MP171
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700 V Non-Isolated Off-Line Regulator
Up to 60 mA Output Current
NOT RECOMMENDED FOR NEW DESIGNS. REFER TO MP171A
DESCRIPTION
FEATURES
MP171 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 cost. These features make
it an ideal regulator for offline low-power
applications, such as home appliances and
standby power.
MP171 is a green-mode-operation regulator.
Both the peak current and switching frequency
decrease as the load decreases. This feature
provides excellent efficiency at light load and
improves the overall average efficiency.
MP171 has various protection features
including thermal shutdown (TSD), VCC undervoltage lockout (UVLO), overload protection
(OLP), short-circuit protection (SCP), and openloop protection.
MP171 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 2 W Output Power
Maximum DCM Output Current Less than
40 mA
Maximum CCM Output Current Less than
60 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.
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TYPICAL APPLICATION
DRAIN
L
D2
VCC
C2
MP171
R1
FB
C3
R2
SOURCE
Input
SOURCE
VOUT
D1
N
MP171 Rev. 1.01
9/21/2018
L1
C1
C4
GND
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1
MP171 –NON-ISOLATED OFFLINE REGULATOR
NOT RECOMMENDED FOR NEW DESIGNS. REFER TO MP171A
ORDERING INFORMATION
Package
Top Marking
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Part Number
MP171GJ*
MP171GS**
TSOT23-5
SOIC-8
See Below
See Below
* For Tape & Reel, add suffix –Z (e.g. MP171GJ–Z).
** For Tape & Reel, add suffix –Z (e.g. MP171GS–Z).
TOP MARKING(TSOT23-5)
APL: product code of MP171GJ;
Y: year code;
TOP MARKING (SOIC-8)
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MP171: 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
MP171 Rev. 1.01
9/21/2018
7 DRAIN
SOURCE 3
6 NC
SOURCE 4
5 NC
SOIC-8
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2
MP171 –NON-ISOLATED OFFLINE REGULATOR
NOT RECOMMENDED FOR NEW DESIGNS. REFER TO MP171A
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
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θJA
Recommended Operating Conditions (3)
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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.
MP171 Rev. 1.01
9/21/2018
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3
MP171 –NON-ISOLATED OFFLINE REGULATOR
NOT RECOMMENDED FOR NEW DESIGNS. REFER TO MP171A
ELECTRICAL CHARACTERISTICS
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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
DRAIN leakage current
ILeak
VCC = 5.8 V; VDrain = 400 V
V(BR)DSS TJ = 25°C
Breakdown voltage
On resistance
Ron
TJ = 25°C
Supply Voltage Management (VCC)
VCC level (increasing) where the internal
VCCOFF
regulator stops
VCC level (decreasing) where the
VCCON
internal regulator turns on
VCC regulator on and off hysteresis
VCC level (decreasing) where the IC
VCCstop
stops
VCC level (decreasing) where the
VCCpro
protection phase ends
Internal IC consumption
ICC
Internal IC consumption (no switching)
Internal IC consumption, latch-off phase
Internal Current Sense
Peak current limit
ICC
Min
Typ
Max
Units
2.2
4.1
10
6
17
mA
μA
700
20
25
Ω
5.4
5.7
6
V
5.1
5.5
5.8
V
130
250
3
3.4
3.6
V
2
2.5
2.8
V
720
μA
16
200
24
µA
μA
105
125
mA
fs = 36 kHz, D = 64%
ICCLATCH VCC = 5.3 V
ILimit
Leading-edge blanking
τLEB1
SCP threshold
ISCP
Leading-edge blanking for SCP (1)
τLEB2
V
TJ = 25°C
85
mV
350
TJ = 25°C
220
300
ns
400
180
mA
ns
R
Feedback Input (FB)
Minimum off time
Maximum on time
N
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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.
MP171 Rev. 1.01
9/21/2018
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© 2021 MPS. All Rights Reserved.
4
MP171 –NON-ISOLATED OFFLINE REGULATOR
NOT RECOMMENDED FOR NEW DESIGNS. REFER TO MP171A
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TYPICAL CHARACTERISTICS
MP171 Rev. 1.01
9/21/2018
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© 2021 MPS. All Rights Reserved.
5
MP171 –NON-ISOLATED OFFLINE REGULATOR
NOT RECOMMENDED FOR NEW DESIGNS. REFER TO MP171A
TYPICAL PERFORMANCE CHARACTERISTICS
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VIN = 230 VAC, VOUT = 5 V, IOUT = 50 mA, L = 1 mH, COUT = 22 μF, TA = +25°C, unless otherwise
noted.
MP171 Rev. 1.01
9/21/2018
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© 2021 MPS. All Rights Reserved.
6
MP171 –NON-ISOLATED OFFLINE REGULATOR
NOT RECOMMENDED FOR NEW DESIGNS. REFER TO MP171A
PIN FUNCTIONS
Pin #
SOIC8
1
2
3,4
7
5,6,8
Name
Description
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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
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VCC
FB
SOURCE
DRAIN
NC
MP171 Rev. 1.01
9/21/2018
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© 2021 MPS. All Rights Reserved.
7
MP171 –NON-ISOLATED OFFLINE REGULATOR
NOT RECOMMENDED FOR NEW DESIGNS. REFER TO MP171A
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FUNCTIONAL BLOCK DIAGRAM
VCC
DRAIN
Start-Up Unit
Power
Management
Driving Signal
Management
Feedback Control
Peak Current
Limitation
Protection Unit
FB
SOURCE
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Figure 1—Functional block diagram
MP171 Rev. 1.01
9/21/2018
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© 2021 MPS. All Rights Reserved.
8
MP171 –NON-ISOLATED OFFLINE REGULATOR
NOT RECOMMENDED FOR NEW DESIGNS. REFER TO MP171A
OPERATION
The MP171 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 (~16 μA) 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):
VCC VCCpro VCCOFF VCCpro
CVCC
(1)
I
I
CCLATCH
regulator
T
restart
O
Soft Start (SS)
N
48us
18 us
10 us
Driver
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MP171 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 minimal number of external components.
Figure 2— min off at start-up
Constant Voltage (CV) Operation
The MP171 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. In his 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
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.
MP171 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).
MP171 Rev. 1.01
9/21/2018
128 Switching cycle 128 Switching cycle
V FB
2.55V
Figure 3—VFB vs. VO
Equation (2) determines the output voltage:
Vo 2.55V
R1 R2
R2
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© 2021 MPS. All Rights Reserved.
(2)
9
MP171 –NON-ISOLATED OFFLINE REGULATOR
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NOT RECOMMENDED FOR NEW DESIGNS. REFER TO MP171A
Frequency Foldback and Peak Current
Ramp Compensation
Compression
An internal ramp compensation circuit improves
The MP171 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):
fs
(Vin Vo ) Vo
, for CCM
2L(Ipeak Io ) Vin
(3)
fs
2(Vin VO ) Io Vo
, for DCM
LI2peak
Vin
(4)
As the peak current limit decreases from 105 mA,
the off time increases. In standby mode, the
frequency and the peak current are both
minimized, allowing for a smaller dummy load. As
a result, peak current compression helps further
reduce no-load consumption. The peak current
limit can be estimated from Equation (5) where
τoff is the off time of the power module:
IPeak 105mA (0.4mA / s) ( off 10s)
(5)
FB
Comparator
R
-
+
T
EA
O
N
-
+
+
Delay 170ms
36kHz
fs
(6)
Thermal Shutdown (TSD)
M
Vramp
+
Vramp
+
-
V
ref
2.55V
Ipeak
Figure 4—EA and ramp compensation
MP171 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.
MP171 Rev. 1.01
9/21/2018
When the FB voltage drops below VFB_OLP, it is
considered an error flag, and the timer starts. If
the timer reaches 170 ms (fS = 36 kHz), OLP
occurs. This timer duration avoids triggering OLP
when the power supply starts up or the load
transitions. The power supply should start up in
less than 170 ms (fS = 36 kHz). The OLP delay
time is calculated using Equation (6):
Short-Circuit Protection (SCP)
The MP171 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
VFB
The maximum output power of the MP171 is
limited by the maximum switching frequency and
the peak current limit. If the load current is too
large, the output voltage drops, causing the FB
voltage to drop.
To prevent thermal induced damage, the MP171
stops switching when the junction temperature
exceeds 150°C. During thermal shutdown (TSD),
the VCC capacitor is discharged to VCCpro, and
the the internal high-voltage regulator re-charges.
MP171 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.
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10
MP171 –NON-ISOLATED OFFLINE REGULATOR
NOT RECOMMENDED FOR NEW DESIGNS. REFER TO MP171A
Leading-Edge Blanking
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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
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Figure 5—Leading-edge blanking
MP171 Rev. 1.01
9/21/2018
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© 2021 MPS. All Rights Reserved.
11
MP171 –NON-ISOLATED OFFLINE REGULATOR
NOT RECOMMENDED FOR NEW DESIGNS. REFER TO MP171A
APPLICATION INFORMATION
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Table 1—Common topologies using MP171
Topology
Circuit Schematic
DRAIN
5
1
MP171
High-side
buck
SOURCE
4
2
3
Features
VCC
FB
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
Vin
Vo
DRAIN
1
5
MP171
High-side
buck-boost
SOURCE
2
3
4
VCC
FB
SOURCE
Vin
Vo
DRAIN
Boost
5
1
MP171
Vin
3
4
FB
Vo
SOURCE
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SOURCE
2
VCC
Flyback
T
*
Vin
*
DRAIN
1
5
MP171
SOURCE
MP171 Rev. 1.01
9/21/2018
4
2
3
VCC
FB
SOURCE
*
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12
MP171 –NON-ISOLATED OFFLINE REGULATOR
NOT RECOMMENDED FOR NEW DESIGNS. REFER TO MP171A
maximum power using Equation (7) and Equation
(8):
MP171 can be used in common topologies such
V
as buck, boost, buck-boost, and flyback (see
(7)
Po max Vo (Ipeak o min off ) , for CCM
2L
Table 1).
1 2
1 , for DCM
Component selection below is based on the
(8)
Pomax LIpeak
2
minoff
typical application of MP173 (see it on page 1).
For mass production, tolerance on the
Component Selection
parameters (such as peak current limitation) and
Input Capacitor
the minimum off time should be taken into
consideration.
The input capacitor supplies the DC input voltage
for the converter. Figure 6 shows the typical DC
Freewheeling Diode
bus voltage waveform of a half-wave rectifier and
Select a diode with a maximum reverse-voltage
a full-wave rectifier.
rating greater than the maximum input voltage
VDC(max)
Vin
and a current rating determined by the output
DC input voltage
current.
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Topology Options
VDC(min)
AC input voltage
t
Vin
The reverse recovery of the freewheeling diode
affects efficiency and circuit operation during a
CCM condition, so use an ultra-fast diode such
as the EGC10JH.
Output Capacitor
VDC(max)
DC input voltage
VDC( min)
The output capacitor is required to maintain the
DC output voltage. Estimate the output voltage
ripple using Equation (9) and Equation (10):
AC input voltage
VCCM _ ripple
t
Figure 6—Input voltage waveform
i
i RESR , for
8fsCo
(9)
2
N
O
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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.
Under very low input voltage, the inductor current
ramps up slowly; it may not reach the current
limit during τmanon, so the MOSFET maximum on
time should be less than the minimum value of
τmanon.
Inductor
The MP171 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
MP171 Rev. 1.01
9/21/2018
VDCM _ ripple
I
o
fsCo
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
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.
Sampling Capacitor
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):
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13
MP171 –NON-ISOLATED OFFLINE REGULATOR
NOT RECOMMENDED FOR NEW DESIGNS. REFER TO MP171A
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
the capacitance required under normal conditions
A dummy load is required to maintain the load
for different surge voltages. FR1 is a 20 Ω/2 W
regulation. This ensures there is sufficient
fused resistor, and L1 is 1 mH for this
inductor energy to charge the sample and hold
recommendation.
capacitor to detect the output voltage. Normally,
a 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.
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C
Vo
C
1 Vo
o CFB
o
2 R1 R2 Io
R1 R2 Io
Auxiliary VCC Supply
N
R3
D3
C2
MP171
Figure 8—Half-wave rectifier
D2
VCC
R1
FB
C3
R2
SOURCE
SOURCE
L1
VOUT
Figure 7—Auxiliary VCC supply circuit
R
For applications with VO above 7 V, the MP171
achieves the 30 mW no-load power requirement
by adopting an external VCC supply to reduce
power consumption on the internal VCC regulator
(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
recommendation 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.
MP171 Rev. 1.01
9/21/2018
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
PCB Layout Guidelines
Efficient PCB layout is critical for reliable
operation, good EMI, and thermal performance.
For best results, follow the guidelines below:
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.
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MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2021 MPS. All Rights Reserved.
14
MP171 –NON-ISOLATED OFFLINE 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
71
R
A
NOT RECOMMENDED FOR NEW DESIGNS. REFER TO MP171A
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
50 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.
MP171 Rev. 1.01
9/21/2018
www.MonolithicPower.com
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2021 MPS. All Rights Reserved.
15
MP171 –NON-ISOLATED OFFLINE REGULATOR
NOT RECOMMENDED FOR NEW DESIGNS. REFER TO MP171A
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
71
R
A
Figure 9 shows a typical application example of a 5 V, 50 mA non-isolated power supply using the
MP171.
D1
R1
41.2 K
SRGC10JH
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/50 mA
L2
1 mH
Vout
MP171GS
D3
STTH1R06
600 V/1 A
C5
C6
R3
22 µF
NC
1.2 K
D4
N
SRJC10JH
GND
GND
N
O
T
R
Figure 9—Typical application at 5 V, 50 mA
MP171 Rev. 1.01
9/21/2018
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MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2021 MPS. All Rights Reserved.
16
MP171 –NON-ISOLATED OFFLINE REGULATOR
NOT RECOMMENDED FOR NEW DESIGNS. REFER TO MP171A
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
71
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
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