NCP1271 ON Semiconductor, NCP1271 Datasheet - Page 16

• Manufacturer Part Number: NCP1271
• Description: Soft?skip? Mode Standby Pwm Controller With Adjustable Skip Level And External Latch
• Manufacturer: ON Semiconductor

Output Drive
drive a power MOSFET. It is capable of up to +500 mA and
-800 mA peak drive currents and has a typical rise and fall
The output stage of the device is designed to directly
opto
coupler
Figure 40. NCP1271 Operation Threshold
V skip
3 V
0 V
Figure 41. Non-Latchoff Shutdown
V FB
OFF
Fault operation when staying
in this region longer than 130 ms
PWM operation
Non-latched shutdown
1
2
3
4
NCP1271
http://onsemi.com
NCP1271
8
6
5
16
time of 30 ns and 20 ns with a 1.0 nF load. This allows the
NCP1271 to drive a high-current power MOSFET directly
for medium-high power application.
Noise Decoupling Capacitors
external decoupling capacitors.
There are three pins in the NCP1271 that may need
1. Skip/Latch Pin (Pin 1) – If the voltage on
2. Feedback Pin (Pin 2) – The FB pin is a high
3. V
this pin is above 8.0 V, then the circuit enters
latchoff. Hence, a decoupling capacitor on this
pin is essential for improved noise immunity.
Additionally, a resistor should always be placed
from this pin to GND to prevent noise from
causing the pin 1 level to exceed the latchoff
level.
impedance point and is very easily polluted in a
noisy environment. This could effect the circuit
operation.
operation when V
typical). But, if V
of switching noise, then the circuit can incorrectly
recognize it as a fault condition. Hence, it is
important to locate the V
additional decoupling capacitor as close as possible
to the device.
CC
Pin (Pin 6) – The circuit maintains normal
CC
CC
drops below V
is above V
CC
capacitor or an
CC(off)
CC(off)
(9.1 V
because