ncp1396 ON Semiconductor, ncp1396 Datasheet - Page 20

• Manufacturer Part Number: ncp1396
• Description: High Performance Resonant Mode Controller With High And Low Sides Drivers
• Manufacturer: ON Semiconductor

(Mlower and Mupper pulse), the IBO source is activated
and creates a hysteresis. As a result, it becomes possible to
select the turn-on and turn-off levels via a few lines of
algebra:
IBO is off
IBO is on
We can now extract Rlower from equation 1 and plug it into
equation 2, then solve for Rupper:
V()) + V
To the contrary, when the internal BO signal is high
R
bulk2
lower
V()) + V
R
upper
+ VBO
Vout
Figure 46. Adding a comparator on the BO pin offers a way to latch-off the controller
R
lower
+ R
R
450
350
250
150
50
bulk1
lower
) R
lower
IBO
upper
16.0
12.0
8.0
4.0
Figure 45. Simulation Results for 350 / 250 ON / OFF Levels
R
V
0
V
bulk1
lower
) IBO
bulk1
(V
R
bulk1
VBO
* V
lower
) R
20 m
* VBO
NTC
Vin
V
* VBO)
bulk2
upper
CC
Q1
R
R
351 Volts
lower
lower
NCP1396A, NCP1396B
60 m
) R
R
Vbulk
BO
http://onsemi.com
(eq. 1)
(eq. 2)
(eq. 3)
(eq. 4)
upper
upper
time in seconds
Rupper
Rlower
100 m
BO
20
350 V and turn it off for Vbulk2 equals 250 V, then for A
version (IBO_A = 26.5 mA, VBO = 1.04 V) we obtain:
Rupper = 3.77 MW
Rlower = 11.25 kW
The bridge power dissipation is 400
when front-end PFC stage delivers 400 V.
Figure 45 simulation result confirms our calculations.
Latch-off Protection
fully turned-off and stay latched. This can happen in
presence of an over-voltage (the feedback loop is drifting)
or when an over temperature is detected. Thanks to the
addition of a comparator on the BO pin, a simple external
circuit can lift up this pin above VLATCH (4 V typical) and
permanently disable pulses. The V
down below 6.5 V typically to reset the controller.
If we decide to turn-on our converter for Vbulk1 equals
There are some situations where the converter shall be
+
VBO
140 m
+
Vlatch
+
-
IBO
+
-
250 Volts
20 ms
RC
180 m
To permanent
latch
Vdd
2
CC
/ 3.781 MW = 42 mW
BO
needs to be cycled