NCP1216AFORWEVB ON Semiconductor, NCP1216AFORWEVB Datasheet - Page 10

• Manufacturer Part Number: NCP1216AFORWEVB
• Description: Power Management IC Development Tools NCP1216A 35W FORWRD EVB
• Manufacturer: ON Semiconductor
• Type: PWM Controllersr

Specifications of NCP1216AFORWEVB

• Product: Evaluation Boards
• Tool Is For Evaluation Of: NCP1216A

Dynamic Self−Supply
V
can easily describe the current source operation with a bunch
of simple logical equations:
is ON, no output pulses
OFF, output is pulsing
ON, output is pulsing
offers the necessary light:
consumption and the MOSFET’s gate charge Q
select a 600 V 10 A MOSFET featuring a 30 nC Q
can compute the resulting average consumption supported
by the DSS which is:
The total IC heat dissipation incurred by the DSS only is
given by:
Suppose that we select the NCP1216P065 with the above
MOSFET, the total current is
Supplied from a 350 VDC rail (250 VAC), the heat
dissipated by the circuit would then be:
As you can see, it exists a tradeoff where the dissipation
capability of the NCP1216 fixes the maximum Q
circuit can drive, keeping its dissipation below a given
target. Please see the “Power Dissipation” section for a
complete design example and discover how a resistor can
help to heal the NCP1216 heat equation.
CC
I total [ F sw
I total
(30 n
350 V
The DSS principle is based on the charge/discharge of the
POWER−ON: If V
If V
If V
Typical values are: VCC
To better understand the operational principle, Figure 18
The DSS behavior actually depends on the internal IC
bulk capacitor from a low level up to a higher level. We
Figure 18. The Charge/Discharge Cycle Over a
CC
CC
V
10
ripple
decreasing > VCC
increasing < VCC
V pin8 .
65 k) ) 900 m + 2.9 mA.
2.9 mA + 1 W
= 2.2 V
ON, I = 8 mA
Q g ) I CC1 .
30
10 mF V
CC
< VCC
OFF
CC
OFF
50
ON
Capacitor
VCC
Output Pulse
OFF
= 12.2 V, VCC
then the Current Source is
then the Current Source is
VCC
OFF
then the Current Source
ON
OFF, I = 0 mA
70
= 12.2 V
= 10 V
ON
90
g
g
= 10 V
, then we
g
that the
. If we
http://onsemi.com
(eq. 1)
(eq. 2)
(eq. 3)
(eq. 4)
10
NCP1216 driving implementation, in particular for large Q
MOSFETs. This document can be downloaded at
www.onsemi.com/pub/Collateral/AND8069−D.PDF.
Ramp Compensation
sub−harmonic oscillations. These oscillations take place at
half the switching frequency and occur only during
Continuous Conduction Mode (CCM) with a duty−cycle
greater than 50%. To lower the current loop gain, one usually
injects between 50% and 100% of the inductor down−slope.
Figure 19 depicts how internally the ramp is generated:
a Duty cycle max at 75%. Over a 65 kHz frequency, it
corresponds to a
In our FLYBACK design, let’s suppose that our primary
inductance L
ratio of 1:0.1. The OFF time primary current slope is thus
given by:
when projected over an R
select 75% of the down−slope as the required amount of
ramp compensation, then we shall inject 27 mV/ms. Our
internal compensation being of 251 mV/ms, the divider ratio
(divratio) between R
of algebra to determine R
Frequency Jittering
signature by spreading the energy in the vicinity of the main
switching component. NCP1216 offers a $4% deviation of
0.75
V out ) V f
Application note AND8069/D details tricks to widen the
Ramp compensation is a known mean to cure
In the NCP1216, the ramp features a swing of 2.9 V with
19 k
Frequency jittering is a method used to soften the EMI
2.9
Figure 19. Inserting a Resistor in Series with the
1 * divratio
L p
Current Sense Information brings Ramp
65 kHz + 251 mV ms ramp.
divratio
+
−
From Set−point
p
is 350 mH, delivering 12 V with a Np : Ns
N p
N s
L.E.B
+ 2.37 kW
+ 371 mA ms or37 mV ms
comp
DC
Compensation
max
19 k
and the 19 kW is 0.107. A few lines
comp
sense
= 75°C
CS
:
of 0.1 W, for instance. If we
R
2.9V
comp
0V
R
sense
(eq. 5)
(eq. 6)
(eq. 7)
g