ncp1397a ON Semiconductor, ncp1397a Datasheet - Page 22

• Manufacturer Part Number: ncp1397a
• Description: High Performance Resonant Mode Controller With Integrated High-voltage Drivers
• Manufacturer: ON Semiconductor

primary current, once averaged, gives an image of the input
power in case V
output loading increases above a certain level, the voltage on
this pin will pass the 1 V threshold and start the timer. If the
UVLO
On Figures 43 and 44 examples, a voltage proportional to
Reset
in
+
Reset
VtimerOFF
VtimerON
is kept constant via a PFC circuit. If the
Itimer1
DRIVING
LOGIC
+ -
VDD
1 = ok
0 = fault
SS
Figure 44. Fault Input Logic for NCP1397B
Vref(skip)
-
+
0 = fault
+
1 = ok
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discharge at VCC(on)/
restart if VFB < 0.3 V
22
Vref(fault)
to latch
overload stays there, after a few tens of milli −seconds,
switching pulses will disappear and a protective
auto−recovery cycle will take place. Adjusting the resistor
R in parallel with the timer capacitor will give the flexibility
to adjust the fault burst mode (refer to Figure 45).
-
+
Vref(OCP)
+
FB
+
-
Skip/Disable
+
Ctimer
A
B
SS(dis)
Fault
A
B
FB
Ctimer
Rtimer
Css
VCC
Skip
Average
Current
To Primary
Current Sensing
Circuitry
Input