ncp1395 ON Semiconductor, ncp1395 Datasheet - Page 22

• Manufacturer Part Number: ncp1395
• Description: High Performance Resonant Mode Controller
• Manufacturer: ON Semiconductor

Protection Circuitry
its protection features. The device can react to various
inputs like:
•
UVLO
This resonant controller differs from competitors due to
Fast events input: Like an overcurrent condition, a
need to shutdown (sleep mode) or a way to force a
controlled burst mode (skip cycle at low output
power): as soon as the input level exceeds 1.0 V
typical, pulses are immediately stopped. On the
A version, when the input is released, the controller
performs a clean startup sequence without soft−start
unless the feedback voltage goes down below 0.6 V
Figure 48. This Circuit Combines a Slow and Fast Input for Improved Protection Features
Reset
+
Reset
VtimerOFF
VtimerON
DRIVING
Itimer
LOGIC
+ −
Vdd
1 = ok
0 = fault
SS
Vref Fault
ON/OFF
−
+
1 = fault
0 = ok
Vref Fault
http://onsemi.com
+
1 = ok
0 = fault
NCP1395A/B
−
+
22
+
•
Figure 48 depicts the architecture of the fault circuitry.
during fault time (please see above for details). The
B version restarts with a soft−start sequence.
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 1.0 V. The decrease rate is actually depending
on the resistor the user will put in parallel with the
capacitor, giving another flexibility during design.
Vref
+
−
Ctimer
Slow Fault
Fast Fault
+
NINV
A
B
Out
Ctimer
Rtimer
A
B
Compensation
CC Regulation
To FB
Output
Current
Image
Fast
Input