MP020A-5GS [MPS]

Offline, Primary-Side Regulator with CC/CV Control and a 700V MOSFET;
MP020A-5GS
型号: MP020A-5GS
厂家: MONOLITHIC POWER SYSTEMS    MONOLITHIC POWER SYSTEMS
描述:

Offline, Primary-Side Regulator with CC/CV Control and a 700V MOSFET

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MP020A-5  
Offline, Primary-Side Regulator  
with CC/CV Control and a 700V MOSFET  
DESCRIPTION  
FEATURES  
The MP020A-5 is an offline, primary-side  
regulator that provides accurate constant  
voltage and constant current regulation without  
an optocoupler or a secondary feedback circuit.  
The MP020A-5 has an integrated 700V  
MOSFET.  
Primary-Side Control without Optocoupler or  
Secondary Feedback Circuit  
Precise Constant Current and Constant  
Voltage Control (CC/CV)  
Integrated 700V MOSFET with Minimal  
External Components  
Variable Off Time, Peak-Current Control  
550µA High-Voltage Current Source  
30mW No-Load Power Consumption  
Programmable Cable Compensation  
OVP, OCP, OCkP, OTP, and VCC UVLO  
Natural Spectrum Shaping for Improved  
EMI Signature  
The MP020A-5's variable off-time control allows  
a flyback converter to operate in discontinuous  
conduction mode (DCM). The MP020A-5 also  
features protection functions such as VCC  
under-voltage lockout (UVLO), over-current  
protection (OCP), over-temperature protection  
(OTP), open-circuit protection (OCkP), and  
over-voltage protection (OVP). Its internal high-  
voltage start-up current source and power-  
saving technologies limit the no-load power  
consumption to less than 30mW.  
Low Cost and Simple External Circuit  
Available in a SOIC8-7A Package  
APPLICATIONS  
Cell Phone Chargers  
The MP020A-5's variable switching frequency  
technology provides natural spectrum shaping  
to smooth the EMI signature, making it suitable  
for offline, low-power battery chargers and  
adapters.  
Adapters for Handheld Electronics  
Standby and Auxiliary Power Supplies  
Small Appliances  
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.  
The MP020A-5 is available in a SOIC8-7A  
package.  
Maximum Output  
Power (85 - 265VAC  
)
Part Number RDS(ON)  
Open  
Adapter  
Frame  
MP020A-5GS  
10Ω  
5W  
8W  
TYPICAL APPLICATION  
MP020A-5 Rev. 1.0  
www.MonolithicPower.com  
1
6/23/2017  
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© 2017 MPS. All Rights Reserved.  
MP020A-5 OFFLINE, PRIMARY-SIDE REGULATOR W/ CC/CV CONTROL AND 700V MOSFET  
ORDERING INFORMATION  
Part Number*  
Package  
Top Marking  
MP020A-5GS  
SOIC8-7A  
See Below  
* For Tape & Reel, add suffix Z (e.g. MP020A-5GSZ)  
TOP MARKING  
MP020A-5: Product code of MP020A-5GS  
LLLLLLLL: Lot number  
MPS: MPS prefix  
Y: Year code  
WW: Week code  
PACKAGE REFERENCE  
TOP VIEW  
SOIC8-7A  
MP020A-5 Rev. 1.0  
6/23/2017  
www.MonolithicPower.com  
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© 2017 MPS. All Rights Reserved.  
2
MP020A-5 OFFLINE, PRIMARY-SIDE REGULATOR W/ CC/CV CONTROL AND 700V MOSFET  
ABSOLUTE MAXIMUM RATINGS (1)  
DRAIN to GND............................. -0.7V to 700V  
VCC to GND.................................. -0.3V to 30V  
CP to GND....................................... -0.3V to 7V  
FB input......................................... -0.7V to 10V  
Thermal Resistance (4) θJA  
SOIC8-7A ............................. 76.......45 ... °C/W  
θJC  
NOTES:  
1) Exceeding these ratings may damage the device.  
2) The maximum allowable power dissipation is a function of the  
maximum junction temperature TJ (MAX), the junction-to-  
ambient thermal resistance θJA, and the ambient temperature  
TA. The maximum allowable continuous power dissipation at  
any ambient temperature is calculated by PD (MAX) = (TJ  
(MAX)-TA)/θJA. Exceeding the maximum allowable power  
dissipation produces an excessive die temperature, causing  
the regulator to go into thermal shutdown. Internal thermal  
shutdown circuitry protects the device from permanent  
damage.  
(2)  
Continuous power dissipation (TA = +25°C)  
SOIC8-7A..................................................1.3W  
Junction temperature...............................150°C  
Lead temperature ....................................260°C  
Storage temperature................-60°C to +150°C  
ESD capability human body mode ............2.0kV  
ESD capability machine mode ...................200V  
3) The device is not guaranteed to function outside of its  
operating conditions.  
Recommended Operating Conditions (3)  
Operating junction temp. (TJ). ..-40°C to +125°C  
Operating VCC range ..................... 6.6V to 28V  
4) Measured on JESD51-7, 4-layer PCB.  
MP020A-5 Rev. 1.0  
6/23/2017  
www.MonolithicPower.com  
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© 2017 MPS. All Rights Reserved.  
3
MP020A-5 OFFLINE, PRIMARY-SIDE REGULATOR W/ CC/CV CONTROL AND 700V MOSFET  
ELECTRICAL CHARACTERISTICS  
VCC = 15V, TA = 25°C, unless otherwise noted.  
Parameter  
Symbol Condition  
Min  
Typ  
Max  
Units  
Supply Voltage Management (VCC)  
VCC on threshold  
VCCH  
VCCL  
16.8  
6
17.3  
6.3  
17.8  
6.6  
V
V
VCC off threshold  
VCC operating voltage  
Quiescent current  
6.6  
28  
V
IQ  
At no load condition, VCC = 20V  
60kHz, VCC = 20V  
360  
500  
0.1  
410  
μA  
μA  
μA  
Operating current  
IOP  
Leakage current from VCC  
Internal MOSFET (DRAIN)  
Break-down voltage  
Supply current from DRAIN  
ILeak_VCC VCC = 0 16V, DRAIN floating  
1
VBRDSS VCC = 20V, VFB = 7V  
700  
450  
V
ICharge VCC = 4V, VDRAIN = 100V  
550  
1
750  
10  
µA  
µA  
Leakage current from DRAIN ILeak_Drain VDS = 500VDC  
On-state resistance  
Minimum switching frequency  
Internal Current Sense  
Current limit  
RON  
fMIN  
ID = 10mA, TJ = 20°C  
At no load condition  
10  
13  
120  
Hz  
ILimit  
tLEB  
VFB = -0.5V  
365  
230  
380  
300  
395  
370  
mA  
ns  
Leading-edge blanking  
Feedback Input (FB)  
FB input current  
IFB  
VFB  
VFB = 4V, VCP = 3V  
10  
3.93  
80  
14  
4
18  
4.07  
160  
-0.08  
6.5  
μA  
V
FB threshold  
DCM detect threshold  
FB open-circuit threshold  
FB OVP threshold  
VDCM  
VFBOPEN  
VFBOVP  
tOVP  
120  
-0.15  
6.35  
3.5  
mV  
V
-0.22  
6.2  
V
OVP sample delay  
µs  
Output Cable Compensation (CP)  
Cable compensation voltage  
Thermal Shutdown  
VCP  
Full load  
2
V
Thermal shutdown threshold  
150  
120  
°C  
°C  
Thermal shutdown recovery  
threshold  
MP020A-5 Rev. 1.0  
www.MonolithicPower.com  
4
6/23/2017  
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© 2017 MPS. All Rights Reserved.  
MP020A-5 OFFLINE, PRIMARY-SIDE REGULATOR W/ CC/CV CONTROL AND 700V MOSFET  
TYPICAL CHARACTERISTICS  
MP020A-5 Rev. 1.0  
6/23/2017  
www.MonolithicPower.com  
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© 2017 MPS. All Rights Reserved.  
5
MP020A-5 OFFLINE, PRIMARY-SIDE REGULATOR W/ CC/CV CONTROL AND 700V MOSFET  
TYPICAL CHARACTERISTICS (continued)  
MP020A-5 Rev. 1.0  
6/23/2017  
www.MonolithicPower.com  
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6
MP020A-5 OFFLINE, PRIMARY-SIDE REGULATOR W/ CC/CV CONTROL AND 700V MOSFET  
TYPICAL PERFORMANCE CHARACTERISTICS  
Performance waveforms are tested on the evaluation board in the Design Example section.  
VIN = 230VAC, VOUT = 5V, IOUT = 1A, L = 1.6mH, TA = 25°C, unless otherwise noted.  
MP020A-5 Rev. 1.0  
6/23/2017  
www.MonolithicPower.com  
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© 2017 MPS. All Rights Reserved.  
7
MP020A-5 OFFLINE, PRIMARY-SIDE REGULATOR W/ CC/CV CONTROL AND 700V MOSFET  
TYPICAL PERFORMANCE CHARACTERISTICS (continued)  
Performance waveforms are tested on the evaluation board in the Design Example section.  
VIN = 230VAC, VOUT = 5V, IOUT = 1A, L = 1.6mH, TA = 25°C, unless otherwise noted.  
MP020A-5 CV/CC Characteristics  
25CV/CC  
5
4
3
2
265Vac  
230Vac  
115Vac  
1
85Vac  
0
0
0.1  
0.2  
0.3  
0.4  
0.5 0.6  
Io(A)  
0.7  
0.8  
0.9  
1
1.1  
MP020A-5 Rev. 1.0  
6/23/2017  
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8
MP020A-5 OFFLINE, PRIMARY-SIDE REGULATOR W/ CC/CV CONTROL AND 700V MOSFET  
PIN FUNCTIONS  
SOIC8-7A  
Pin #  
Name Description  
Supply. The IC begins functioning when VCC charges to the on threshold (VCCH) through  
an internal high-voltage current source. When VCC falls below the off threshold (VCCL),  
the internal high-voltage current source turns on to charge VCC. Connect a 0.1µF  
decoupling ceramic capacitor for most applications.  
1
VCC  
2, 5, 6  
3
GND  
FB  
Ground.  
Feedback. FB provides the output reference voltage and detects the falling voltage  
edges to determine the operation mode (CV mode or CC mode).  
Output cable compensation. Connect a 1μF ceramic capacitor as a low pass filter. The  
upper resistor of the resistor divider connected to FB adjusts the compensation voltage.  
4
8
CP  
DRAIN Internal MOSFET drain. DRAIN is the input for the high-voltage start-up current source.  
MP020A-5 Rev. 1.0  
6/23/2017  
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MP020A-5 OFFLINE, PRIMARY-SIDE REGULATOR W/ CC/CV CONTROL AND 700V MOSFET  
BLOCK DIAGRAM  
Protection  
Unit  
Power  
Management  
VCC  
FB  
Start Up Unit  
Constant  
Current Control  
DRV  
Drain  
Driving Signal  
Management  
Constant  
Voltage Control  
Current  
Sense  
Cable  
Compensation  
GND  
CP  
Figure 1: Functional Block Diagram  
MP020A-5 Rev. 1.0  
6/23/2017  
www.MonolithicPower.com  
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10  
MP020A-5 OFFLINE, PRIMARY-SIDE REGULATOR W/ CC/CV CONTROL AND 700V MOSFET  
Working Principle  
OPERATION  
After start-up, the internal MOSFET turns on,  
and the current sense resistor (RCS) senses the  
primary current (iP(t)) internally (see Figure 3).  
The current rises linearly at a rate that can be  
calculated with Equation (1):  
Start-Up  
Initially, the IC is self-supplying through an  
internal high-voltage current source, which is  
drawn from DRAIN. The internal high-voltage  
current source turns off for better efficiency  
when VCC reaches its on threshold (VCCH).  
Then the transformer’s auxiliary winding takes  
over as the power source. When VCC falls  
below its off threshold (VCCL), the IC stops  
switching, and the internal high-voltage current  
source turns on again (see Figure ).  
diP(t)  
dt  
V
IN  
(1)  
LM  
IPK  
iP  
Vcc  
0
VCCH  
VCCL  
Figure 1: Primary Current Waveform  
When iP(t) rises up to IPK, the internal MOSFET  
turns off (see Figure 4). Then the energy stored  
in the inductor transfers to the secondary side  
through the transformer.  
Drain  
SwitchingPulses  
The inductor (LM) stores energy with each cycle  
as a function shown in Equation (2):  
1
E LM IP2K  
(2)  
High-voltage  
current source  
2
ON  
The power transferred from the input to the  
output can be determined with Equation (3):  
1
OFF  
P LM IP2K fS  
(3)  
2
Where fS is the switching frequency. When IPK is  
constant, the output power depends on fS.  
Figure 2: VCC UVLO  
Constant Voltage (CV) Operation  
The MP020A-5 detects the auxiliary winding  
voltage from FB and operates in constant  
voltage (CV) mode to regulate the output  
voltage. Assume the secondary winding is the  
master and the auxiliary winding is the slave.  
When the secondary-side diode turns on, the  
FB voltage can be calculated with Equation (4):  
N
RDOWN  
VFB P _ AU (VO VD )  
(4)  
NS  
RUP RDOWN  
Where VD is the secondary-side diode forward-  
drop voltage, Vo is the output voltage, NP_AU is  
the number of auxiliary winding turns, NS is the  
number of secondary side winding turns, and  
RUP and RDOWN are the resistor divider for  
sampling.  
Figure 3: Simplified Flyback Converter  
MP020A-5 Rev. 1.0  
6/23/2017  
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MP020A-5 OFFLINE, PRIMARY-SIDE REGULATOR W/ CC/CV CONTROL AND 700V MOSFET  
Leading-Edge Blanking  
The parasitic capacitances induce a spike on  
the sense resistor when the power switch turns  
on. The MP020A-5 includes a 300ns leading-  
edge blanking period to avoid falsely  
terminating the switching pulse. During this  
blanking period, the current sense comparator  
Figure 2: Auxiliary Voltage Waveform  
is disabled, and the gate driver cannot switch  
off (see Figure 4).  
The output voltage differs from the secondary  
voltage due to the current-dependent forward-  
diode voltage drop. If the secondary voltage is  
always detected at a fixed secondary current,  
the difference between the output voltage and  
the secondary voltage is a fixed VD. The  
MP020A-5 samples the auxiliary winding  
voltage 3.5µs after the primary switch turns off  
(see Figure 5). The CV loop control function  
turns the secondary-side diode off to regulate  
the output voltage.  
tLEB  
VLimit  
t
Figure 4: Leading-Edge Blanking  
Constant Current (CC) Operation  
DCM Detection  
Figure 3 shows the constant-current operation.  
The MP020A-5 operates in DCM in both CV  
and CC modes. To avoid operating in  
continuous conduction mode (CCM), the  
MP020A-5 detects the falling edge of the FB  
input voltage with each cycle. If the chip does  
not detect a 120mV falling edge, it stops  
switching.  
VFB  
ZCD  
Sample  
VZCD  
IPK  
VCOMP_I  
Io estimator  
IO_REF  
OVP and OCkP  
Figure 3: CC Control Loop  
The MP020A-5 includes over-voltage protection  
(OVP) and open-circuit protection (OCkP). If the  
voltage at FB exceeds 6.35V for 3.5µs, or the  
FB input’s 0.15V falling edge cannot be  
monitored, the MP020A-5 immediately shuts off  
the driving signals and enters hiccup mode. The  
MP020A-5 resumes normal operation when the  
fault has been removed.  
The flyback always works in discontinuous  
conduction mode (DCM), and the zero-current  
detection (ZCD) sample block can detect the  
duty cycle of the secondary-side diode.  
In constant current (CC) operation, the product  
of VZCD times Ipk approximately equals IO_REF, as  
shown in Equation (5):  
Thermal Shutdown  
(5)  
IO_REF VZCD IPK  
When the temperature of the IC exceeds 150°C,  
over-temperature protection (OTP) is triggered,  
and the IC enters auto-recovery mode. When  
the temperature falls below 120°C, the IC  
recovers.  
The calculated output current from the IO  
estimator block is compared with the reference  
value (IO_REF), and the error signal (VCOMP_I  
controls the turn-on signal of the integral  
MOSFET. IO can be calculated with Equation  
(6):  
)
1 NP  
(6)  
IO   
IO _REF  
2 NS  
The MP020A-5 maintains IO_REF at 0.152A.  
MP020A-5 Rev. 1.0  
www.MonolithicPower.com  
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6/23/2017  
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MP020A-5 OFFLINE, PRIMARY-SIDE REGULATOR W/ CC/CV CONTROL AND 700V MOSFET  
Output Cable Compensation  
Determine the compensation voltage with  
Equation (7):  
To compensate for the secondary-side cable  
voltage drop for a more precise output voltage,  
the MP020A-5 has an internal output cable  
compensation circuit (see Figure 5). The  
internal ZCD sample can detect the duty of the  
secondary-side diode. A low-pass filter converts  
the duty signal to a DC voltage (VCP) that  
changes as the load current varies.  
5.6DS  
360103  
NS  
(7)  
VFCP  
2RUP   
N
P _ AU  
Where  
VFCP  
is  
the  
secondary-side  
compensation voltage drop, DS is the  
secondary-diode duty cycle in CC mode (0.4 for  
the MP020A-5), RUP is the upper resistor of the  
resistor divider, NS is the number of turns for the  
secondary-side transformer windings, and NP_AU  
is the number of transformer auxiliary winding  
turns.  
VCP can be converted to a current signal drawn  
from FB. The voltage drop on RUP helps the  
output cable compensation. When the system  
operates in the maximum load, the CP voltage  
reaches a maximum of 2V.  
T1  
RUP  
VFCP  
*
*
Vo  
FB  
RDOWN  
-
+
VCP  
CP  
DS  
Figure 5: Output Cable Compensator  
MP020A-5 Rev. 1.0  
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MP020A-5 OFFLINE, PRIMARY-SIDE REGULATOR W/ CC/CV CONTROL AND 700V MOSFET  
Output Capacitor  
APPLICATION INFORMATION  
Use low ESR or very low ESR output capacitors  
to meet the output voltage ripple requirement  
without using an LC post filter. Using low ESR  
capacitors improves output voltage regulation  
and feedback voltage sampling at high  
temperatures or low temperatures. Use an  
output capacitor with an ESR below 100mΩ for  
better efficiency over high ESR output  
capacitors.  
Input Filter  
The input filter helps convert the AC input to a  
DC source through the rectifier. Figure 6 shows  
the input filter, and Figure 7 shows the typical  
DC bus voltage waveform.  
L
+
R
Output Diode  
C2  
C1  
+
+
AC Input  
DC Input  
Use a Schottky diode because of its fast  
switching speed and low forward-voltage drop  
for better high- or low-temperature CV  
regulation and efficiency.  
If the lower average efficiency (3% to 4%) is  
sufficient, replace the output diode with a fast or  
ultra-fast diode to reduce costs. Be sure to  
readjust the resistor divider values to the  
correct output voltage because the forward  
voltage drop is higher than the Schottky diode’s.  
Figure 6: Input Filter  
VDC(max)  
Vin  
DC input voltage  
VDC(min)  
AC input voltage  
Leakage Inductance  
The  
transformer’s  
leakage  
inductance  
decreases the system efficiency and affects the  
output current or voltage constant precision.  
Optimize the transformer structure to minimize  
the leakage inductance. Aim for a leakage  
inductance less than 5% of the primary  
inductance.  
VAC  
t
0
Figure 7: DC Input Voltage Waveform  
Bulk capacitors (C1 and C2) filter the rectified  
AC input. The inductor (L) forms a π filter with  
C1 and C2 to restrain the differential mode EMI  
noise. The resistor (R) parallel with L restrains  
the mid-frequency band EMI noise. Normally, R  
is 1 - 10k.  
RCD Snubber  
The transformer’s leakage inductance causes  
the MOSFET drain voltage to spike and  
excessive ringing on the drain voltage  
waveform, which affects the output voltage  
sampling 3.5µs after the MOSFET turns off.  
C1 and C2 are usually set as 2µF/W to 3µF/W  
for the universal input condition. For 230VAC  
single-range applications, halve the capacitor  
values. Avoid using very low minimum DC  
voltages to ensure that the converter can  
supply the maximum power load, which can be  
calculated with Equation (8):  
The RCD snubber circuit can limit the DRAIN  
voltage spike. Figure 8 shows the RCD snubber  
circuit.  
NP  
NS  
DS  
(8)  
VDC(min)  
(VO VD )  
1DS  
If VDC(min) cannot satisfy this expression,  
increase the value of the input capacitors to  
increase VDC(min)  
.
MP020A-5 Rev. 1.0  
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MP020A-5 OFFLINE, PRIMARY-SIDE REGULATOR W/ CC/CV CONTROL AND 700V MOSFET  
The damping resistor in series with the RCD  
has a relatively large value to prevent any  
excessive voltage ringing that can affect the CV  
sampling and increase the output ripple. Use a  
200 - 500Ω damping resistor to restrain the  
drain-voltage ringing.  
Divided Resistor  
For better application performance, select the  
resistor divider’s total value to be between 40 -  
100kΩ. Smaller resistors draw larger currents  
from the auxiliary winding, which increases the  
no-load consumption. Larger resistors may also  
pick up noise from adjacent components.  
Figure 8: RCD Snubber  
If necessary, use a resistor between 1kΩ and  
2kΩ connected between the FB and resistor  
divider. RFB can also limit substrate injection  
current effects (see Figure 9).  
Select RSN and CSN to meet the voltage spike  
requirements and improve system operation.  
The power dissipated in the snubber circuit can  
be approximated with Equation (9):  
VSN  
1
2
LK IPK2   
fS  
(9)  
P
SN  
VSN NPS VO  
Where LK is the leakage inductance, VSN is the  
clamp voltage, and NPS is the turn ratio of  
primary and secondary side.  
Since RSN consumes the majority of the power,  
RSN is approximated with Equation (10):  
2
VSN  
(10)  
RSN  
P
Figure 9: Feedback Resistor Divider Circuit  
SN  
For more accurate CV regulation, the accuracy  
of these feedback resistors should be at least  
1%.  
The maximum ripple of the snubber capacitor  
voltage can then be calculated with Equation  
(11):  
Dummy Load  
VSN  
VSN   
(11)  
When the system operates without a load and  
no dummy load, the output voltage rises above  
the normal operation because of the minimum  
switching frequency limitation. Use a dummy  
load for good load regulation. However, a large  
dummy load deteriorates efficiency and no-load  
consumption, so selecting the dummy load is  
tradeoff between efficiency and load regulation.  
For most applications, use a dummy load  
around 10mW, which satisfies the 30mW  
requirement.  
CSN RSN fS  
Generally, a 15% ripple is reasonable, so CSN  
can be estimated with Equation (11) as well.  
Normally, select a time constant (τ = RSN x CSN)  
below 0.1ms for better CV sampling. Adjust the  
resistor based on the power loss and the  
acceptable  
applications.  
clamp  
voltage in  
practical  
MP020A-5 Rev. 1.0  
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MP020A-5 OFFLINE, PRIMARY-SIDE REGULATOR W/ CC/CV CONTROL AND 700V MOSFET  
Maximum Switching Frequency  
Use a secondary-side diode conduction time  
that exceeds 5.4µs, as shown in Equation (12):  
NS LM  
NP (VO VD )  
(12)  
5.4s  
TS _ON IPK   
For high- or low-temperature applications,  
select a maximum switching frequency below  
75kHz.  
PCB Layout Guide  
Efficient PCB layout is critical for reliable  
operation, good EMI, and good thermal  
performance. For best results, refer to Figure  
10 and follow the guidelines below.  
Top Layer  
1. Minimize the loop area formed by the input  
capacitor, the MP020A-5 drain-source, and  
the primary winding to reduce EMI noise.  
2. Provide at least 1in2 of top-side copper for  
adequate heat-sinking.  
3. The copper area connected to GND is the  
heat conduction path for the MP020A-5.  
4. Minimize the clamp circuit loop to reduce  
EMI.  
Bottom Layer  
Figure 10: Recommended Layout  
5. Minimize the secondary loop area of the  
output diode and output filter to reduce EMI  
noise.  
Design Example  
Table 1 shows a design example following the  
application guidelines based the specifications  
below.  
6. Provide sufficient copper area at the anode  
and cathode terminal of the output diode to  
act as a heat sink.  
Table 1: Design Example  
VIN  
VOUT  
IOUT  
fS  
85 ~ 265VAC  
5V  
7. Place the AC input away from the switching  
nodes to minimize the noise coupling that  
may bypass the input filter.  
1A  
60kHz  
Figure 14 through Figure 16 show the detailed  
application schematic. This circuit was used for  
the typical performance and circuit waveforms.  
For more device applications, please refer to  
the related evaluation board datasheets.  
8. Place the bypass capacitor as close as  
possible to the IC and source.  
9. Place the feedback resistors next to FB.  
10. Minimize the feedback sampling loop to  
minimize noise coupling.  
The transformer structure used in Figure 14 can  
benefit from passing the 3-wire conducted EMI  
test (output GND connect to earth) without the  
Y-cap. The Y-cap results in leakage current,  
which is prohibited in some cell phone charger  
applications. Figure 15 illustrates how the  
common noise of the secondary-side diode is  
restrained. The secondary-side winding splits to  
two separate windings (NSEC1 and NSEC2), which  
11. Use a single-point connection at the  
negative terminal of the input filter capacitor  
for the MP020A-5 source pin and bias  
winding return.  
MP020A-5 Rev. 1.0  
6/23/2017  
www.MonolithicPower.com  
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.  
© 2017 MPS. All Rights Reserved.  
16  
 
MP020A-5 OFFLINE, PRIMARY-SIDE REGULATOR W/ CC/CV CONTROL AND 700V MOSFET  
have the same turns and approximate parasitic  
capacitors (CSP1 and CSP2), but their hot spot is  
opposite (Point 9 and Point 10 in Figure 15).  
Therefore, the common mode noise current  
produced at the secondary-side windings can  
counteract each other.  
The transformer structure is simple if the  
application does not need to pass the 3-wire  
conducted EMI or uses a Y-cap. Figure 16  
shows a schematic with a simple transformer  
structure.  
MP020A-5 Rev. 1.0  
6/23/2017  
www.MonolithicPower.com  
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.  
© 2017 MPS. All Rights Reserved.  
17  
MP020A-5 OFFLINE, PRIMARY-SIDE REGULATOR W/ CC/CV CONTROL AND 700V MOSFET  
TYPICAL APPLICATION CIRCUITS  
Figure 11: 5V/1A with Complicated Transformer Structure  
Figure 15: Secondary Side Windings Structure to Restrain the Common Mode Noise  
MP020A-5 Rev. 1.0  
6/23/2017  
www.MonolithicPower.com  
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.  
© 2017 MPS. All Rights Reserved.  
18  
MP020A-5 OFFLINE, PRIMARY-SIDE REGULATOR W/ CC/CV CONTROL AND 700V MOSFET  
TYPICAL APPLICATION CIRCUITS  
Figure 16: 5V/1A with Simple Transformer Structure  
MP020A-5 Rev. 1.0  
6/23/2017  
www.MonolithicPower.com  
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.  
© 2017 MPS. All Rights Reserved.  
19  
MP020A-5 OFFLINE, PRIMARY-SIDE REGULATOR W/ CC/CV CONTROL AND 700V MOSFET  
FLOW CHART  
Start  
Y
VCC<VCCL  
Monitor VCC  
N
N
Monitor VCC  
VCC>VCCH  
Y
N
Monitor Io  
Monitor VFB  
N
VFB>-0.15V  
for entire  
cycle  
VFB>6.35V  
for 3.5us  
Y
Io<Io_ref  
Y
N
Y
CV  
CC  
OVP  
OCkP  
Operation  
Operation  
Operation  
Operation  
Shut Off  
Switching  
Pulse  
Figure 17: Flow Chart  
MP020A-5 Rev. 1.0  
www.MonolithicPower.com  
20  
6/23/2017  
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.  
© 2017 MPS. All Rights Reserved.  
MP020A-5 OFFLINE, PRIMARY-SIDE REGULATOR W/ CC/CV CONTROL AND 700V MOSFET  
PACKAGE INFORMATION  
SOIC8-7A  
0.189(4.80)  
0.197(5.00)  
0.050(1.27)  
0.024(0.61)  
8
5
0.063(1.60)  
0.150(3.80)  
0.157(4.00)  
0.228(5.80)  
0.244(6.20)  
0.213(5.40)  
PIN 1 ID  
1
4
TOP VIEW  
RECOMMENDED LAND PATTERN  
0.053(1.35)  
0.069(1.75)  
0.0075(0.19)  
0.0098(0.25)  
SEATING PLANE  
0.004(0.10)  
0.010(0.25)  
0.013(0.33)  
0.020(0.51)  
SEE DETAIL "A"  
SIDE VIEW  
0.050(1.27)  
BSC  
FRONT VIEW  
0.010(0.25)  
0.020(0.50)  
x 45o  
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.  
GAUGE PLANE  
0.010(0.25) BSC  
3) PACKAGE WIDTH DOES NOT INCLUDE INTERLEAD FLASH  
OR PROTRUSIONS.  
4) LEAD COPLANARITY(BOTTOM OF LEADS AFTER FORMING)  
SHALL BE0.004" INCHES MAX.  
0.016(0.41)  
0.050(1.27)  
0o-8o  
5) JEDEC REFERENCE ISMS-012.  
6) DRAWING IS NOT TO SCALE.  
DETAIL "A"  
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.  
MP020A-5 Rev. 1.0  
6/23/2017  
www.MonolithicPower.com  
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.  
© 2017 MPS. All Rights Reserved.  
21  

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