MC44605_06 ONSEMI [ON Semiconductor], MC44605_06 Datasheet - Page 15

• Manufacturer Part Number: MC44605_06
• Description: High Safety, Latched Mode, GreenLine TM PWM Controller for (Multi) Synchronized Applications
• Manufacturer: ONSEMI [ON Semiconductor]

where: V
much lower than the primary one (less than 5% generally),
the overcurrent is much higher in the WSCD case. That is
why this fault can be detected by detecting the high
overcurrents.
current to a reference equal to: (V
a voltage proportional to the current injected in the pin 15
(refer to Figure 13).
V
voltage instead of a constant V
be connected to V
adjusting the current injected in this pin 15.
Pin 7
in
Now, in normal working, this overcurrent DIpk is equal to:
While in a WSCD case:
Consequently, as the leakage inductor value is generally
So, the WSCD block consists of comparing the sensed
Now, as the overcurrent level depends on the input voltage
, it is preferable to use a V
Figure 12. Overcurrent in a WSCD Case
in
(V
Vcs
I
sense
CS
is the input voltage (rectified a.c. line)
V
CS
+ V
V
/R
shift
(DIpk)
shift
S
in
)/R
Figure 13. WSCD
DIpk + Vin
through a resistor that fixes V
V
S
WSCD
C
dt
shift shift
WSCD
MC44605
shift
V
shift
+ Vin
= 500 W
(Vin x dt/L
WSCD
L
dt
P
cs
proportional to this input
. So, the WSCD pin must
L
+ V
δt
Leak
Disabling
3.75 W
Block
shift
δt
leak
I
Vin x dt/L
shift
), where V
Pin 15
p
time
shift
http://onsemi.com
shift
Vin
by
MC44605
R
is
15
overcurrent is detected by the WSCD comparator. The
output of this comparator, V
disabling block (refer to the disabling block §).
Maximum Power Limitation Section (MPL)
using the following equation:
where: Lp is the inductor value
(V
building a current source proportional to V
is chopped by a calibrated pulse Sf, generated at each new
oscillator cycle (refer to Figure 14).
(R
proportional to the input power can be obtained.
In effect,
where: k
level, (Sf) is proportional to R
where: k1 is a constant
current source I
where: k2 is a constant
So:
where: C
Finally:
where: Γ
Now, as:
Finally, when there is a winding short circuit, an
The MPL block is designed to calculate this input power
As V
Finally, using an external resistor and capacitor network
Now, as Sf is built comparing the oscillator to a constant
On the other hand, k
MPL
cs
= R
V
, C
V
Ipk is the inductor peak current
f is the switching frequency
(Sf) is the width of the calibrated pulse
T is the switching (oscillator) period
specification. This is a constant equal to the product
(k1 x k2).
MPL
cs
s
MPL
MPL
V
MPL
T
x Ipk), the squared Ipk value is estimated by
MPL
MPL
is the oscillator capacitor
is proportional to the inductor peak current
+ R
is the multiplier gain
+ R
is the MPL parameter as defined in the
) on the MPL pin, a voltage V
+ R
ref
Pin + 1
Pin + 1
(Sf) + k1
k
MPL
, is proportional to 1/R
MPL
MPL
MPL
MPL
2
2
+ k2
k1
that is depending on the reference
Γ
L
L
MPL
k
P
P
MPL
ref
R
WSCD
k2
ref
R
and C
Ipk 2
Ipk 2
1
ref
Vcs 2
, is connected to the
Vcs 2
Vcs 2
C
T
T
:
ref
f
f
cs
:
f
2
f
. This current
(Sf)
T
C
C
T
T
MPL
,