MP2234SGJ [MPS]
High-Efficiency, 2A, 16V, 800kHz Synchronous, Step-Down Converter;
| 型号： | MP2234SGJ |
| 厂家： | 
MONOLITHIC POWER SYSTEMS |
| 描述： | High-Efficiency, 2A, 16V, 800kHz Synchronous, Step-Down Converter |
| 文件： | 总19页 (文件大小：722K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
MP2234S
High-Efficiency, 2A, 16V, 800kHz
Synchronous, Step-Down Converter
The Future of Analog IC Technology
DESCRIPTION
FEATURES
The
MP2234S
is
a
high-frequency,
•
•
Wide 4.5V-to-16V Operating Input Range
140mΩ/60mΩ Low RDS(ON) Internal Power
MOSFETs
High-Efficiency Synchronous Mode
Operation
Fixed 800kHz Switching Frequency
Synchronizes from a 300kHz-to-2MHz
External Clock
Power-Save Mode at Light Load
External Soft-Start
Over Current Protection and Hiccup
Thermal Shutdown
Output Adjustable from 0.804V
Available in a 8-pin TSOT-23 Package
synchronous, rectified, step-down, switch-mode
converter with built-in power MOSFETs. It
offers a compact solution to achieve a 2A
continuous output current with excellent load
and line regulation over a wide input-supply
range. The MP2234S has synchronous mode
operation for higher efficiency over the output
current load range.
•
•
•
•
•
•
•
•
•
Current-mode operation provides fast transient
response and eases loop stabilization.
Full protection features include over-current
protection (OCP) and thermal shut down (TSD).
The MP2234S requires a minimal number of
readily-available standard external components,
and is available in a space-saving 8-pin
TSOT23 package.
APPLICATIONS
•
•
•
•
Notebook Systems and I/O Power
Digital Set-Top Boxes
Flat-Panel Television and Monitors
Distributed Power Systems
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
R3
20
12V
C4
0.1µ
F
C1
L1
4.7µH
22µF
MP2234S
3.
C2
R1
40.2k
47µF
C3
µF
R5
5.6k
0.1
R2
13k
C5
22nF
MP2234S Rev.1.0
4/3/2015
www.MonolithicPower.com
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© 2015 MPS. All Rights Reserved.
1
MP2234S – SYNCHRONOUS STEP-DOWN CONVERTER
ORDERING INFORMATION
Part Number*
Package
Top Marking
MP2234SGJ
See Below
TSOT-23
* For Tape & Reel, add suffix –Z (e.g. MP2234SGJ–Z).
TOP MARKING
ALZ: product code of MP2234SGJ;
Y: year code;
PACKAGE REFERENCE
1
2
3
4
8
7
6
5
MP2234S Rev.1.0
4/3/2015
www.MonolithicPower.com
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© 2015 MPS. All Rights Reserved.
2
MP2234S – SYNCHRONOUS STEP-DOWN CONVERTER
ABSOLUTE MAXIMUM RATINGS (1)
VIN ................................................ -0.3V to 17V
VSW ....................................................................
-0.3V (-5V for <10ns) to 17V (19V for <10ns)
VBST ...................................................... VSW+6V
All Other Pins................................-0.3V to 6V(2)
Thermal Resistance (5)
TSOT23-8 ............................. 100..... 55... °C/W
θJA θJC
Notes:
1) Exceeding these ratings may damage the device.
2) About the details of EN pin’s ABS MAX rating, please refer to
Page 12, Enable/SYNC control section.
3) The maximum allowable power dissipation is a function of the
maximum junction temperature TJ (MAX), the junction-to-
ambient 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)
Continuous Power Dissipation (TA = +25°C)
..........................................................1.25W
Junction Temperature..............................150°C
Lead Temperature ...................................260°C
Storage Temperature.................-65°C to 150°C
Recommended Operating Conditions (4)
Supply Voltage VIN .......................... 4.5V to 16V
Output Voltage VOUT........... 0.804V to VIN x DMAX
Operating Junction Temp. (TJ). -40°C to +125°C
4) The device is not guaranteed to function outside of its
operating conditions.
5) Measured on JESD51-7, 4-layer PCB.
MP2234S Rev.1.0
4/3/2015
www.MonolithicPower.com
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© 2015 MPS. All Rights Reserved.
3
MP2234S – SYNCHRONOUS STEP-DOWN CONVERTER
ELECTRICAL CHARACTERISTICS
VIN=12V, TJ=-40°C to +125°C(6), typical value is tested at TJ=+25°C, unless otherwise noted.
Parameter
Symbol Condition
Min
Typ
Max
Units
V
EN = 0V, TJ=+25°C
1
5
1
μA
Supply Current (Shutdown)
IIN
Iq
VEN = 0V, TJ=-40°C to +125°C
VEN = 2V, VFB = 1V
μA
mA
mΩ
mΩ
μA
Supply Current (Quiescent)
HS Switch-On Resistance
LS Switch-On Resistance
Switch Leakage
0.5
140
60
HSRDS-ON VBST-SW=5V
LSRDS-ON VCC =5V
SWLKG
ILIMIT
VEN = 0V, VSW =12V or 0V
1
Current Limit
Under 40% Duty Cycle
VFB=0.75V,TJ=+25°C
VFB=0.75V,TJ=-40°C to +125°C
VFB<400mV
3
4
A
620
550
800
800
0.5
92
900
900
kHz
kHz
fSW
%
Oscillator Frequency
fSW
Fold-Back Frequency
Maximum Duty Cycle
Minimum On Time(7)
Sync Frequency Range
fFB
DMAX
τON_MIN
fSYNC
VFB=700mV
40
ns
0.3
2
MHz
TJ =25°C
788
804
804
820
mV
mV
Feedback Voltage
VFB
TJ=-40°C to +125°C
VFB=830mV
784
824
Feedback Current
EN Rising Threshold
EN Hysteresis
IFB
10
1.4
150
50
nA
V
VEN_RISING
VEN Hysteresis
1
1.8
mV
VEN=2V
VEN=0
2
μA
EN Input Current
IEN
0
μA
μs
EN Turn-Off Delay
ENtd-off
10
VIN Under-Voltage Lockout
Threshold—Rising
INUVVth
3.5
3.9
4.3
V
VIN Under-Voltage Lockout
Threshold—Hysteresis
INUVHYS
VCC
700
mV
VCC Regulator
VCC Load Regulation
Soft-Start Current
Thermal Shutdown (7)
Thermal Hysteresis (7)
Notes:
4.6
8
5
2
5.4
14
V
ICC=5mA
%
ISS
11
150
20
μA
°C
°C
6) Not tested in production. Guaranteed by over-temperature correlation.
7) Guaranteed by design.
MP2234S Rev.1.0
4/3/2015
www.MonolithicPower.com
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© 2015 MPS. All Rights Reserved.
4
MP2234S – SYNCHRONOUS STEP-DOWN CONVERTER
TYPICAL CHARACTERISTICS
Performance waveforms are tested on the evaluation board of the Design Example section.
VIN = 12V, VOUT = 3.3V, L=4.7μH, TA = 25°C, unless otherwise noted.
MP2234S Rev.1.0
4/3/2015
www.MonolithicPower.com
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© 2015 MPS. All Rights Reserved.
5
MP2234S – SYNCHRONOUS STEP-DOWN CONVERTER
TYPICAL PERFORMANCE CHARACTERISTICS
Performance waveforms are tested on the evaluation board of the Design Example section.
VIN = 12V, VOUT = 3.3V, L=4.7μH, TA = 25°C, unless otherwise noted.
MP2234S Rev.1.0
4/3/2015
www.MonolithicPower.com
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© 2015 MPS. All Rights Reserved.
6
MP2234S – SYNCHRONOUS STEP-DOWN CONVERTER
TYPICAL PERFORMANCE CHARACTERISTICS (contiuned)
Performance waveforms are tested on the evaluation board of the Design Example section.
VIN = 12V, VOUT = 3.3V, L=4.7μH, TA = 25°C, unless otherwise noted.
MP2234S Rev.1.0
4/3/2015
www.MonolithicPower.com
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© 2015 MPS. All Rights Reserved.
7
MP2234S – SYNCHRONOUS STEP-DOWN CONVERTER
TYPICAL PERFORMANCE CHARACTERISTICS (contiuned)
Performance waveforms are tested on the evaluation board of the Design Example section.
VIN = 12V, VOUT = 3.3V, L=4.7μH, TA = 25°C, unless otherwise noted.
V
/AC
OUT
10mV/div.
V
OUT
2V/div.
V
/AC
IN
V
/AC
OUT
200mV/div.
20mV/div.
V
IN
5V/div.
SW
5V/div.
V
V
SW
10V/div.
I
I
INDUCTOR
2A/div.
INDUCTOR
I
OUT
2A/div.
1A/div.
MP2234S Rev.1.0
4/3/2015
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MP2234S – SYNCHRONOUS STEP-DOWN CONVERTER
PIN FUNCTIONS
Package
Pin #
Name Description
Soft-Start. Connect an external capacitor to program the soft start time for the switch mode
regulator.
1
SS
IN
Supply Voltage. The IN pin supplies power for internal MOSFET and regulator. The
MP2234S operates from a +4.5V to +16V input rail. Requires a low-ESR, and low-
inductance capacitor (C1) to decouple the input rail. Place the input capacitor very close to
this pin and connect it with wide PCB traces and multiple vias.
2
3
Switch Output. Connect to the inductor and bootstrap capacitor. This pin is driven up to VIN
by the high-side switch during the PWM duty cycle ON time. The inductor current drives
the SW pin negative during the OFF time. The ON resistance of the low-side switch and
the internal body diode fixes the negative voltage. Connect using wide PCB traces and
multiple vias.
SW
System Ground. Reference ground of the regulated output voltage. PCB layout Requires
extra care. For best results, connect to GND with copper and vias.
4
5
GND
BST
Bootstrap. Requires a capacitor connected between SW and BST pins to form a floating
supply across the high-side switch driver.
Enable/Synchronize. EN/SYNC=high to enable the MP2234S. Apply an external clock
6
7
EN/SYNC change the switching frequency. For automatic start-up, connect EN/SYNC pin to VIN with
a 100kꢀ resistor.
Internal 5V LDO output. Powers the driver and control circuits. Decouple with 0.1μF to
0.22μF capacitor. Do not use a capacitor ≥0.22μF.
VCC
Feedback. Connect to the tap of an external resistor divider from the output to GND to set
the output voltage. The frequency fold-back comparator lowers the oscillator frequency
8
FB
when the FB voltage is below 400mV to prevent current limit runaway during a short circuit
fault. Place the resistor divider as close to the FB pin as possible. Avoid placing vias on
the FB traces.
MP2234S Rev.1.0
4/3/2015
www.MonolithicPower.com
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© 2015 MPS. All Rights Reserved.
9
MP2234S – SYNCHRONOUS STEP-DOWN CONVERTER
FUNCTIONAL BLOCK DIAGRAM
Figure 1. Functional Block Diagram
MP2234S Rev.1.0
4/3/2015
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MP2234S – SYNCHRONOUS STEP-DOWN CONVERTER
clock initiates the PWM cycle, the HS-FET turns
on and remains on until VILsense reaches the
OPERATION
The
MP2234S
is
a
high-frequency,
value set by VCOMP (after a period of dead time),
and the low-side MOSFET (LS-FET) turns on
and remains on until the inductor-current value
decreases to zero. The device repeats the
same operation in every clock cycle to regulate
the output voltage (see Figure 3).
synchronous, rectified, step-down, switch-mode
converter with built-in power MOSFETs. It
offers a compact solution that achieves a 2A
continuous output current with excellent load
and line regulation over 4.5V to 16V input-
supply range.
The MP2234S has three working modes:
advanced asynchronous modulation (AAM)
mode, discontinuous conduction mode (DCM),
and continuous conduction mode (CCM). The
load current increases as the device transitions
from AAM mode to DCM to CCM.
IL
AAM Control Operation
Figure 3. DCM Control Operation
In a light-load condition, MP2234S works in
advanced asynchronous modulation (AAM)
mode (see Figure 2). The VAAM is an internal
fixed voltage when input and output voltages
are fixed. VCOMP is the error-amplifier output
(which represents the peak inductor-current
CCM Control Operation
The device enters continuous conduction mode
(CCM) from DCM once the inductor current no
longer drops to zero in a clock cycle. In CCM,
the internal clock initiates the PWM cycle, the
HS-FET turns on and remains on until VILsense
reaches the value set by VCOMP (after a period
of dead time), and the LS-FET turns on and
remains on until the next clock cycle begins.
The device repeats the same operation in every
clock cycle to regulate the output voltage.
information). When VCOMP is lower than VAAM
,
the internal clock is blocked. This causes the
MP2234S to skip pulses, achieving the light-
load power save. Refer to AN032 for additional
details.
The internal clock re-sets every time VCOMP is
higher than VAAM. At the same time, the high-
side MOSFET (HS-FET) turns on and remains
on until VILsense reaches the value set by VCOMP.
If VILsense does not reach the value set by VCOMP
within 92% of one PWM period, the HS-FET is
forced off.
Internal Regulator
The light-load feature in this device is optimized
for 12V input applications.
A 5V internal regulator powers most of the
internal circuitries. This regulator takes VIN and
operates in the full VIN range. When VIN
exceeds 5.0V, the output of the regulator is in
full regulation. When VIN is less than 5.0V, the
output decreases, and the part requires a 0.1µF
ceramic decoupling capacitor.
Error Amplifier (EA)
The error amplifier compares the FB pin voltage
to the internal 0.804V reference (VREF) and
outputs a current proportional to the difference
between the two. This output current then
Figure 2. Simplified AAM Control Logic
DCM Control Operation
The VCOMP voltage ramps up as the output
current increases. When its minimum value
exceeds VAAM, the device enters discontinuous
conduction mode (DCM). In DCM, the internal
charges
or
discharges
the
internal
compensation network to form the COMP
voltage, which controls the power MOSFET
current. The optimized internal compensation
MP2234S Rev.1.0
4/3/2015
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11
MP2234S – SYNCHRONOUS STEP-DOWN CONVERTER
network minimizes the external component
counts and simplifies the control loop design.
(see Figure 5). For best results, set the UVLO
falling threshold (VSTOP) above 4.5V using the
enable resistors. Set the rising threshold
(VSTART) to provide enough hysteresis to
allow for input-supply variations.
Enable/SYNC Control
EN/SYNC is a digital control pin that turns the
regulator on and off. Drive EN high to turn on
the regulator; drive it low to turn it off. An
internal 1Mꢀ resistor from EN/SYNC to GND
allows EN/SYNC to be floated to shut down the
chip. The EN/SYNC pin is clamped internally
using a 6.5V series-Zener-diode (see Figure 4).
Connecting the EN/SYNC input pin through a
pull-up resistor to the voltage on the IN pin
limits the EN input current to less than 100µA.
RENUP
RENDOWN
For example, with 12V connected to IN, RPULLUP
≥ (12V – 6.5V) ÷ 100µA = 55kꢀ.
Figure 5. Adjustable UVLO
Connecting the EN pin directly to a voltage
source without any pull-up resistor requires
limiting the amplitude of the voltage source to
≤6V to prevent damage to the Zener diode.
Soft-Start (SS)
Adjust the soft-start time by connecting a
capacitor from SS pin to ground. When the soft-
start begins, an internal 11µA current source
charges the external capacitor. The soft-start
capacitor connects to the non-inverting input of
the error amplifier. The soft-start period
continues until the voltage on the soft-start
capacitor exceeds the 0.804V reference. Then
the non-inverting amplifier takes the reference
voltage as the input. Use the following equation
to calculate the soft-start time:
Figure 4. 6.5V Zener Diode Connection
0.804V ×Css(nF)
For external clock synchronization, connect a
clock with a frequency range between 300kHz
and 2MHz 2ms after the output voltage is set:
The internal clock rising edge will synchronize
with the external clock rising edge. Select an
external clock signal with a pulse width less
than 1μs.
tSS(ms) =
11μA
Over-Current-Protection (OCP) and Hiccup
The MP2234S has a cycle-by-cycle over-
current limit when the inductor current peak
value exceeds the set current limit threshold.
Meanwhile, the output voltage drops until VFB is
below the Under-Voltage (UV) threshold—
typically 50% below the reference. Once UV is
triggered, the MP2234S enters hiccup mode to
periodically restart the part. This protection
mode is especially useful when the output is
dead-shorted to ground, and greatly reduces
the average short circuit current to alleviate
thermal issues and protect the regulator. The
MP2234S exits the hiccup mode once the over-
current condition is removed.
Under-Voltage Lockout (UVLO)
The MP2234S has under-voltage lock-out
protection (UVLO). When the VCC voltage
exceeds the UVLO rising threshold voltage, the
device begins to power-up. It shuts off when
the VCC voltage drops below the UVLO falling
threshold voltage. This is non-latch protection.
The MP2234S is disabled when the input
voltage falls below 3.2V (Typ). If an application
requires a higher under-voltage lockout (UVLO)
threshold, use the EN pin to adjust the input
voltage UVLO by using two external resistors
MP2234S Rev.1.0
4/3/2015
www.MonolithicPower.com
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© 2015 MPS. All Rights Reserved.
12
MP2234S – SYNCHRONOUS STEP-DOWN CONVERTER
Thermal Shutdown (TSD)
Thermal shutdown prevents the chip from
operating at exceedingly high temperatures.
When the silicon die reaches temperatures that
exceed 150°C, it shuts down the whole chip.
When the temperature drops below its lower
threshold, typically 130°C, the chip is enabled
again.
Floating Driver and Bootstrap Charging
An external bootstrap capacitor powers the
floating power MOSFET driver. This floating
driver has its own UVLO protection. This
UVLO’s rising threshold is 2.2V with a
hysteresis of 150mV. The bootstrap capacitor
voltage is regulated internally by VIN through D1,
M1, R3, C4, L1 and C2 (see Figure 6). If (VIN-
VSW) exceeds 5V, U1 will regulate M1 to
maintain a 5V BST voltage across C4. A 20ꢀ
resistor placed between SW and BST cap is
strongly recommended to reduce SW spike
voltage.
D1
VIN
M1
BST
U1
R3
5V
C4
VOUT
C2
L1
SW
Figure 6. Internal Bootstrap Charging Circuit
Startup and Shutdown
If both VIN and VEN exceed their respective
thresholds, the chip starts. The reference block
starts first, generating stable reference voltage
and currents, and then the internal regulator is
enabled. The regulator provides a stable supply
for the remaining circuitries.
Three events can shut down the chip: VEN low,
VIN low and thermal shutdown. During the
shutdown procedure, the signal path is first
blocked to avoid any fault triggering. The
COMP voltage and the internal supply rail are
then pulled down. The floating driver is not
subject to this shutdown command.
MP2234S Rev.1.0
4/3/2015
www.MonolithicPower.com
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© 2015 MPS. All Rights Reserved.
13
MP2234S – SYNCHRONOUS STEP-DOWN CONVERTER
VOUT ×(V − VOUT
)
APPLICATION INFORMATION
IN
L1 =
V × ΔIL × fOSC
IN
Setting the Output Voltage
The external resistor divider sets the output
voltage (see Typical Application on page 1).
Where ΔIL is the inductor ripple current.
Choose the inductor ripple current to be
approximately 30% of the maximum load
current. The maximum inductor peak current is:
Choose R1 around 40kꢀ for VOUT>1.2V, R2 is
then given by:
R1
ΔIL
R2 =
IL(MAX) = ILOAD
+
V
OUT
2
− 1
0.804V
Use a larger inductor for improved efficiency
under light-load conditions—below 100mA.
The T-Type network is recommended highly
(see Figure 7)
Selecting the Input Capacitor
The input current to the step-down converter is
discontinuous, therefore requires a capacitor is
to supply the AC current to the step-down
converter while maintaining the DC input
voltage. Use low ESR capacitors for the best
performance. Use ceramic capacitors with X5R
or X7R dielectrics for best results because of
their low ESR and small temperature
coefficients. For most applications, use a 22µF
capacitor.
Figure 7. T-Type Network
Table 1 lists the recommended resistors and
compensation values for common output
voltages.
Table 1: Resistor Selection for Common Output
Voltages(8)
Since C1 absorbs the input switching current, it
requires an adequate ripple current rating. The
RMS current in the input capacitor can be
estimated by:
VOUT
R1 (kΩ) R2 (kΩ) Rt (kΩ)
(V)
1
20.5
30.1
40.2
40.2
40.2
40.2
84.5
61.9
32.4
19.1
13
34
24
15
6.8
5.6
2
1.2
1.8
2.5
3.3
5
⎛
⎞
⎟
VOUT
VIN
VOUT
VIN
⎜
IC1 = ILOAD
×
× 1−
⎜
⎝
⎟
⎠
The worst case condition occurs at VIN = 2VOUT
,
where:
7.68
ILOAD
Notes:
IC1
=
8) The recommended parameters are based on a 800kHz
switching frequency; a different input voltage, output-inductor
value, and output-capacitor value may affect the selection of
R1, R2, and Rt. For additional component parameters, please
refer to the “Typical Application Circuits” section on pages 17
and 18.
2
For simplification, choose an input capacitor
with an RMS current rating greater than half of
the maximum load current.
Selecting the Inductor
The input capacitor can be electrolytic, tantalum
or ceramic. When using electrolytic or tantalum
capacitors, add a small, high quality ceramic
capacitor (e.g. 0.1μF) placed 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 input. The input
Use a 1µH-to-22µH inductor with a DC current
rating of at least 25% percent higher than the
maximum load current for most applications.
For highest efficiency, use an inductor with a
DC resistance less than 15mꢀ. For most
designs, the inductance value can be derived
from the following equation.
MP2234S Rev.1.0
4/3/2015
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14
MP2234S – SYNCHRONOUS STEP-DOWN CONVERTER
z VOUT is 5V or 3.3V; and
VOUT
voltage ripple caused by capacitance can be
estimated as:
z Duty cycle is high: D=
>65%
VIN
⎛
⎞
⎟
⎠
ILOAD
VOUT
VOUT
ΔV
=
×
× 1−
⎜
IN
If the BST voltage is insufficient, the output-
ripple voltage may become extremely large
during a light-load condition. If this occurs, add
an external BST diode from VCC to BST (see
Figure 8).
fS ×C1
V
IN
V
IN
⎝
Selecting the Output Capacitor
The output capacitor (C2) maintains the DC
output voltage. Use ceramic, tantalum, or low-
ESR electrolytic capacitors. For best results,
use low ESR capacitors to keep the output
voltage ripple low. The output voltage ripple can
be estimated as:
MP2234S
⎛
⎞ ⎛
VOUT
⎞
⎟
⎠
VOUT
1
ΔVOUT
=
× 1−
× R
⎟ ⎜
+
⎜
ESR
fS ×L1
V
8× fS ×C2
⎝
IN ⎠ ⎝
Figure 8. Optional External Bootstrap Diode to
Enhance Efficiency
Where L1 is the inductor value and RESR is the
equivalent series resistance (ESR) value of the
output capacitor.
The recommended external BST diode is
IN4148, and the BST capacitor value is 0.1µF
to 1μF.
PC Board Layout (9)
PCB layout is very important to achieve stable
operation especially for VCC capacitor and
input capacitor placement. For best results,
refer to Figure 9 and the guidelines below:
For ceramic capacitors, the capacitance
dominates the impedance at the switching
frequency, and the capacitance causes the
majority of the output voltage ripple. For
simplification, the output voltage ripple can be
estimated as:
VOUT
8× fS2 ×L1 ×C2
⎛
VOUT
⎞
⎟
⎠
ΔVOUT
=
× 1−
⎜
1. Use large ground plane directly connect to
GND pin. Add vias near the GND pin if
bottom layer is ground plane.
V
⎝
IN
For tantalum or electrolytic capacitors, the ESR
dominates the impedance at the switching
frequency. For simplification, the output ripple
can be approximated as:
2. Place the VCC capacitor to VCC pin and
GND pin as close as possible. Make the
trace length of VCC pin-VCC capacitor
anode-VCC capacitor cathode-chip GND
pin as short as possible.
VOUT
VOUT
⎛
⎞
ΔVOUT
=
× 1−
×RESR
⎜
⎟
⎠
fS ×L1
V
IN
⎝
3. Place the ceramic input capacitor close to
IN and GND pins. Keep the connection of
input capacitor and IN pin as short and
wide as possible.
The characteristics of the output capacitor also
affect the stability of the regulation system. The
MP2234S can be optimized for a wide range of
capacitance and ESR values.
4. Route SW, BST away from sensitive
analog areas such as FB.
External Bootstrap Diode
In particular conditions, BST voltage may
become insufficient (see equations below).
During these conditions an external bootstrap
diode can enhance the efficiency of the
regulator and avoid insufficient BST voltage at
light-load PFM operation. Insufficient BST
voltage is more likely to occur during either of
the following conditions:
5. Place the T-type feedback resistor R5 close
to chip to ensure the trace which connects
to FB pin as short as possible.
Notes:
9) The recommended layout is based on the Figure 10 Typical
Application circuit on page 17.
MP2234S Rev.1.0
4/3/2015
www.MonolithicPower.com
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2015 MPS. All Rights Reserved.
15
MP2234S – SYNCHRONOUS STEP-DOWN CONVERTER
GND
C6
R1
C4
SW
C3
C1A
L1
R4
C1
Vin
C 2
Vout
C2A
GND
Top Layer
GND
EN/SYNC
Vout Sense
Bottom Layer
Figure 9. Recommended PCB Layout
Design Example
Below is a design example following the
application guidelines for the specifications:
Table 2: Design Example
VIN
VOUT
IOUT
12V
3.3V
2A
The detailed application schematic is shown in
Figure 11. The typical performance and circuit
waveforms have been shown in the Typical
Performance Characteristics section. For more
device applications, please refer to the related
Evaluation Board Datasheets.
MP2234S Rev.1.0
4/3/2015
www.MonolithicPower.com
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2015 MPS. All Rights Reserved.
16
MP2234S – SYNCHRONOUS STEP-DOWN CONVERTER
TYPICAL APPLICATION CIRCUITS
Figure 10. 12VIN, 5V/2A Output
Figure 11. 12VIN, 3.3V/2A Output
Figure 12. 12VIN, 2.5V/2A Output
MP2234S Rev.1.0
4/3/2015
www.MonolithicPower.com
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2015 MPS. All Rights Reserved.
17
MP2234S – SYNCHRONOUS STEP-DOWN CONVERTER
Figure 13. 12VIN, 1.8V/2A Output
Figure 14. 12VIN, 1.2V/2A Output
Figure 15. 12VIN, 1V/2A Output
MP2234S Rev.1.0
4/3/2015
www.MonolithicPower.com
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2015 MPS. All Rights Reserved.
18
MP2234S – SYNCHRONOUS STEP-DOWN CONVERTER
PACKAGE INFORMATION
TSOT23-8
See note 7
EXAMPLE
TOP MARK
IAAAA
PIN 1 ID
RECOMMENDED LAND PATTERN
TOP VIEW
SEATING PLANE
SEE DETAIL ''A''
FRONT VIEW
SIDE VIEW
NOTE:
1) ALL DIMENSIONS ARE IN MILLIMETERS.
2) PACKAGE LENGTH DOES NOT INCLUDE MOLD
FLASH, PROTRUSION OR GATE BURR.
3) PACKAGE WIDTH DOES NOT INCLUDE
INTERLEAD FLASH OR PROTRUSION.
4) LEAD COPLANARITY (BOTTOM OF LEADS
AFTER FORMING) SHALL BE 0.10 MILLIMETERS
MAX.
DETAIL ''A''
5) JEDEC REFERENCE IS MO-193, VARIATION BA.
6) DRAWING IS NOT TO SCALE.
7) PIN 1 IS LOWER LEFT PIN WHEN READING TOP
MARK FROM LEFT TO RIGHT, (SEE EXAMPLE TOP
MARK)
NOTICE: The information in this document is subject to change without notice. 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.
MP2234S Rev.1.0
4/3/2015
www.MonolithicPower.com
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2015 MPS. All Rights Reserved.
19
相关型号：
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Switching Regulator, Current-mode, 6A, 800kHz Switching Freq-Max, PDSO8, MO-193BA, TSOT-23, 8 PIN
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MP2235SGJ-Z
Switching Regulator, Current-mode, 2000kHz Switching Freq-Max, PDSO8, TSOT-23, 8-PIN
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