MPQ4462 [MPS]
3.5A, 4MHz, 36V, Step-Down Converter AEC-Q100 Qualified;
| 型号： | MPQ4462 |
| 厂家： | 
MONOLITHIC POWER SYSTEMS |
| 描述： | 3.5A, 4MHz, 36V, Step-Down Converter AEC-Q100 Qualified |
| 文件： | 总20页 (文件大小：620K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
MPQ4462
3.5A, 4MHz, 36V, Step-Down Converter
AEC-Q100 Qualified
The Future of Analog IC Technology
DESCRIPTION
FEATURES
The MPQ4462 is a high-frequency, step-down,
switching regulator with an integrated, high-side,
high-voltage, power MOSFET. It provides a 3.5A
output with current-mode control for fast loop
response and easy compensation.
•
•
•
•
120μA Quiescent Current
Wide 3.8V-to-36V Input Range
150mΩ Internal Power MOSFET
Up to 4MHz Programmable Switching
Frequency
•
•
•
Stable with a Ceramic Capacitor
Internal Soft-Start
Internally-Set Current Limit without a Current
Sensing Resistor
Output Adjustable from 0.8V to 30V
Available in 3mm×3mm QFN10 and SOIC8E
Packages.
The wide 3.8V-to-36V input range accommodates
a variety of step-down applications, including
those in an automotive input environment. A
120µA operational quiescent current allows for
battery-powered applications.
•
•
Switching-frequency scaling allows for high
power-conversion efficiency over a wide load
range by scaling down the switching frequency at
light loads to reduce the switching and gate
driving losses.
•
Available in AEC-Q1000 Qualified Grade 1
APPLICATIONS
•
•
•
•
•
High-Voltage Power Conversion
Automotive Systems
Industrial Power Systems
Distributed Power Systems
Battery Powered Systems
The frequency foldback prevent inductor-current
runaway during startup, and thermal shutdown
provides reliable and fault tolerant operation.
The MPQ4462 can operate at up to 4MHz for
EMI-sensitive applications, such as AM radio
and ADSL applications.
All MPS parts are lead-free and adhere to the RoHS directive. For MPS green
status, please visit MPS website under Products, Quality Assurance page.
“MPS” and “The Future of Analog IC Technology” are registered trademarks of
Monolithic Power Systems, Inc.
The MPQ4462 is available in both 3mm×3mm
QFN10 and SOIC8E packages.
TYPICAL APPLICATION
MPQ4462 Rev. 1.11
7/17/2013
www.MonolithicPower.com
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© 2013 MPS. All Rights Reserved.
1
MPQ4462 – 3.5A, 4MHz, 36V, STEP-DOWN CONVERTER, AEC-Q100 QUALIFIED
ORDERING INFORMATION
Part Number
Package
Top Marking
MPQ4462DQ*
QFN10 (3mm×3mm)
Z2
MPQ4462DN**
SOIC8E
QFN10 (3mm×3mm)
SOIC8E
MP4462DN
Z2
MPQ4462DQ-AEC1*
MPQ4462DN-AEC1**
MP4462DN
*For Tape & Reel, add suffix –Z (e.g. MPQ4462DQ–AEC1-Z);
For RoHS, compliant packaging, add suffix –LF (e.g. MPQ4462DQ–AEC1-LF–Z).
**For Tape & Reel, add suffix –Z (e.g. MPQ4462DN–AEC1-Z);
For RoHS, compliant packaging, add suffix –LF (e.g. MPQ4462DN–AEC1-LF–Z).
PACKAGE REFERENCE
TOP VIEW
TOP VIEW
SW
SW
1
2
3
4
5
10 BST
9
8
7
6
VIN
SW
EN
1
2
3
4
8
7
6
5
BST
EN
VIN
VIN
COMP
FB
FREQ
GND
COMP
FB
FREQ
GND
EXPOSED PAD
ON BACKSIDE
QFN10
SOIC8E
ABSOLUTE MAXIMUM RATINGS (1)
Supply Voltage (VIN).....................–0.3V to +40V
Switch Voltage (VSW)............ –0.3V to VIN + 0.3V
BST to SW.....................................–0.3V to +6V
All Other Pins.................................–0.3V to +6V
Thermal Resistance (4)
QFN10 (3mm×3mm)...............50...... 12... °C/W
SOIC8E ..................................50...... 10... °C/W
θJA
θJC
Notes:
1) Exceeding these ratings may damage the device.
2) The maximum allowable power dissipation is a function of the
maximum junction temperature TJ (MAX), the junction-to-
ambient thermal resistance 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.
(2)
Continuous Power Dissipation (TA = +25°C)
QFN10 (3mmx3mm) .................................. 2.5W
SOIC8E...................................................... 2.5W
Junction Temperature...............................150°C
Lead Temperature ....................................260°C
Storage Temperature.............. –65°C to +150°C
Recommended Operating Conditions (3)
Supply Voltage VIN ...........................3.8V to 36V
Output Voltage VOUT.........................0.8V to 30V
Operating Junct. Temp. .......... –40°C to +125°C
3) The device is not guaranteed to function outside of its
operating conditions.
4) Measured on JESD51-7, 4-layer PCB.
MPQ4462 Rev. 1.11
7/17/2013
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2
MPQ4462 – 3.5A, 4MHz, 36V, STEP-DOWN CONVERTER, AEC-Q100 QUALIFIED
ELECTRICAL CHARACTERISTICS
VIN = 12V, VEN = 2.5V, VCOMP = 1.4V, TJ = −40°C to +125°C, unless otherwise noted. Typical values
are at TJ = 25°C.
Parameter
Symbol Condition
VIN = 4.5V to 36V, TJ = 25°C
VIN = 4.5V to 36V
RDS(ON) VBST – VSW = 5V
VEN = 0V, VSW = 0V, VIN = 36V
Min
Typ
Max Units
0.786 0.792 0.803
Feedback Voltage
VFB
V
0.773
4.0
0.812
1
Upper Switch On Resistance (5)
Upper Switch Leakage
Current Limit
150
0.01
5.5
mꢀ
μA
A
Duty Cycle = 50%
COMP to Current Sense
Transconductance (5)
GCS
9
A/V
Error Amp Voltage Gain (6)
Error Amp Transconductance
Error Amp Min Source Current
Error Amp Min Sink Current
VIN UVLO Threshold
200
60
V/V
µA/V
µA
µA
V
ICOMP = ±3µA
VFB = 0.7V
VFB = 0.9V
35
2.6
1.6
95
5
–5
3.0
400
1.5
2
3.4
VIN UVLO Hysteresis
Soft-Start Time (5)
mV
ms
MHz
µA
µA
°C
VFB = 0V to 0.8V
RFREQ = 45.3kꢀ
VEN = 0V
Oscillator Frequency
2.4
18
Shutdown Supply Current
Quiescent Supply Current
Thermal Shutdown (5)
Thermal Shutdown Hysteresis(5)
Minimum OFF Time (5)
Minimum ON Time (5)
11
No load, VFB = 0.9V
120
150
15
160
°C
100
80
ns
ns
EN Rising Threshold
1.4
1.1
1.5
1.2
300
1.7
1.4
V
EN Falling Threshold
V
EN Threshold Hysteresis
mV
Note:
5) Derived from bench characterization. Not tested in production.
6) Guaranteed by design. Not tested in production.
MPQ4462 Rev. 1.11
7/17/2013
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MPQ4462 – 3.5A, 4MHz, 36V, STEP-DOWN CONVERTER, AEC-Q100 QUALIFIED
PIN FUNCTIONS
QFN SOIC8E
Name Description
Pin #
Pin #
Switch Node. Output of the high-side switch. Requires a low-forward-drop Schottky
diode to ground. Place the diode close to the SW pins to reduce switching spikes.
1, 2
1
SW
EN
Enable. Pull below the specified threshold to shut the chip down. Pull it up above the
specified threshold or leave it floating to enable the chip.
3
4
2
3
Compensation. Output of the error amplifier. Includes control-loop frequency
compensation.
COMP
FB
Feedback. Input to the error amplifier. The tap of a resistor divider between the
output and GND sets the output voltage to the internal +0.8V reference.
5
6
7
4
5
6
GND Ground.
Switching Frequency Set. Connect a resistor from this pin to ground to set the
switching frequency.
FREQ
VIN
Input Supply. Supplies power to all internal control circuitry. Requires a decoupling
capacitor to ground to minimize switching spikes.
8, 9
10
7
8
Bootstrap. Positive power supply to the internal, floating, high-side MOSFET driver.
Connect a bypass capacitor between this pin and SW.
BST
Exposed
Pad
Ground Pad. Connect to GND plane for optimal thermal performance.
MPQ4462 Rev. 1.11
7/17/2013
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MPQ4462 – 3.5A, 4MHz, 36V, STEP-DOWN CONVERTER, AEC-Q100 QUALIFIED
TYPICAL CHARACTERISTICS
MPQ4462 Rev. 1.11
7/17/2013
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MPQ4462 – 3.5A, 4MHz, 36V, STEP-DOWN CONVERTER, AEC-Q100 QUALIFIED
TYPICAL CHARACTERISTICS (continued)
MPQ4462 Rev. 1.11
7/17/2013
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MPQ4462 – 3.5A, 4MHz, 36V, STEP-DOWN CONVERTER, AEC-Q100 QUALIFIED
TYPICAL PERFORMANCE CHARACTERISTICS
VIN = 12V, VOUT = 3.3V, C1 = 10µF, C2 = 22µF, L = 10µH and TA = +25°C, unless otherwise noted.
MPQ4462 Rev. 1.11
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MPQ4462 – 3.5A, 4MHz, 36V, STEP-DOWN CONVERTER, AEC-Q100 QUALIFIED
TYPICAL PERFORMANCE CHARACTERISTICS (continued)
VIN = 12V, VOUT = 3.3V, C1 = 10µF, C2 = 22µF, L = 10µH and TA = +25°C, unless otherwise noted.
MPQ4462 Rev. 1.11
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MPQ4462 – 3.5A, 4MHz, 36V, STEP-DOWN CONVERTER, AEC-Q100 QUALIFIED
BLOCK DIAGRAM
Figure 1: Functional Block Diagram
MPQ4462 Rev. 1.11
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MPQ4462 – 3.5A, 4MHz, 36V, STEP-DOWN CONVERTER, AEC-Q100 QUALIFIED
disable the chip. Its falling threshold is precisely
1.2V, and its rising threshold is 1.5V (300mV
higher).
OPERATION
The MPQ4462 is
a
variable-frequency,
asynchronous, step-down switching regulator
with an integrated, high-side, high-voltage,
power MOSFET. It provides a highly efficient
output with current mode control for fast loop
response and easy compensation. It features a
wide input-voltage range, internal soft-start
control, and precise current limiting. Its very-low
operational quiescent current makes it suitable
for battery-powered applications.
When floating, EN is pulled up to about 3.0V by
an internal 1µA current source to remain
enabled. To pull-down requires a 1µA current.
When VEN is pulled down below 1.2V, the chip
enters its lowest shutdown current mode. When
VEN exceeds 0V but remains below its rising
threshold, the chip remains in shutdown mode
but the shutdown current increases slightly.
PWM Control
Under-Voltage Lockout (UVLO)
At moderate-to-high output current, the
MPQ4462 operates in a fixed-frequency, peak-
current-control mode to regulate the output
voltage. The internal clock initiates a PWM
cycle that turns the power MOSFET on. This
MOSFET remains on until its current reaches
the value set by VCOMP. When the power
MOSFET is off, it remains off for at least 100ns
before the next cycle starts. If the current in the
power MOSFET does not reach the COMP set
current value within one PWM period, the
power MOSFET remains on to save a turn-off
operation.
Under-voltage lockout (UVLO) protects the chip
from operating at insufficient supply voltages.
The UVLO rising threshold is about 3.0V while
its falling threshold is a consistent 2.6V.
Internal Soft-Start
The soft-start prevents the converter output
voltage from overshooting during startup. When
the chip starts, the internal circuitry generates a
soft-start voltage (VSS) that ramps up from 0V to
2.6V. When VSS<VREF, VSS becomes the
reference. When VSS>VREF, VREF resumes as
the reference.
Thermal Shutdown
Error Amplifier
Thermal shutdown prevents the chip from
operating at exceedingly high temperatures.
When the die temperature exceeds its upper
threshold, the chip shuts down. When the
temperature falls below its lower threshold, chip
function resumes.
The error amplifier compares VFB to the internal
reference (VREF
)
and outputs
a
current
proportional to the difference between the two.
This output current charges the external
compensation network to form VCOMP, which
controls the power MOSFET current.
Floating Driver and Bootstrap Charging
An external bootstrap capacitor powers the
floating power MOSFET driver. This floating
driver has its own UVLO protection, with a
UVLO rising threshold of 2.2V with a falling
threshold of 150mV.
While operating, the VCOMP minimum is clamped
to 0.9V and its maximum is clamped to 2.0V.
COMP is internally pulled down to GND in
shutdown mode. COMP should not be pulled up
beyond 2.6V.
Internal Regulator
A
dedicated, internal, bootstrap regulator
The 2.6V internal regulator powers most of the
internal circuits. This regulator takes VIN and
operates in the full VIN range. When VIN
exceeds 3.0V, the output of the regulator is in
full regulation. When VIN falls below 3.0V, the
output decreases.
charges and regulates the bootstrap capacitor
~5V. When the voltage between the BST and
SW nodes falls below its regulation voltage, a
PMOS pass transistor connected from VIN to
BST turns on. The current-charging path is VIN
→ BST → SW. The external circuit should
provide enough voltage headroom to facilitate
charging.
Enable Control
The MPQ4462 has a dedicated enable-control
pin (EN). Enable uses logic-high to enable and
MPQ4462 Rev. 1.11
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MPQ4462 – 3.5A, 4MHz, 36V, STEP-DOWN CONVERTER, AEC-Q100 QUALIFIED
If VIN is sufficiently higher than VSW, the
any faults. VCOMP and the internal supply rail are
then pulled down.
bootstrap capacitor charges. When the power
MOSFET is ON, VIN≈VSW so the bootstrap
capacitor cannot charge. When the external
diode is ON, the VIN−VSW is at its maximum for
optimal charging. When there is no current in
the inductor, VSW=VOUT so VIN−VOUT charges the
bootstrap capacitor.
Programmable Oscillator
An external resistor (RFREQ) from the FREQ pin
to ground sets the MPQ4462 oscillating
frequency.
At higher duty cycles, the bootstrap-charging
period is shorter so the bootstrap capacitor may
not charge sufficiently. If the internal circuit
does not have sufficient voltage and the
bootstrap capacitor is not charged, an external
circuit can ensure the bootstrap voltage is in the
normal operational region.
The floating driver’s DC quiescent current
~20µA. Select a bleeding current at the SW
node meets the following criterion:
VO
IO
+
> 20μA
(R1+ R2)
Current Comparator and Current Limit
A current-sense MOSFET accurately senses
the power-MOSFET current. The sense value is
compared to VCOMP by a high-speed current
comparator. When the power MOSFET turns on,
the comparator is first blanked till the end of the
turn-on transition. When the sensed current
exceeds VCOMP, the comparator output is low,
turning off the power MOSFET. The cycle-by-
cycle maximum current of the internal power
MOSFET is internally limited.
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 circuits.
While the internal supply rail is up, an internal
timer holds the power MOSFET OFF for about
50µs to blank the startup noise. When the
internal soft-start block is enabled, it first holds
VSS low before slowly ramping up.
Three events can shut down the chip: VEN LOW,
VIN LOW, and thermal shutdown. For shutdown,
the power MOSFET turn off to avoid triggering
MPQ4462 Rev. 1.11
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MPQ4462 – 3.5A, 4MHz, 36V, STEP-DOWN CONVERTER, AEC-Q100 QUALIFIED
The inductor supplies constant current to the
APPLICATION INFORMATION
`COMPONENT SELECTION
output load while being driven by the switching
input voltage. A larger inductor will reduce
ripple current and lower output ripple voltage,
but is physically larger, and have a higher
series resistance and/or lower saturation
current.
Frequency
The MPQ4462 has an externally-adjustable
frequency using RFREQ. See Table1 for a list of
recommended RFREQ value for various fS.
Table 1: fS vs. RFREQ
To choose a balanced inductor value, allow the
peak-to-peak
inductor
ripple
current
RFREQ (kΩ)
fS (MHz)
approximately equal 30% of the maximum
switching current limit. To ensure that the peak
inductor current is below the maximum switch
current limit estimate and inductor value as:
18
20
4
3.8
3.5
3.3
3
22.1
24
⎛
⎞
⎟
⎠
VOUT
VOUT
L1 =
× 1−
⎜
fS × ΔIL
V
26.7
30
⎝
IN
2.8
2.5
2.2
2
Where VOUT is the output voltage, VIN is the
input voltage, fS is the switching frequency, and
ΔIL is the peak-to-peak inductor-ripple current.
33.2
39
45.3
51
Choose an inductor that will not saturate under
the maximum inductor peak current, which is:
1.8
1.6
1.4
1.2
1
57.6
68
⎛
⎞
⎟
⎠
VOUT
VOUT
ILP = ILOAD
+
× 1−
⎜
2× fS ×L1
V
IN
⎝
80.6
100
133
200
340
536
Where ILOAD is the load current.
Output Rectifier Diode
0.8
0.5
0.3
0.2
The output rectifier diode supplies the current to
the inductor when the high-side switch is off. To
reduce losses due to the diode forward voltage
and recovery times, use a Schottky diode.
Output Voltage
Connecting FB to the tap of a resistor divider
from VOUT to ground sets VOUT such that:
Choose a diode whose maximum reverse
voltage rating exceeds the maximum input
voltage, and whose current rating exceeds the
maximum load current.
(R1+ R2)
VOUT = VFB
R2
Input Capacitor
Without a load, the MPQ4462 outputs ~20µA
from its high-side BST circuitry. Keep R2 ≤40kꢀ
to absorb this small amount of current.
Selecting R2=40.2kꢀ, R1 is then:
The input current to the step-down converter is
discontinuous and requires a capacitor to
supply the AC current to the step-down
converter while maintaining the DC input
voltage. Use low-ESR capacitors for the best
performance. Ceramic capacitors are best, but
tantalum or low-ESR electrolytic capacitors may
also suffice.
R1= 50.25×(VOUT − 0.8)(kΩ)
For example, for VOUT=3.3V and R2=40.2kꢀ,
then R1 is 127kꢀ.
Inductor
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MPQ4462 – 3.5A, 4MHz, 36V, STEP-DOWN CONVERTER, AEC-Q100 QUALIFIED
For simplicity, choose an input capacitor with an
Compensation Components
RMS current rating greater than half of the
maximum load current.
The MPQ4462 employs current-mode control
for easy compensation and fast transient
response. The COMP pin—the output of the
internal error amplifier—controls system
stability and transient response. A series RC
combination adds a pole-zero pair to the control
system . The DC gain of the voltage feedback
loop is:
The input capacitor (C1) can be electrolytic,
tantalum, or ceramic. Electrolytic or tantalum
capacitors will need a small, high-quality
ceramic capacitor (0.1μF) placed as close to
the IC as possible. Ceramic capacitors must
have enough capacitance to prevent excessive
input voltage ripple. The capacitor-incurred
input voltage ripple is approximately:
VFB
AVDC = RLOAD ×GCS × AVEA
×
VOUT
⎛
⎞
⎟
⎠
ILOAD
VOUT
VOUT
ΔV =
×
× 1−
⎜
Where
IN
fS ×C1
V
IN
V
IN
⎝
AVEA is the error amplifier voltage gain (200V/V)
Output Capacitor
GCS is the current sense transconductance
(9A/V), and
The output capacitor (C2) maintains the output
DC voltage. Use ceramic, tantalum, or low-ESR
electrolytic capacitors. Low-ESR capacitors are
best at limiting the output voltage ripple. The
output voltage ripple is approximately:
RLOAD is the load resistor value.
The system has two important poles: the
compensation capacitor (C3) and the error
amplifier’s output resistor; and the output
capacitor and the load resistor. These poles are
located at:
⎛
⎞ ⎛
VOUT
⎞
⎟
⎠
VOUT
1
ΔVOUT
=
× 1−
× R
⎟ ⎜
+
⎜
ESR
fS ×L
V
8× fS ×C2
⎝
IN ⎠ ⎝
GEA
fP1 =
Where L is the inductor and RESR is the output
capacitor’s equivalent series resistance.
2π×C3× AVEA
1
If using ceramic capacitors, the capacitance
dominates the impedance at the switching
frequency and contributes to the majority of the
output voltage ripple. The output voltage ripple
is approximately:
fP2
=
2π×C2×RLOAD
Where,
GEA
is the error
transconductance, 60μA/V.
amplifier’s
The system has one important zero due to the
compensation capacitor (C3) and the
compensation resistor (R3). This zero is located
at:
⎛
⎞
⎟
⎠
VOUT
VOUT
ΔVOUT
=
× 1−
⎜
2
8× fS ×L×C2
V
IN
⎝
If using either tantalum or electrolytic capacitors,
the ESR dominates the impedance at the
switching frequency. The output ripple is
approximately:
1
fZ1 =
2π×C3×R3
The system may have another important zero if
the output capacitor is large and/or has a high-
ESR. The zero is located at:
VOUT
VOUT
⎛
⎞
ΔVOUT
=
× 1−
×RESR
⎜
⎟
⎠
fS ×L
V
IN
⎝
1
fESR
=
The output capacitor also affects the regulatory-
system’s stability. The MPQ4462 can be
optimized for a wide range of capacitances and
ESR values.
2π×C2×RESR
In case requires a third pole set by the
compensation capacitor (C6) and the
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MPQ4462 – 3.5A, 4MHz, 36V, STEP-DOWN CONVERTER, AEC-Q100 QUALIFIED
compensation resistor (R3). This pole is
located at:
3. Determine if C6 is required. Add C6 if the
ESR zero of the output capacitor is located at
<0.5×fC, or if the following relationship is true:
1
fP3
=
fS
2
1
2π×C6×R3
<
2π×C2×RESR
The compensator shapes the converter transfer
function for a desired loop gain. The feedback
loop’s unity-gain crossover frequency is
important. Lower crossover frequencies result
slow line and load transient responses, while
higher crossover frequencies increase system
instability. For most applications, set the
crossover frequency to ~0.1×fS. Table 2 lists
some typical compensation-component values
for standard output voltages. The component
values are optimized for fast transient
responses and good stability at given conditions.
Select C6 to set the pole (fP3) at the the ESR
zero. Determine the C6 as:
C2×RESR
C6 =
R3
High-Frequency Operation
Set the MP4462’s switching frequency up to
4MHz through an external resistor. For
switching frequencies above 2MHz, take the
following into consideration:
•
The minimum ON-time is ~80ns. Pulse
skipping occurs more often at higher
switching frequencies due to the minimum
ON-time.
Table 2: Compensation Values for Typical
Output Voltage/Capacitor Combinations
VOUT
(V)
C2
(µF)
R3
(kꢀ)
C3
(pF)
L (µH)
C6
•
The recommended operating voltage is
<12V, and <24V at 2MHz. Refer to Figure 2
for more information.
1.8
2.5
3.3
5
4.7
47
22
22
22
22
105
54.9
68.1
100
147
100
220
220
150
150
None
4.7 - 6.8
6.8 -10
15 - 22
22 - 33
None
None
None
None
Recommended VIN (max)
vs Switching Frequency
30
25
20
12
To optimize the compensation components for
conditions not listed in Table 2:
V
=3.3V
OUT
15
10
5
1. Choose R3 for the desired crossover
frequency:
V
=2.5V
OUT
2π×C2× fC VOUT
1500 2000 2500 3000 3500 4000
R3 =
×
f (KHz)
s
GEA ×GCS
VFB
Figure 2: Recommended Max. VIN vs fS
Where fC is the desired crossover frequency.
2. Choose C3 for the desired phase margin. For
applications with typical inductor values, setting
the compensation zero (fZ1) below 0.25×fC
provides sufficient phase margin. C3 must meet
the following criterion:
4
C3 >
2π × R3 × fC
MPQ4462 Rev. 1.11
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MPQ4462 – 3.5A, 4MHz, 36V, STEP-DOWN CONVERTER, AEC-Q100 QUALIFIED
•
•
The internal bootstrap circuit’s impedance
may limit the charge to the bootstrap
capacitor during each (1-D)×TS charging
period. Add an external bootstrap charging
diode if the switching frequency is above
2MHz.
At higher switching frequencies, the
capacitor’s
inductive
reactance
(XL
dominates, so that the ESL of the
input/output capacitor determines the
input/output ripple voltage at higher
switching frequencies. Select
a
high-
frequency ceramic capacitor as the input
decoupling capacitor and the output filtering
capacitor for high-frequency operation.
•
Layout becomes more important when the
device switches at higher frequencies.
Please refer to the PCB Layout Guide for
more details.
External Bootstrap Diode
Add an external bootstrap diode if the input
voltage is no greater than 5V or if the 5V rail is
available. This diode improves regulator
efficiency. The bootstrap diode can be a low-
cost one, such as the IN4148 or the BAT54.
5V
BS
SW
Figure 3: External Bootstrap Diode
This diode is also recommended for high-duty-
cycle operation (when VOUT /VIN >65%) or low
VIN (<5V) applications.
At no load or light load, the converter may
operate in pulse-skipping mode to maintain
output-voltage regulation. However, pulse-
skipping limits the BST voltage’s charging time.
For sufficient gate voltage, make sure that VIN–
VOUT>3V. For example, if VOUT is 3.3V, VIN
needs to be higher than 3.3V+3V=6.3V to
maintain the BST voltage at no load or light
load. To meet this requirement, use the EN pin
to program the input UVLO voltage to VOUT+3V.
MPQ4462 Rev. 1.11
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15
MPQ4462 – 3.5A, 4MHz, 36V, STEP-DOWN CONVERTER, AEC-Q100 QUALIFIED
TYPICAL APPLICATION CIRCUITS
10
BST
V
8,9
3
1,2
5
V
IN
OUT
SW
FB
VIN
1.8V
6V - 36V
D1
EN
EN
7
4
COMP
FREQ
GND
C6
NS
6
Figure 4: Typical Application, 1.8V Output
10
V
8,9
3
1,2
5
BST
V
IN
OUT
SW
FB
VIN
5V
10V - 36V
D1
EN
EN
7
4
COMP
FREQ
GND
C6
NS
6
Figure 5: Typical Application, 5V Output
MPQ4462 Rev. 1.11
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MPQ4462 – 3.5A, 4MHz, 36V, STEP-DOWN CONVERTER, AEC-Q100 QUALIFIED
PCB LAYOUT GUIDE
PCB layout is very important for system stability.
It is highly recommended to duplicate EVB
layout for optimum performance.
the proper ground plane must be in place to
isolate those.
4) Connect VIN, SW, and especially GND
respectively to large copper areas to cool
the chip to improve thermal performance
and long-term reliability. To help to improve
the thermal conduction at high frequencies,
add a grid of thermal vias under the
exposed pad. Use small vias (15mil barrel
diameter) so that the hole fills up during the
plating process and improve thermal
conduction. Larger vias can cause solder
wicking during the reflow process. A pitch
(distance between the centers) of 40mil
between thermal vias is typical.
If change is necessary, please follow these
guidelines and take Figure 6 for reference.
1) Keep the path of switching current short
and minimize the loop area formed by input
capacitor, high-side MOSFET and external
switching diode. Place ceramic bypass
capacitors close to the VIN Pin.
2) Make all feedback connections short and
direct. Try to run the feedback trace as far
from the inductor and noisy power traces
as possible. If possible run the feedback
trace on the opposite PCB side to the
inductor with a ground plane separating the
two.
5) Place the input decoupling capacitor, catch
diode and the MPQ4462 (VIN, SW and
PGND) as close as possible, with traces
that are very short and fairly wide. This can
help to greatly reduce the voltage spike on
SW node, and lower the EMI noise level as
well.
3) Place the feedback resistors and
compensation components as close to the
chip as possible. Do not place the
compensation components close to or
under high dv/dt SW node, or inside the
high di/dt power loop. If you have to do so,
6) Please refer to the layout example on
EVQ4460 datasheet.
C4
L1
BST
V
V
OUT
SW
FB
IN
VIN
D1
R2
C2
C1
R4
R5
EN
EN
R1
COMP
FREQ
C3
R3
GND
R6
Figure 6: Typical Application Circuit
MPQ4462 Rev. 1.11
7/17/2013
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17
MPQ4462 – 3.5A, 4MHz, 36V, STEP-DOWN CONVERTER, AEC-Q100 QUALIFIED
GND
L1
R1
SW
C4
D1
R6
C2
C1
Vin
GND
GND
Vo
MPQ4462DQ Top Layer
MPQ4462DQ Bottom Layer
MPQ4462 Rev. 1.11
7/17/2013
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18
MPQ4462 – 3.5A, 4MHz, 36V, STEP-DOWN CONVERTER, AEC-Q100 QUALIFIED
PACKAGE INFORMATION
3mm x 3mm QFN10
MPQ4462 Rev. 1.11
7/17/2013
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19
MPQ4462 – 3.5A, 4MHz, 36V, STEP-DOWN CONVERTER, AEC-Q100 QUALIFIED
SOIC8E
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
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.
MPQ4462 Rev. 1.11
7/17/2013
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© 2013 MPS. All Rights Reserved.
20
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