NCP1396B ON Semiconductor, NCP1396B Datasheet - Page 20

• Manufacturer Part Number: NCP1396B
• Description: High Performance Resonant Mode Controller featuring High-voltage Drivers
• Manufacturer: ON Semiconductor

On figure 45, Q1 is blocked and does not bother the BO
measurement as long as the NTC and the optocoupler are
not activated. As soon as the secondary optocoupler
senses an OVP condition, or the NTC reacts to a high
ambient temperature, Q1 base is brought to ground and
the BO pin goes up, permanently latching off the
controller.
Protection circuitry
thanks to its protection features. The device can react to
various inputs like:
- Fast events input: like an over-current condition, a need
to shut down (sleep mode) or a way to force a controlled
burst mode (skip cycle at low output power): as soon as
Vout
This resonant controller differs from competitors
Figure 45. Adding a comparator on the BO pin offers a way to latch-off the controller
NTC
Vcc
Q1
Vbulk
NCP1396A, NCP1396B
Rupper
Rlower
http://onsemi.com
BO
20
the input level exceeds 1V typical, pulses are immediately
stopped. When the input is released, the controller
performs a clean startup sequence including a soft-start
period.
-Slow events input: this input serves as a delayed
shutdown, where an event like a transient overload does
not immediately stopped pulses but start a timer. If the
event duration lasts longer than what the timer imposes,
then all pulses are disabled. The voltage on the timer
capacitor (pin 3) starts to decrease until it reaches 1V. The
decrease rate is actually depending on the resistor the user
will put in parallel with the capacitor, giving another
flexibility during design.
Figure 46 depicts the architecture of the fault circuitry.
VBO
Vlatch
IBO
+
+
-
-
20us
RC
Vdd
BO
to permanent
latch