MP28311DQ-Z [MPS]
Switching Regulator, Current-mode, 6.3A, 380kHz Switching Freq-Max, 3 X 3 MM, MO-229VEED-5, QFN-10;
| 型号： | MP28311DQ-Z |
| 厂家： | 
MONOLITHIC POWER SYSTEMS |
| 描述： | Switching Regulator, Current-mode, 6.3A, 380kHz Switching Freq-Max, 3 X 3 MM, MO-229VEED-5, QFN-10 开关 输出元件 |
| 文件： | 总14页 (文件大小：421K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
MP28311
3A, 28V, 340KHz Synchronous Rectified
Step-Down Converter
The Future of Analog IC Technology
DESCRIPTION
FEATURES
The MP28311 is a monolithic synchronous buck
regulator. The device integrates power
MOSFETS that provide 3A continuous load
current over a wide operating input voltage of
4.75V to 28V. Current mode control provides
fast transient response and cycle-by-cycle
current limit.
•
•
•
•
•
•
•
•
•
•
•
3A Output Current
Wide 4.75V to 28V Operating Input Range
Integrated Power MOSFET Switches
Output Adjustable from 0.8V to 25V
Up to 95% Efficiency
Programmable Soft-Start
Stable with Low ESR Ceramic Output Capacitors
Fixed 340KHz Frequency
Cycle-by-Cycle Over Current Protection
Input Under Voltage Lockout
Thermally Enhanced 8-Pin SOIC and
3x3 QFN10 Packages
An adjustable soft-start prevents inrush current
at turn-on. In shutdown mode, the supply
current drops to 1μA.
This device, available in 8-pin SOIC and 3x3
10-pin QFN packages, provides a very compact
system solution with minimal reliance on
external components.
APPLICATIONS
•
•
•
Distributed Power Systems
Pre-Regulator for Linear Regulators
Notebook Computers
“MPS” and “The Future of Analog IC Technology” are Registered Trademarks of
Monolithic Power Systems, Inc.
TYPICAL APPLICATION
Efficiency vs
Load Current
C5
10nF
100
V
IN = 12V
BS
IN
SS
EN
90
80
70
60
50
VIN
4.75V-28V
MP28311
SW
V
IN = 24V
COMP
C3
3.3nF
GND
FB
V
OUT = 5V
VOUT
5V/3A
0
0.5
1.0
1.5
2.0
2.5
3.0
LOAD CURRENT (A)
MP28311 Rev. 0.92
12/13/2007
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1
MP28311 – 3A, 28V, 340KHz SYNCHRONOUS RECTIFIED, STEP-DOWN CONVERTER
PACKAGE REFERENCE
TOP VIEW
TOP VIEW
IN
SW
1
2
3
4
5
10 SS
9
8
7
6
BS
BS
IN
1
2
3
4
8
7
6
5
SS
GND
GND
GND
EN
EN
COMP
FB
SW
GND
COMP
FB
EXPOSED PAD
ON BACKSIDE
Part Number*
Package
Temperature
Part Number*
Package
Temperature
3mm x 3mm
QFN10
SOIC8N
(Exposed Pad)
MP28311DQ
–40°C to +85°C
MP28311DN
–40°C to +85°C
For Tape & Reel, add suffix –Z (eg. MP28311DQ–Z)
For RoHS compliant packaging, add suffix –LF (eg.
MP28311DQ–LF–Z)
For Tape & Reel, add suffix –Z (eg. MP28311DN–Z)
For RoHS compliant packaging, add suffix –LF (eg.
MP28311DN–LF–Z)
*
*
Recommended Operating Conditions (2)
Input Voltage VIN............................ 4.75V to 28V
Output Voltage VOUT ........................ 0.8V to 25V
Ambient Operating Temperature ... –40°C to +85°C
ABSOLUTE MAXIMUM RATINGS (1)
Supply Voltage VIN .......................–0.3V to +30V
Switch Voltage VSW ................. –1V to VIN + 0.3V
Boost Voltage VBS ..........VSW – 0.3V to VSW + 6V
All Other Pins.................................–0.3V to +6V
Junction Temperature...............................150°C
Lead Temperature ....................................260°C
Storage Temperature ............. –65°C to +150°C
Thermal Resistance (3)
θJA
θJC
SOIC8N ..................................50...... 10... °C/W
3x3 QFN10 .............................50...... 12... °C/W
Notes:
1) Exceeding these ratings may damage the device.
2) The device is not guaranteed to function outside of its
operating conditions.
3) Measured on approximately 1” square of 1 oz copper.
ELECTRICAL CHARACTERISTICS (4)
VIN = 12V, TA = +25°C, unless otherwise noted.
Parameter
Symbol Condition
Min
Typ (4)
0.3
Max
3.0
Units
μA
Shutdown Supply Current
Supply Current
VEN = 0V
VEN = 2.7V, VFB = 1.0V
1.3
1.5
mA
4.75V ≤ VIN ≤ 28V,
TA = +25°C
0.780
0.800
0.820
V
Feedback Voltage
VFB
0.772
0.90
0.828
1.00
V
V
–40°C ≤ TA ≤ +85°C
ΔIC = ±10μA
OVP Threshold Voltage
0.95
400
820
Error Amplifier Voltage Gain
Error Amplifier Transconductance
AEA
GEA
V/V
μA/V
550
1100
MP28311 Rev. 0.92
12/13/2007
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MP28311 – 3A, 28V, 340KHz SYNCHRONOUS RECTIFIED, STEP-DOWN CONVERTER
ELECTRICAL CHARACTERISTICS (4) (continued)
VIN = 12V, TA = +25°C, unless otherwise noted.
Parameter
Symbol Condition
RDS(ON)1
RDS(ON)2
Min
Typ (4)
125
125
0
Max
Units
mΩ
mΩ
μA
High-Side Switch-On Resistance
Low-Side Switch-On Resistance
High-Side Switch Leakage Current
Upper-Switch Current Limit
Lower-Switch Current Limit
VEN = 0V, VSW = 0V
10
4.3
6.3
A
From Drain to Source
1.25
A
COMP to Current Sense
Transconductance
GCS
9
A/V
300
270
340
380
400
KHz
KHz
KHz
%
TA = +25°C
Oscillation Frequency
Fosc1
Fosc2
–40°C ≤ TA ≤ +85°C
VFB = 0V
Short Circuit Oscillation Frequency
Maximum Duty Cycle
110
90
DMAX VFB = 0.7V
Minimum On-Time
220
1.5
ns
EN Shutdown Threshold Voltage
VEN Rising
1.1
2.0
V
EN Shutdown Threshold Voltage
Hysteresis
220
2.5
mV
2.2
2.1
2.7
2.8
V
V
EN Lockout Threshold Voltage
–40°C ≤ TA ≤ +85°C
EN Lockout Hysteresis
210
mV
V
3.8
3.5
4.05
4.30
4.70
VIN rising, TA = +25°C
Input Under Voltage Lockout
Threshold
UVLO
V
–40°C ≤ TA ≤ +85°C
Input Under Voltage Lockout
Threshold Hysterisis
210
mV
Soft-Start Current
Thermal Shutdown
Note:
VSS = 0V
6
μA
160
°C
4) 100% production test at +25°C. Specifications over the temperature range are guaranteed by design and characterization.
MP28311 Rev. 0.92
12/13/2007
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3
MP28311 – 3A, 28V, 340KHz SYNCHRONOUS RECTIFIED, STEP-DOWN CONVERTER
PIN FUNCTIONS
3x3
SOIC8N
Pin #
QFN10 Name Description
Pin #
High-Side Gate Drive Boost Input. BS supplies the drive for the high-side N-
1
2
9
BS
Channel MOSFET switch. Connect a 0.01μF or greater capacitor from SW to BS
to power the high side switch.
Power Input. IN supplies the power to the IC, as well as the step-down converter
switches. Drive IN with a 4.75V to 28V power source. Bypass IN to GND with a
suitably large capacitor to eliminate noise on the input to the IC. See Input
Capacitor.
1
IN
Power Switching Output. SW is the switching node that supplies power to the
output. Connect the output LC filter from SW to the output load. Note that a
capacitor is required from SW to BS to power the high-side switch.
3
4
5
2
3, 4, 5
6
SW
GND
FB
Ground. SOIC8: Connect the exposed pad to pin 4. 3x3 QFN10: Connect to pins
3, 4 and 5 and ensure that said pins are tied together.
Feedback Input. FB senses the output voltage to regulate that voltage. Drive FB
with a resistive voltage divider from the output voltage. The feedback reference
voltage is 0.8V. See Setting the Output Voltage.
Compensation Node. COMP is used to compensate the regulation control loop.
Connect a series RC network from COMP to GND to compensate the regulation
control loop. In some cases, an additional capacitor from COMP to GND is
required. See Compensation Components.
6
7
COMP
Enable Input. EN is a digital input that turns the regulator on or off. Drive EN higher
than 2.7V to turn on the regulator, drive it lower than 1.1V to turn it off. Pull up to
the IN pin with 100kΩ resistor for automatic startup.
7
8
8
EN
SS
Soft-start Control Input. SS controls the soft-start period. Connect a capacitor from
SS to GND to set the soft-start period. See Soft-Start Capacitor.
10
MP28311 Rev. 0.92
12/13/2007
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MP28311 – 3A, 28V, 340KHz SYNCHRONOUS RECTIFIED, STEP-DOWN CONVERTER
TYPICAL PERFORMANCE CHARACTERISTICS
VIN = 12V, VO = 3.3V, L = 10µH, C1 = 10µF, C2 = 22µF x 2, TA = +25°C, unless otherwise noted.
Feeback Voltage vs.
Temperature
Efficiency vs
Load Current
0.810
0.805
0.800
0.795
0.790
0.7850
0.780
95
90
85
80
75
70
65
60
55
50
V
IN = 12V
V
V
IN = 12V
IN = 28V
V
IN = 24V
V
IN = 4.75V
VOUT = 2.5V
1.5
3.0
0.5 1.0
2.5
0
2.0
-20
40
0
20
60
80
-40
o
LOAD CURRENT (A)
TEMPERATURE ( C)
Oscillator Frequency
UVLO Rising vs.
Temperature
Enable Lockout Threshold
vs. Temperature
4.5
4.4
4.3
4.2
4.1
4.0
3.9
3.8
3.7
345
340
335
330
325
2.70
2.65
2.60
2.55
2.50
2.45
2.40
2.35
2.30
-20
40
0
20
60
80
-40
-20
40
0
20
60
80
-40
-20
40
o
0
20
60
80
-40
o
o
TEMPERATURE ( C)
TEMPERATURE ( C)
TEMPERATURE ( C)
MP28311 Rev. 0.92
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MP28311 – 3A, 28V, 340KHz SYNCHRONOUS RECTIFIED, STEP-DOWN CONVERTER
TYPICAL PERFORMANCE CHARACTERISTICS (continued)
VIN = 12V, VO = 3.3V, L = 10µH, C1 = 10µF, C2 = 22µF x 2, TA = +25°C, unless otherwise noted.
Power Off through Enable
V
= 24V, V
= 3.3V, I
= 2A
IN
OUT
OUT
V
OUT
1V/div.
V
EN
5V/div.
V
OUT
1V/div.
I
L
1A/div.
I
L
V
SW
1A/div.
10V/div.
4ms/div.
Steady State Test
Load Transient Test
Short Circuit Protection
V
= 12V, V
= 3.3V, I
= 1A
V
= 24V, V
= 3.3V,
V = 24V, V
IN OUT
= 3.3V, I = 0A
OUT
IN
OUT
OUT
IN
OUT
= 0A-1A step with C = 470pF
I
OUT
FF
V
COMP
V
IN
200mV/div.
200mV/div.
V
V
OUT
OUT
1V/div.
100mV/div.
V
COMP
1V/div.
I
L
500mA/div.
I
V
L
OUT
1A/div.
AC Coupled
10mV/div.
I
L
2A/div.
V
SW
20V/div.
MP28311 Rev. 0.92
12/13/2007
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MP28311 – 3A, 28V, 340KHz SYNCHRONOUS RECTIFIED, STEP-DOWN CONVERTER
OPERATION
+
CURRENT
SENSE
AMPLIFIER
IN
OVP
+
--
--
+
0.95V
0.3V
0.8V
5V
RAMP
CLK
OSCILLATOR
340KHz
FB
SS
BS
--
S
Q
Q
--
+
--
+
+
SW
R
CURRENT
COMPARATOR
ERROR
AMPLIFIER
COMP
EN
GND
--
EN OK
OVP
IN < 4.05V
1.2V
LOCKOUT
COMPARATOR
2.5V
1.5V
+
+
IN
INTERNAL
REGULATORS
--
SHUTDOWN
COMPARATOR
Figure 1—Functional Block Diagram
The MP28311 is a synchronous rectified,
current-mode, step-down regulator. It regulates
input voltages from 4.75V to 28V down to an
output voltage as low as 0.8V, and supplies up
to 3A of load current.
The converter uses internal N-Channel
MOSFET switches to step-down the input
voltage to the regulated output voltage. Since
the high-side MOSFET requires a gate voltage
greater than the input voltage, a boost capacitor
connected between SW and BS is needed to
drive the high-side gate. The boost capacitor is
charged from the internal 5V rail when SW is low.
The MP28311 uses current-mode control to
regulate the output voltage. The output voltage
is measured at FB through a resistive voltage
divider and amplified through the internal
transconductance error amplifier. The voltage at
COMP pin is compared to the switch current
measured internally to control the output
voltage.
When the MP28311 FB pin exceeds 20% of the
nominal regulation voltage of 0.8V, the over
voltage comparator is tripped; the COMP pin
and the SS pin are discharged to GND, forcing
the high-side switch off.
MP28311 Rev. 0.92
12/13/2007
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MP28311 – 3A, 28V, 340KHz SYNCHRONOUS RECTIFIED, STEP-DOWN CONVERTER
APPLICATIONS INFORMATION
COMPONENT SELECTION
Setting the Output Voltage
Choose an inductor that will not saturate under
the maximum inductor peak current. The peak
inductor current can be calculated by:
The output voltage is set using a resistive
voltage divider from the output voltage to FB pin.
The voltage divider divides the output voltage
down to the feedback voltage by the ratio:
⎛
⎜
⎝
⎞
VOUT
VOUT
VIN
⎜
⎟
⎟
⎠
ILP = ILOAD
+
× 1−
2× fS ×L
Where ILOAD is the load current.
R2
VFB = VOUT
Optional Schottky Diode
R1+ R2
During the transition between high-side switch
and low-side switch, the body diode of the low-
side power MOSFET conducts the inductor
current. The forward voltage of this body diode
is high. An optional Schottky diode may be
paralleled between the SW pin and GND pin to
improve overall efficiency. Table 2 lists example
Schottky diodes and their Manufacturers.
Thus the output voltage is:
R1+ R2
VOUT = 0.8 ×
R2
Where VFB is the feedback voltage and VOUT is
the output voltage.
A typical value for R2 can be as high as 100kΩ,
but a typical value is 10kΩ. Using that value, R1
is determined by:
Table 2—Diode Selection Guide
Voltage/Current
R1 = 12.5 × (VOUT − 0.8)(kΩ)
Part Number
B130
Rating
30V, 1A
30V, 1A
Vendor
Diodes, Inc.
Diodes, Inc.
International
Rectifier
For example, for a 3.3V output voltage, R2 is
10kΩ, and R1 is 31.3kΩ.
SK13
MBRS130
30V, 1A
Inductor
The inductor is required to supply constant
current to the output load while being driven by
the switched input voltage. A larger value
inductor will result in less ripple current that will
result in lower output ripple voltage. However,
the larger value inductor will have a larger
physical size, higher series resistance, and/or
lower saturation current. A good rule for
determining the inductance to use is to allow
the peak-to-peak ripple current in the inductor
to be approximately 30% of the maximum
switch current limit. Also, make sure that the
peak inductor current is below the maximum
switch current limit. The inductance value can
be calculated by:
Input Capacitor
The input current to the step-down converter is
discontinuous, therefore a capacitor is required
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 are preferred,
but tantalum or low-ESR electrolytic capacitors
may also suffice. Choose X5R or X7R
dielectrics when using ceramic capacitors.
Since the input capacitor (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
VOUT
VOUT
VOUT
⎜
⎜
L =
× 1−
IC1 = ILOAD
×
× 1−
⎜
⎝
⎟
⎠
V
V
fS × ΔI
V
IN
IN
IN
Where VIN is the input voltage, fS is the 340KHz
switching frequency, and ΔIL is the peak-to-
peak inductor ripple current.
The worst-case condition occurs at VIN = 2VOUT
where:
,
ILOAD
IC1
=
2
MP28311 Rev. 0.92
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MP28311 – 3A, 28V SYNCHRONOUS RECTIFIED, STEP-DOWN CONVERTER
For simplification, choose the input capacitor
whose RMS current rating greater than half of
the maximum load current.
MP28311 can be optimized for a wide range of
capacitance and ESR values.
Compensation Components
MP28311 employs current mode control for
easy compensation and fast transient response.
The system stability and transient response are
controlled through the COMP pin. COMP pin is
the output of the internal transconductance
error amplifier. A series capacitor-resistor
combination sets a pole-zero combination to
control the characteristics of the control system.
The input capacitor can be electrolytic, tantalum
or ceramic. When using electrolytic or tantalum
capacitors, a small, high quality ceramic
capacitor, i.e. 0.1μF, should be 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 voltage ripple caused by capacitance can
be estimated by:
The DC gain of the voltage feedback loop is
given by:
VFB
AVDC = RLOAD × GCS × AVEA
×
⎛
⎜
⎝
⎞
⎟
⎟
ILOAD
VOUT
VIN
VOUT
VIN
VOUT
Where AVEA is the error amplifier voltage gain,
400V/V; GCS is the current sense
⎜
ΔVIN
=
×
× 1−
fS × C1
⎠
Output Capacitor
transconductance, 7.0A/V; RLOAD is the load
resistor value.
The output capacitor is required to maintain the
DC output voltage. Ceramic, tantalum, or low
ESR electrolytic capacitors are recommended.
Low ESR capacitors are preferred to keep the
output voltage ripple low. The output voltage
ripple can be estimated by:
The system has 2 poles of importance. One is
due to the compensation capacitor (C3) and the
output resistor of error amplifier, and the other
is due to the output capacitor and the load
resistor. These poles are located at:
GEA
⎛
⎜
⎝
⎞
⎟
⎟
⎛
⎜
⎝
⎞
⎟
⎟
⎠
VOUT
VOUT
VIN
1
⎜
⎜
ΔVOUT
=
× 1−
× RESR
+
fP1
=
fS × L
8 × fS × C2
⎠
2π× C3× AVEA
Where C2 is the output capacitance value and
RESR is the equivalent series resistance (ESR)
value of the output capacitor.
1
fP2
GEA
=
2π × C2× RLOAD
Where,
is
the
error
amplifier
In the case of ceramic capacitors, the
impedance at the switching frequency is
dominated by the capacitance. The output
voltage ripple is mainly caused by the
capacitance. For simplification, the output
voltage ripple can be estimated by:
transconductance, 820μA/V, and RLOAD is the load
resistor value.
The system has one zero of importance, due to the
compensation
capacitor
(C3)
and
the
compensation resistor (R3). This zero is located at:
1
⎛
⎜
⎝
⎞
⎟
⎟
⎠
VOUT
8 × fS2 × L × C2
VOUT
fZ1
=
⎜
ΔVOUT
=
× 1−
2π × C3×R3
V
IN
The system may have another zero of
importance, if the output capacitor has a large
capacitance and/or a high ESR value. The zero,
due to the ESR and capacitance of the output
capacitor, is located at:
In the case of tantalum or electrolytic capacitors,
the ESR dominates the impedance at the
switching frequency. For simplification, the
output ripple can be approximated to:
VOUT
VOUT
⎛
⎞
1
ΔVOUT
=
× ⎜1−
⎟ ×RESR
⎜
⎟
fESR
=
fS ×L
VIN
⎝
⎠
2π × C2× RESR
The characteristics of the output capacitor also
affect the stability of the regulation system. The
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MP28311 – 3A, 28V, 340KHz SYNCHRONOUS RECTIFIED, STEP-DOWN CONVERTER
In this case, a third pole set by the optional
Table 3—Compensation Values for Typical
Output Voltage/Capacitor Combinations
compensation capacitor (C6) and the
compensation resistor (R3) is used to
compensate the effect of the ESR zero on the
loop gain. This pole is located at:
VOUT
L
C2
R3
C3
C6
1.8V 4.7μH
100μF
5.6kΩ 5.6nF None
Ceramic
1
2.5V 4.7μH - 47μF Ceramic 3.65kΩ 8.2nF None
6.8μH
fP3
=
2π× C6×R3
3.3V 6.8μH -
10μH
22μFx2
Ceramic
4.42kΩ 4.7nF None
6.98kΩ 3.3nF None
16.5kΩ 1.8nF None
8.4kΩ 2.2nF None
5.6kΩ 3.3nF None
6.8kΩ 2.2nF None
10kΩ 2.2nF None
The goal of compensation design is to shape
the converter transfer function to get a desired
loop gain. The system crossover frequency
where the feedback loop has the unity gain is
important.
5V
10μH -
15μH
22μFx2
Ceramic
12V 15μH -
22μH
22μFx2
Ceramic
1.8
4.7μH 100μF/100mΩ
Lower crossover frequencies result in slower
line and load transient responses, while higher
crossover frequencies could cause system
instability. A good rule of thumb is to set the
crossover frequency to approximately one-tenth
of the switching frequency. Switching frequency
for the MP28311 is 340KHz, so the desired
crossover frequency is 34KHz.
SP-CAP
2.5V 4.7μH -
6.8μH
47μF
SP-CAP
3.3V 6.8μH -
10μH
47μF
SP-CAP
5V
10μH -
15μH
47μF
SP CAP
2.5V 4.7μH -
6.8μH
560μF Al.
30mΩ ESR
10kΩ
10kΩ
12nF 1.8nF
10nF 1.5nF
Table 3 lists the typical values of compensation
components for some standard output voltages
with various output capacitors and inductors. The
values of the compensation components have
been optimized for fast transient responses and
good stability at given conditions.
3.3V 6.8μH -
10μH
560μF Al.
30mΩ ESR
5V
10μH -
15μH
470μF Al.
30mΩ ESR
15kΩ 8.2nF
1nF
12V 15μH -
22μH
220μF Al.
30mΩ ESR
15kΩ 10nF 390pF
MP28311 Rev. 0.92
12/13/2007
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10
MP28311 – 3A, 28V, 340KHz SYNCHRONOUS RECTIFIED, STEP-DOWN CONVERTER
To optimize the compensation components for
Soft-Start Capacitor
conditions not listed in Table 2, the following
procedure can be used.
To reduce input inrush current during startup, a
programmable soft-start is provided by
connecting a capacitor (C4) from pin SS to
GND. The soft-start time is given by:
1. Choose the compensation resistor (R3) to set
the desired crossover frequency. Determine the
R3 value by the following equation:
0.8V
tSS = C4 ×
2π × C2× fC VOUT
6μA
R3 =
×
GEA × GCS
VFB
To reduce the susceptibility to noise, do not
leave SS pin open. Use a capacitor with small
value if you do not need soft-start function.
Where fC is the desired crossover frequency,
34KHz.
2. Choose the compensation capacitor (C3) to
achieve the desired phase margin. For
applications with typical inductor values, setting
the compensation zero, fZ1, below one forth of
the crossover frequency provides sufficient
phase margin. Determine the C3 value by the
following equation:
External Bootstrap Diode
It is recommended that an external bootstrap
diode be added when the system has a 5V
fixed input or the power supply generates a 5V
output. This helps improve the efficiency of the
regulator. The bootstrap diode can be a low
cost one such as IN4148 or BAT54.
5V
4
C3 >
2π × R3 × fC
BS
3. Determine if the second compensation
capacitor (C6) is required. It is required if the
ESR zero of the output capacitor is located at
less than half of the 340KHz switching
frequency, or the following relationship is valid:
10nF
MP28311
SW
Figure 2—External Bootstrap Diode
fS
2
1
<
This diode is also recommended for high duty
VOUT
2π × C2× RESR
cycle operation (
>65%) and high output
VIN
If this is the case, then add the optional
compensation capacitor (C6) to set the pole fP3
at the location of the ESR zero. Determine the
C6 value by the equation:
voltage (VOUT>12V) applications.
C2 × RESR
C6 =
R3
MP28311 Rev. 0.92
12/13/2007
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© 2007 MPS. All Rights Reserved.
11
MP28311 – 3A, 28V, 340KHz SYNCHRONOUS RECTIFIED, STEP-DOWN CONVERTER
TYPICAL APPLICATION CIRCUITS
C5
10nF
INPUT
4.75V to 28V
IN
EN
BS
SW
OUTPUT
2.5V
3A
MP28311
SS
GND
FB
COMP
D1
B130
(optional)
C3
8.2nF
C6
(optional)
Figure 3—MP28311 with 2.5V Output, 47μF/6.3V Ceramic Output Capacitor
D2
INPUT
4.75V to 28V
C5
10nF
IN
EN
BS
SW
OUTPUT
3.3V/3A
MP28311
SS
GND
FB
COMP
D1
B130
(optional)
C3
4.7nF
C6
(optional)
Figure 4—MP28311 with 3.3V Output, 47μF/6.3V Ceramic Output Capacitor
MP28311 Rev. 0.92
12/13/2007
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© 2007 MPS. All Rights Reserved.
12
MP28311 – 3A, 28V, 340KHz SYNCHRONOUS RECTIFIED, STEP-DOWN CONVERTER
PACKAGE INFORMATION
SOIC8N (EXPOSED PAD)
0.189(4.80)
0.197(5.00)
0.124(3.15)
0.136(3.45)
8
5
0.150(3.80)
0.157(4.00)
0.228(5.80)
0.244(6.20)
0.089(2.26)
0.101(2.56)
PIN 1 ID
1
4
TOP VIEW
BOTTOM VIEW
SEE DETAIL "A"
0.051(1.30)
0.067(1.70)
SEATING PLANE
0.000(0.00)
0.006(0.15)
0.0075(0.19)
0.0098(0.25)
0.013(0.33)
0.020(0.51)
SIDE VIEW
0.050(1.27)
BSC
FRONT VIEW
0.010(0.25)
0.020(0.50)
x 45o
GAUGE PLANE
0.010(0.25) BSC
0.050(1.27)
0.024(0.61)
0.063(1.60)
0.016(0.41)
0.050(1.27)
0o-8o
DETAIL "A"
0.103(2.62)
0.213(5.40)
NOTE:
1) CONTROL DIMENSION IS IN INCHES. DIMENSION IN
BRACKET IS IN MILLIMETERS.
2) PACKAGE LENGTH DOES NOT INCLUDE MOLD FLASH,
PROTRUSIONS OR GATE BURRS.
3) PACKAGE WIDTH DOES NOT INCLUDE INTERLEAD FLASH
OR PROTRUSIONS.
0.138(3.51)
4) LEAD COPLANARITY (BOTTOM OF LEADS AFTER FORMING)
SHALL BE 0.004" INCHES MAX.
5) DRAWING CONFORMS TO JEDEC MS-012, VARIATION BA.
6) DRAWING IS NOT TO SCALE.
RECOMMENDED LAND PATTERN
MP28311 Rev. 0.92
12/13/2007
www.MonolithicPower.com
MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.
© 2007 MPS. All Rights Reserved.
13
MP28311 – 3A, 28V, 340KHz SYNCHRONOUS RECTIFIED, STEP-DOWN CONVERTER
3mm x 3mm QFN10
2.90
3.10
0.30
0.50
1.45
1.75
PIN 1 ID
SEE DETAIL A
PIN 1 ID
MARKING
0.18
0.30
10
1
5
2.25
2.55
2.90
3.10
PIN 1 ID
INDEX AREA
0.50
BSC
6
TOP VIEW
BOTTOM VIEW
PIN 1 ID OPTION A
R0.20 TYP.
PIN 1 ID OPTION B
R0.20 TYP.
0.80
1.00
0.20 REF
0.00
0.05
SIDE VIEW
DETAIL A
NOTE:
2.90
1.70
1) ALL DIMENSIONS ARE IN MILLIMETERS.
0.70
0.25
2) EXPOSED PADDLE SIZE DOES NOT INCLUDE MOLD FLASH.
3) LEAD COPLANARITY SHALL BE 0.10 MILLIMETER MAX.
4) DRAWING CONFORMS TO JEDEC MO-229, VARIATION VEED-5.
5) DRAWING IS NOT TO SCALE.
2.50
0.50
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.
MP28311 Rev. 0.92
12/13/2007
www.MonolithicPower.com
MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.
© 2007 MPS. All Rights Reserved.
14
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