MP9485
100V Input, 500mA,
Step-Down Converter
DESCRIPTION
FEATURES
The MP9485 is a high-voltage, step-down,
switching regulator that delivers up to 0.5A of
current to the load. It integrates a high-side,
high-voltage power MOSFET with a current limit
of 1.0A, typically. The wide 4.5V to 100V input
range accommodates a variety of step-down
applications, making it ideal for automotive,
industry, and lighting applications. Hysteretic
voltage-mode control is employed for very fast
response. MPS’s proprietary feedback control
scheme minimizes the number of required
external components.
The switching frequency can be up to 2MHz,
allowing for small component size. Thermal
shutdown and short-circuit protection (SCP)
provide reliable and fault-tolerant operations. A
170µA quiescent current allows the MP9485 to
be used in battery-powered applications.
The MP9485 is available in a SOIC-8 package
with an exposed pad.
Wide 4.5V to 100V Input Range
Hysteretic Control: No Compensation
Up to 2MHz Switching Frequency
PWM Dimming Control Input for LED
Application
Short-Circuit Protection (SCP) with
Integrated High-Side MOSFET
170μA Quiescent Current
Thermal Shutdown
Available in a SOIC-8 Package with an
Exposed Pad
APPLICATIONS
E-Bike Control Power Supplies
Solar Energy Systems
Automotive System Power
Industrial Power Supplies
High-Power LED Drivers
All MPS parts are lead-free, halogen-free, and adhere to the RoHS directive.
For MPS green status, please visit the MPS website under Quality Assurance.
“MPS” and “The Future of Analog IC Technology” are registered trademarks of
Monolithic Power Systems, Inc.
TYPICAL APPLICATION
Efficiency vs. Output Current
VOUT=5V, L=33µH
C3
VIN
C1
EN
EN
DIM
BST
D1
MP9485
GND
VOUT
SW
R1
FB
R2
C2
Efficiency(%)
VIN
L1
100
90
80
70
60
50
40
30
20
10
0
Vin=36V
Vin=60V
1
10
100
1000
Output Current(mA)
MP9485 Rev. 1.11
10/10/2019
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© 2019 MPS. All Rights Reserved.
1
MP9485 – 100V INPUT, 500mA, STEP-DOWN CONVERTER
ORDERING INFORMATION
Part Number*
Package
Top Marking
MP9485GN
SOIC-8 EP
See Below
* For Tape & Reel, add suffix –Z (e.g. MP9485GN–Z)
TOP MARKING
MP9485: Product code of MP9485GN
LLLLLLLL: Lot number
MPS: MPS prefix
Y: Year code
WW: Week code
PACKAGE REFERENCE
TOP VIEW
FB
1
8
GND
NC
2
7
EN
VIN
3
6
DIM
BST
4
5
SW
SOIC-8 EP
MP9485 Rev. 1.11
10/10/2019
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© 2019 MPS. All Rights Reserved.
2
MP9485 – 100V INPUT, 500mA, STEP-DOWN CONVERTER
ABSOLUTE MAXIMUM RATINGS (1)
Thermal Resistance (4)
Supply voltage (VIN) ...................-0.3V to +100V
Switch voltage (VSW) ......... -0.5V (-4V for 30V
VFB = 5V or 0V
Falling edge of VFB from 0.25V
to 0V to VSW rising edge
Rising edge of VFB from 0V to
0.25V to VSW falling edge
Hysteresis = 20°C
1.55
320
0.01
2
1.15
300
-1
5
220
1
1.7
1
3
1.5
1
50
ns
50
ns
209
215
221
mV
179
185
191
mV
300
nA
-300
100
ns
100
ns
150
°C
NOTES:
5) Guaranteed by design, not tested.
6) Guaranteed by characterization, not production tested.
MP9485 Rev. 1.11
10/10/2019
www.MonolithicPower.com
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© 2019 MPS. All Rights Reserved.
4
MP9485 – 100V INPUT, 500mA, STEP-DOWN CONVERTER
TYPICAL ELECTRICAL CHARACTERISTICS
VIN = 60V, TA= +25C, unless otherwise noted.
Shutdown Current vs. Input Voltage
Quiesvent Current vs. Input Voltage
EN=HIGH, DIM=LOW, V FB=250mV
220
5
4.5
4
3.5
3
2.5
2
1.5
1
0.5
0
Input Current(uA)
Input Current(uA)
EN=LOW
210
200
190
180
4
17
30
43
56
69
82
4
95
17
30
Input Voltage(V)
56
69
82
95
Quiescent Current vs. Temperature
Shutdown Current vs. Temperature
V IN =95V, DIM=LOW,EN=HIGH,VFB=250mV
V IN =95V, EN=LOW
20
220
16
Input Current( uA)
Input Current (uA)
43
Input Voltage(V)
12
8
4
0
-40 -20
0
210
200
190
180
20 40 60 80 100 120 140
-40 -20
Junction Temperature (°
C)
0
20 40 60 80 100 120 140
Junction Temperature (°C)
EN Threshold vs. Temperature
UVLO Threshold vs. Temperature
2
4.5
falling
4.1
3.9
1.7
EN Threshold(V)
Vin Threshold(V)
rising
4.3
1.4
1.1
rising
0.8
3.7
falling
0.5
3.5
-40 -20
0
20
40
60
80 100 120 140
Junction Temperature (°
C)
MP9485 Rev. 1.11
10/10/2019
-40 -20
0
20
40
60
80 100 120 140
Junction Temperature (°
C)
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5
MP9485 – 100V INPUT, 500mA, STEP-DOWN CONVERTER
TYPICAL PERFORMANCE CHARACTERISTICS (continued)
VIN = 60V, VOUT = 5V, IOUT = 1A, L=33μH, COUT = 100μF, TA= +25C, unless otherwise noted.
Load Regulation
0.8
100
90
80
70
60
50
40
30
20
10
0
Vin=36V
Regulation Error(%)
Efficiency(%)
Efficiency vs. Output Current
Vin=60V
0.6
Vin=36V
0.4
Vin=60V
0.2
0
-0.2
-0.4
-0.6
-0.8
1
10
100
1000
Output Current(mA)
0
100
200
300
400
500
Output Current(mA)
Regulation Error(%)
Line Regulation
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
-0.1
-0.2
Iout=1mA
Iout=500mA
0
10 20 30 40 50 60 70 80 90 100
Input Voltage(V)
MP9485 Rev. 1.11
10/10/2019
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© 2019 MPS. All Rights Reserved.
6
MP9485 – 100V INPUT, 500mA, STEP-DOWN CONVERTER
TYPICAL PERFORMANCE CHARACTERISTICS (continued)
VIN = 60V, VOUT = 5V, IOUT = 1A, L=33μH, COUT = 100μF, TA= +25C, unless otherwise noted.
Steady State
Steady State
IOUT=0A
IOUT=0.5A
CH1:
CH1:
VOUT/AC
VOUT/AC
100mV/div.
100mV/div.
CH2: VIN
50V/div.
CH2: VIN
50V/div.
CH3: VSW
50V/div.
CH3: VSW
50V/div.
CH4: IL
1A/div.
CH4: IL
1A/div.
4µs/div.
4µs/div.
Power On
Power On
IOUT=0A
IOUT=0.5A
CH1: VOUT
CH1: VOUT
2V/div.
2V/div.
CH2: VIN
50V/div.
CH2: VIN
50V/div.
CH3: VSW
50V/div.
CH3: VSW
50V/div.
CH4: IL
1A/div.
CH4: IL
1A/div.
20ms/div.
20ms/div.
Power Off
Power Off
IOUT=0A
IOUT=0.5A
CH1: VOUT
CH1: VOUT
2V/div.
2V/div.
CH2: VIN
50V/div.
CH2: VIN
50V/div.
CH3: VSW
10V/div.
CH3: VSW
50V/div.
CH4: IL
500mA/div.
CH4: IL
1A/div.
100ms/div.
MP9485 Rev. 1.11
10/10/2019
20ms/div.
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© 2019 MPS. All Rights Reserved.
7
MP9485 – 100V INPUT, 500mA, STEP-DOWN CONVERTER
TYPICAL PERFORMANCE CHARACTERISTICS (continued)
VIN = 60V, VOUT = 5V, IOUT = 1A, L=33μH, COUT = 100μF, TA= +25C, unless otherwise noted.
EN Start-Up
EN Start-Up
IOUT=0A
IOUT=0.5A
CH1: VOUT
CH1: VOUT
2V/div.
2V/div.
CH2: VEN
5V/div.
CH2: VEN
5V/div.
CH3: VSW
50V/div.
CH3: VSW
50V/div.
CH4: IL
1A/div.
CH4: IL
1A/div.
20ms/div.
20ms/div.
EN Shutdown
EN Shutdown
IOUT=0A
IOUT=0.5A
CH3: VEN
2V/div.
CH3: VEN
2V/div.
CH2: VOUT
5V/div.
CH2: VOUT
5V/div.
CH1: VSW
20V/div.
CH1: VSW
50V/div.
CH4: IL
500mA/div.
CH4: IL
1A/div.
100ms/div.
400µs/div.
SCP Entry
SCP Recovery
IOUT=0A
IOUT=0A
CH1: VOUT
CH1: VOUT
2V/div.
2V/div.
CH2: VIN
50V/div.
CH2: VIN
50V/div.
CH3: VSW
50V/div.
CH3: VSW
50V/div.
CH4: IL
1A/div.
CH4: IL
1A/div.
400µs/div.
MP9485 Rev. 1.11
10/10/2019
40ms/div.
www.MonolithicPower.com
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© 2019 MPS. All Rights Reserved.
8
MP9485 – 100V INPUT, 500mA, STEP-DOWN CONVERTER
TYPICAL PERFORMANCE CHARACTERISTICS (continued)
VIN = 60V, VOUT = 5V, IOUT = 1A, L=33μH, COUT = 100μF, TA= +25C, unless otherwise noted.
SCP Entry
SCP Recovery
IOUT=0.5A
IOUT=0.5A, E-load turn-on Threshold=0.32V
CH1: VOUT
CH1: VOUT
2V/div.
2V/div.
CH2: VIN
50V/div.
CH2: VIN
50V/div.
CH3: VSW
50V/div.
CH3: VSW
50V/div.
CH4: IL
1A/div.
CH4: IL
1A/div.
1ms/div.
20ms/div.
Load Transient
IOUT=0A-->0.5A
CH1:
VOUT/AC
50mV/div.
CH4: ILOAD
500mA/div.
200µs/div.
MP9485 Rev. 1.11
10/10/2019
www.MonolithicPower.com
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© 2019 MPS. All Rights Reserved.
9
MP9485 – 100V INPUT, 500mA, STEP-DOWN CONVERTER
PIN FUNCTIONS
SOIC-8 EP
Pin #
1
2
Name
FB
NC
3
VIN
4
BST
5
SW
6
DIM
7
EN
8
GND
MP9485 Rev. 1.11
10/10/2019
Description
Feedback. FB is the input to the voltage feedback hysteretic comparator.
No connection. NC is not connected.
Input supply. VIN supplies power to all of the internal control circuitries, both BST
regulators, and the high-side switch. A decoupling capacitor to ground must be placed
close to VIN to minimize switching spikes.
Bootstrap. BST is the positive power supply for the internal, floating, high-side
MOSFET driver. Connect a bypass capacitor between BST and SW.
Switch node. SW is the output from the high-side switch. A low forward voltage (VF)
Schottky rectifier to ground is required. The rectifier must be placed close to SW to
reduce switching spikes.
PWM dimming input. DIM is useful in LED driver applications. Pull DIM below the
specified threshold for dimming off; pull DIM above the specified threshold for dimming
on. If there is no need for a dimming function, such as in common buck applications,
then connect DIM and EN together.
Enable input. Pull EN below the specified threshold to shut down the MP9485; pull EN
above the specified threshold or leave EN floating to enable the MP9485.
Ground. GND should be placed as close to the output capacitor as possible to avoid
the high-current switch paths. Connect the exposed pad to the GND plane for optimal
thermal performance.
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10
MP9485 – 100V INPUT, 500mA, STEP-DOWN CONVERTER
BLOCK DIAGRAM
Figure 1: Functional Block Diagram
MP9485 Rev. 1.11
10/10/2019
www.MonolithicPower.com
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© 2019 MPS. All Rights Reserved.
11
MP9485 – 100V INPUT, 500mA, STEP-DOWN CONVERTER
OPERATION
Hysteresis Current Control with Adaptive
Threshold Adjustment
The MP9485 operates in a hysteretic voltagemode control to regulate the output voltage. FB
is connected to the tap of a resistor divider,
which determines the output voltage. The
power MOSFET is turned on and remains on
until FB rises to 215mV. The power MOSFET is
turned off and remains off until FB falls to
185mV. The two thresholds of 215mV and
185mV are adaptively adjusted to compensate
for all the circuit delays so that the output
voltage is regulated with an average 200mV
value at FB.
Enable (EN) Control
The MP9485 has a dedicated enable control pin
(EN) with positive logic. Its falling threshold is
1.23V, and its rising threshold is 1.55V (320mV
higher).
When floating, EN is pulled up to about 3.0V by
an internal 2µA current source, so it is enabled.
A current capability over 2µA is needed to pull
EN down.
Floating Driver and Bootstrap Charging
The floating power MOSFET driver is powered
by an external bootstrap capacitor. This floating
driver has its own UVLO protection. This
UVLO’s rising threshold is 2.2V with a threshold
of 150mV.
The bootstrap capacitor is charged and
regulated at about 5V by the dedicated internal
bootstrap regulator.
If the internal circuit does not have sufficient
voltage, and the bootstrap capacitor is not
sufficiently charged, extra external circuitry can
be used to ensure that the bootstrap voltage is
in the normal operating region. Refer to the
External Bootstrap Diode section on page 12
for more detail.
MP9485 Rev. 1.11
10/10/2019
Under-Voltage Lockout (UVLO)
Under-voltage lockout (UVLO) is implemented
to protect the chip from operating at an
insufficient supply voltage. The UVLO rising
threshold is about 4.0V, while its falling
threshold is a consistent 3.6V.
Dimming Function for LED Applications
Because the FB reference of the MP9485 is
very low, it is a good idea for the LED driver to
have the LED current sense resistor connected
between FB and GND. In such applications, the
MP9485 uses DIM for dimming. To achieve
dimming, apply a pulse on DIM. The high level
of the pulse should be >1.5V, and the low level
should be 65%) and very
high frequency (over 1.5MHz) applications.
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13
MP9485 – 100V INPUT, 500mA, STEP-DOWN CONVERTER
The bootstrap diode can be a low-cost one,
such as IN4148 or BAT54.
5V
Via
Top Layer
Bottom Layer
VIN
C1A
C1B C1C
BST
MP9485
C4
R1
R2
U1
0.1µF
C4
SW
Figure 2: External Bootstrap Diode
GND
C2B
D1
C2A
L1
PCB Layout Guidelines
Efficient PCB layout is critical for stable
operation. Refer to Figure 3 and follow the
guidelines below.
1, Place the input decoupling capacitor, catch
diode, and MP9485 (VIN, SW, and PGND pin)
as close to each other as possible.
2, Power traces should be short and wide to
reduce voltage spikes on the SW node and
lower EMI noise level.
3, Run the feedback trace as far from the
inductor and noisy power traces as possible.
4, Thermal vias with 15mil barrel diameter and
40mil pitch (instance between the centers) are
suggested under the exposed pad to improve
thermal conduction.
MP9485 Rev. 1.11
10/10/2019
VOUT
Figure 3: Layout Recommendation
Design Example
Table 1 is a design example following the
application guidelines for the specifications
below.
Table 1: Design Example
8V to 95V
VIN
5V
VOUT
0A to 0.5A
IOUT
The typical application circuit for VOUT = 5V in
Figure 4 shows the detailed application
schematic and is the basis for the typical
performance waveforms. This circuit can work
down to 4.5V after start-up, but VOUT may drop
when VIN is low due to the maximum duty cycle
limit. For more detailed device applications,
please refer to the related evaluation board
datasheet.
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14
MP9485 – 100V INPUT, 500mA, STEP-DOWN CONVERTER
TYPICAL APPLICATION CIRCUIT
VIN
C3 0.1µF
2.2µF/ 2.2µF/ 0.1µF/
100V 100V 100V
C1A
EN
C1B
C1C
VIN
EN
DIM
BST
SW
C4 C2A
0.1µF 4.7µF
R1
D1
B1100 240kΩ
MP9485
GND
L1 33µH
FB
VOUT
+
C2B
TR3C107K010C0200
100µF/10V
R2
10kΩ
Figure 4: VIN = 60V, VOUT = 5V, IOUT = 0.5A
MP9485 Rev. 1.11
10/10/2019
www.MonolithicPower.com
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© 2019 MPS. All Rights Reserved.
15
MP9485 – 100V INPUT, 500mA, STEP-DOWN CONVERTER
PACKAGE INFORMATION
SOIC-8 EP
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.
MP9485 Rev. 1.11
10/10/2019
www.MonolithicPower.com
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© 2019 MPS. All Rights Reserved.
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