3424A Rev. 1.0
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MP3424A – CONFIGURABLE-CURRENT, OUTPUT DISCONNECT BOOST CONVERTER
REVISION HISTORY
Revision #
Revision Date
1.0
06/22/2021
Description
Pages Updated
Initial Release
-
Notice: The information in this document is subject to change without notice. Users should warrant and guarantee that thirdparty 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.
MP3424A Rev. 1.0
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6/22/2021
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© 2021 MPS. All Rights Reserved.
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