NCP1203GEVB ON Semiconductor, NCP1203GEVB Datasheet - Page 7

• Manufacturer Part Number: NCP1203GEVB
• Description: EVAL BOARD FOR NCP1203G
• Manufacturer: ON Semiconductor

Specifications of NCP1203GEVB

• Design Resources: NCP1203GEVB BOM NCP1203GEVB Gerber Files NCP1203 EVB Schematic
• Main Purpose: AC/DC, Primary Side
• Outputs And Type: 1, Isolated
• Voltage - Output: 19V
• Current - Output: 4A
• Voltage - Input: 85 ~ 230VAC
• Regulator Topology: Flyback
• Frequency - Switching: 60kHz
• Board Type: Fully Populated
• Utilized Ic / Part: NPC1200
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Power - Output: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant
• For Use With/related Products: NCP1203G
• Other names: NCP1203GEVBOS

maximum RMS current occur at the lowest line where the
duty-cycle is pushed to the limit.
subharmonic oscillations can be noted. Once everything is
extracted, below are summarized the most important design
constraints:
MOSFET
simulated losses, including switching events are evaluated to
be around 2.6 W. Further breadboard measurements confirmed
this number. If we want to keep the junction temperature
around 100 C at an ambient of 50 C, then we shall add a
proper heatsink according to the following calculation:
Rq
Important results appear in Figure 9. Please note that the
As you can see, the ramp compensation works fine and no
Rdson @ 100 C = 1.2 ohms
RthetaJC = 2.8 C/W
Pcond = 1.2 * 1.1
The conduction losses are the strongest at low line. The total
heatsink- air
800 M
-1.00
10.00
-2.00
-6.00
3.00
2.00
1.00
2.40
2.00
1.60
1.20
6.00
2.00
156
154
152
150
148
Figure 9. Complete Simulation Results of the 70 W Converter Operated at 120 VDC Input Voltage
0
1
Idrain
+
[ 15°C W
* Rq
(Tj
2.01 M
2
= 1.5 W
max
Junction- Case
2
* Tamb
Iprim
P
max
3
* Rq
Iripple1
)
2.03 M
Case- Heatsink
4
VCLAMP
http://onsemi.com
AND8076/D
2.05 M
7
y (mean) = 152 volts
x (first) = 2.00 M secs
Lower R
run the device cooler.
Diode
equal current thanks to their equal forward drops. The total
forward drop dissipation will remain the same but the RMS
losses sensitive to the dynamic resistance will divide by two:
or 3.7 W for the whole TO-220 package. Simulations gives
a bit less to 3.4 W. Heat calculations (Tj < 100 C and 50 C
ambient) recommend a heatsink of 8 C/W for the
MBR20100. As stated before, lower R
resistances can of course be selected to run the device cooler.
Capacitors
ripple current shared between all the devices. We selected
three 2.2 mF capacitors capable of handling 1.7 Arms each.
The MBR20100 welcomes two diodes that share nearly
I
I
Rd @ 3.4 A
Vf @ 2.2 A
Pcond for one diode = 3.4
Icapacitor RMS = 5 A
The paralleling of capacitors will help achieve the right
RMS = 4.65 amps between
2.04 M and 2.05 M secs
RMS
AVG
RMS = 1.53 amps between
2.05 M and 2.06 M secs
total = Iout = 4.2 A
total = 6.8 A
RMS = 1.10 amps between
2.05 M and 2.06 M secs
heatsink- air
avg
rms
2.07 M
= 0.7 V
= 27 m
resistances can of course be selected to
2
0.027 + 2.2 0.7 = 1.85 W
2.09 M
heatsink- air
1
2
3
4