MP172
EC
R NE O
EF W M
ER D ME
E
N
TO S D
IG E
M N D
P1 S F
O
72
R
A
700 V Non-Isolated Off-Line Regulator
Up to 120 mA Output Current
NOT RECOMMENDED FOR NEW DESIGNS. REFER TO MP172A
DESCRIPTION
FEATURES
MP172 is a primary-side regulator that provides
accurate constant voltage (CV) regulation
without an opto-coupler. It supports buck, boost,
buck-boost, and flyback topologies. It has an
integrated 700 V MOSFET to simplify the
structure and reduce costs. These features
make it an ideal regulator for off-line, low-power
applications, such as home appliances and
standby power.
MP172 is a green-mode-operation regulator.
Both the peak current and the switching
frequency decrease as the load decreases.
This feature provides excellent efficiency at light
load and improves the overall average
efficiency.
MP172 has various protection features
including thermal shutdown (TSD), VCC undervoltage lockout (UVLO), overload protection
(OLP), short-circuit protection (SCP), and openloop protection.
MP172 is available in a small TSOT23-5
package and SOIC-8 package.
Primary-Side CV Control, Supporting Buck,
Boost, Buck-Boost, and Flyback Topologies
Integrated 700 V MOSFET and Current
Source
< 30 mW No-Load Power Consumption
Up to 3 W Output Power
Maximum DCM Output Current Less than
80 mA
Maximum CCM Output Current Less than
120 mA
Low VCC Operating Current
Frequency Foldback
Limited Maximum Frequency
Peak-Current Compression
Internally Biased VCC
TSD, UVLO, OLP, SCP, Open-Loop
Protection
APPLICATIONS
Home Appliances, White Goods, and
Consumer Electronics
Industrial Controls
Standby Power
R
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.
N
O
T
TYPICAL APPLICATION
DRAIN
L
D2
VCC
C2
MP172
R1
FB
C3
R2
SOURCE
Input
SOURCE
VOUT
D1
N
MP172 Rev. 1.01
9/17/2018
L1
C1
C4
GND
www.MonolithicPower.com
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2021 MPS. All Rights Reserved.
1
MP172– NON-ISOLATED OFF-LINE REGULATOR
NOT RECOMMENDED FOR NEW DESIGNS. REFER TO MP172A
ORDERING INFORMATION
Package
Top Marking
EC
R NE O
EF W M
ER D ME
E
N
TO S D
IG E
M N D
P1 S F
O
72
R
A
Part Number
MP172GJ*
MP172GS**
TSOT23-5
SOIC-8
See Below
See Below
* For Tape & Reel, add suffix –Z (e.g. MP172GJ–Z).
** For Tape & Reel, add suffix –Z (e.g. MP172GS–Z).
TOP MARKING (TSOT23-5)
APK: product code of MP172GJ;
Y: year code;
TOP MARKING (SOIC-8)
N
O
T
R
MP172: part number;
LLLLLLLL: lot number;
MPS: MPS prefix:
Y: year code;
WW: week code:
PACKAGE REFERENCE
TOP VIEW
TOP VIEW
8 NC
VCC 1
FB 2
TSOT23-5
MP172 Rev. 1.01
9/17/2018
7 DRAIN
SOURCE 3
6 NC
SOURCE 4
5 NC
SOIC-8
www.MonolithicPower.com
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2021 MPS. All Rights Reserved.
2
MP172– NON-ISOLATED OFF-LINE REGULATOR
NOT RECOMMENDED FOR NEW DESIGNS. REFER TO MP172A
ABSOLUTE MAXIMUM RATINGS (1)
Thermal Resistance (4)
DRAIN to SOURCE (TJ=+25°C) . -0.3 V to 700 V
All other pins ................................ -0.3 V to 6.5 V
Continuous power dissipation ..... (TA = +25°C)(2)
TSOT23-5 .................................................... 1 W
SOIC-8 ......................................................... 1 W
Junction temperature ................................150°C
Lead temperature .....................................260°C
Storage temperature ................ -60°C to +150°C
TSOT23-5 .............................. 100 ..... 55... °C/W
SOIC-8 .................................... 96 ...... 45... °C/W
θJC
EC
R NE O
EF W M
ER D ME
E
N
TO S D
IG E
M N D
P1 S F
O
72
R
A
θJA
Recommended Operating Conditions (3)
N
O
T
R
Operating junction temp (TJ). ... -40°C to +125°C
Operating VCC range ................... 5.5 V to 5.7 V
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 allowance continuous power dissipation at
any ambient temperature is calculated by PD(MAX)=(TJ(MAX)TA)/θJA. Exceeding the maximum allowance power dissipation
will produce an excessive die temperature, causing the
regulator to go into thermal shutdown. Internal thermal
shutdown circuit 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 PCB.
MP172 Rev. 1.01
9/17/2018
www.MonolithicPower.com
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2021 MPS. All Rights Reserved.
3
MP172– NON-ISOLATED OFF-LINE REGULATOR
NOT RECOMMENDED FOR NEW DESIGNS. REFER TO MP172A
ELECTRICAL CHARACTERISTICS
EC
R NE O
EF W M
ER D ME
E
N
TO S D
IG E
M N D
P1 S F
O
72
R
A
VCC = 5.5 V, TJ = -40°C~125°C, min and max are guaranteed by characterization, typical is tested
under 25°C, unless otherwise specified.
Parameter
Symbol
Condition
Start-up Current Source and Internal MOSFET (DRAIN)
Internal regulator supply current
Iregulator VCC = 4 V; VDrain = 100 V
VCC = 5.8 V; VDrain = 400
DRAIN leakage current
ILeak
V
Breakdown voltage
On resistance
Supply Voltage Management (VCC)
VCC level (increasing) where the internal
regulator stops
VCC level (decreasing) where the
internal regulator turns on
VCC regulator on and off hysteresis
VCC level (decreasing) where the IC
stops
VCC level (decreasing) where the
protection phase ends
V(BR)DSS
TJ = 25°C
Ron
TJ = 25°C
Min
Typ
Max
Units
2.2
4.1
6
mA
10
17
μA
700
6
V
VCCON
5.1
5.5
5.8
V
130
250
VCCstop
3
3.4
3.6
V
VCCpro
2
2.5
2.8
V
fs = 36 kHz, D = 64%
720
μA
VCC = 5.3 V
16
200
24
µA
μA
210
232
mA
ICC
ICCLATCH
ILimit
TJ = 25°C
188
τLEB1
ISCP
Leading-edge blanking for SCP
Ω
5.7
Internal IC consumption (no switching)
Internal IC consumption, latch-off phase
Internal Current Sense
Peak current limit
mV
350
TJ = 25°C
330
τLEB2
(1)
20
5.4
ICC
SCP threshold
16
VCCOFF
Internal IC consumption
Leading-edge blanking
V
400
ns
510
180
mA
ns
R
Feedback Input (FB)
Minimum off time
T
Maximum on time
N
O
Primary MOSFET feedback turn-on
threshold
OLP feedback trigger threshold
τminoff
τmanon
7.5
10
12.5
μs
13
18
23
μs
VFB
2.45
2.55
2.65
V
VFB_OLP
1.64
1.74
1.84
V
OLP delay time
τOLP
Open-loop detection
Thermal Shutdown
VOLD
Thermal shutdown threshold
(1)
Thermal shutdown recovery hysteresis
(1)
fs = 36 kHz
175
0.4
0.5
ms
0.6
V
150
°C
30
°C
NOTE:
1) This parameter is guaranteed by design.
MP172 Rev. 1.01
9/17/2018
www.MonolithicPower.com
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2021 MPS. All Rights Reserved.
4
MP172– NON-ISOLATED OFF-LINE REGULATOR
NOT RECOMMENDED FOR NEW DESIGNS. REFER TO MP172A
N
O
T
R
EC
R NE O
EF W M
ER D ME
E
N
TO S D
IG E
M N D
P1 S F
O
72
R
A
TYPICAL CHARACTERISTICS
MP172 Rev. 1.01
9/17/2018
www.MonolithicPower.com
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2021 MPS. All Rights Reserved.
5
MP172– NON-ISOLATED OFF-LINE REGULATOR
NOT RECOMMENDED FOR NEW DESIGNS. REFER TO MP172A
TYPICAL PERFORMANCE CHARACTERISTICS
N
O
T
R
EC
R NE O
EF W M
ER D ME
E
N
TO S D
IG E
M N D
P1 S F
O
72
R
A
VIN = 230 VAC, VOUT = 5 V, IOUT = 120 mA, L = 1 mH, COUT = 47 μF, TA = +25°C, unless otherwise
noted.
MP172 Rev. 1.01
9/17/2018
www.MonolithicPower.com
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2021 MPS. All Rights Reserved.
6
MP172– NON-ISOLATED OFF-LINE REGULATOR
NOT RECOMMENDED FOR NEW DESIGNS. REFER TO MP172A
PIN FUNCTIONS
Pin #
SOIC8
1
2
3,4
7
5,6,8
Name
Description
EC
R NE O
EF W M
ER D ME
E
N
TO S D
IG E
M N D
P1 S F
O
72
R
A
Pin #
TSOT23-5
1
2
3,4
5
Control circuit power supply.
Regulator feedback.
Internal power MOSFET source and ground reference for VCC and FB.
Internal power MOSFET drain and high-voltage current source input.
No connection.
N
O
T
R
VCC
FB
SOURCE
DRAIN
NC
MP172 Rev. 1.01
9/17/2018
www.MonolithicPower.com
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2021 MPS. All Rights Reserved.
7
MP172– NON-ISOLATED OFF-LINE REGULATOR
NOT RECOMMENDED FOR NEW DESIGNS. REFER TO MP172A
EC
R NE O
EF W M
ER D ME
E
N
TO S D
IG E
M N D
P1 S F
O
72
R
A
FUNCTIONAL BLOCK DIAGRAM
VCC
DRAIN
Start-Up Unit
Power
Management
Driving Signal
Management
Feedback Control
Peak Current
Limitation
Protection Unit
FB
SOURCE
N
O
T
R
Figure 1—Functional block diagram
MP172 Rev. 1.01
9/17/2018
www.MonolithicPower.com
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2021 MPS. All Rights Reserved.
8
MP172– NON-ISOLATED OFF-LINE REGULATOR
NOT RECOMMENDED FOR NEW DESIGNS. REFER TO MP172A
OPERATION
The MP172 acts as a fully integrated regulator
when used in buck topology (see Typical
Application on page 1).
Start-Up and Under-Voltage Lockout
The internal high-voltage regulator self-supplies
the IC from DRAIN. When VCC voltage reaches
VCCOFF, the IC starts switching, and the internal
high-voltage regulator turns off. The internal highvoltage regulator turns on to charge the external
VCC capacitor when the VCC voltage falls below
VCCON. A small capacitor (in the low μF range)
maintains the VCC voltage and thus lowers the
capacitor cost.
The IC stops switching when the VCC voltage
drops blow VCCstop.
R
Under fault conditions—such as OLP, SCP, and
TSD—the IC stops switching and an internal
current source discharges the VCC capacitor.
The internal high-voltage regulator will not charge
the VCC capacitor until the VCC voltage drops
below VCCpro. The re-start time can be estimated
using Equation (1).
T
VCC VCCpro VCCOFF VCCPRO (1)
restart CVCC
ICCLATCH
Iregulator
O
18 us
10 us
The IC stops operation when the VCC voltage
drops below VCCstop; the IC begins operation
when VCC charges to VCCOFF. Every time the
chip starts operation, there is a soft-start period.
The soft start prevents the inductor current from
overshooting by limiting the minimum off time.
MP172 adopts a 2 phase minimum off time limit
soft start. Each soft-start phase retains 128
switching cycles. During the soft start, the off
time limit gradually shortens from 48 μs to 18 μs
and finally reaches the normal operation off time
limit (see Figure 2).
MP172 Rev. 1.01
9/17/2018
128 Switching cycle 128 Switching cycle
Figure 2— min off at start-up
Constant Voltage (CV) Operation
The MP172 regulates the output voltage by
monitoring the sampling capacitor.
At the beginning of each cycle, the integrated
MOSFET turns on while the feedback voltage
drops below the 2.55 V reference voltage, which
indicates insufficient output voltage. The peak
current limitation determines the on period. After
the on period elapses, the integrated MOSFET
turns off. The sampling capacitor (C3) voltage is
charged to the output voltage when the
freewheeling diode (D1) turns on. This way, the
sampling capacitor (C3) samples and holds the
output voltage for output regulation. The
sampling capacitor (C3) voltage decreases when
the L1 inductor current falls below the output
current. When the feedback voltage falls below
the 2.55 V reference voltage, a new switching
cycle begins. Figure 3 shows this operation in
continuous conduction mode (CCM).
MOSFET
Diode
IL
Ipeak
Io
Vo
Soft Start (SS)
N
48us
Driver
EC
R NE O
EF W M
ER D ME
E
N
TO S D
IG E
M N D
P1 S F
O
72
R
A
MP172 is a green-mode-operation regulator: The
peak current and the switching frequency both
decrease with a decreasing load. As a result, it
offers excellent light-load efficiency and improves
overall average efficiency. Also, the regulator
incorporates multiple features and operates with
a minimum number of external components.
V FB
2.55V
Figure 3— VFB vs. VO
Equation (2) determines the output voltage:
Vo 2.55V
R1 R2
R2
www.MonolithicPower.com
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2021 MPS. All Rights Reserved.
(2)
9
MP172– NON-ISOLATED OFF-LINE REGULATOR
EC
R NE O
EF W M
ER D ME
E
N
TO S D
IG E
M N D
P1 S F
O
72
R
A
NOT RECOMMENDED FOR NEW DESIGNS. REFER TO MP172A
Frequency Foldback and Peak Current
Ramp Compensation
Compression
An internal ramp compensation circuit improves
The MP172 remains highly efficient at light-load
the load regulation. As shown in Figure 4, a
conditions by reducing the switching frequency
voltage sinking source is added to pull down the
automatically.
reference voltage of the feedback comparator.
The ramp compensation is relative to the
Under light-load or no-load conditions, the output
MOSFET off time, and increases exponentially
voltage drops very slowly, which increases the
as the off time increases. The compensation is
MOSFET off time. Thus, the frequency
about 1mV/µs under min off time switching
decreases along with the load.
condition.
The switching frequency is determined with
Over-Load Protection (OLP)
Equation (3) and Equation (4):
The maximum output power of the MP172 is
(Vin Vo ) Vo
limited by the maximum switching frequency and
, for CCM
(3)
fs
the peak current limit. If the load current is too
2L(Ipeak Io ) Vin
large, the output voltage drops, causing the FB
2(Vin VO ) Io Vo
voltage to drop.
, for DCM
(4)
fs
2
LI peak
Vin
When the FB voltage drops below VFB_OLP, it is
considered an error flag, and the timer starts. If
As the peak current limit decreases from 210 mA,
the timer reaches 170 ms (fS = 36 kHz), OLP
the off time increases. In standby mode, the
occurs. This timer duration avoids triggering OLP
frequency and the peak current are both
when the power supply starts up or the load
minimized, allowing for a smaller dummy load. As
transitions. The power supply should start up in
a result, the peak current compression helps
less than 170 ms (fS = 36 kHz). The OLP delay
reduce no-load consumption. The peak current
time is calculated using Equation (6):
limit can be estimated from Equation (5) where
36kHz
τoff is the off time of the power module:
Delay 170ms
(6)
fs
IPeak 210mA (0.8mA / s) ( off 10s) (5)
Short-Circuit Protection (SCP)
The MP172 monitors the peak current and shuts
down when the peak current rises above the
SCP threshold through short-circuit protection.
The power supply resumes operation with the
removal of the fault.
EA Compensation
R
FB
Comparator
-
+
T
EA
N
O
VFB
-
+
+
Thermal Shutdown (TSD)
M
Vramp
+
Vramp
+
-
V
ref
2.55V
Ipeak
Figure 4—EA and ramp compensation
MP172 has an internal error amplifier (EA)
compensation loop. It samples the feedback
voltage 6 µs after the MOSFET turns off and
regulates the output based on the 2.55 V
reference voltage.
MP172 Rev. 1.01
9/17/2018
To prevent thermal induced damage, the MP172
stops switching when the junction temperature
exceeds 150°C. During thermal shutdown (TSD),
the VCC capacitor is discharged to VCCpro, and
the internal high-voltage regulator re-charges.
The MP172 recovers when the junction
temperature drops below 120°C.
Open-Loop Detection
If VFB is less than 0.5 V, the IC stops switching,
and a re-start cycle begins. During a soft start,
the open-loop detection is blanked.
www.MonolithicPower.com
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2021 MPS. All Rights Reserved.
10
MP172– NON-ISOLATED OFF-LINE REGULATOR
NOT RECOMMENDED FOR NEW DESIGNS. REFER TO MP172A
Leading-Edge Blanking
EC
R NE O
EF W M
ER D ME
E
N
TO S D
IG E
M N D
P1 S F
O
72
R
A
An internal leading-edge blanking (LEB) unit
avoids premature switching pulse termination
due to a turn-on spike. A turn-on spike is caused
by parasitic capacitance and reverse recovery of
the freewheeling diode. During the blanking time,
the current comparator is disabled and cannot
turn off the external MOSFET. Figure 5 shows
the leading-edge blanking.
IDS
350ns
ILIMIT
t
N
O
T
R
Figure 5—Leading-edge blanking
MP172 Rev. 1.01
9/17/2018
www.MonolithicPower.com
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2021 MPS. All Rights Reserved.
11
MP172– NON-ISOLATED OFF-LINE REGULATOR
NOT RECOMMENDED FOR NEW DESIGNS. REFER TO MP172A
APPLICATION INFORMATION
EC
R NE O
EF W M
ER D ME
E
N
TO S D
IG E
M N D
P1 S F
O
72
R
A
Table 1—Common topologies using MP172
Topology
Circuit Schematic
DRAIN
5
High-side
buck
SOURCE
VCC
1
MP172
FB
2
4
Features
1.
2.
3.
4.
No isolation
Positive output
Low cost
Direct feedback
1.
2.
3.
4.
No isolation
Negative output
Low cost
Direct feedback
1.
2.
3.
4.
No isolation
Positive output
Low cost
Direct feedback
1.
2.
3.
4.
Isolation
Positive output
Low cost
Indirect feedback
SOURCE
3
Vin
Vo
DRAIN
1
5
MP172
High-side
buck-boost
SOURCE
2
3
4
VCC
FB
SOURCE
Vin
Vo
DRAIN
Boost
5
1
MP172
Vin
3
4
FB
Vo
SOURCE
N
O
T
R
SOURCE
2
VCC
Flyback
T
*
Vin
*
DRAIN
1
5
MP172
SOURCE
MP172 Rev. 1.01
9/17/2018
4
2
3
VCC
FB
SOURCE
*
www.MonolithicPower.com
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2021 MPS. All Rights Reserved.
12
MP172– NON-ISOLATED OFF-LINE REGULATOR
NOT RECOMMENDED FOR NEW DESIGNS. REFER TO MP172A
maximum power using Equation (7) and Equation
(8):
The MP172 can be used in common topologies
V
such as buck, boost, buck-boost, and flyback
(7)
Po max Vo (Ipeak o min off ) , for CCM
(see Table 1).
2L
1 2
1
Component selection below is based on the
, for DCM
(8)
Pomax LIpeak
typical application of MP173 (see it on page 1).
2
EC
R NE O
EF W M
ER D ME
E
N
TO S D
IG E
M N D
P1 S F
O
72
R
A
Topology Options
minoff
Component Selection
Input Capacitor
The input capacitor supplies the DC input voltage
for the converter. Figure 6 shows the typical DC
bus voltage waveform of a half-wave rectifier and
a full-wave rectifier.
Vin
VDC(max)
DC input voltage
VDC(min)
AC input voltage
t
Vin
VDC(max)
For mass production, tolerance on the
parameters (such as peak current limitation and
the minimum off time) should be taken into
consideration.
Freewheeling Diode
Select a diode with a maximum reverse-voltage
rating greater than the maximum input voltage
and a current rating determined by the output
current.
The reverse recovery of the freewheeling diode
affects the efficiency and circuit operation during
a CCM condition, so use an ultra-fast diode such
as the EGC10JH.
Output Capacitor
DC input voltage
The output capacitor is required to maintain the
DC output voltage. Estimate the output voltage
ripple using Equation (9) and Equation (10):
VDC( min)
AC input voltage
t
VCCM _ ripple
i
i RESR , for CCM
8fsCo
VDCM _ ripple
Io
fsCo
Figure 6—Input voltage waveform
N
O
T
R
Typically, the use of a half-wave rectifier requires
an input capacitor rated at 3 µF/W for the
universal input condition. When using a full-wave
rectifier, an input capacitor is chosen between
1.5~2 µF/W for the universal input condition. A
half-wave rectifier is recommended for a < 2 W output
application, otherwise use a full-wave rectifier.
(9)
2
I I
pk o Ipk RESR , for DCM (10)
I
pk
It is recommended to use ceramic, tantalum, or
low ESR electrolytic capacitors to reduce the
output voltage ripple.
Feedback Resistors
Under very low input voltage, the inductor current
ramps up slowly; it may not reach the current
limit during τmanon, so the MOSFET on time
should be less than the minimum value of τmanon.
The resistor divider determines the output
voltage. Choose appropriate R1 and R2 values to
maintain VFB at 2.55 V. An excessively large
value for R2 should be avoided.
Inductor
Sampling Capacitor
The MP172 has a minimum off-time limit that
determines the maximum power output. A power
inductor with a larger inductance increases the
maximum power. Using a very small inductor
may cause failure at full load. Estimate the
The sampling capacitor (C3) samples and holds
the output voltage for feedback. With R1 and R2
fixed, a small sampling capacitor result in poor
regulation at light loads, and large sampling
capacitor affect the circuit operation. Roughly
estimate an optimal capacitor value using
Equation (11):
MP172 Rev. 1.01
9/17/2018
www.MonolithicPower.com
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2021 MPS. All Rights Reserved.
13
MP172– NON-ISOLATED OFF-LINE REGULATOR
NOT RECOMMENDED FOR NEW DESIGNS. REFER TO MP172A
Surge Performance
(11)
An appropriate input capacitor value should be
chosen to obtain good surge performance. Figure
Dummy Load
8 shows the half-wave rectifier. Table 2 shows
A dummy load is required to maintain the load
the capacitance required under normal conditions
regulation. This ensures there is sufficient
for different surge voltages. FR1 is a 20 Ω/2 W
inductor energy to charge the sample and hold
fused resistor, and L1 is 1 mH for this
capacitor to detect the output voltage. Normally a
recommendation.
3 mA dummy load is needed and can be
L1
FR1
L
adjusted according to the regulated voltage.
There is a compromise between small, no-load
consumption and good, no-load regulation,
especially for applications that require 30 mW noload consumption. Use a Zener to reduce noC1
C2
load consumption if no-load regulation is not a
concern.
EC
R NE O
EF W M
ER D ME
E
N
TO S D
IG E
M N D
P1 S F
O
72
R
A
C
Vo
C
1 Vo
o CFB
o
2 R1 R2 Io
R1 R2 Io
Auxiliary VCC Supply
R3
N
D3
C2
MP172
SOURCE
Table 2—Recommended capacitance
Surge
500 V
1000 V
2000 V
Voltage
1 μF
2.2 μF
3.3 μF
C1
1 μF
2.2 μF
3.3 μF
C2
R1
FB
C3
R2
SOURCE
Figure 8—Half-wave rectifier
D2
VCC
L1
VOUT
Figure 7—Auxiliary VCC supply circuit
R
For applications with VO above 7 V, the MP172
achieves the 30 mW no-load power requirement.
In order to do this, the chip requires an external
VCC supply to reduce overall power consumption
(see Figure 7).
N
O
T
This auxiliary VCC supply is derived from the
resistor connected between C2 and C3. C3
should be set larger than the value
recommended above. D3 is used in case VCC
interferes with FB. R3 is determined using
Equation (12):
R3
Vo VFW 5.8V
IS
(12)
Where IS is the VCC consumption under a noload condition, and VFW is the forward voltage
drop of D3. Because IS varies in different
applications, R3 should be adjusted to meet the
application’s specific IS. In a particular
configuration, IS is measured at about 200 µA.
MP172 Rev. 1.01
9/17/2018
PCB Layout Guidelines
Efficient PCB layout is critical for reliable
operation, good EMI, and thermal performance.
Please follow the guidelines below to optimize
performance.
1) Minimize the loop area formed by the input
capacitor, IC, freewheeling diode, inductor,
and output capacitor.
2) Place the power inductor far away from the
input filter while keeping the loop area to the
inductor at a minimum (see example below).
3) Place a capacitor valued at several hundred
pF between FB and SOURCE as close to the
IC as possible.
4) Connect the exposed pads or large copper
area with DRAIN to improve thermal
performance.
www.MonolithicPower.com
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2021 MPS. All Rights Reserved.
14
MP172– NON-ISOLATED OFF-LINE REGULATOR
EC
R NE O
EF W M
ER D ME
E
N
TO S D
IG E
M N D
P1 S F
O
72
R
A
NOT RECOMMENDED FOR NEW DESIGNS. REFER TO MP172A
Top layer
Bottom layer
Design Example
Table 3 shows a design example for the following
application guideline specifications:
Table 3—Design example
85 VAC to 265 VAC
VIN
5V
VOUT
120 mA
IOUT
N
O
T
R
The detailed application schematic is shown in
Figure 9. The typical performance and circuit
waveforms have been shown in the “Typical
Performance Characteristics” section. For
additional device applications, please refer to the
related evaluation board datasheets.
MP172 Rev. 1.01
9/17/2018
www.MonolithicPower.com
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2021 MPS. All Rights Reserved.
15
MP172– NON-ISOLATED OFF-LINE REGULATOR
NOT RECOMMENDED FOR NEW DESIGNS. REFER TO MP172A
TYPICAL APPLICATION CIRCUITS
EC
R NE O
EF W M
ER D ME
E
N
TO S D
IG E
M N D
P1 S F
O
72
R
A
Figure 9 shows a typical application example of a 5 V, 120 mA non-isolated power supply using the
MP172.
D1
SRGC10JH
R1
41.2 K
C1
22 nF
8
RF1
L
39
85 VAC~265VAC
NC
VCC
1
L1
D2
SRGC10JH
U1
7
1 mH
6
C3
C4
2.2 µF/400 V
2.2 µF/400 V
5
DRAIN
FB
2
NC
SOURC
E
3
NC
SOURC
E
4
C2
2.2 µF
C7
470 pF
R2
39.2 K
5 V/120 mA
L2
1 mH
Vout
MP172GS
D3
STTH1R06
600 V/1 A
C5
C6
1 µF
47 µF
R3
1.2 K
D4
N
SRJC10JH
GND
GND
N
O
T
R
Figure 9—Typical application at 5 V, 120 mA
MP172 Rev. 1.01
9/17/2018
www.MonolithicPower.com
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2021 MPS. All Rights Reserved.
16
MP172– NON-ISOLATED OFF-LINE REGULATOR
NOT RECOMMENDED FOR NEW DESIGNS. REFER TO MP172A
FLOW CHART
EC
R NE O
EF W M
ER D ME
E
N
TO S D
IG E
M N D
P1 S F
O
72
R
A
Power On
Vcc Decrease
to VCCPRO
Internal High Voltage
Regulator On
Shut Down
Internal High Voltage
Regulator
Y
Y
N
VCC>VCCOFF
N
Soft Start
Shuts Down
Internal High Voltage
Regulator
Stop Operation
Y
VCC>VCCSTOP
Y
Fault Logic N
High?
Monitor VCC
Y
VCC>VCCOFF
N
VCC
工商网监
湘ICP备2023018690号
