MPS MPQ4558DQ 1a, 2mhz, 55v step-down converter aec-q100 qualified Datasheet

MPQ4558
1A, 2MHz, 55V
Step-Down Converter
AEC-Q100 Qualified
The Future of Analog IC Technology
DESCRIPTION
FEATURES
The MPQ4558 is a high-frequency, step-down
switching regulator with an integrated internal
high-side high-voltage power MOSFET. It
provides up to a 1A output with current-mode
control for fast loop response and easy
compensation.
•
The wide 3.8V-to-55V input range accommodates
a variety of step-down applications, including
automotive input. A 12µA shutdown-mode supply
current makes it suitable for battery-powered
applications.
•
•
•
•
•
•
•
•
•
A scaled-down switching frequency in light-load
conditions provides high power-conversion
efficiency over a wide load range while reducing
switching and gate driver losses.
•
Guaranteed Industrial/Automotive
Temperature Range Limits
Wide 3.8V-to-55V Operating Input Range
250mΩ Internal Power MOSFET
Up to 2MHz Programmable Switching
Frequency
140μA Quiescent Current
Stable with Ceramic Capacitors
Internal Soft-Start
Up to 95% Efficiency
Output Adjustable from 0.8V to 52V
Available in SOIC8E and 3mm x 3mm
QFN10 Packages
Available in AEC-Q100 Grade 1
APPLICATIONS
The frequency fold-back prevents inductor current
runaway during startup and thermal shutdown
provides reliable, fault-tolerant operation.
•
•
•
•
•
By switching at 2MHz, the MPQ4558 can prevent
EMI
(electromagnetic
interference)
noise
problems, such as those found in AM radio and
ADSL applications.
High-Voltage Power Conversion
Automotive Systems
Industrial Power Systems
Distributed Power Systems
Battery Powered Systems
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 MPQ4558 is available in an SOIC8E and a
10-pin 3mm x 3mm QFN package.
TYPICAL APPLICATION
Efficiency @VOUT=3.3V
fs=500kHz
C4
680pF
COMP
CONTROL
EN
R3
200k
BST
MPQ4558
FREQ
FB
R2
40.2k
VIN
C1
C3
100nF
SW
GND
VIN
8V to 55V
L1
C2
D1
VOUT
3.3V @ 1A
R1
127k
EFFICIENCY (%)
R4
24k
100
90
80
70
60
50
VIN=12V
VIN=55V
40
30
20
10
0
0
0.5
0.75
0.25
OUTPUT CURRENT (A)
MPQ4558 Rev. 1.01
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1
MPQ4558 – 1A, 2MHz, 55V STEP-DOWN CONVERTER, AEC-Q100 QUALIFIED
ORDERING INFORMATION
Part Number
MPQ4558DN*
MPQ4558DQ**
MPQ4558DQ-AEC1***
Package
SOIC8E
QFN10 (3 x 3mm)
QFN10 (3 x 3mm)
Top Marking
MP4558DN
ABP
ABP
Junction Temperature (TJ)
-40°C to +125°C
* For Tape & Reel, add suffix –Z (e.g. MPQ4558DN–Z)
For RoHS Compliant Packaging, add suffix –LF, (e.g. MPQ4558DN–LF–Z)
** For Tape & Reel, add suffix –Z (e.g. MPQ4558DQ–Z)
For RoHS Compliant Packaging, add suffix –LF, (e.g. MPQ4558DQ–LF–Z)
***Available End Sept. 2011
PACKAGE REFERENCE
TOP VIEW
TOP VIEW
SW
1
8
BST
SW
1
10
BST
EN
2
7
VIN
SW
2
9
VIN
EN
3
8
VIN
COMP
4
7
FREQ
FB
5
6
GND
COMP
3
6
FREQ
FB
4
5
GND
EXPOSED PAD
EXPOSED PAD
ON BACKSIDE
SOIC8E
QFN10 (3mm x 3mm)
ABSOLUTE MAXIMUM RATINGS (1)
Supply Voltage (VIN).....................–0.3V to +60V
Switch Voltage (VSW)..........–0.5V to (VIN + 0.5V)
BST to SW .....................................–0.3V to +5V
All Other Pins .................................–0.3V to +5V
Continuous Power Dissipation
(TJ = +25°C)(2)
SOIC8E……………………………………….2.5W
QFN10………………………………………. 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 55V
Output Voltage VOUT .........................0.8V to 52V
Maximum Junction Temp. (TJ) ................ 125°C
Thermal Resistance
(4)
θJA
θJC
SOIC8E ...................................50 ...... 10 ... °C/W
QFN10(3mm x 3mm) ..............50 ...... 12 ... °C/W
Notes:
1) Exceeding these ratings may damage the device
2) The maximum allowable power dissipation is a function of the
maximum junction temperature TJ(MAX), the junction-toambient thermal resistance θJA, and the ambient temperature
TA. The maximum allowable continuous power dissipation at
any ambient temperature is calculated by PD(MAX)=(TJ(MAX)TA)/ θJA. Exceeding the maximum allowable power dissipation
will cause excessive die temperature, and the regulator will go
into thermal shutdown. Internal thermal shutdown circuitry
protects the device from permanent damage.
3) The device is not guaranteed to function outside of its
operating conditions.
4) Measured on JESD51-7 4-layer board.
MPQ4558 Rev. 1.01
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MPQ4558 – 1A, 2MHz, 55V STEP-DOWN CONVERTER, AEC-Q100 QUALIFIED
ELECTRICAL CHARACTERISTICS
VIN = 12V, VEN = 2.5V, VCOMP = 1.4V, TJ= –40°C to +125°C. Typical Values are at TJ=25°C, unless
otherwise noted.
Parameter
Symbol Condition
Feedback Voltage
VFB
Feedback Leakage Current
IFB
Upper Switch On Resistance (5)
RDS(ON)
Upper Switch Leakage
ISW
Current Limit
ILIM
COMP to Current Sense
Transconductance
Error Amp Voltage Gain
Error Amp Transconductance
Error Amp Min Source current
Error Amp Min Sink current
TJ=25°C
4.5V < VIN < 55V -40°C≤TJ≤85°C
-40°C≤TJ≤125°C
VBST – VSW = 5V
TJ=25°C
VEN = 0V, VSW = 0V
TJ=25°C
Duty cycle ≤60%
175
160
1.3
1.1
GCS
ICOMP = ±3µA
VFB = 0.7V
VFB = 0.9V
TJ=25°C
VIN UVLO Threshold
VIN UVLO Hysteresis
Soft-Start Time (5)
2.7
2.4
0V < VFB < 0.8V
TJ=25°C
Oscillator Frequency
fSW
RFREQ = 95kΩ
Shutdown Supply Current
Quiescent Supply Current
Thermal Shutdown
Minimum Off Time
Minimum On Time (5)
IS
IQ
VEN < 0.3V
No load, VFB = 0.9V (no switching)
Hysteresis = 20°C
EN Rising Threshold
Min
0.780
0.772
0.766
0.19
0.8
0.7
tOFF
tON
TJ=25°C
EN Threshold Hysteresis
1.4
1.3
Typ
0.800
0.1
250
1
1.9
Max
0.820
0.829
0.829
1.0
330
400
Units
V
μA
mΩ
μA
3.5
3.7
A
5.7
A/V
400
120
10
-10
3.0
V/V
µA/V
µA
µA
V
0.35
0.5
1
12
140
150
100
100
1.55
320
3.3
3.6
1.2
1.3
20
200
1.7
1.8
V
ms
MHz
µA
µA
°C
ns
ns
V
mV
Notes:
5) Derived from bench characterization. Not tested in production..
MPQ4558 Rev. 1.01
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MPQ4558 – 1A, 2MHz, 55V STEP-DOWN CONVERTER, AEC-Q100 QUALIFIED
PIN FUNCTIONS
SOIC8
Pin #
QFN10
Pin#
1
1, 2
2
3
3
4
4
5
5
6
6
7
7
8, 9
8
10
Name
Description
Switch Node. Output of the high-side switch. Requires a low VF Schottky rectifier
to ground. Place the rectifier close to the SW pins to reduce switching spikes.
Enable Input. Pull this pin below the specified threshold to shut the chip down. Pull
EN
it above the specified threshold or leaving it floating to enable the chip.
Compensation. GM error amplifier output. Apply control-loop frequency
COMP
compensation to this pin.
Feedback. Input to the error amplifier. Connect an external resistive divider
FB
between the output and GND: Compare to the internal +0.8V reference to set the
regulation voltage.
GND, Ground. Connect as close as possible to the output capacitor and avoid highExposed current switching paths. Connect the exposed pad to GND plane for optimal
pad
thermal performance.
Switching Frequency Program Input. Connect a resistor from this pin to ground to
FREQ
set the switching frequency.
Input Supply. Supplies power to all the internal control circuitry, both BS
VIN
regulators, and the high-side switch. Place a decoupling capacitor to ground close
to this pin to minimize switching spikes.
Bootstrap. Positive power supply for the internal floating high-side MOSFET driver.
BST
Connect a bypass capacitor between this pin and the SW pin.
SW
MPQ4558 Rev. 1.01
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MPQ4558 – 1A, 2MHz, 55V STEP-DOWN CONVERTER, AEC-Q100 QUALIFIED
TYPICAL CHARACTERISTICS
On Resistance vs.
Junction Temperature
2.2
2.2
450
2.0
2.0
IPEAK_LIMIT (A)
400
350
300
250
1.8
1.6
1.4
150
-50 -25
0 25
50
1.0
0%
75 100 125
Vin Start-up vs.
Junction Temperature
40% 60%
DUTY CYCLE
3.15
3.10
3.05
3.00
2.95
0
25
50
75 100 125
2.67
2.64
2.61
2.58
2.55
-50 -25
0
25
50
75 100 125
1.45
1.40
1.35
1.30
-50 -25
0.800
0.795
0.790
0.785
0.780
-50 -25
SWITCHING FREQUENCY (kHz)
VEN LOW VOLTAGE(V)
VEN HIGH VOLTAGE(V)
1.50
0
25
50
75 100 125
75 100 125
0
25
50
75 100 125
0
25
50
75 100 125
510
1.70
1.55
50
0.805
1.26
1.60
25
Venable-low vs.
Junction Temperature
1.75
1.65
0
0.810
2.70
Venable-high vs.
Junction Temperature
1.4
Voltage Reference vs.
Junction Temperature
VOLTAGE REFERENCE (V)
3.20
1.6
1.0
-50 -25
80%
2.73
VIN SHUT-DOWN VOLTAGE(V)
VIN START-UP VOLTAGE(V)
20%
Vin Shut-down vs.
Junction Temperature
3.25
1.8
1.2
1.2
200
2.90
-50 -25
IPEAK_LIMIT (A)
500
1.25
1.24
1.23
1.22
1.21
-50 -25
0
25
50
75 100 125
505
500
495
490
485
480
-50 -25
MPQ4558 Rev. 1.01
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MPQ4558 – 1A, 2MHz, 55V STEP-DOWN CONVERTER, AEC-Q100 QUALIFIED
TYPICAL CHARACTERISTICS (continued)
Frequency vs. FREQ
Resistor
SWITCHING FREQUENCY (kHz)
SWITCHING FREQUENCY (kHz)
2000
1500
1000
500
0
0
100
200
300
400
500
600
170
500
160
150
400
140
300
130
200
120
100
110
0
100
0
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8
10
Vin Quiescent Current vs.
Junction Temperature
VIN=12V
170
30
40
50
60
Shutdown Current vs.
Junction Temperature
VIN=12V
20
18
160
20
INPUT VOLTAGE(V)
FEEDBACK VOLTAGE(V)
16
15
150
14
140
12
130
10
120
5
8
110
100
-50 -25
10
0
25
50
75 100 125
6
0
10
20
30 40
50
INPUT VOLTAGE(V)
60
0
-50 -25
0
25
MPQ4558 Rev. 1.01
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50
75 100 125
6
MPQ4558 – 1A, 2MHz, 55V STEP-DOWN CONVERTER, AEC-Q100 QUALIFIED
TYPICAL PERFORMANCE CHARACTERISTICS
VIN = 12V, VOUT =3.3V, C1 = 4.7µF, C2 = 22µF, L1 = 10µH and TJ = 25°C, unless otherwise noted.
Efficiency @VOUT=5V
90
100
VIN=12V
80
80
EFFICIENCY ( )
EFFICIENCY ( )
VIN=48V
60
50
40
30
20
VIN=55V
70
60
50
Vsw
10V/div
40
30
20
IL
500mA/div
0
0
0.25
0.5
0.75
1
0.25
0
0.75
1
Output Voltage Ripple
Start up
Start up
IOUT=1A
IOUT=0.1A
IOUT=1A
VOUT
AC Coupled
10mV/div
Vsw
10V/div
IL
1A/div
VEN
2V/div
V
EN
2V/div
VOUT
2V/div
V
OUT
2V/div
Vsw
10V/div
IL
1A/div
V
sw
10V/div
Shut down
LI
1A/div
IShut
=1A
down
IOUT=0.1A
EN
0.5
OUTPUT CURRENT (A)
OUTPUT CURRENT (A)
2V/div
VOUT
AC Coupled
10mV/div
10
10
0
IOUT=0.1A
VIN=12V
90
70
Output Voltage Ripple
Short Circuit Entry
IOUT=0.1A to Short
OUT
VEN
2V/div
OUT
OUT
VOUT
2V/div
sw
10V/div
IL
1A/div
Vsw
10V/div
2V/div
IL
1A/div
2V/div
sw
10V/div
IL
1A/div
MPQ4558 Rev. 1.01
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MPQ4558 – 1A, 2MHz, 55V STEP-DOWN CONVERTER, AEC-Q100 QUALIFIED
TYPICAL PERFORMANCE CHARACTERISTICS (continued)
VIN = 12V, VOUT =3.3V, C1 = 4.7µF, C2 = 22µF, L1 = 10µH and TJ= 25°C, unless otherwise noted.
Short Circuit Steady State
Short Circuit Recovery
IOUT=Short to 0A
VOUT
2V/div
VOUT
2V/div
Vsw
10V/div
Vsw
10V/div
IL
1A/div
IL
2A/div
MPQ4558 Rev. 1.01
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MPQ4558 – 1A, 2MHz, 55V STEP-DOWN CONVERTER, AEC-Q100 QUALIFIED
BLOCK DIAGRAM
VIN
REFERENCE
UVLO
EN
INTERNAL
REGULATORS
BST
ISW
0.5ms SS
-+
SS
LOGIC
SW
FB
SS
0V8
--
COMP
+
OSCILLATOR
COMP
GND
FREQ
Figure 1: Functional Block Diagram
OPERATION
The MPQ4558 is a programmable-frequency,
non-synchronous, step-down, switching regulator
with an integrated high-side, high-voltage power
MOSFET. It provides a single, highly efficient
solution with current-mode control for fast loop
response and easy compensation. It features a
wide input voltage range, internal soft-start
control, and precision current limiting. Its very low
operational quiescent current makes it suitable
for battery-powered applications.
PWM Control Mode
At moderate-to-high output current, the
MPQ4558 operates in a fixed-frequency, peakcurrent–control mode to regulate the output
voltage. The internal clock initiates a PWM cycle.
The power MOSFET turns on and remains on
until its current reaches the value set by the
COMP voltage. When the power MOSFET is off,
it remains off for at least 100ns before the next
cycle starts. If, in one PWM period, the power
MOSFET current does not reach the COMP set
current value, the power MOSFET remains on to
saves on a turn-off operation.
Pulse-Skipping Mode
Under light-load condition, the switching
frequency drops to zero to reduce switching and
driving losses.
Error Amplifier
The error amplifier compares the FB pin voltage
with the internal reference (REF) and outputs a
current proportional to the difference between the
two. This output current then charges the
external compensation network to form the
COMP voltage, which controls the power
MOSFET current.
While in operation, the minimum COMP voltage
is clamped to 0.9V and its maximum is clamped
to 2.0V. COMP is internally pulled down to GND
in shutdown mode. Avoid pulling COMP up
beyond 2.6V.
MPQ4558 Rev. 1.01
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MPQ4558 – 1A, 2MHz, 55V STEP-DOWN CONVERTER, AEC-Q100 QUALIFIED
Internal Regulator
The 2.6V internal regulator powers most of the
internal circuits. This regulator takes the VIN
input and operates in the full VIN range. When
VIN exceeds 3.0V, the output of the regulator is in
full regulation: When VIN is less than 3.0V, the
output drops to 0V.
Enable Control
The MPQ4558 has a dedicated enable control
pin (EN): An input voltage that exceeds an upper
threshold enables the chip, while a voltage the
drops below a lower threshold disables the chip.
Its falling threshold is precisely 1.2V, and its
rising threshold is 300mV higher, or 1.5V.
When floating, EN is pulled up to about 3.0V by
an internal 1µA current source to enable the chip.
Pulling it down requires a 1µA current.
When EN drops below 1.2V, the chip enters the
lowest shutdown current mode. When EN
exceeds 0V but remains below its rising
threshold, the chip is still in shutdown mode but
with a slightly higher shutdown current.
Under-Voltage Lockout
Under-voltage lockout (UVLO) protects the chip
from operating at an insufficient supply voltage.
The UVLO rising threshold is about 3.0V while its
falling threshold is a consistent 2.6V.
Internal Soft-Start
Soft-Start prevents the converter output voltage
from overshooting during start-up and shortcircuit recovery. When the chip starts, the internal
circuitry generates a soft-start (SS) voltage that
ramps up from 0V to 2.6V. When this voltage is
less than the internal reference (REF), SS
overrides REF so the error amplifier uses SS as
the reference. When SS exceeds REF, REF
regains control.
Thermal Shutdown
Thermal shutdown prevents the chip from
operating at exceedingly high temperatures.
When the silicon die temperature exceeds its
upper threshold, it shuts down the whole chip.
When the temperature falls below its lower
threshold, 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 with a rising
threshold of 2.2V and a hysteresis of 150mV.
The driver’s UVLO is connected to the SS: If the
bootstrap voltage hits its UVLO, the soft-start
circuit resets. To prevent noise, there is 20µs
delay before the reset action. When the device
exits the bootstrap UVLO condition, the reset
turns off and then soft-start process resumes.
The dedicated internal bootstrap regulator
charges and regulates the bootstrap capacitor to
about 5V. When the voltage between the BST
and SW nodes falls below regulation, a PMOS
pass transistor connected from VIN to BST turns
on. The charging current path goes from VIN, to
BST and then to SW. The external circuit must
provide enough voltage headroom to facilitate
charging.
As long as VIN is sufficiently higher than SW, the
bootstrap capacitor will charge. When the power
MOSFET is ON, VIN is about equal to SW so the
bootstrap capacitor cannot charge. When the
external diode is on, the difference between VIN
and SW is at its largest, thus making it the best
period to charge. When there is no current in the
inductor, SW equals the output voltage VOUT so
the difference between VIN and VOUT can charge
the bootstrap capacitor.
Under higher duty-cycle operation conditions, the
time period available for bootstrap charging is
smaller so the bootstrap capacitor may not
sufficiently charge.
In case the internal circuit does not have
sufficient voltage and the bootstrap capacitor is
not charged, extra external circuitry can ensure
the bootstrap voltage is in the normal operational
region. Refer to the External Bootstrap Diode in
Application section.
The DC quiescent current of the floating driver is
about 20µA. Make sure the bleeding current at
the SW node is higher than this value, such that:
IO +
VO
> 20μA
(R1 + R2)
MPQ4558 Rev. 1.01
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MPQ4558 – 1A, 2MHz, 55V STEP-DOWN CONVERTER, AEC-Q100 QUALIFIED
Current Comparator and Current Limit
A current-sense MOSFET accurately senses the
current in the power MOSFET. This signal is then
fed to the high speed current comparator for
current-mode–control purposes, which uses it as
one of its inputs with the COMP voltage. When
the power MOSFET turns on, the comparator is
first blanked until the end of the turn-on transition
to avoid noise issues. When the sensed current
exceeds the COMP voltage, the comparator
output is low and the power MOSFET turns off.
The cycle-by-cycle maximum current of the
internal power MOSFET is internally limited.
Short-Circuit Protection
When the output is shorted to the ground, the
switching frequency folds back and the current
limit falls to reduce the short circuit current. When
the FB voltage equals 0V, the current limit falls to
about 50% of its full current limit. The FB voltage
reaches its 100% of its current limit when it
exceeds 0.4V
When the short-circuit FB voltage is low, the SS
drops by VFB and SS ≈ VFB + 100mV. If the short
circuit is removed, the output voltage recovers at
the SS rate. When FB is high enough, the
frequency and current limit return to normal
values.
Startup and Shutdown
If both VIN and VEN exceed their appropriate
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 stable supply for
the remaining circuitries.
While the internal supply rail is up, an internal
timer blanks the power MOSFET OFF for about
50µs to avoid start-up glitches. When the internal
soft-start block is enabled, it first holds its SS
output low to ensure the other circuits are ready
and then slowly ramps up.
Three events can shut down the chip: EN low, VIN
low and thermal shutdown. In shutdown, the
power MOSFET turns off first to avoid any fault
triggering. The COMP voltage and the internal
supply rail are then pulled down.
Programmable Oscillator
An external resistor—RFREQ connected from the
FREQ pin to GND—sets the MPQ4558
oscillating frequency. Calculate the value of
RFREQ from:
RFREQ (kΩ) =
100000
-5
fS (kHz)
For fSW=500kHz, RFREQ=195kΩ.
MPQ4558 Rev. 1.01
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MPQ4558 – 1A, 2MHz, 55V STEP-DOWN CONVERTER, AEC-Q100 QUALIFIED
APPLICATION INFORMATION
COMPONENT SELECTION
Setting the Output Voltage
Set the output voltage with a resistor divider
between the output voltage and the FB pin. The
voltage divider drops the output voltage down to
the feedback voltage by the ratio:
VFB =VOUT ×
R2
R1+R2
Thus the output voltage is:
VOUT =VFB ×
R1+R2
R2
For example, for R2 = 10kΩ, R1 can be
determined by:
R1 = 12.5 × (VOUT − 0.8)(kΩ)
For example, for a 3.3V output voltage, R2 is
10kΩ, and R1 is 31.6kΩ.
Inductor
The inductor supplies 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 lower the output ripple
voltage. However, a larger-valued inductor is
physically larger, has a higher series resistance,
or lower saturation current.
maximum switch current limit. Also, make sure
that the peak inductor current is below the
maximum switch current limit. Calculate the
inductance value with:
L1=
VOUT
fs × ΔIL
× (1-
VOUT
VIN
)
Where:
•
VOUT is the output voltage,
•
VIN is the input voltage,
•
fS is the switching frequency, and
•
∆IL is the peak-to-peak inductor ripple current.
Choose an inductor that will not saturate under
the maximum inductor peak current. Calculate
the peak inductor current with:
ILP = ILOAD +
⎛
⎞
VOUT
V
× ⎜1 − OUT ⎟⎟
2 × fS × L1 ⎜⎝
VIN ⎠
Where ILOAD is the load current.
Table 1 lists a number of suitable inductors from
various manufacturers. The choice the inductor
style mainly depends on the price vs. size
requirements and any EMI requirement.
Generally, determine an appropriate inductance
value by selecting the peak-to-peak inductor
ripple current equal to approximately 30% of the
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MPQ4558 – 1A, 2MHz, 55V STEP-DOWN CONVERTER, AEC-Q100 QUALIFIED
Part Number
Table 1: Inductor Selection Guide
Inductance
Max DCR
Current Rating
Dimensions
(µH)
(Ω)
(A)
L x W x H (mm)
7447789004
4.7
0.033
2.9
7.3x7.3x3.2
744066100
10
0.035
3.6
10x10x3.8
744771115
15
0.025
3.75
12x12x6
744771122
22
0.031
3.37
12x12x6
RLF7030T-4R7
4.7
0.031
3.4
7.3x6.8x3.2
SLF10145T-100
10
0.0364
3
10.1x10.1x4.5
SLF12565T-150M4R2
15
0.0237
4.2
12.5x12.5x6.5
SLF12565T-220M3R5
22
0.0316
3.5
12.5x12.5x6.5
FDV0630-4R7M
4.7
0.049
3.3
7.7x7x3
919AS-100M
10
0.0265
4.3
10.3x10.3x4.5
919AS-160M
16
0.0492
3.3
10.3x10.3x4.5
919AS-220M
22
0.0776
3
10.3x10.3x4.5
Wurth Electronics
TDK
Toko
Output Rectifier Diode
The output rectifier diode supplies the current to
the inductor when the high-side switch is off. To
reduce losses due to the forward diode voltage
and recovery times, use a Schottky diode.
Choose a diode whose maximum reverse voltage
rating is greater than the maximum input voltage,
and whose current rating is greater than the
maximum load current. Table 2 lists example
Schottky diodes and manufacturers.
Table 2: Diode Selection Guide
Voltage/
Diodes
Manufacturer
Current
Rating
B290-13-F
90V, 2A
Diodes Inc.
B380-13-F
80V, 3A
Diodes Inc.
CMSH2-100M
100V, 2A
Central Semi
CMSH3-100MA
100V, 3A
Central Semi
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MPQ4558 – 1A, 2MHz, 55V STEP-DOWN CONVERTER, AEC-Q100 QUALIFIED
Input Capacitor
The input current to the step-down converter is
discontinuous and therefore requires a capacitor
to supply the AC current to the step-down
converter while maintaining the DC input voltage.
Use capacitors with low equivalent series
resistance (ESR) for the best performance.
Ceramic capacitors are preferred, but tantalum or
low-ESR electrolytic capacitors may also suffice.
frequency. For simplification, the output ripple
can be approximated as:
For simplification, choose the input capacitor with
an RMS current rating greater than half of the
maximum load current. The input capacitor (C1)
can be electrolytic, tantalum or ceramic.
Compensation Components
MPQ4558 employs current-mode control for easy
compensation and fast transient response. The
COMP pin controls the system stability and
transient response—the COMP pin is the output
of the internal error amplifier. A capacitor-resistor
combination in series sets a pole-zero
combination to control the characteristics of the
control system. The DC gain of the voltage
feedback loop is given by:
When using electrolytic or tantalum capacitors,
include a small, high-quality ceramic capacitor—
i.e. 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 the input. The input voltage ripple
caused by the capacitance can be estimated by:
ΔVIN =
⎛
ILOAD
V
V
× OUT × ⎜1 − OUT
fS × C1 VIN ⎜⎝
VIN
⎞
⎟⎟
⎠
Output Capacitor
The output capacitor (C2) maintains the DC
output voltage. Use ceramic, tantalum, or lowESR electrolytic capacitors for best results. Low
ESR capacitors are preferred to keep the output
voltage ripple low. The output voltage ripple can
be estimated by:
ΔVOUT =
VOUT ⎛
V
× ⎜⎜1 − OUT
fS × L ⎝
VIN
⎞
⎞ ⎛
1
⎟
⎟⎟ × ⎜ R ESR +
⎜
8 × f S × C2 ⎟⎠
⎠ ⎝
Where L is the inductor value and RESR is the
ESR value of the output capacitor.
For 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:
ΔVOUT =
⎛
⎞
V
× ⎜⎜1 − OUT ⎟⎟
V
× L × C2 ⎝
IN ⎠
VOUT
8 × fS
2
For tantalum or electrolytic capacitors, the ESR
dominates the impedance at the switching
ΔVOUT =
VOUT ⎛
V
× ⎜⎜1 − OUT
fS × L ⎝
VIN
⎞
⎟⎟ × R ESR
⎠
The characteristics of the output capacitor also
affect the stability of the regulation system. The
MPQ4558 can be optimized for a wide range of
capacitances and ESR values.
A VDC = R LOAD × G CS × A VEA ×
VFB
VOUT
Where
•
AVEA is the error amplifier voltage gain,
400V/V,
•
GCS
is
the
current
transconductance,5.6A/V, and
•
RLOAD is the load resistor value.
sense
The system has two poles of importance: One is
caused by the compensation capacitor (C3) and
the output resistor of error amplifier; the other is
caused by the output capacitor and the load
resistor. These poles are located at:
fP1 =
GEA
2 π× C3 × A VEA
fP 2 =
1
2 π× C 2 × RLOAD
is
the
Where,
GEA
transconductance, 120μA/V.
error
amplifier
The system has one zero of importance from C3
and the compensation resistor (R3). This zero is
located at:
fZ1 =
1
2 π× C3 × R 3
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MPQ4558 – 1A, 2MHz, 55V STEP-DOWN CONVERTER, AEC-Q100 QUALIFIED
The system may have another important zero if
the output capacitor has a large capacitance or a
high ESR value. The zero, due to the ESR and
the output capacitor value, is located at:
fESR =
1
2π × C2 × RESR
In this case, a third pole set by the compensation
capacitor (C5) and R3 compensates for the effect
of the ESR zero on the loop gain. This pole is
located at:
fP 3 =
1
2 π× C5 × R 3
The compensation network shapes the converter
transfer function for a desired loop gain. The
feedback-loop unity gain at the system crossover
frequency is important: Lower crossover
frequencies result in slower line and load
transient responses, while higher crossover
frequencies can destabilize the system.
Generally, set the crossover frequency to
approximately 1/10 of the switching frequency.
Table 3: Compensation Values for Typical Output
Voltage/Capacitor Combinations
VOUT
C2
R3
C3
C6
L (µH)
(V)
(µF)
(kΩ)
(pF)
(pF)
1.8
4.7
33
32.4
680
None
2.5
4.7 - 6.8
22
26.1
680
None
3.3
6.8 -10
22
68.1
220
None
5
15 - 22
33
47.5
330
None
12
10
22
16
470
2
To optimize the compensation components for
conditions not listed in Table 3, use the following
procedure.
1. Choose R3 to set the desired crossover
frequency. Determine the R3 value from the
following equation:
R3 =
2 π× C2 × fC VOUT
×
GEA × GCS
VFB
Where fC is the desired crossover frequency.
2. Choose C3 to achieve the desired phase
margin. For applications with typical inductor
values, set the compensation zero—fZ1—below ¼
the crossover frequency to provide sufficient
phase margin. Determine C3 from the following
equation:
C3 >
4
2 π× R 3 × fC
3. Determine if C5 is required—if the ESR zero of
the output capacitor is located at less than 1/2 fS,
or if the following relationship is valid:
f
1
< S
2π × C2 × RESR 2
If this is the case, then add C5 to set the pole fP3
at the location of the ESR zero. Determine the
C5 value by the equation:
C5 =
C 2 × RESR
R3
High-Frequency Operation
The MPQ4558 switching frequency can be
programmed up to 2MHz by an external resistor.
The minimum MPQ4558 ON-time is typically
about 100ns. Pulse-skipping operation can be
seen more easily at higher switching frequencies
due to the minimum ON-time.
Since the internal bootstrap circuitry has higher
impedance that may not be adequate to charge
the
bootstrap
capacitor
during
each
(1-D)×tS charging period, add an external
bootstrap charging diode if the switching
frequency is about 2MHz (see External Bootstrap
Diode section for detailed implementation
information).
With higher switching frequencies, the inductive
reactance (XL) of the capacitor dominates so that
the ESL of the input/output capacitor determines
the input/output ripple voltage at higher switching
frequencies. Because of this ripple, use highfrequency ceramic capacitors for the input
decoupling capacitor and output the filtering
capacitor for high-frequency operation.
Layout becomes more important when the device
switches at higher frequencies. For best results,
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MPQ4558 – 1A, 2MHz, 55V STEP-DOWN CONVERTER, AEC-Q100 QUALIFIED
place the input decoupling capacitor and the
catch diode as close to the MPQ4558 (VIN pin,
SW pin and PGND) as close as possible with
short and wide traces. This can help to greatly
reduce the voltage spikes on the SW node, and
lower the EMI noise level.
Route the feedback trace as far from the inductor
and noisy power traces as possible. If possible,
run the feedback trace on the opposite side of
the PCB opposite from the inductor with a ground
plane separating the two. Placing the
compensation components close to the
MPQ4558. Avoid placing the compensation
components close to or under the high-dv/dt SW
node, or inside the high-di/dt power loop. If this is
not possible, route a ground plane to isolate the
circuit. Switching loss is expected to increase at
high switching frequencies.
To help to improve the thermal conduction, add
grid of thermal vias under the exposed pad. use
small vias (15mil barrel diameter) so that the
plating process fills the holes, thus aiding
conduction to the other side. Excessively large
holes can cause solder wicking during the reflow
soldering process. The typical pitch (distance
between the centers) between thermal vias is
typically 40mil.
This diode is also recommended for high-duty–
cycle operation (when VOUT/VIN > 65%)
applications.
The bootstrap diode can be a low-cost one such
as IN4148 or BAT54.
5V
BST
MPQ4558
0.1υF
SW
Figure 2: External Bootstrap Diode
At no load or light load, the converter may
operate in pulse-skipping mode to maintain the
output voltage in regulation: there is less time to
refresh the BS voltage. For sufficient gate voltage
under such operating conditions, chose VIN –
VOUT > 3V. For example, if VOUT = 3.3V, VIN needs
to be greater than 3.3V+3V=6.3V for sufficient
BST voltage at no load or light load. To meet this
requirement, the EN pin can program the input
UVLO voltage to VOUT+3V.
External Bootstrap Diode
An external bootstrap diode may enhance the
regulator efficiency. For the cases described
below, add an external BST diode from 5V to the
BST pin:
•
There is a 5V rail available in the system;
•
VIN is no greater than 5V;
•
VOUT is between 3.3V and 5V;
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MPQ4558 – 1A, 2MHz, 55V STEP-DOWN CONVERTER, AEC-Q100 QUALIFIED
TYPICAL APPLICATION CIRCUITS
C4
100nF
10
8,9
VIN
C1
4.7uF
100V
R5
100kΩ
EN
R6
36.5kΩ
BST
VIN
SW
L1
4.7uH
1,2
C2
33uF
16V
D1
3
7
EN
MPQ4558
FB
COMP
FREQ
5
R1
R2
40.2kΩ 49.9kΩ
4
C3
680pF
GND
R4
200kΩ
VOUT
1.8V
6
R3
32.4kΩ
C5
NS
Figure 3—1.8V Output Typical Application Schematic
C4
100nF
10
8,9
VIN
C1
4.7uF
100V
EN
R6
17.4kΩ
R5
100kΩ
BST
VIN
SW
L1
15uH
1,2
C2
33uF
16V
D1
3
7
R4
200kΩ
EN
MPQ4558
FB
COMP
FREQ
GND
6
VOUT
5V
5
R1
R2
40.2kΩ 210kΩ
4
C3
330pF
R3
47.5kΩ
C5
NS
Figure 4—5V Output Typical Application Schematic
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MPQ4558 – 1A, 2MHz, 55V STEP-DOWN CONVERTER, AEC-Q100 QUALIFIED
PCB LAYOUT GUIDE
2)
PCB layout is very important to achieve stable
operation. Duplicate the EVB layout below for
optimal performance.
Place the bypass ceramic capacitors close
to the VIN pin.
3)
Use short and direct feedback connections.
Place the feedback resistors and
compensation components as close to the
chip as possible.
4)
Route the SW path away from sensitive
analog areas such as the FB path.
5)
Connect IN, SW, and GND, respectively, to
a large copper area to cool the chip to
improve thermal performance and longterm reliability.
For changes, please follow these guidelines
and use Figure 3 for reference.
1)
Keep the switching-current path short and
minimize the loop area formed by the input
capacitor, high-side MOSFET and external
switching diode.
R4
24k
C4
680pF
COMP
CONTROL
VIN
EN
R3
200k
BST
MPQ4558
FREQ
VIN
8V to 55V
C1
C3
100nF
L1
SW
FB
GND
VOUT
3.3V @ 1A
C2
D1
R1
127k
R2
40.2k
MPQ4558 Typical Application Circuit
GND
R1
R5
R4
C3
R2
R3
L1
2
FB
COMP FREQ
EN
SW
VIN
BST
1
3
GND
4
SW
C4
D1
8
7
6
5
R6
C2
C1
Vin
GND
GND
Vo
TOP Layer
Bottom Layer
MPQ4558DN Layout Guide
MPQ4558 Rev. 1.01
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MPQ4558 – 1A, 2MHz, 55V STEP-DOWN CONVERTER, AEC-Q100 QUALIFIED
GND
C3
R4
R5
SW 1
EN 3
SW 2
FB 5
COMP 4
R1
R2
R3
L1
SW
C4
8
9
Vin
Vin
10 BST
7 FREQ
6 GND
D1
R6
C2
C1
Vin
GND
GND
Vo
TOP Layer
Bottom Layer
MPQ4558DQ Layout Guide
Figure 3: MPQ4558 Typical Application Circuit and PCB Layout Guide
MPQ4558 Rev. 1.01
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MPQ4558 – 1A, 2MHz, 55V STEP-DOWN CONVERTER, AEC-Q100 QUALIFIED
PACKAGE INFORMATION
SOIC8 (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)
PIN 1 ID
1
0.228(5.80)
0.244(6.20)
0.089(2.26)
0.101(2.56)
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)
0.013(0.33)
0.020(0.51)
0.0075(0.19)
0.0098(0.25)
SIDE VIEW
0.050(1.27)
BSC
FRONT VIEW
0.010(0.25)
x 45o
0.020(0.50)
GAUGE PLANE
0.010(0.25) BSC
0.050(1.27)
0.024(0.61)
0o-8o
0.016(0.41)
0.050(1.27)
0.063(1.60)
DETAIL "A"
0.103(2.62)
0.138(3.51)
RECOMMENDED LAND PATTERN
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.
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.
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MPQ4558 – 1A, 2MHz, 55V STEP-DOWN CONVERTER, AEC-Q100 QUALIFIED
QFN10 (3mm x 3mm)
2.90
3.10
0.30
0.50
PIN 1 ID
MARKING
0.18
0.30
2.90
3.10
PIN 1 ID
INDEX AREA
1.45
1.75
PIN 1 ID
SEE DETAIL A
10
1
2.25
2.55
0.50
BSC
5
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
0.70
1) ALL DIMENSIONS ARE IN MILLIMETERS.
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.
1.70
0.25
2.50
0.50
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.
MPQ4558 Rev. 1.01
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21