NCP1012GEVB ON Semiconductor, NCP1012GEVB Datasheet - Page 10

• Manufacturer Part Number: NCP1012GEVB
• Description: EVAL BOARD FOR NCP1012G
• Manufacturer: ON Semiconductor

Specifications of NCP1012GEVB

• Design Resources: NCP1012 Eval Brd BOM NCP1012GEVB Gerber Files NCP1012 Eval Brd Schematic
• Main Purpose: AC/DC, Primary Side
• Outputs And Type: 1, Isolated
• Voltage - Output: 12V
• Voltage - Input: 230VAC
• Regulator Topology: Flyback
• Frequency - Switching: 100kHz
• Board Type: Fully Populated
• Utilized Ic / Part: NCP1012
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Current - Output: -
• Power - Output: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant
• For Use With/related Products: NCP1012G
• Other names: NCP1012GEVBOS

is expressed by:
the IC actually pulses is given by
Finally,
using the same formula topology:
From these three definitions, the burst duty- -cycle
can be computed:
equation with values extracted from the parameter section
gives a typical duty- -cycle of 13%, precluding any lethal
thermal runaway while in a fault condition.
DSS Internal Dissipation
drain pin. In Flyback- -based converters, this drain level can
easily go above 600 V peak and thus increase the stress on the
DSS startup source. However, the drain voltage evolves with
time and its period is small compared to that of the DSS. As
a result, the averaged dissipation, excluding capacitive losses,
can be derived by:
Figure 17 portrays a typical drain- -ground waveshape where
leakage effects have been removed.
dc =
The rising slope from the latch- -off level up to 8.5 V
The Dynamic Self- -Supplied pulls energy out from the
ICC1 ·
the

ICC1
ΔV2
ΔV2
Tstart =
latch- -off
+
P DSS = ICC1 · < Vds(t) > .
ΔV1
IC1
dc =
+
ΔV1 · C
ICC2
Tstart + Tsw + TLatch
ΔV3
IC1
Figure 16. NCP101X Facing a Fault Condition (Vin = 150 Vdc)
time

Tstart
(eq. 3)
. The time during which
Tsw
can
TLatch =
.
Tsw
tsw =
Feeding
be
ΔV3 · C
ΔV2 · C
derived
ICC2
ICC1
(eq. 2)
(eq. 4)
http://onsemi.com
the
TLatch
.
.
.
.
10
derived by additive square area calculation:
toff can be expressed by:
can be evaluated by:
1 V Ripple
By looking at Figure 17, the average result can easily be
By developing Equation 5, we obtain:
Vds(t)
Figure 17. A typical drain- -ground waveshape
where leakage effects are not accounted for.
Latch--off
< Vds(t) >= Vin − Vin · ton
Vin
Level
< Vds(t) >= Vin · (1 − d) + Vr · toff
ton
Vr
Tsw
ton = Ip ·
toff
toff = Ip ·
dt
Vin
Lp
Tsw
(eq. 8)
Lp
Vr
+ Vr · toff
(eq. 7)
.
Tsw
Tsw
where ton
(eq. 5)
(eq. 6)
t